<?xml version='1.0'encoding='utf-8'?>encoding='UTF-8'?> <!DOCTYPE rfc [ <!ENTITY nbsp " "> <!ENTITY zwsp "​"> <!ENTITY nbhy "‑"> <!ENTITY wj "⁠"> ]><?xml-stylesheet type="text/xsl" href="rfc2629.xslt" ?> <!-- generated by https://github.com/cabo/kramdown-rfc version 1.7.11 (Ruby 3.2.4) --><rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" docName="draft-ietf-lamps-rfc5990bis-10" number="9690" category="std" consensus="true" submissionType="IETF" updates="" obsoletes="5990" tocInclude="true" sortRefs="true" symRefs="true"version="3"> <!-- xml2rfc v2v3 conversion 3.21.0 -->version="3" xml:lang="en"> <front> <title abbrev="RSA-KEM with CMS KEMRecipientInfo">Use of the RSA-KEM Algorithm in the Cryptographic Message Syntax (CMS)</title> <seriesInfoname="Internet-Draft" value="draft-ietf-lamps-rfc5990bis-10"/>name="RFC" value="9690"/> <author initials="R." surname="Housley" fullname="Russ Housley"> <organization abbrev="Vigil Security">Vigil Security, LLC</organization> <address> <postal> <street>516 Dranesville Road</street><city>Herndon, VA</city><city>Herndon</city> <region>VA</region> <code>20170</code><country>US</country><country>United States of America</country> </postal> <email>housley@vigilsec.com</email> </address> </author> <author initials="S." surname="Turner" fullname="Sean Turner"> <organization>sn3rd</organization> <address> <email>sean@sn3rd.com</email> </address> </author> <dateyear="2024" month="June" day="05"/> <area>Security</area> <workgroup>Limited Additional Mechanisms for PKIX and SMIME</workgroup>year="2025" month="January"/> <area>SEC</area> <workgroup>lamps</workgroup> <keyword>Key Encapsulation Mechanism (KEM)</keyword> <keyword>KEMRecipientInfo</keyword> <abstract><?line 138?><t>The RSA Key Encapsulation Mechanism (RSA-KEM)Algorithmalgorithm is a one-pass (store-and-forward) cryptographic mechanism for an originator to securely send keying material to a recipient using the recipient's RSA public key. The RSA-KEMAlgorithmalgorithm is specified in Clause 11.5 of ISO/IEC: 18033-2:2006. This document specifies the conventions for using the RSA-KEMAlgorithmalgorithm as a standalone KEM algorithm and the conventions for using the RSA-KEMAlgorithmalgorithm with the Cryptographic Message Syntax (CMS) using KEMRecipientInfo as specified in RFCXXXX.9629. This document obsoletes RFC 5990.</t><t>RFC EDITOR: Please replace XXXX with the RFC number assigned to draft-ietf-lamps-cms-kemri.</t></abstract><note removeInRFC="true"> <name>About This Document</name> <t> Status information for this document may be found at <eref target="https://datatracker.ietf.org/doc/draft-ietf-lamps-rfc5990bis/"/>. </t> <t> Discussion of this document takes place on the Limited Additional Mechanisms for PKIX and SMIME Working Group mailing list (<eref target="mailto:spasm@ietf.org"/>), which is archived at <eref target="https://mailarchive.ietf.org/arch/browse/spasm/"/>. Subscribe at <eref target="https://www.ietf.org/mailman/listinfo/spasm/"/>. </t> </note></front> <middle><?line 151?><section anchor="introduction"> <name>Introduction</name> <t>The RSA Key Encapsulation Mechanism (RSA-KEM)Algorithmalgorithm is a one-pass (store-and-forward) cryptographic mechanism for an originator to securely send keying material to a recipient using the recipient's RSA public key. The RSA-KEMAlgorithmalgorithm is specified in Clause 11.5 of <xref target="ISO18033-2"/>.</t> <t>The RSA-KEMAlgorithmalgorithm takes a different approach than other RSA key transport mechanisms <xreftarget="RFC8017"/>,target="RFC8017"/> with the goal of providing higher security assurance while also satisfying the KEM interface. The RSA-KEMAlgorithmalgorithm encrypts a random integer with the recipient's RSA publickey,key and derives a shared secret from the random integer. The originator and recipient can derive a symmetric key from the shared secret. For example, a key-encryption key (KEK) can be derived from the shared secret to wrap a content-encryptionkey.</t>key (CEK).</t> <t>In the Cryptographic Message Syntax (CMS) <xref target="RFC5652"/> using KEMRecipientInfo <xreftarget="I-D.ietf-lamps-cms-kemri"/>,target="RFC9629"/>, theshared secretshared-secret value is input to akey-derivationkey derivation function (KDF) to compute a key-encryptionkey,key and wrap a symmetric content-encryption key with the key-encryption key. In this way, the originator and the recipient end up with the same content-encryption key.</t> <t>For completeness, a specification of the RSA-KEMAlgorithmalgorithm is given inAppendix A<xref target="app-alg" format="default"/> of thisdocument;document. ASN.1 syntax is given inAppendix B.</t><xref target="app-asn1" format="default"/>.</t> <section anchor="rsa-kem-algorithm-rationale"> <name>RSA-KEM Algorithm Rationale</name> <t>The RSA-KEMAlgorithmalgorithm provides higher security assurance than other variants of the RSA cryptosystem for two reasons. First, the input to the underlying RSA operation is a string-encoded random integer between 0 and n-1, where n is the RSA modulus, so it does not have any structure that could be exploited by an adversary. Second, the input is independent of the keyingmaterialmaterial, so the result of the RSA decryption operation is not directly available to an adversary. As a result, the RSA-KEMAlgorithmalgorithm enjoys a "tight" security proof in the random oracle model. (In other padding schemes, such as PKCS #1 v1.5 <xref target="RFC8017"/>, the input has structureand/orand depends on the keyingmaterial, andmaterial. Additionally, the provable security assurances are not as strong.)</t> <t>The approach is also architecturally convenient because the public-key operations are separate from the symmetric operations on the keying material. Another benefit is that the length of the keying material is determined by the symmetric algorithms, not the size of the RSA modulus.</t> </section> <section anchor="rsa-kem-algorithm-summary"> <name>RSA-KEM Algorithm Summary</name> <t>All KEM algorithms provide three functions: KeyGen(), Encapsulate(), and Decapsulate().</t> <t>The following summarizes these three functions for RSA-KEM:</t><t>KeyGen()<dl spacing="normal" newline="true"> <dt>KeyGen() -> (pk,sk):</t> <ul empty="true"> <li> <t>Generatesk):</dt> <dd><t>Generate the public key (pk) and a private key (sk) as described in <xref section="3" sectionFormat="of"target="RFC8017"/>.</t> </li> </ul> <t>Encapsulate(pk)target="RFC8017"/>.</t></dd> <dt>Encapsulate(pk) -> (ct,SS):</t> <ul empty="true"> <li>SS):</dt> <dd> <t>Given the recipient's public key (pk), produce a ciphertext (ct) to be passed to the recipient and a shared secret (SS) for use by theoriginator,originator as follows:</t></li> </ul> <ul empty="true"> <li> <t>1. Generate<ol type="1" spacing="normal"> <li>Generate a random integer z between 0 andn-1.</t> </li> </ul> <ul empty="true"> <li> <t>2. Encryptn-1.</li> <li><t>Encrypt the integer z with the recipient's RSA public key to obtain the ciphertext:</t></li> </ul><artwork><![CDATA[ ct = z^e modn ]]></artwork> <ul empty="true"> <li> <t>3. Deriven]]></artwork> </li> <li><t>Derive a shared secret from the integer z using a Key Derivation Function (KDF):</t></li> </ul><artwork><![CDATA[ SS = KDF(Z,ssLen) ]]></artwork> <ul empty="true"> <li> <t>4. ThessLen)]]></artwork> </li> <li><t>The ciphertext and the shared secret are returned by the function. The originator sends the ciphertext to the recipient.</t> </li></ul> <t>Decapsulate(sk,</ol> </dd> <dt>Decapsulate(sk, ct) ->SS:</t> <ul empty="true"> <li> <t>GivenSS:</dt> <dd><t>Given the private key (sk) and the ciphertext (ct), produce the shared secret (SS) for the recipient as follows:</t></li> </ul> <ul empty="true"> <li> <t>1. Decrypt<ol type="1" spacing="normal"> <li><t>Decrypt the ciphertext with the recipient's RSA private key to obtain the random integer z:</t></li> </ul><artwork><![CDATA[ z = ct^d modn ]]></artwork> <ul empty="true"> <li> <t>2. Deriven]]></artwork> </li> <li><t>Derive a shared secret from the integer z:</t></li> </ul><artwork><![CDATA[ SS = KDF(Z,ssLen) ]]></artwork> <t>3. ThessLen)]]></artwork> </li> <li><t>The shared secret is returned by thefunction.</t>function.</t></li> </ol> </dd> </dl> </section> <section anchor="cms-kemrecipientinfo-processing-summary"> <name>CMS KEMRecipientInfo Processing Summary</name> <t>To support the RSA-KEM algorithm, the CMS originator <bcp14>MUST</bcp14> implement Encapsulate().</t> <t>Given a content-encryption key CEK, the RSA-KEMAlgorithmalgorithm processing by the originator to produce the values that are carried in the CMS KEMRecipientInfo can be summarizedas:</t> <ul empty="true">as follows:</t> <ol type="1" spacing="normal"> <li><t>1. Obtain<t>Obtain the shared secret using the Encapsulate() function of the RSA-KEM algorithm and the recipient's RSA public key:</t></li> </ul><artwork><![CDATA[ (ct, SS) =Encapsulate(pk) ]]></artwork> <ul empty="true">Encapsulate(pk)]]></artwork> </li> <li><t>2. Derive<t>Derive a key-encryption key KEK from the shared secret:</t></li> </ul><artwork><![CDATA[ KEK = KDF(SS, kekLength,otherInfo) ]]></artwork> <ul empty="true">otherInfo)]]></artwork> </li> <li><t>3. Wrap<t>Wrap the CEK with the KEK to obtain wrapped keying material WK:</t></li> </ul><artwork><![CDATA[ WK = WRAP(KEK, CEK) ]]></artwork><ul empty="true"></li> <li><t>4. The<t>The originator sends the ciphertext and WK to the recipient in the CMS KEMRecipientInfo structure.</t> </li></ul></ol> <t>To support the RSA-KEM algorithm, the CMS recipient <bcp14>MUST</bcp14> implement Decapsulate().</t> <t>The RSA-KEM algorithm recipient processing of the values obtained from the KEMRecipientInfo structurecan beis summarizedas:</t> <ul empty="true">as follows:</t> <ol type="1" spacing="normal"> <li><t>1. Obtain<t>Obtain the shared secret using the Decapsulate() function of the RSA-KEM algorithm and the recipient's RSA private key:</t></li> </ul><artwork><![CDATA[ SS = Decapsulate(sk,ct) ]]></artwork> <ul empty="true">ct)]]></artwork> </li> <li><t>2. Derive<t>Derive a key-encryption key KEK from the shared secret:</t></li> </ul><artwork><![CDATA[ KEK = KDF(SS, kekLength,otherInfo) ]]></artwork> <ul empty="true">otherInfo)]]></artwork> </li> <li><t>3. Unwrap<t>Unwrap the WK with the KEK to obtain the content-encryption key CEK:</t></li> </ul><artwork><![CDATA[ CEK = UNWRAP(KEK,WK) ]]></artwork>WK)]]></artwork> </li> </ol> <t>Note that the KDF used to process the KEMRecipientInfo structure <bcp14>MAY</bcp14> be different from the KDF used to derive the shared secret in the RSA-KEM algorithm.