draft-ietf-smime-cms-rsa-kem-08.txt   draft-ietf-smime-cms-rsa-kem-09.txt 
S/MIME WG James Randall, Randall Consulting
Internet Draft Burt Kaliski, EMC
Intended Status: Standards Track John Brainard, RSA
Sean Turner, IECA
Expires: June 8, 2010 December 8, 2009
S/MIME Working Group James Randall, Randall Consulting Use of the RSA-KEM Key Transport Algorithm in CMS
Internet Draft Burt Kaliski, EMC <draft-ietf-smime-cms-rsa-kem-09.txt>
John Brainard, RSA
Sean Turner, IECA
Expires: June 6, 2010 Category: Standards
December 7, 2009
Use of the RSA-KEM Key Transport Algorithm in CMS Status of this Memo
<draft-ietf-smime-cms-rsa-kem-08.txt>
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Copyright Notice This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Copyright (c) 2009 IETF Trust and the persons identified as the Abstract
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward)
Provisions Relating to IETF Documents in effect on the date of mechanism for transporting keying data to a recipient using the
publication of this document (http://trustee.ietf.org/license-info). recipient's RSA public key. This document specifies the conventions
Please review these documents carefully, as they describe your for using the RSA-KEM Key Transport Algorithm with the Cryptographic
rights and restrictions with respect to this document. Message Syntax (CMS). The ASN.1 syntax is aligned with ANS X9.44 and
ISO/IEC 18033-2.
Comments or suggestions for improvement may be made on the "ietf- Conventions Used in This Document
smime" mailing list, or directly to the authors.
Abstract The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [STDWORDS].
The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward) Table of Contents
mechanism for transporting keying data to a recipient using the
recipient's RSA public key. 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 ANS X9.44 and
ISO/IEC 18033-2.
Conventions Used in This Document 1. Introduction...................................................3
2. Use in CMS.....................................................4
2.1. Underlying Components.....................................4
2.2. RecipientInfo Conventions.................................5
2.3. Certificate Conventions...................................5
2.4. SMIMECapabilities Attribute Conventions...................6
3. Security Considerations........................................7
4. References.....................................................9
4.1. Normative References......................................9
4.2. Informative References....................................9
Appendix A. RSA-KEM Key Transport Algorithm......................11
A.1. Underlying Components....................................11
A.2. Sender's Operation.......................................11
A.3. Recipient's Operations...................................12
Appendix B. ASN.1 Syntax.........................................14
B.2 Selected Underlying Components............................16
B.2.1. Key Derivation Functions............................16
B.2.2 Symmetric Key-Wrapping Schemes.......................18
B.3 ASN.1 module..............................................19
B.4 Examples..................................................24
IANA Considerations..............................................25
Acknowledgements.................................................25
Authors' Addresses...............................................26
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 1. Introduction
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [STDWORDS].
1. Introduction 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.
The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward) Most previous key transport algorithms based on the RSA public-key
mechanism for transporting keying data to a recipient using the cryptosystem (e.g., the popular PKCS #1 v1.5 algorithm [PKCS1]) have
recipient's RSA public key. the following general form:
Most previous key transport algorithms based on the RSA public-key 1. Format or "pad" the keying data to obtain an integer m.
cryptosystem (e.g., the popular PKCS #1 v1.5 algorithm [PKCS1]) have
the following general form:
1. Format or "pad" the keying data to obtain an integer m. 2. Encrypt the integer m with the recipient's RSA public key:
2. Encrypt the integer m with the recipient's RSA public key: c = m^e mod n
c = m^e mod n 3. Output c as the encrypted keying data.