</t> </section> <section anchor="conventions-and-definitions"> <name>Conventions and Definitions</name><t>The<t> The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as described inBCP 14BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, as shownhere.</t> <?line -18?>here. </t> </section> <section anchor="asn1"> <name>ASN.1</name> <t>CMS values are generated using ASN.1 <xref target="X.680"/>, which uses the Basic Encoding Rules (BER) and the Distinguished Encoding Rules (DER) <xref target="X.690"/>.</t> </section> <section anchor="changes-since-rfc-5990"> <name>Changes Since RFC 5990</name> <t>RFC 5990 <xref target="RFC5990"/> specified the conventions for using the RSA-KEMAlgorithmalgorithm in CMS as a key transport algorithm. That is, it used KeyTransRecipientInfo <xref target="RFC5652"/> for each recipient. Since the publication of RFC 5990, a new KEMRecipientInfo structure <xreftarget="I-D.ietf-lamps-cms-kemri"/>target="RFC9629"/> has been defined to support KEM algorithms. When the id-rsa-kem algorithm identifier appears in the SubjectPublicKeyInfo field of a certificate, the complex parameter structure defined in RFC 5990 can be omitted; however, the parameters are allowed for backward compatibility. Also, to avoid visual confusion with id-kem-rsa, id-rsa-kem-spki is introduced as an alias for id-rsa-kem.</t> <t>RFC 5990 used EK as the EncryptedKey, which is the concatenation of the ciphertext C and the wrapped key WK, EK = (C || WK). The use of EK was necessary to align with the KeyTransRecipientInfo structure. In this document, the ciphertext and the wrapped key are sent in separate fields of the KEMRecipientInfo structure. In particular, the ciphertext is carried in the kemct field, and the wrapped key is carried in the encryptedKey field. See <xref target="app-alg"/> for details about the computation of the ciphertext.</t> <t>RFC 5990 included support for Camellia and Triple-DES block ciphers; discussion of these block ciphersis removed fromdoes not appear in this document, but the algorithm identifiers remain in the ASN.1Modulemodule (see <xreftarget="app-asn1-module"/>.</t>target="app-asn1-module"/>).</t> <t>RFC 5990 included support for SHA-1 hash function; discussion of this hash functionis removed fromdoes not appear this document, but the algorithm identifier remains in the ASN.1 module (see <xreftarget="app-asn1-module"/>.</t>target="app-asn1-module"/>).</t> <t>RFC 5990 required support for the KDF3key-derivationkey derivation function <xref target="ANS-X9.44"/>; this document continues to require support for the KDF3key-derivationkey derivation function, but it requires support for SHA-256 <xref target="SHS"/> as the hash function.</t> <t>RFC 5990 recommended support for alternatives to KDF3 and AES-Wrap-128; this document simply states that otherkey-derivationkey derivation functions and other key-encryption algorithms <bcp14>MAY</bcp14> be supported.</t> <t>RFC 5990 supported the future definition of additional KEM algorithms that use RSA; this document supports only one, and it is identified by the id-kem-rsa object identifier.</t> <t>RFC 5990 included an ASN.1 module; this document provides an alternative ASN.1 module that follows the conventions established in <xref target="RFC5911"/>, <xref target="RFC5912"/>, and <xref target="RFC6268"/>. The new ASN.1 module<xref target="app-asn1-module"/>(<xref target="app-asn1-module"/>) produces the same bits-on-the-wire as the one in RFC 5990.</t> </section> </section> <section anchor="use-of-the-rsa-kem-algorithm-in-cms"> <name>Use of the RSA-KEM Algorithm in CMS</name> <t>The RSA-KEMAlgorithmalgorithm <bcp14>MAY</bcp14> be employed for one or more recipients in the CMS enveloped-data content type <xref target="RFC5652"/>, the CMS authenticated-data content type <xref target="RFC5652"/>, or the CMS authenticated-enveloped-data content type <xref target="RFC5083"/>. In each case, the KEMRecipientInfo <xreftarget="I-D.ietf-lamps-cms-kemri"/>target="RFC9629"/> is used with the RSA-KEMAlgorithmalgorithm to securely transfer the content-encryption key from the originator to the recipient.</t> <section anchor="mandatory-to-implement"> <name>Mandatory To Implement</name> <t>A CMS implementation that supports the RSA-KEMAlgorithmalgorithm <bcp14>MUST</bcp14> support at least the following underlying components:</t> <ul spacing="normal"> <li> <t>For thekey-derivationkey derivation function, an implementation <bcp14>MUST</bcp14> support KDF3 <xref target="ANS-X9.44"/> with SHA-256 <xref target="SHS"/>.</t> </li> <li> <t>For key-wrapping, an implementation <bcp14>MUST</bcp14> support the AES-Wrap-128 <xref target="RFC3394"/> key-encryption algorithm.</t> </li> </ul> <t>An implementation <bcp14>MAY</bcp14> also support otherkey-derivationkey derivation functions and other key-encryptionalgorithms as well.</t>algorithms.</t> </section> <section anchor="recipientinfo-conventions"> <name>RecipientInfo Conventions</name> <t>When the RSA-KEMAlgorithmalgorithm is employed for a recipient, the RecipientInfo alternative for that recipient <bcp14>MUST</bcp14> be OtherRecipientInfo using the KEMRecipientInfo structure <xreftarget="I-D.ietf-lamps-cms-kemri"/>.target="RFC9629"/>. The fields of the KEMRecipientInfo <bcp14>MUST</bcp14> have the following values:</t> <ulempty="true"> <li> <t>versionspacing="normal"> <li>version is the syntax version number; it <bcp14>MUST</bcp14> be0.</t> </li> </ul> <ul empty="true"> <li> <t>rid0.</li> <li>rid identifies the recipient's certificate or publickey.</t> </li> </ul> <ul empty="true"> <li> <t>kemkey.</li> <li>kem identifies the KEM algorithm; it <bcp14>MUST</bcp14> containid-kem-rsa.</t> </li> </ul> <ul empty="true"> <li> <t>kemctid-kem-rsa.</li> <li>kemct is the ciphertext produced for this recipient; it contains C from steps 1 and 2 of Originator's Operations in <xreftarget="app-alg"/>.</t> </li> </ul> <ul empty="true"> <li> <t>kdftarget="app-alg"/>.</li> <li>kdf identifies thekey-derivationkey derivation function (KDF). Note that the KDF used for CMS RecipientInfo process <bcp14>MAY</bcp14> be different than the KDF used within the RSA-KEMAlgorithm.</t> </li> </ul> <ul empty="true"> <li> <t>kekLengthalgorithm.</li> <li>kekLength is the size of the key-encryption key inoctets.</t> </li> </ul> <ul empty="true"> <li> <t>ukmoctets.</li> <li>ukm is an optional random input to thekey-derivation function.</t> </li> </ul> <ul empty="true"> <li> <t>wrapkey derivation function.</li> <li>wrap identifies a key-encryption algorithm used to encrypt the keyingmaterial.</t> </li> </ul> <ul empty="true"> <li> <t>encryptedKeymaterial.</li> <li>encryptedKey is the result of encrypting the keying material with the key-encryption key. When used with the CMS enveloped-data content type <xref target="RFC5652"/>, the keying material is a content-encryption key. When used with the CMS authenticated-data content type <xref target="RFC5652"/>, the keying material is a message-authentication key. When used with the CMS authenticated-enveloped-data content type <xref target="RFC5083"/>, the keying material is a content-authenticated-encryptionkey.</t> </li>key (CAEK).</li> </ul> <t>NOTE: For backward compatibility, implementations <bcp14>MAY</bcp14> also support the RSA-KEM Key TransportAlgorithm,algorithm, identified by id-rsa-kem-spki, which uses KeyTransRecipientInfo as specified in <xref target="RFC5990"/>.</t> </section> <section anchor="certificate-conventions"> <name>Certificate Conventions</name> <t>The conventions specified in this section augment RFC 5280 <xref target="RFC5280"/>.</t> <t>A recipient who employs the RSA-KEMAlgorithmalgorithm <bcp14>MAY</bcp14> identify the public key in a certificate by the same AlgorithmIdentifier as for the PKCS #1 v1.5 algorithm, that is, using the rsaEncryption object identifier <xref target="RFC8017"/>. The fact that the recipient will accept RSA-KEM with this public key is not indicated by the use of this object identifier. The willingness to accept the RSA-KEMAlgorithmalgorithm <bcp14>MAY</bcp14> be signaled by the use of the SMIMECapabilities Attribute as specified in <xrefsection="2.5.2."section="2.5.2" sectionFormat="of" target="RFC8551"/> or the SMIMECapabilities certificate extension as specified in <xref target="RFC4262"/>.</t> <t>If the recipient wishes only to employ the RSA-KEMAlgorithmalgorithm with a given public key, the recipient <bcp14>MUST</bcp14> identify the public key in the certificate using the id-rsa-kem-spki object identifier; see <xref target="app-asn1"/>. The use of the id-rsa-kem-spki object identifier allows certificates that were issued to be compatible with RSA-KEM Key Transport to also be used with this specification. When the id-rsa-kem-spki object identifier appears in the SubjectPublicKeyInfo algorithm field of the certificate, the parameters field from AlgorithmIdentifier <bcp14>SHOULD</bcp14> be absent. That is, the AlgorithmIdentifier <bcp14>SHOULD</bcp14> be a SEQUENCE of one component, the id-rsa-kem-spki object identifier. With absent parameters, the KDF3key-derivationkey derivation function <xref target="ANS-X9.44"/> with SHA-256 <xref target="SHS"/> are used to derive the shared secret.</t> <t>When the AlgorithmIdentifier parameters are present, the GenericHybridParameters <bcp14>MUST</bcp14> be used. Within the kem element, the algorithm identifier <bcp14>MUST</bcp14> be set to id-kem-rsa, and RsaKemParameters <bcp14>MUST</bcp14> be included. As described in <xref target="smimecap"/>, the GenericHybridParameters constrain the values that can be used with the RSA public key for the kdf, kekLength, and wrap fields of the KEMRecipientInfo structure.</t> <t>Regardless of the AlgorithmIdentifier used, the RSA public key <bcp14>MUST</bcp14> be carried in the subjectPublicKey BIT STRING within the SubjectPublicKeyInfo field of the certificate using the RSAPublicKey type defined in <xref target="RFC8017"/>.</t> <t>The intended application for the public key <bcp14>MAY</bcp14> be indicated in the key usage certificate extension as specified in <xref section="4.2.1.3" sectionFormat="of" target="RFC5280"/>. If the keyUsage extension is present in a certificate that conveys an RSA public key with the id-rsa-kem-spki object identifier as discussed above, then the key usage extension <bcp14>MUST</bcp14> contain only the following value:</t><ul empty="true"> <li> <t>keyEncipherment</t> </li> </ul><t indent="3">keyEncipherment</t> <t>Other keyUsage extension values <bcp14>MUST NOT</bcp14> be present. That is, a public key intended to be employed only with the RSA-KEMAlgorithmalgorithm <bcp14>MUST NOT</bcp14> also be employed for data encryption or for digital signatures. Good cryptographic practice employs a given RSA key pair in only one scheme. This practice avoids the risk that vulnerability in one scheme may compromise the security of theother,other and may be essential to maintain provable security.</t> </section> <section anchor="smimecap"> <name>SMIMECapabilities Attribute Conventions</name> <t><xref section="2.5.2" sectionFormat="of" target="RFC8551"/> defines the SMIMECapabilities attribute to announce a partial list of algorithms that an S/MIME implementation can support. When constructing a CMS signed-data content type <xref target="RFC5652"/>, a compliant implementation <bcp14>MAY</bcp14> include the SMIMECapabilities attribute that announces support for the RSA-KEMAlgorithm.</t>algorithm.</t> <t>The SMIMECapability SEQUENCE representing the RSA-KEMAlgorithmalgorithm <bcp14>MUST</bcp14> include the id-rsa-kem-spki object identifier in the capabilityID field; see <xref target="app-asn1"/> for the object identifiervalue,value andsee<xref target="app-example"/> for examples. When the id-rsa-kem-spki object identifier appears in the capabilityID field and the parameters are present, then the parameters field <bcp14>MUST</bcp14> use the GenericHybridParameters type.</t><artwork><![CDATA[<sourcecode type="asn.1"> GenericHybridParameters ::= SEQUENCE { kem KeyEncapsulationMechanism, dem DataEncapsulationMechanism} ]]></artwork>}</sourcecode> <t>The fields of the GenericHybridParameters type have the following meanings:</t><ul empty="true"><ul> <li> <t>kem is an AlgorithmIdentifer. The algorithm field <bcp14>MUST</bcp14> be set to id-kem-rsa, and the parameters field <bcp14>MUST</bcp14> be RsaKemParameters, which is a SEQUENCE of an AlgorithmIdentifier that identifies the supportedkey-derivationkey derivation function and a positive INTEGER that identifies the length of the key-encryption key in octets.</t> </li></ul> <ul empty="true"><li> <t>dem is an AlgorithmIdentifier. The algorithm field <bcp14>MUST</bcp14> be present, and it identifies the key-encryption algorithm. The parameters are optional. If the GenericHybridParameters are present, then the provided dem value <bcp14>MUST</bcp14> be used in the wrap field of KEMRecipientInfo.</t> </li> </ul> <t>If the GenericHybridParameters are present, then the provided kem value <bcp14>MUST</bcp14> be used as thekey-derivationkey derivation function in the kdf field ofKEMRecipientInfo,KEMRecipientInfo and the provided key length <bcp14>MUST</bcp14> be used in the kekLength of KEMRecipientInfo.</t> </section> </section> <section anchor="security-considerations"> <name>Security Considerations</name> <t>The RSA-KEMAlgorithmalgorithm should be considered as a replacement for the key transport portion of the widely implemented PKCS #1 v1.5 <xref target="RFC8017"/> for new applications that use CMS to avoid potential vulnerabilities to chosen-ciphertext attacks and gain a tighter securityproof; however,proof. However, the RSA-KEMAlgorithmalgorithm has the disadvantage of slightly longer encrypted keying material. With PKCS #1 v1.5, the originator encrypts the key-encryption key directly with the recipient's RSA public key. With the RSA-KEM, the key-encryption key is encrypted separately.</t><t>The<t> The security of the RSA-KEMAlgorithmalgorithm can be shown to be tightly related to the difficulty of either solving the RSAproblem,problem or breaking the underlying symmetric key-encryptionalgorithm,algorithm if the underlyingkey-derivationkey derivation function is modeled as a random oracle,andassuming that the symmetric key-encryption algorithm satisfies the properties of a data encapsulation mechanism <xref target="SHOUP"/>. While in practice a random-oracle result does not provide an actual security proof for any particularkey-derivationkey derivation function, the result does provide assurance that the general construction is reasonable; akey-derivationkey derivation function would need to be particularly weak to lead to an attack that is not possible in the random-oracle model.</t> <t>The RSA key size and the underlying components need to be selected consistent with the desired security level. Several security levels have been identified in the NIST SP 800-57 Part 1 <xref target="NISTSP800-57pt1r5"/>. For example, one way to achieve 128-bit security, the RSA key size would be at least 3072 bits, thekey-derivationkey derivation function would be SHA-256, and the symmetric key-encryption algorithm would be AES Key Wrap with a 128-bit key.</t> <t>Implementations <bcp14>MUST</bcp14> protect the RSA private key, the key-encryption key, the content-encryption key, message-authentication key, and the content-authenticated-encryption key. Disclosure of the RSA private key could result in the compromise of all messages protected with that key. Disclosure of the key-encryption key, the content-encryption key, or the content-authenticated-encryption key could result in compromise of the associated encrypted content. Disclosure of the key-encryption key, the message-authentication key, or the content-authenticated-encryption key could allow modification of the associated authenticated content.</t> <t>Additional considerations related to key management may be found in <xref target="NISTSP800-57pt1r5"/>.</t> <t>The security of the RSA-KEMAlgorithmalgorithm depends on a quality random number generator. For further discussion on random number generation, see <xref target="RFC4086"/>.</t> <t>The RSA-KEMAlgorithmalgorithm does not use an explicit paddingscheme; instead,scheme. Instead, an encoded random value (z) between zero and the RSA modulus minus one (n-1) is directly encrypted with the recipient's RSA public key. The IntegerToString(z, nLen) encoding produces a string that is the full length of the RSA modulus. In addition, the random value is passed through akey-derivation function (KDF)KDF to reduce possible harm from a poorly implemented random number source or a maliciously chosen random value (z). Implementations <bcp14>MUST NOT</bcp14> use z directly for any purpose.</t> <t>As long as a fresh random integer z is chosen as part of each invocation of the Encapsulate() function, RSA-KEM does not degrade as the number of ciphertexts increases. Since RSA encryption provides a bijective map, a collision in the KDF is the only way that RSA-KEM can produce more than one ciphertext that encapsulates the same shared secret.</t> <t>The RSA-KEMAlgorithmalgorithm provides a fixed-length ciphertext. The recipient <bcp14>MUST</bcp14> check that the received byte string is the expected length and the length corresponds to an integer in the expected range prior to attempting decryption with their RSA private key as described in Steps 1 and 2 of <xref target="app-alg-decap"/>.</t> <t>Implementations <bcp14>SHOULD NOT</bcp14> reveal information about intermediate values or calculations, whether by timing or other "sidechannels", otherwisechannels"; otherwise, an opponent may be able to determine information about the keying data and/or the recipient's private key. Although not all intermediate information may be useful to an opponent, it is preferable to conceal as much information as is practical, unless analysis specifically indicates that the information would not be useful to an opponent.</t> <t>Generally, good cryptographic practice employs a given RSA key pair in only one scheme. This practice avoids the risk that vulnerability in one scheme may compromise the security of the other, and may be essential to maintain provable security. RSA public keys have often been employed for multiple purposes such as key transport and digital signature without any known bad interactions; however, such combined use of an RSA key pair is <bcp14>NOT RECOMMENDED</bcp14> in the future (unless the different schemes are specifically designed to be used together).</t> <t>Accordingly, an RSA key pair used for the RSA-KEMAlgorithmalgorithm <bcp14>SHOULD NOT</bcp14> also be used for digital signatures. Indeed, the Accredited Standards Committee X9 (ASC X9) requires such a separation between key pairs used for key establishment and key pairs used for digital signature <xref target="ANS-X9.44"/>. Continuing this principle of key separation, a key pair used for the RSA-KEMAlgorithmalgorithm <bcp14>SHOULD NOT</bcp14> be used with other key establishment schemes, or for data encryption, or with more than one set of underlying algorithm components.</t> <t>It is acceptable to use the same RSA key pair for RSA-KEM Key Transport as specified in <xref target="RFC5990"/> and this specification. This is acceptable because the operations involving the RSA public key and the RSA private key are identical in the two specifications.</t> <t>Parties can gain assurance that implementations are correct through formal implementation validation, such as the NIST Cryptographic Module Validation Program (CMVP) <xref target="CMVP"/>.</t> </section> <section anchor="iana-considerations"> <name>IANA Considerations</name> <t>For the ASN.1 Module in <xref target="app-asn1-module"/>, IANAis requested to assignhas assigned an object identifier (OID) for the module identifier. The OID for the moduleshould behas been allocated in the "SMI Security for S/MIME Module Identifier" registry (1.2.840.113549.1.9.16.0), and the Description for the new OIDshould behas been set to "id-mod-cms-rsa-kem-2023".</t> <t>IANAis requested to updatehas updated the id-alg-rsa-kem entry in theSMI"SMI Security for S/MIME Algorithms(1.2.840.113549.1.9.16.3)(1.2.840.113549.1.9.16.3)" repository to refer to this document. In addition, IANAis requested to addhas added the following note to the registry:</t> <t>Value 14, "id-alg-rsa-kem," is also referred to as "id-rsa-kem-spki."