3. Output c as the encrypted keying data. The RSA-KEM Key Transport Algorithm takes a different approach that
provides higher security assurance, by encrypting a _random_ integer
with the recipient's public key, and using a symmetric key-wrapping
scheme to encrypt the keying data. It has the following form:
The RSA-KEM Key Transport Algorithm takes a different approach that 1. Generate a random integer z between 0 and n-1.
provides higher security assurance, by encrypting a _random_ integer
with the recipient's public key, and using a symmetric key-wrapping
scheme to encrypt the keying data. It has the following form:
1. Generate a random integer z between 0 and n-1. 2. Encrypt the integer z with the recipient's RSA public key:
2. Encrypt the integer z with the recipient's RSA public key: c = z^e mod n
c = z^e mod n 3. Derive a key-encrypting key KEK from the integer z.
3. Derive a key-encrypting key KEK from the integer z. 4. Wrap the keying data using KEK to obtain wrapped keying data WK.
4. Wrap the keying data using KEK to obtain wrapped keying data WK. 5. Output c and WK as the encrypted keying data.
5. Output c and WK as the encrypted keying data. This different approach provides higher security assurance because
(a) the input to the underlying RSA operation is effectively a 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, and (b)
the input is independent of the keying data so the result of the RSA
decryption operation is not directly available to an adversary. As a
result, the algorithm enjoys a "tight" security proof in the random
oracle model. (In other padding schemes, such as PKCS #1 v1.5, the
input has structure and/or depends on the keying data, and the
provable security assurances are not as strong.) The approach is also
architecturally convenient because the public-key operations are
separate from the symmetric operations on the keying data. One
benefit is that the length of the keying data is bounded only by the
symmetric key-wrapping scheme, not the size of the RSA modulus.
This different approach provides higher security assurance because The RSA-KEM Key Transport Algorithm in various forms is being adopted
(a) the input to the underlying RSA operation is effectively a random in several draft standards as well as in ANS-X9.44 and ISO/IEC 18033-
integer between 0 and n-1, where n is the RSA modulus, so it does not 2. It has also been recommended by the NESSIE project [NESSIE].
have any structure that could be exploited by an adversary, and (b)
the input is independent of the keying data so the result of the RSA
decryption operation is not directly available to an adversary. As a
result, the algorithm enjoys a "tight" security proof in the random
oracle model. (In other padding schemes, such as PKCS #1 v1.5, the
input has structure and/or depends on the keying data, and the
provable security assurances are not as strong.) The approach is also
architecturally convenient because the public-key operations are
separate from the symmetric operations on the keying data. One
benefit is that the length of the keying data is bounded only by the
symmetric key-wrapping scheme, not the size of the RSA modulus.
The RSA-KEM Key Transport Algorithm in various forms is being adopted For completeness, a specification of the algorithm is given in
in several draft standards as well as in ANS-X9.44 and ISO/IEC 18033- Appendix A of this document; ASN.1 syntax is given in Appendix B.
2. It has also been recommended by the NESSIE project [NESSIE].
For completeness, a specification of the algorithm is given in NOTE: The term KEM stands for "key encapsulation mechanism" and
Appendix A of this document; ASN.1 syntax is given in Appendix B. refers to the first three steps of the process above. The
formalization of key transport algorithms (or more generally,
asymmetric encryption schemes) in terms of key encapsulation
mechanisms is described further in research by Victor Shoup leading
to the development of the ISO/IEC 18033-2 standard [SHOUP].
NOTE: The term KEM stands for "key encapsulation mechanism" and 2. Use in CMS
refers to the first three steps of the process above. The
formalization of key transport algorithms (or more generally,
asymmetric encryption schemes) in terms of key encapsulation
mechanisms is described further in research by Victor Shoup leading
to the development of the ISO/IEC 18033-2 standard [SHOUP].
2. Use in CMS The RSA-KEM Key Transport Algorithm MAY be employed for one or more
recipients in the CMS enveloped-data content type (Section 6 of
[CMS]), where the keying data processed by the algorithm is the CMS
content-encryption key.