</t> </section> </middle> <back> <references> <name>References</name> <references anchor="sec-normative-references"> <name>Normative References</name><reference anchor="I-D.ietf-lamps-cms-kemri" target="https://datatracker.ietf.org/doc/html/draft-ietf-lamps-cms-kemri-08" xml:base="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-lamps-cms-kemri.xml"> <front> <title>Using Key Encapsulation Mechanism (KEM) Algorithms in the Cryptographic Message Syntax (CMS)</title> <author fullname="Russ Housley" initials="R." surname="Housley"> <organization>Vigil Security, LLC</organization> </author> <author fullname="John Gray" initials="J." surname="Gray"> <organization>Entrust</organization> </author> <author fullname="Tomofumi Okubo" initials="T." surname="Okubo"> <organization>DigiCert, Inc.</organization> </author> <date day="6" month="February" year="2024"/> <abstract> <t>The Cryptographic Message Syntax (CMS) supports key transport and key agreement algorithms. In recent years, cryptographers have been specifying Key Encapsulation Mechanism (KEM) algorithms, including quantum-secure KEM algorithms. This document defines conventions for the use of KEM algorithms by the originator and recipients to encrypt and decrypt CMS content. This document updates RFC 5652.</t> </abstract> </front> <seriesInfo name="Internet-Draft" value="draft-ietf-lamps-cms-kemri-08"/> </reference> <reference anchor="RFC3394" target="https://www.rfc-editor.org/info/rfc3394" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3394.xml"> <front> <title>Advanced Encryption Standard (AES) Key Wrap Algorithm</title> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <author fullname="R. Housley" initials="R." surname="Housley"/> <date month="September" year="2002"/> </front> <seriesInfo name="RFC" value="3394"/> <seriesInfo name="DOI" value="10.17487/RFC3394"/> </reference> <reference anchor="RFC5083" target="https://www.rfc-editor.org/info/rfc5083" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5083.xml"> <front> <title>Cryptographic Message Syntax (CMS) Authenticated-Enveloped-Data Content Type</title> <author fullname="R. Housley" initials="R." surname="Housley"/> <date month="November" year="2007"/> <abstract> <t>This document describes an additional content type for the Cryptographic Message Syntax (CMS). The authenticated-enveloped-data content type is intended for use with authenticated encryption modes. All of the various key management techniques that are supported in the CMS enveloped-data content type are also supported by the CMS authenticated-enveloped-data content type. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="RFC" value="5083"/> <seriesInfo name="DOI" value="10.17487/RFC5083"/> </reference> <reference anchor="RFC5280" target="https://www.rfc-editor.org/info/rfc5280" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5280.xml"> <front> <title>Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile</title> <author fullname="D. Cooper" initials="D." surname="Cooper"/> <author fullname="S. Santesson" initials="S." surname="Santesson"/> <author fullname="S. Farrell" initials="S." surname="Farrell"/> <author fullname="S. Boeyen" initials="S." surname="Boeyen"/> <author fullname="R. Housley" initials="R." surname="Housley"/> <author fullname="W. Polk" initials="W." surname="Polk"/> <date month="May" year="2008"/> <abstract> <t>This memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="RFC" value="5280"/> <seriesInfo name="DOI" value="10.17487/RFC5280"/> </reference> <reference anchor="RFC5652" target="https://www.rfc-editor.org/info/rfc5652" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5652.xml"> <front> <title>Cryptographic Message Syntax (CMS)</title> <author fullname="R. Housley" initials="R." surname="Housley"/> <date month="September" year="2009"/> <abstract> <t>This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="STD" value="70"/> <seriesInfo name="RFC" value="5652"/> <seriesInfo name="DOI" value="10.17487/RFC5652"/> </reference> <reference anchor="RFC5911" target="https://www.rfc-editor.org/info/rfc5911" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5911.xml"> <front> <title>New ASN.1 Modules for Cryptographic Message Syntax (CMS) and S/MIME</title> <author fullname="P. Hoffman" initials="P." surname="Hoffman"/> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <date month="June" year="2010"/> <abstract> <t>The Cryptographic Message Syntax (CMS) format, and many associated formats, are expressed using ASN.1. The current ASN.1 modules conform to the 1988 version of ASN.1. This document updates those ASN.1 modules to conform to the 2002 version of ASN.1. There are no bits-on-the-wire changes to any of the formats; this is simply a change to the syntax. This document is not an Internet Standards Track specification; it is published for informational purposes.</t> </abstract> </front> <seriesInfo name="RFC" value="5911"/> <seriesInfo name="DOI" value="10.17487/RFC5911"/> </reference> <reference anchor="RFC5912" target="https://www.rfc-editor.org/info/rfc5912" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5912.xml"> <front> <title>New ASN.1 Modules for the Public Key Infrastructure Using X.509 (PKIX)</title> <author fullname="P. Hoffman" initials="P." surname="Hoffman"/> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <date month="June" year="2010"/> <abstract> <t>The Public Key Infrastructure using X.509 (PKIX) certificate format, and many associated formats, are expressed using ASN.1. The current ASN.1 modules conform to the 1988 version of ASN.1. This document updates those ASN.1 modules to conform to the 2002 version of ASN.1. There are no bits-on-the-wire changes to any of the formats; this is simply a change to the syntax. This document is not an Internet Standards Track specification; it is published for informational purposes.</t> </abstract> </front> <seriesInfo name="RFC" value="5912"/> <seriesInfo name="DOI" value="10.17487/RFC5912"/> </reference> <reference anchor="RFC6268" target="https://www.rfc-editor.org/info/rfc6268" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6268.xml"> <front> <title>Additional New ASN.1 Modules for the Cryptographic Message Syntax (CMS) and the Public Key Infrastructure Using X.509 (PKIX)</title> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <author fullname="S. Turner" initials="S." surname="Turner"/> <date month="July" year="2011"/> <abstract> <t>The Cryptographic Message Syntax (CMS) format, and many associated formats, are expressed using ASN.1. The current ASN.1 modules conform to the 1988 version of ASN.1. This document updates some auxiliary ASN.1 modules to conform to the 2008 version of ASN.1; the 1988 ASN.1 modules remain the normative version. There are no bits- on-the-wire changes to any of the formats; this is simply a change to the syntax. This document is not an Internet Standards Track specification; it is published for informational purposes.</t> </abstract> </front> <seriesInfo name="RFC" value="6268"/> <seriesInfo name="DOI" value="10.17487/RFC6268"/> </reference> <reference anchor="RFC8017" target="https://www.rfc-editor.org/info/rfc8017" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8017.xml"> <front> <title>PKCS #1: RSA Cryptography Specifications Version 2.2</title> <author fullname="K. Moriarty" initials="K." role="editor" surname="Moriarty"/> <author fullname="B. Kaliski" initials="B." surname="Kaliski"/> <author fullname="J. Jonsson" initials="J." surname="Jonsson"/> <author fullname="A. Rusch" initials="A." surname="Rusch"/> <date month="November" year="2016"/> <abstract> <t>This document provides recommendations for the implementation of public-key cryptography based on the RSA algorithm, covering cryptographic primitives, encryption schemes, signature schemes with appendix, and ASN.1 syntax for representing keys and for identifying the schemes.</t> <t>This document represents a republication of PKCS #1 v2.2 from RSA Laboratories' Public-Key Cryptography Standards (PKCS) series. By publishing this RFC, change control is transferred to the IETF.</t> <t>This document also obsoletes RFC 3447.</t> </abstract> </front> <seriesInfo name="RFC" value="8017"/> <seriesInfo name="DOI" value="10.17487/RFC8017"/> </reference> <reference anchor="RFC8551" target="https://www.rfc-editor.org/info/rfc8551" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8551.xml"> <front> <title>Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 Message Specification</title> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <author fullname="B. Ramsdell" initials="B." surname="Ramsdell"/> <author fullname="S. Turner" initials="S." surname="Turner"/> <date month="April" year="2019"/> <abstract> <t>This document defines Secure/Multipurpose Internet Mail Extensions (S/MIME) version 4.0. S/MIME provides a consistent way to send and receive secure MIME data. Digital signatures provide authentication, message integrity, and non-repudiation with proof of origin. Encryption provides data confidentiality. Compression can be used to reduce data size. This document obsoletes RFC 5751.</t> </abstract> </front> <seriesInfo name="RFC" value="8551"/> <seriesInfo name="DOI" value="10.17487/RFC8551"/> </reference><xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9629.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3394.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5083.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5280.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5652.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5911.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5912.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6268.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8017.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8551.xml"/> <reference anchor="SHS"> <front> <title>Secure Hash Standard</title> <author> <organization>National Institute of Standards and Technology</organization> </author> <date year="2015" month="July"/> </front> <seriesInfo name="NIST FIPS PUB" value="180-4"/> <seriesInfo name="DOI"value="10.6028/nist.fips.180-4"/>value="10.6028/NIST.FIPS.180-4"/> </reference> <reference anchor="X.680" target="https://www.itu.int/rec/T-REC-X.680"> <front> <title>Information technology--- Abstract Syntax Notation One (ASN.1): Specification of basic notation</title> <author> <organization>ITU-T</organization> </author> <date year="2021" month="February"/> </front> <seriesInfo name="ITU-T Recommendation" value="X.680"/> <seriesInfo name="ISO/IEC" value="8824-1:2021"/> </reference> <reference anchor="X.690"target="https://www.itu.int/rec/T-REC-X.680">target="https://www.itu.int/rec/T-REC-X.690"> <front> <title>Information technology--- ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)</title> <author> <organization>ITU-T</organization> </author> <date year="2021" month="February"/> </front> <seriesInfo name="ITU-T Recommendation" value="X.690"/> <seriesInfo name="ISO/IEC" value="8825-1:2021"/> </reference> <referenceanchor="ANS-X9.44">anchor="ANS-X9.44" target="https://webstore.ansi.org/standards/ascx9/ansix9442007r2017"> <front> <title>Public Key Cryptography for the Financial Services Industry -- Key Establishment Using Integer Factorization Cryptography</title> <author> <organization>American National Standards Institute</organization> </author> <date year="2007"/> </front> <seriesInfoname="American National Standard" value="X9.44"/>name="ANSI" value="X9.44-2007 (R2017)"/> </reference> <reference anchor="ISO18033-2" target="https://www.iso.org/standard/37971.html"> <front> <title>Information technology -- Security techniques -- Encryption algorithms -- Part 2: Asymmetric ciphers</title> <author><organization>ISO/IEC JTC 1/SC 27</organization><organization>ISO/IEC</organization> </author> <date year="2006"/> </front> <seriesInfo name="ISO/IEC" value="18033-2:2006"/> </reference><reference anchor="RFC2119" target="https://www.rfc-editor.org/info/rfc2119" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"> <front> <title>Key words for use in RFCs to Indicate Requirement Levels</title> <author fullname="S. Bradner" initials="S." surname="Bradner"/> <date month="March" year="1997"/> <abstract> <t>In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t> </abstract> </front> <seriesInfo name="BCP" value="14"/> <seriesInfo name="RFC" value="2119"/> <seriesInfo name="DOI" value="10.17487/RFC2119"/> </reference> <reference anchor="RFC8174" target="https://www.rfc-editor.org/info/rfc8174" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"> <front> <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title> <author fullname="B. Leiba" initials="B." surname="Leiba"/> <date month="May" year="2017"/> <abstract> <t>RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.</t> </abstract> </front> <seriesInfo name="BCP" value="14"/> <seriesInfo name="RFC" value="8174"/> <seriesInfo name="DOI" value="10.17487/RFC8174"/> </reference><xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> </references> <references anchor="sec-informative-references"> <name>Informative References</name><reference anchor="RFC4086" target="https://www.rfc-editor.org/info/rfc4086" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4086.xml"> <front> <title>Randomness Requirements for Security</title> <author fullname="D. Eastlake 3rd" initials="D." surname="Eastlake 3rd"/> <author fullname="J. Schiller" initials="J." surname="Schiller"/> <author fullname="S. Crocker" initials="S." surname="Crocker"/> <date month="June" year="2005"/> <abstract> <t>Security systems are built on strong cryptographic algorithms that foil pattern analysis attempts. However, the security of these systems is dependent on generating secret quantities for passwords, cryptographic keys, and similar quantities. The use of pseudo-random processes to generate secret quantities can result in pseudo-security. A sophisticated attacker may find it easier to reproduce the environment that produced the secret quantities and to search the resulting small set of possibilities than to locate the quantities in the whole of the potential number space.</t> <t>Choosing random quantities to foil a resourceful and motivated adversary is surprisingly difficult. This document points out many pitfalls in using poor entropy sources or traditional pseudo-random number generation techniques for generating such quantities. It recommends the use of truly random hardware techniques and shows that the existing hardware on many systems can be used for this purpose. It provides suggestions to ameliorate the problem when a hardware solution is not available, and it gives examples of how large such quantities need to be for some applications. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t> </abstract> </front> <seriesInfo name="BCP" value="106"/> <seriesInfo name="RFC" value="4086"/> <seriesInfo name="DOI" value="10.17487/RFC4086"/> </reference> <reference anchor="RFC4262" target="https://www.rfc-editor.org/info/rfc4262" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4262.xml"> <front> <title>X.509 Certificate Extension for Secure/Multipurpose Internet Mail Extensions (S/MIME) Capabilities</title> <author fullname="S. Santesson" initials="S." surname="Santesson"/> <date month="December" year="2005"/> <abstract> <t>This document defines a certificate extension for inclusion of Secure/Multipurpose Internet Mail Extensions (S/MIME) Capabilities in X.509 public key certificates, as defined by RFC 3280. This certificate extension provides an optional method to indicate the cryptographic capabilities of an entity as a complement to the S/MIME Capabilities signed attribute in S/MIME messages according to RFC 3851. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="RFC" value="4262"/> <seriesInfo name="DOI" value="10.17487/RFC4262"/> </reference> <reference anchor="RFC5990" target="https://www.rfc-editor.org/info/rfc5990" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5990.xml"> <front> <title>Use of the RSA-KEM Key Transport Algorithm in the Cryptographic Message Syntax (CMS)</title> <author fullname="J. Randall" initials="J." surname="Randall"/> <author fullname="B. Kaliski" initials="B." surname="Kaliski"/> <author fullname="J. Brainard" initials="J." surname="Brainard"/> <author fullname="S. Turner" initials="S." surname="Turner"/> <date month="September" year="2010"/> <abstract> <t>The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward) mechanism for transporting keying data to a recipient using the recipient's RSA public key. ("KEM" stands for "key encapsulation mechanism".) This document specifies the conventions for using the RSA-KEM Key Transport Algorithm with the Cryptographic Message Syntax (CMS). The ASN.1 syntax is aligned with an expected forthcoming change to American National Standard (ANS) X9.44.</t> </abstract> </front> <seriesInfo name="RFC" value="5990"/> <seriesInfo name="DOI" value="10.17487/RFC5990"/> </reference> <reference anchor="RFC6194" target="https://www.rfc-editor.org/info/rfc6194" xml:base="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6194.xml"> <front> <title>Security Considerations for the SHA-0 and SHA-1 Message-Digest Algorithms</title> <author fullname="T. Polk" initials="T." surname="Polk"/> <author fullname="L. Chen" initials="L." surname="Chen"/> <author fullname="S. Turner" initials="S." surname="Turner"/> <author fullname="P. Hoffman" initials="P." surname="Hoffman"/> <date month="March" year="2011"/> <abstract> <t>This document includes security considerations for the SHA-0 and SHA-1 message digest algorithm. This document is not an Internet Standards Track specification; it is published for informational purposes.</t> </abstract> </front> <seriesInfo name="RFC" value="6194"/> <seriesInfo name="DOI" value="10.17487/RFC6194"/> </reference><xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4086.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4262.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5990.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6194.xml"/> <reference anchor="NISTSP800-57pt1r5"> <front> <title>Recommendation for KeyManagement:PartManagement: Part 1 - General</title><author><author fullname="Elaine Barker"> <organization>National Institute of Standards and Technology</organization> </author> <date year="2020" month="May"/> </front> <seriesInfo name="NIST SP" value="800-57, Part 1, Revision 5"/> <seriesInfo name="DOI" value="10.6028/nist.sp.800-57pt1r5"/> </reference> <reference anchor="CMVP" target="https://csrc.nist.gov/projects/cryptographic-module-validation-program"> <front> <title>Cryptographic Module Validation Program</title> <author> <organization>National Institute of Standards and Technology</organization> </author> <date year="2016"/> </front> </reference> <reference anchor="SHOUP" target="https://eprint.iacr.org/2001/112"> <front> <title>A Proposal for an ISO Standard for Public Key Encryption</title> <author initials="V." surname="Shoup" fullname="Victor Shoup"> <organization/> </author> <date year="2001"/> </front> <seriesInfo name="Cryptology ePrint Archive" value="Paper 2001/112"/> </reference> </references> </references><?line 665?><section anchor="app-alg"> <name>RSA-KEM Algorithm</name> <t>The RSA-KEMAlgorithmalgorithm is a one-pass (store-and-forward) cryptographic mechanism for an originator to securely send keying material to a recipient using the recipient's RSA public key.</t> <t>With the RSA-KEMAlgorithm,algorithm, an originator encrypts a random integer (z) with the recipient's RSA public key to produce a ciphertext (ct), and the originator derives a shared secret (SS) from the random integer (z). The originator then sends the ciphertext (ct) to the recipient. The recipient decrypts the ciphertext (ct) using their private key to recover the random integer (z), and the recipient derives a shared secret (SS) from the randominteger(z).integer (z). In this way, the originator and recipient obtain the same shared secret (SS).</t> <t>The RSA-KEMAlgorithmalgorithm depends on akey-derivationkey derivation function (KDF), which is used to derive the shared secret (SS). Manykey-derivationkey derivation functions support the inclusion of other information in addition to the shared secret (SS) in the input to the function; however, no other information is included as an input to the KDF by the RSA-KEMAlgorithm.</t>algorithm.</t> <section anchor="app-alg-encap"> <name>Originator's Operations: RSA-KEM Encapsulate()</name> <t>Let (n,e) be the recipient's RSA public key; see <xref target="RFC8017"/> for details.</t> <t>Let nLen denote the length in bytes of the modulus n, i.e., the least integer such that2^(8*nLen)2<sup>(8*nLen)</sup> > n.</t> <t>The originator performs the following operations:</t> <ol spacing="normal" type="1"><li> <t>Generate a random integer z between 0 and n-1 (seenote),NOTE below), and convert z to a byte string Z of length nLen, most significant byte first: </t> <artwork><![CDATA[ z = RandomInteger (0, n-1) Z = IntegerToString (z,nLen) ]]></artwork>nLen)]]></artwork> </li> <li> <t>Encrypt the random integer z using the recipient's RSA public key(n,e),(n,e) and convert the resulting integer c to a ciphertext C, a byte string of length nLen: </t> <artwork><![CDATA[ c = z^e mod n ct = IntegerToString (c,nLen) ]]></artwork>nLen)]]></artwork> </li> <li> <t>Derive a symmetric shared secret SS of length ssLen bytes (which <bcp14>MUST</bcp14> be the length of the key-encryption key) from the byte string Z using the underlyingkey-derivationkey derivation function: </t> <artwork><![CDATA[ SS = KDF (Z,ssLen) ]]></artwork>ssLen)]]></artwork> </li> <li> <t>Output the shared secret SS and the ciphertext ct. Send the ciphertext ct to the recipient.</t> </li> </ol> <t>NOTE: The random integer z <bcp14>MUST</bcp14> be generated independently at random for different encryption operations, whether for the same or different recipients.</t> </section> <section anchor="app-alg-decap"> <name>Recipient's Operations: RSA-KEM Decapsulate()</name> <t>Let (n,d) be the recipient's RSA private key; see <xref target="RFC8017"/> for details, but other private key formats are allowed.</t> <t>Let ct be the ciphertext received from the originator.</t> <t>Let nLen denote the length in bytes of the modulus n.</t> <t>The recipient performs the following operations:</t> <ol spacing="normal" type="1"><li> <t>If the length of the encrypted keying material is less than nLen bytes, output "decryption error", and stop.</t> </li> <li> <t>Convert the ciphertext ct to an integer c, most significant byte first (see NOTE below): </t> <artwork><![CDATA[ c = StringToInteger(ct) ]]></artwork> <t> If(ct)]]></artwork> <t>If the integer c is not between 0 and n-1, output "decryption error", and stop.</t> </li> <li> <t>Decrypt the integer c using the recipient's private key (n,d) to recover an integer z (see NOTE below): </t> <artwork><![CDATA[ z = c^d modn ]]></artwork>n]]></artwork> </li> <li> <t>Convert the integer z to a byte string Z of length nLen, most significant byte first (see NOTE below): </t> <artwork><![CDATA[ Z = IntegerToString (z,nLen) ]]></artwork>nLen)]]></artwork> </li> <li> <t>Derive a shared secret SS of length ssLen bytes from the byte string Z using thekey-derivationkey derivation function (see NOTE below): </t> <artwork><![CDATA[ SS = KDF (Z, ssLen) ]]></artwork> </li> <li> <t>Output the shared secret SS.</t> </li> </ol> <t>NOTE: Implementations <bcp14>SHOULD NOT</bcp14> reveal information about the integer z, the string Z, or about the calculation of the exponentiation in Step 2, the conversion in Step 3, or the key derivation in Step 4, whether by timing or other "side channels". The observable behavior of the implementation <bcp14>SHOULD</bcp14> be the same at these steps for all ciphertexts C that are in range. For example, IntegerToString conversion should take the same amount of time regardless of the actual value of the integer z. The integer z, the string Z, and other intermediate results <bcp14>MUST</bcp14> be securely deleted when they are no longer needed.</t> </section> </section> <section anchor="app-asn1"> <name>ASN.1 Syntax</name> <t>The ASN.1 syntax for identifying the RSA-KEMAlgorithmalgorithm is an extension of the syntax for the "generic hybrid cipher" in ANS X9.44 <xref target="ANS-X9.44"/>.</t> <t>The ASN.1 Module is unchanged from RFC 5990. The id-rsa-kem-spki object identifier is used in a backward compatible manner in certificates <xref target="RFC5280"/> and SMIMECapabilities <xref target="RFC8551"/>. Of course, the use of the id-kem-rsa object identifier in the new KEMRecipientInfo structure <xreftarget="I-D.ietf-lamps-cms-kemri"/>target="RFC9629"/> was not yet defined at the time that RFC 5990 was written.</t> <section anchor="app-asn1-intro"> <name>Underlying Components</name> <t>Implementations that conform to this specification <bcp14>MUST</bcp14> support the KDF3 <xref target="ANS-X9.44"/>key-derivationkey derivation function using SHA-256 <xref target="SHS"/>.</t> <t>KDF2 <xref target="ANS-X9.44"/> and KDF3 are bothkey-derivationkey derivation functions based on a hash function. The only difference between KDF2 and KDF3 is the order of the components to be hashed.</t> <artwork><![CDATA[ KDF2 calculates T as: T = T || Hash (Z || D || otherInfo) KDF3 calculates T as: T = T || Hash (D || Z ||otherInfo) ]]></artwork>otherInfo)]]></artwork> <t>The object identifier for KDF3 is:</t><artwork><![CDATA[<sourcecode type="asn.1"> id-kdf-kdf3 OBJECT IDENTIFIER ::= { x9-44-components kdf3(2)} ]]></artwork>}</sourcecode> <t>The KDF3 parameters identify the underlying hash function. For alignment withtheANS X9.44, the hash function <bcp14>MUST</bcp14> be an ASC X9-approved hash function. While the SHA-1 hash algorithm is included in the ASN.1 definitions, SHA-1 <bcp14>MUST NOT</bcp14> be used. SHA-1 is considered to be obsolete; see <xref target="RFC6194"/>. SHA-1 remains in the ASN.1 module for compatibility with RFC 5990. In addition, other hash functions <bcp14>MAY</bcp14> be used with CMS.</t><artwork><![CDATA[<sourcecode type="asn.1"> kda-kdf3 KEY-DERIVATION ::= { IDENTIFIER id-kdf-kdf3 PARAMS TYPE KDF3-HashFunction ARE required -- No S/MIME caps defined -- } KDF3-HashFunction ::= AlgorithmIdentifier { DIGEST-ALGORITHM, {KDF3-HashFunctions} } KDF3-HashFunctions DIGEST-ALGORITHM ::= { X9-HashFunctions, ... } X9-HashFunctions DIGEST-ALGORITHM ::= { mda-sha1 | mda-sha224 | mda-sha256 | mda-sha384 | mda-sha512, ...} ]]></artwork>}</sourcecode> <t>Implementations that conform to this specification <bcp14>MUST</bcp14> support the AES Key Wrap <xref target="RFC3394"/> key-encryption algorithm with a 128-bit key. There are three object identifiers for the AES Key Wrap, one for each permitted size of the key-encryption key. There are three object identifiers imported from <xref target="RFC5912"/>, and none of these algorithm identifiers have associated parameters:</t><artwork><![CDATA[<sourcecode type="asn.1"> kwa-aes128-wrap KEY-WRAP ::= { IDENTIFIER id-aes128-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-aes128-wrap } } kwa-aes192-wrap KEY-WRAP ::= { IDENTIFIER id-aes192-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-aes192-wrap } } kwa-aes256-wrap KEY-WRAP ::= { IDENTIFIER id-aes256-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-aes256-wrap }} ]]></artwork>}</sourcecode> </section> <section anchor="app-asn1-module"> <name>ASN.1 Module</name><t>RFC EDITOR: Please replace TBD2 with the value assigned by IANA during the publication of <xref target="I-D.ietf-lamps-cms-kemri"/>.</t><sourcecode type="asn.1" markers="true"><![CDATA[ CMS-RSA-KEM-2023 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) modules(0)id-mod-cms-rsa-kem-2023(TBD1)id-mod-cms-rsa-kem-2023(79) } DEFINITIONS EXPLICIT TAGS ::= BEGIN -- EXPORTS ALL IMPORTS KEM-ALGORITHM FROM KEMAlgorithmInformation-2023 -- [I-D.ietf-lamps-cms-kemri] { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)id-mod-kemAlgorithmInformation-2023(TBD2)id-mod-kemAlgorithmInformation-2023(109) } AlgorithmIdentifier{}, PUBLIC-KEY, DIGEST-ALGORITHM, KEY-DERIVATION, KEY-WRAP, SMIME-CAPS FROM AlgorithmInformation-2009 -- [RFC5912] { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-algorithmInformation-02(58) } kwa-aes128-wrap, kwa-aes192-wrap, kwa-aes256-wrap FROM CMSAesRsaesOaep-2009 -- [RFC5911] { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) modules(0) id-mod-cms-aes-02(38) } kwa-3DESWrap FROM CryptographicMessageSyntaxAlgorithms-2009 -- [RFC5911] { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) modules(0) id-mod-cmsalg-2001-02(37) } id-camellia128-wrap, id-camellia192-wrap, id-camellia256-wrap FROM CamelliaEncryptionAlgorithmInCMS -- [RFC3657] { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) modules(0) id-mod-cms-camellia(23) } mda-sha1, pk-rsa, RSAPublicKey FROM PKIXAlgs-2009 -- [RFC5912] { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-pkix1-algorithms2008-02(56) } mda-sha224, mda-sha256, mda-sha384, mda-sha512 FROM PKIX1-PSS-OAEP-Algorithms-2009 -- [RFC5912] { iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-pkix1-rsa-pkalgs-02(54) } ; -- Useful types and definitions OID ::= OBJECT IDENTIFIER -- alias NullParms ::= NULL -- ISO/IEC 18033-2 arc is18033-2 OID ::= { iso(1) standard(0) is18033(18033) part2(2) } -- NIST algorithm arc nistAlgorithm OID ::= { joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101) csor(3) nistAlgorithm(4) } -- PKCS #1 arc pkcs-1 OID ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) } -- X9.44 arc x9-44 OID ::= { iso(1) identified-organization(3) tc68(133) country(16) x9(840) x9Standards(9) x9-44(44) } x9-44-components OID ::= { x9-44 components(1) } -- RSA-KEM Algorithm id-rsa-kem OID ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 14 } id-rsa-kem-spki OID ::= id-rsa-kem GenericHybridParameters ::= SEQUENCE { kem KeyEncapsulationMechanism, dem DataEncapsulationMechanism } KeyEncapsulationMechanism ::= AlgorithmIdentifier { KEM-ALGORITHM, {KEMAlgorithms} } KEMAlgorithms KEM-ALGORITHM ::= { kema-kem-rsa | kema-rsa-kem, ... } kema-rsa-kem KEM-ALGORITHM ::= { IDENTIFIER id-rsa-kem-spki PARAMS TYPE GenericHybridParameters ARE optional PUBLIC-KEYS { pk-rsa | pk-rsa-kem } UKM ARE optional SMIME-CAPS { TYPE GenericHybridParameters IDENTIFIED BY id-rsa-kem-spki } } kema-kem-rsa KEM-ALGORITHM ::= { IDENTIFIER id-kem-rsa PARAMS TYPE RsaKemParameters ARE optional PUBLIC-KEYS { pk-rsa | pk-rsa-kem } UKM ARE optional SMIME-CAPS { TYPE GenericHybridParameters IDENTIFIED BY id-rsa-kem-spki } } id-kem-rsa OID ::= { is18033-2 key-encapsulation-mechanism(2) rsa(4) } RsaKemParameters ::= SEQUENCE { keyDerivationFunction KeyDerivationFunction, keyLength KeyLength } pk-rsa-kem PUBLIC-KEY ::= { IDENTIFIER id-rsa-kem-spki KEY RSAPublicKey PARAMS TYPE GenericHybridParameters ARE preferredAbsent -- Private key format is not specified here -- CERT-KEY-USAGE {keyEncipherment} } KeyDerivationFunction ::= AlgorithmIdentifier { KEY-DERIVATION, {KDFAlgorithms} } KDFAlgorithms KEY-DERIVATION ::= { kda-kdf2 | kda-kdf3, ... } KeyLength ::= INTEGER (1..MAX) DataEncapsulationMechanism ::= AlgorithmIdentifier { KEY-WRAP, {DEMAlgorithms} } DEMAlgorithms KEY-WRAP ::= { X9-SymmetricKeyWrappingSchemes | Camellia-KeyWrappingSchemes, ... } X9-SymmetricKeyWrappingSchemes KEY-WRAP ::= { kwa-aes128-wrap | kwa-aes192-wrap | kwa-aes256-wrap | kwa-3DESWrap, ... } X9-SymmetricKeyWrappingScheme ::= AlgorithmIdentifier { KEY-WRAP, {X9-SymmetricKeyWrappingSchemes} } Camellia-KeyWrappingSchemes KEY-WRAP ::= { kwa-camellia128-wrap | kwa-camellia192-wrap | kwa-camellia256-wrap, ... } Camellia-KeyWrappingScheme ::= AlgorithmIdentifier { KEY-WRAP, {Camellia-KeyWrappingSchemes} } kwa-camellia128-wrap KEY-WRAP ::= { IDENTIFIER id-camellia128-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-camellia128-wrap } } kwa-camellia192-wrap KEY-WRAP ::= { IDENTIFIER id-camellia192-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-camellia192-wrap } } kwa-camellia256-wrap KEY-WRAP ::= { IDENTIFIER id-camellia256-wrap PARAMS ARE absent SMIME-CAPS { IDENTIFIED BY id-camellia256-wrap } } -- Key Derivation Functions id-kdf-kdf2 OID ::= { x9-44-components kdf2(1) } kda-kdf2 KEY-DERIVATION ::= { IDENTIFIER id-kdf-kdf2 PARAMS TYPE KDF2-HashFunction ARE required -- No S/MIME caps defined -- } KDF2-HashFunction ::= AlgorithmIdentifier { DIGEST-ALGORITHM, {KDF2-HashFunctions} } KDF2-HashFunctions DIGEST-ALGORITHM ::= { X9-HashFunctions, ... } id-kdf-kdf3 OID ::= { x9-44-components kdf3(2) } kda-kdf3 KEY-DERIVATION ::= { IDENTIFIER id-kdf-kdf3 PARAMS TYPE KDF3-HashFunction ARE required -- No S/MIME caps defined -- } KDF3-HashFunction ::= AlgorithmIdentifier { DIGEST-ALGORITHM, {KDF3-HashFunctions} } KDF3-HashFunctions DIGEST-ALGORITHM ::= { X9-HashFunctions, ... } -- Hash Functions X9-HashFunctions DIGEST-ALGORITHM ::= { mda-sha1 | mda-sha224 | mda-sha256 | mda-sha384 | mda-sha512, ... } -- Updates for the SMIME-CAPS Set from RFC 5911 SMimeCapsSet SMIME-CAPS ::= { kema-kem-rsa.&smimeCaps | kwa-aes128-wrap | kwa-aes192-wrap | kwa-aes256-wrap | kwa-camellia128-wrap.&smimeCaps | kwa-camellia192-wrap.&smimeCaps | kwa-camellia256-wrap.&smimeCaps, ... }END ]]></sourcecode>END]]></sourcecode> </section> </section> <section anchor="app-example"> <name>SMIMECapabilities Examples</name> <t>To indicate support for the RSA-KEM algorithm coupled with the KDF3key-derivationkey derivation function with SHA-256 and the AES Key Wrap symmetric key-encryption algorithm 128-bit key-encryption key, the SMIMECapabilities will include the following entry:</t> <artwork><![CDATA[ SEQUENCE { id-rsa-kem-spki, -- RSA-KEM Algorithm SEQUENCE { -- GenericHybridParameters SEQUENCE { -- key encapsulation mechanism id-kem-rsa, -- RSA-KEM SEQUENCE { -- RsaKemParameters SEQUENCE { -- key derivation function id-kdf-kdf3, -- KDF3 SEQUENCE { -- KDF3-HashFunction id-sha256 -- SHA-256; no parameters (preferred) }, 16 -- KEK length in bytes }, SEQUENCE { -- data encapsulation mechanism id-aes128-Wrap -- AES-128 Wrap; no parameters } }} ]]></artwork>}]]></artwork> <t>This SMIMECapability value has the following DER encoding (in hexadecimal):</t> <artwork><![CDATA[ 30 47 06 0b 2a 86 48 86 f7 0d 01 09 10 03 0e -- id-rsa-kem-spki 30 38 30 29 06 07 28 81 8c 71 02 02 04 -- id-kem-rsa 30 1e 30 19 06 0a 2b 81 05 10 86 48 09 2c 01 02 -- id-kdf-kdf3 30 0b 06 09 60 86 48 01 65 03 04 02 01 -- id-sha256 02 01 10 -- 16 bytes 30 0b 06 09 60 86 48 01 65 03 04 01 05 --id-aes128-Wrap ]]></artwork>id-aes128-Wrap]]></artwork> <t>To indicate support for the RSA-KEM algorithm coupled with the KDF3key-derivationkey derivation function with SHA-384 and the AES Key Wrap symmetric key-encryption algorithm 192-bit key-encryption key, the SMIMECapabilities will include the following SMIMECapability value (in hexadecimal):</t> <artwork><![CDATA[ 30 47 06 0b 2a 86 48 86 f7 0d 01 09 10 03 0e 30 38 30 29 06 07 28 81 8c 71 02 02 04 30 1e 30 19 06 0a 2b 81 05 10 86 48 09 2c 01 02 30 0b 06 09 60 86 48 01 65 03 04 02 02 02 01 18 30 0b 06 09 60 86 48 01 65 03 04 0119 ]]></artwork>19]]></artwork> <t>To indicate support for the RSA-KEM algorithm coupled with the KDF3key-derivationkey derivation function with SHA-512 and the AES Key Wrap symmetric key-encryption algorithm 256-bit key-encryption key, the SMIMECapabilities will include the following SMIMECapability value (in hexadecimal):</t> <artwork><![CDATA[ 30 47 06 0b 2a 86 48 86 f7 0d 01 09 10 03 0e 30 38 30 29 06 07 28 81 8c 71 02 02 04 30 1e 30 19 06 0a 2b 81 05 10 86 48 09 2c 01 02 30 0b 06 09 60 86 48 01 65 03 04 02 03 02 01 20 30 0b 06 09 60 86 48 01 65 03 04 012d ]]></artwork>2d]]></artwork> </section> <section anchor="rsa-kem-cms-enveloped-data-example"> <name>RSA-KEM CMS Enveloped-Data Example</name> <t>This example shows the establishment of an AES-128 content-encryption key using:</t> <ul spacing="normal"> <li> <t>RSA-KEM with a 3072-bit key and KDF3 with SHA-256;</t> </li> <li> <t>KEMRecipientInfo key derivation using KDF3 with SHA-256; and</t> </li> <li> <t>KEMRecipientInfokey wrapKey Wrap using AES-128-KEYWRAP.</t> </li> </ul> <t>In real-world use, the originator would encrypt the content-encryption key in a manner that would allow decryption with their own private key as well as the recipient's private key. This is omitted in an attempt to simplify the example.</t> <section anchor="originator-rsa-kem-encapsulate-processing"> <name>Originator RSA-KEM Encapsulate() Processing</name> <t>Alice obtains Bob's public key:</t> <artwork><![CDATA[ -----BEGIN PUBLIC KEY----- MIIBojANBgkqhkiG9w0BAQEFAAOCAY8AMIIBigKCAYEA3ocW14cxncPJ47fnEjBZ AyfC2lqapL3ET4jvV6C7gGeVrRQxWPDwl+cFYBBR2ej3j3/0ecDmu+XuVi2+s5JH Keeza+itfuhsz3yifgeEpeK8T+SusHhn20/NBLhYKbh3kiAcCgQ56dpDrDvDcLqq vS3jg/VO+OPnZbofoHOOevt8Q/roahJe1PlIyQ4udWB8zZezJ4mLLfbOA9YVaYXx 2AHHZJevo3nmRnlgJXo6mE00E/6qkhjDHKSMdl2WG6mO9TCDZc9qY3cAJDU6Ir0v SH7qUl8/vN13y4UOFkn8hM4kmZ6bJqbZt5NbjHtY4uQ0VMW3RyESzhrO02mrp39a uLNnH3EXdXaV1tk75H3qC7zJaeGWMJyQfOE3YfEGRKn8fxubji716D8UecAxAzFy FL6m1JiOyV5acAiOpxN14qRYZdHnXOM9DqGIGpoeY1UuD4Mo05osOqOUpBJHA9fS whSZG7VNf+vgNWTLNYSYLI04KiMdulnvU6ds+QPz+KKtAgMBAAE= -----END PUBLICKEY----- ]]></artwork>KEY-----]]></artwork> <t>Bob's RSA public key has the following key identifier:</t> <artwork><![CDATA[9eeb67c9b95a74d44d2f16396680e801b5cba49c ]]></artwork>9eeb67c9b95a74d44d2f16396680e801b5cba49c]]></artwork> <t>Alice randomly generates integer z between 0 and n-1:</t> <artwork><![CDATA[ 9c126102a5c1c0354672a3c2f19fc9ddea988f815e1da812c7bd4f8eb082bdd1 4f85a7f7c2f1af11d5333e0d6bcb375bf855f208da72ba27e6fb0655f2825aa6 2b93b1f9bbd3491fed58f0380fa0de36430e3a144d569600bd362609be5b9481 0875990b614e406fa6dff500043cbca95968faba61f795096a7fb3687a51078c 4ca2cb663366b0bea0cd9cccac72a25f3f4ed03deb68b4453bba44b943f4367b 67d6cd10c8ace53f545aac50968fc3c6ecc80f3224b64e37038504e2d2c0e2b2 9d45e46c62826d96331360e4c17ea3ef89a9efc5fac99eda830e81450b6534dc 0bdf042b8f3b706649c631fe51fc2445cc8d447203ec2f41f79cdfea16de1ce6 abdfdc1e2ef2e5d5d8a65e645f397240ef5a26f5e4ff715de782e30ecf477293 e89e13171405909a8e04dd31d21d0c57935fc1ceea8e1033e31e1bc8c56da0f3 d79510f3f380ff58e5a61d361f2f18e99fbae5663172e8cd1f21deaddc5bbbea060d55f1842b93d1a9c888d0bf85d0af9947fe51acf940c7e7577eb79cabecb3 ]]></artwork>060d55f1842b93d1a9c888d0bf85d0af9947fe51acf940c7e7577eb79cabecb3]]></artwork> <t>Alice encrypts integer z using the Bob's RSA publickey, thekey. The result is called ct:</t> <artwork><![CDATA[ c071fc273af8e7bdb152e06bf73310361074154a43abcf3c93c13499d2065344 3eed9ef5d3c0685e4aa76a6854815bb97691ff9f8dac15eea7d74f452bf350a6 46163d68288e978cbf7a73089ee52712f9a4f49e06ace7bbc85ab14d4e336c97 c5728a2654138c7b26e8835c6b0a9fbed26495c4eadf745a2933be283f6a88b1 6695fc06666873cfb6d36718ef3376cefc100c3941f3c494944078325807a559 186b95ccabf3714cfaf79f83bd30537fdd9aed5a4cdcbd8bd0486faed73e9d48 6b3087d6c806546b6e2671575c98461e441f65542bd95de26d0f53a64e7848d7 31d9608d053e8d345546602d86236ffe3704c98ad59144f3089e5e6d527b5497 ba103c79d62e80d0235410b06f71a7d9bd1c38000f910d6312ea2f20a3557535 ad01b3093fb5f7ee507080d0f77d48c9c3b3796f6b7dd3786085fb895123f04c a1f1c1be22c747a8dface32370fb0d570783e27dbb7e74fca94ee39676fde3d8a9553d878224736e37e191dab953c7e228c07ad5ca3122421c14debd072a9ab6 ]]></artwork>a9553d878224736e37e191dab953c7e228c07ad5ca3122421c14debd072a9ab6]]></artwork> <t>Alice derives the shared secret (SS) using KDF3 with SHA-256:</t> <artwork><![CDATA[3cf82ec41b54ed4d37402bbd8f805a52 ]]></artwork>3cf82ec41b54ed4d37402bbd8f805a52]]></artwork> </section> <section anchor="originator-cms-processing"> <name>Originator CMS Processing</name> <t>Alice encodes the CMSORIforKEMOtherInfo structure with the algorithm identifier for AES-128-KEYWRAP and a key length of 16 octets. The DER encoding of CMSORIforKEMOtherInfo produces 18 octets:</t> <artwork><![CDATA[3010300b0609608648016503040105020110 ]]></artwork>3010300b0609608648016503040105020110]]></artwork> <t>The CMSORIforKEMOtherInfo structure contains:</t><ul empty="true"> <li><artwork><![CDATA[ 0 16: SEQUENCE { 2 11: SEQUENCE { 4 9: OBJECT IDENTIFIER aes128-wrap (2 16 840 1 101 3 4 1 5) : } 15 1: INTEGER 16 :} ]]></artwork> </li> </ul>}]]></artwork> <t>Alice derives the key-encryption key from shared secret produced by RSA-KEM Encapsulate() and the CMSORIforKEMOtherInfo structure with KDF3 andSHA-256, theSHA-256. The KEK is:</t> <artwork><![CDATA[e6dc9d62ff2b469bef604c617b018718 ]]></artwork>e6dc9d62ff2b469bef604c617b018718]]></artwork> <t>Alice randomly generates a 128-bit content-encryption key:</t> <artwork><![CDATA[77f2a84640304be7bd42670a84a1258b ]]></artwork>77f2a84640304be7bd42670a84a1258b]]></artwork> <t>Alice uses AES-128-KEYWRAP to encrypt the 128-bit content-encryption key with the derived key-encryption key:</t> <artwork><![CDATA[28782e5d3d794a7616b863fbcfc719b78f12de08cf286e09 ]]></artwork>28782e5d3d794a7616b863fbcfc719b78f12de08cf286e09]]></artwork> <t>Alice encrypts the padded content using AES-128-CBC with the content-encryption key. The 16-octet IV used is:</t> <artwork><![CDATA[480ccafebabefacedbaddecaf8887781 ]]></artwork>480ccafebabefacedbaddecaf8887781]]></artwork> <t>The padded content plaintext is:</t> <artwork><![CDATA[48656c6c6f2c20776f726c6421030303 ]]></artwork>48656c6c6f2c20776f726c6421030303]]></artwork> <t>The resulting ciphertext is:</t> <artwork><![CDATA[c6ca65db7bdd76b0f37e2fab6264b66d ]]></artwork>c6ca65db7bdd76b0f37e2fab6264b66d]]></artwork> <t>Alice encodes the EnvelopedData (using KEMRecipientInfo) and ContentInfo, and then sends the result to Bob. The Base64-encoded result is:</t><ul empty="true"> <li><artwork><![CDATA[ MIICXAYJKoZIhvcNAQcDoIICTTCCAkkCAQMxggIEpIICAAYLKoZIhvcNAQkQDQMw ggHvAgEAgBSe62fJuVp01E0vFjlmgOgBtcuknDAJBgcogYxxAgIEBIIBgMBx/Cc6 +Oe9sVLga/czEDYQdBVKQ6vPPJPBNJnSBlNEPu2e9dPAaF5Kp2poVIFbuXaR/5+N rBXup9dPRSvzUKZGFj1oKI6XjL96cwie5ScS+aT0ngas57vIWrFNTjNsl8VyiiZU E4x7JuiDXGsKn77SZJXE6t90Wikzvig/aoixZpX8BmZoc8+202cY7zN2zvwQDDlB 88SUlEB4MlgHpVkYa5XMq/NxTPr3n4O9MFN/3ZrtWkzcvYvQSG+u1z6dSGswh9bI BlRrbiZxV1yYRh5EH2VUK9ld4m0PU6ZOeEjXMdlgjQU+jTRVRmAthiNv/jcEyYrV kUTzCJ5ebVJ7VJe6EDx51i6A0CNUELBvcafZvRw4AA+RDWMS6i8go1V1Na0Bswk/ tffuUHCA0Pd9SMnDs3lva33TeGCF+4lRI/BMofHBviLHR6jfrOMjcPsNVweD4n27 fnT8qU7jlnb949ipVT2HgiRzbjfhkdq5U8fiKMB61coxIkIcFN69ByqatjAbBgor gQUQhkgJLAECMA0GCWCGSAFlAwQCAQUAAgEQMAsGCWCGSAFlAwQBBQQYKHguXT15 SnYWuGP7z8cZt48S3gjPKG4JMDwGCSqGSIb3DQEHATAdBglghkgBZQMEAQIEEEgMyv66vvrO263eyviId4GAEMbKZdt73Xaw834vq2Jktm0= ]]></artwork> </li> </ul>yv66vvrO263eyviId4GAEMbKZdt73Xaw834vq2Jktm0=]]></artwork> <t>This result decodes to:</t><ul empty="true"> <li><artwork><![CDATA[ 0 604: SEQUENCE { 4 9: OBJECT IDENTIFIER envelopedData (1 2 840 113549 1 7 3) 15 589: [0] { 19 585: SEQUENCE { 23 1: INTEGER 3 26 516: SET { 30 512: [4] { 34 11: OBJECT IDENTIFIER : KEMRecipientInfo (1 2 840 113549 1 9 16 13 3) 47 495: SEQUENCE { 51 1: INTEGER 0 54 20: [0] : 9E EB 67 C9 B9 5A 74 D4 4D 2F 16 39 66 80 E8 01 : B5 CB A4 9C 76 9: SEQUENCE { 78 7: OBJECT IDENTIFIER kemRSA (1 0 18033 2 2 4) : } 87 384: OCTET STRING : C0 71 FC 27 3A F8 E7 BD B1 52 E0 6B F7 33 10 36 : 10 74 15 4A 43 AB CF 3C 93 C1 34 99 D2 06 53 44 : 3E ED 9E F5 D3 C0 68 5E 4A A7 6A 68 54 81 5B B9 : 76 91 FF 9F 8D AC 15 EE A7 D7 4F 45 2B F3 50 A6 : 46 16 3D 68 28 8E 97 8C BF 7A 73 08 9E E5 27 12 : F9 A4 F4 9E 06 AC E7 BB C8 5A B1 4D 4E 33 6C 97 : C5 72 8A 26 54 13 8C 7B 26 E8 83 5C 6B 0A 9F BE : D2 64 95 C4 EA DF 74 5A 29 33 BE 28 3F 6A 88 B1 : 66 95 FC 06 66 68 73 CF B6 D3 67 18 EF 33 76 CE : FC 10 0C 39 41 F3 C4 94 94 40 78 32 58 07 A5 59 : 18 6B 95 CC AB F3 71 4C FA F7 9F 83 BD 30 53 7F : DD 9A ED 5A 4C DC BD 8B D0 48 6F AE D7 3E 9D 48 : 6B 30 87 D6 C8 06 54 6B 6E 26 71 57 5C 98 46 1E : 44 1F 65 54 2B D9 5D E2 6D 0F 53 A6 4E 78 48 D7 : 31 D9 60 8D 05 3E 8D 34 55 46 60 2D 86 23 6F FE : 37 04 C9 8A D5 91 44 F3 08 9E 5E 6D 52 7B 54 97 : BA 10 3C 79 D6 2E 80 D0 23 54 10 B0 6F 71 A7 D9 : BD 1C 38 00 0F 91 0D 63 12 EA 2F 20 A3 55 75 35 : AD 01 B3 09 3F B5 F7 EE 50 70 80 D0 F7 7D 48 C9 : C3 B3 79 6F 6B 7D D3 78 60 85 FB 89 51 23 F0 4C : A1 F1 C1 BE 22 C7 47 A8 DF AC E3 23 70 FB 0D 57 : 07 83 E2 7D BB 7E 74 FC A9 4E E3 96 76 FD E3 D8 : A9 55 3D 87 82 24 73 6E 37 E1 91 DA B9 53 C7 E2 : 28 C0 7A D5 CA 31 22 42 1C 14 DE BD 07 2A 9A B6 475 27: SEQUENCE { 477 10: OBJECT IDENTIFIER : kdf3 (1 3 133 16 840 9 44 1 2) 489 13: SEQUENCE { 491 9: OBJECT IDENTIFIER : sha-256 (2 16 840 1 101 3 4 2 1) 502 0: NULL : } : } 504 1: INTEGER 16 507 11: SEQUENCE { 509 9: OBJECT IDENTIFIER : aes128-wrap (2 16 840 1 101 3 4 1 5) : } 520 24: OCTET STRING : 28 78 2E 5D 3D 79 4A 76 16 B8 63 FB CF C7 19 B7 : 8F 12 DE 08 CF 28 6E 09 : } : } : } 546 60: SEQUENCE { 548 9: OBJECT IDENTIFIER data (1 2 840 113549 1 7 1) 559 29: SEQUENCE { 561 9: OBJECT IDENTIFIER : aes128-CBC (2 16 840 1 101 3 4 1 2) 572 16: OCTET STRING : 48 0C CA FE BA BE FA CE DB AD DE CA F8 88 77 81 : } 590 16: [0] C6 CA 65 DB 7B DD 76 B0 F3 7E 2F AB 62 64 B6 6D : } : } : } :} ]]></artwork> </li> </ul>}]]></artwork> </section> <section anchor="recipient-rsa-kem-decapsulate-processing"> <name>Recipient RSA-KEM Decapsulate() Processing</name> <t>Bob's private key:</t> <artwork><![CDATA[ -----BEGIN PRIVATE KEY----- MIIG5AIBAAKCAYEA3ocW14cxncPJ47fnEjBZAyfC2lqapL3ET4jvV6C7gGeVrRQx WPDwl+cFYBBR2ej3j3/0ecDmu+XuVi2+s5JHKeeza+itfuhsz3yifgeEpeK8T+Su sHhn20/NBLhYKbh3kiAcCgQ56dpDrDvDcLqqvS3jg/VO+OPnZbofoHOOevt8Q/ro ahJe1PlIyQ4udWB8zZezJ4mLLfbOA9YVaYXx2AHHZJevo3nmRnlgJXo6mE00E/6q khjDHKSMdl2WG6mO9TCDZc9qY3cAJDU6Ir0vSH7qUl8/vN13y4UOFkn8hM4kmZ6b JqbZt5NbjHtY4uQ0VMW3RyESzhrO02mrp39auLNnH3EXdXaV1tk75H3qC7zJaeGW MJyQfOE3YfEGRKn8fxubji716D8UecAxAzFyFL6m1JiOyV5acAiOpxN14qRYZdHn XOM9DqGIGpoeY1UuD4Mo05osOqOUpBJHA9fSwhSZG7VNf+vgNWTLNYSYLI04KiMd ulnvU6ds+QPz+KKtAgMBAAECggGATFfkSkUjjJCjLvDk4aScpSx6+Rakf2hrdS3x jwqhyUfAXgTTeUQQBs1HVtHCgxQd+qlXYn3/qu8TeZVwG4NPztyi/Z5yB1wOGJEV 3k8N/ytul6pJFFn6p48VM01bUdTrkMJbXERe6g/rr6dBQeeItCaOK7N5SIJH3Oqh 9xYuB5tH4rquCdYLmt17Tx8CaVqU9qPY3vOdQEOwIjjMV8uQUR8rHSO9KkSj8AGs Lq9kcuPpvgJc2oqMRcNePS2WVh8xPFktRLLRazgLP8STHAtjT6SlJ2UzkUqfDHGK q/BoXxBDu6L1VDwdnIS5HXtL54ElcXWsoOyKF8/ilmhRUIUWRZFmlS1ok8IC5IgX UdL9rJVZFTRLyAwmcCEvRM1asbBrhyEyshSOuN5nHJi2WVJ+wSHijeKl1qeLlpMk HrdIYBq4Nz7/zXmiQphpAy+yQeanhP8O4O6C8e7RwKdpxe44su4Z8fEgA5yQx0u7 8yR1EhGKydX5bhBLR5Cm1VM7rT2BAoHBAP/+e5gZLNf/ECtEBZjeiJ0VshszOoUq haUQPA+9Bx9pytsoKm5oQhB7QDaxAvrn8/FUW2aAkaXsaj9F+/q30AYSQtExai9J fdKKook3oimN8/yNRsKmhfjGOj8hd4+GjX0qoMSBCEVdT+bAjjry8wgQrqReuZnu oXU85dmb3jvv0uIczIKvTIeyjXE5afjQIJLmZFXsBm09BG87Ia5EFUKly96BOMJh /QWEzuYYXDqOFfzQtkAefXNFW21Kz4Hw2QKBwQDeiGh4lxCGTjECvG7fauMGlu+q DSdYyMHif6t6mx57eS16EjvOrlXKItYhIyzW8Kw0rf/CSB2j8ig1GkMLTOgrGIJ1 0322o50FOr5oOmZPueeR4pOyAP0fgQ8DD1L3JBpY68/8MhYbsizVrR+Ar4jM0f96 W2bF5Xj3h+fQTDMkx6VrCCQ6miRmBUzH+ZPs5n/lYOzAYrqiKOanaiHy4mjRvlsy mjZ6z5CG8sISqcLQ/k3Qli5pOY/v0rdBjgwAW/UCgcEAqGVYGjKdXCzuDvf9EpV4 mpTWB6yIV2ckaPOn/tZi5BgsmEPwvZYZt0vMbu28Px7sSpkqUuBKbzJ4pcy8uC3I SuYiTAhMiHS4rxIBX3BYXSuDD2RD4vG1+XM0h6jVRHXHh0nOXdVfgnmigPGz3jVJ B8oph/jD8O2YCk4YCTDOXPEi8Rjusxzro+whvRR+kG0gsGGcKSVNCPj1fNISEte4 gJId7O1mUAAzeDjn/VaS/PXQovEMolssPPKn9NocbKbpAoHBAJnFHJunl22W/lrr ppmPnIzjI30YVcYOA5vlqLKyGaAsnfYqP1WUNgfVhq2jRsrHx9cnHQI9Hu442PvI x+c5H30YFJ4ipE3eRRRmAUi4ghY5WgD+1hw8fqyUW7E7l5LbSbGEUVXtrkU5G64T UR91LEyMF8OPATdiV/KD4PWYkgaqRm3tVEuCVACDTQkqNsOOi3YPQcm270w6gxfQ SOEy/kdhCFexJFA8uZvmh6Cp2crczxyBilR/yCxqKOONqlFdOQKBwFbJk5eHPjJz AYueKMQESPGYCrwIqxgZGCxaqeVArHvKsEDx5whI6JWoFYVkFA8F0MyhukoEb/2x 2qB5T88Dg3EbqjTiLg3qxrWJ2OxtUo8pBP2I2wbl2NOwzcbrlYhzEZ8bJyxZu5i1 sYILC8PJ4Qzw6jS4Qpm4y1WHz8e/ElW6VyfmljZYA7f9WMntdfeQVqCVzNTvKn6f hg6GSpJTzp4LV3ougi9nQuWXZF2wInsXkLYpsiMbL6Fz34RwohJtYA== -----END PRIVATEKEY----- ]]></artwork>KEY-----]]></artwork> <t>Bob checks that the length of the ciphertext is less than nLen bytes.</t> <t>Bob checks that the ciphertext is greater than zero and is less than his RSA modulus.</t> <t>Bob decrypts the ciphertext with his RSA private key to obtain the integer z:</t> <artwork><![CDATA[ 9c126102a5c1c0354672a3c2f19fc9ddea988f815e1da812c7bd4f8eb082bdd1 4f85a7f7c2f1af11d5333e0d6bcb375bf855f208da72ba27e6fb0655f2825aa6 2b93b1f9bbd3491fed58f0380fa0de36430e3a144d569600bd362609be5b9481 0875990b614e406fa6dff500043cbca95968faba61f795096a7fb3687a51078c 4ca2cb663366b0bea0cd9cccac72a25f3f4ed03deb68b4453bba44b943f4367b 67d6cd10c8ace53f545aac50968fc3c6ecc80f3224b64e37038504e2d2c0e2b2 9d45e46c62826d96331360e4c17ea3ef89a9efc5fac99eda830e81450b6534dc 0bdf042b8f3b706649c631fe51fc2445cc8d447203ec2f41f79cdfea16de1ce6 abdfdc1e2ef2e5d5d8a65e645f397240ef5a26f5e4ff715de782e30ecf477293 e89e13171405909a8e04dd31d21d0c57935fc1ceea8e1033e31e1bc8c56da0f3 d79510f3f380ff58e5a61d361f2f18e99fbae5663172e8cd1f21deaddc5bbbea060d55f1842b93d1a9c888d0bf85d0af9947fe51acf940c7e7577eb79cabecb3 ]]></artwork>060d55f1842b93d1a9c888d0bf85d0af9947fe51acf940c7e7577eb79cabecb3]]></artwork> <t>Bob checks that the integer z is greater than zero and is less than his RSA modulus.</t> <t>Bob derives the shared secret (SS) using KDF3 with SHA-256:</t> <artwork><![CDATA[3cf82ec41b54ed4d37402bbd8f805a52 ]]></artwork>3cf82ec41b54ed4d37402bbd8f805a52]]></artwork> </section> <section anchor="recipient-cms-processing"> <name>Recipient CMS Processing</name> <t>Bob encodes the CMSORIforKEMOtherInfo structure with the algorithm identifier for AES-128-KEYWRAP and a key length of 16 octets. The DER encoding of CMSORIforKEMOtherInfo is not repeated here.</t> <t>Bob derives the key-encryption key from shared secret and the CMSORIforKEMOtherInfo structure with KDF3 and SHA-256, the KEK is:</t> <artwork><![CDATA[e6dc9d62ff2b469bef604c617b018718 ]]></artwork>e6dc9d62ff2b469bef604c617b018718]]></artwork> <t>Bob uses AES-KEY-WRAP to decrypt the content-encryption key with the key-encryptionkey; thekey. The content-encryption key is:</t> <artwork><![CDATA[77f2a84640304be7bd42670a84a1258b ]]></artwork>77f2a84640304be7bd42670a84a1258b]]></artwork> <t>Bob decrypts the content using AES-128-CBC with the content- encryption key. The 16-octet IV used is:</t> <artwork><![CDATA[480ccafebabefacedbaddecaf8887781 ]]></artwork>480ccafebabefacedbaddecaf8887781]]></artwork> <t>The received ciphertext content is:</t> <artwork><![CDATA[c6ca65db7bdd76b0f37e2fab6264b66d ]]></artwork>c6ca65db7bdd76b0f37e2fab6264b66d]]></artwork> <t>The resulting padded plaintext content is:</t> <artwork><![CDATA[48656c6c6f2c20776f726c6421030303 ]]></artwork>48656c6c6f2c20776f726c6421030303]]></artwork> <t>After stripping the AES-CBC padding, the plaintext content is:</t> <artwork><![CDATA[ Hello,world! ]]></artwork>world!]]></artwork> </section> </section> <section numbered="false" anchor="acknowledgements"> <name>Acknowledgements</name> <t>We thankJames Randall, Burt Kaliski,<contact fullname="James Randall"/>, <contact fullname="Burt Kaliski"/>, andJohn Brainard<contact fullname="John Brainard"/> as the original authors of <xref target="RFC5990"/>; this document is based on their work.</t> <t>We thank the members of the ASC X9F1 working group for their contributions to drafts of ANS X9.44, which led to <xref target="RFC5990"/>.</t> <t>We thankBlake Ramsdell, Jim Schaad, Magnus Nystrom, Bob Griffin,<contact fullname="Blake Ramsdell"/>, <contact fullname="Jim Schaad"/>, <contact fullname="Magnus Nystrom"/>, <contact fullname="Bob Griffin"/>, andJohn Linn<contact fullname="John Linn"/> for helping bring <xref target="RFC5990"/> to fruition.</t> <t>We thankBurt Kaliski, Alex Railean, Joe Mandel, Mike Ounsworth, Peter Campbell, Daniel<contact fullname="Burt Kaliski"/>, <contact fullname="Alex Railean"/>, <contact fullname="Joe Mandel"/>, <contact fullname="Mike Ounsworth"/>, <contact fullname="Peter Campbell"/>, <contact fullname="Daniel VanGeest,Geest"/>, andDavid Ireland<contact fullname="David Ireland"/> for careful review and thoughtful comments that greatly improved this document.</t> </section> </back> <!--##markdown-source: H4sIAAAAAAAAA+29aXPrypEg+h2/AnMc8SzNESXsBM8de5qrRG2USGrt6Y7A 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If there are no objections, we will use the form on the right. PKCS #1 v1.5 vs. PKCS #1 v1.5 algorithm RSA-KEM vs. RSA-KEM algorithm vs. RSA-KEM Algorithm --> </rfc>