The RSA-KEM Key Transport Algorithm MAY be employed for one or more The RSA-KEM Key Transport Algorithm SHOULD be considered for new CMS-
recipients in the CMS enveloped-data content type (Section 6 of based applications as a replacement for the widely implemented RSA
[CMS]), where the keying data processed by the algorithm is the CMS encryption algorithm specified originally in PKCS #1 v1.5 (see
content-encryption key. [PKCS1] and Section 4.2.1 of [CMSALGS]), which is vulnerable to
chosen-ciphertext attacks. The RSAES-OAEP Key Transport Algorithm has
also been proposed as a replacement (see [PKCS1] and [CMS-OAEP]).
RSA-KEM has the advantage over RSAES-OAEP of a tighter security
proof, but the disadvantage of slightly longer encrypted keying data.
The RSA-KEM Key Transport Algorithm SHOULD be considered for new 2.1. Underlying Components
CMS-based applications as a replacement for the widely implemented
RSA encryption algorithm specified originally in PKCS #1 v1.5 (see
[PKCS1] and Section 4.2.1 of [CMSALGS]), which is vulnerable to
chosen-ciphertext attacks. The RSAES-OAEP Key Transport Algorithm has
also been proposed as a replacement (see [PKCS1] and [CMS-OAEP]).
RSA-KEM has the advantage over RSAES-OAEP of a tighter security
proof, but the disadvantage of slightly longer encrypted keying data.
2.1. Underlying Components A CMS implementation that supports the RSA-KEM Key Transport
Algorithm MUST support at least the following underlying components:
A CMS implementation that supports the RSA-KEM Key Transport o For the key derivation function, KDF3 (see [IEEE-P1363a]) based on
Algorithm MUST support at least the following underlying components: SHA-256 (see [FIPS-180-2]). KDF3 is an instantiation of the
Concatenation Key Derivation Function defined in [NIST-SP800-56A].
o For the key derivation function, KDF3 (see [IEEE-P1363a]) based on o For the key-wrapping scheme, AES-Wrap-128, i.e., the AES Key Wrap
SHA-256 (see [FIPS-180-2]). KDF3 is an instantiation of the with a 128-bit key encrypting key (see [AES-WRAP])
Concatenation Key Derivation Function defined in [SP800-56A].
o For the key-wrapping scheme, AES-Wrap-128, i.e., the AES Key Wrap An implementation SHOULD also support KDF2 (see [ANS-X9.44]) based on
with a 128-bit key encrypting key (see [AES-WRAP]) SHA-1 (this function is also specified as the key derivation function
in [ANS-X9.63]). The Camellia key wrap algorithm (see [CAMELLIA])
SHOULD be supported, and, if 3DES is supported as a content-
encryption cipher, then the Triple-DES Key Wrap (see [3DES-WRAP])
SHOULD also be supported.
An implementation SHOULD also support KDF2 (see [ANS-X9.44]) based on It MAY support other underlying components. When AES or Camellia are
SHA-1 (this function is also specified as the key derivation function used the data block size is 128 bits while the key size can be 128,
in [ANS-X9.63]). The Camellia key wrap algorithm (see [CAMELLIA]) 192, or 256 bits while Triple DES requires a data block size of 64
SHOULD be supported, and, if 3DES is supported as a content- bits and a key size of 112 or 168 bits.
encryption cipher, then the Triple-DES Key Wrap (see [3DES-WRAP])
SHOULD also be supported.
It MAY support other underlying components. When AES or Camellia are 2.2. RecipientInfo Conventions
used the data block size is 128 bits while the key size can be 128,
192, or 256 bits while Triple DES requires a data block size of 64
bits and a key size of 112 or 168 bits.
2.2. RecipientInfo Conventions When the RSA-KEM Key Transport Algorithm is employed for a recipient,
the RecipientInfo alternative for that recipient MUST be
KeyTransRecipientInfo. The algorithm-specific fields of the
KeyTransRecipientInfo value MUST have the following values:
When the RSA-KEM Key Transport Algorithm is employed for a recipient, o keyEncryptionAlgorithm.algorithm MUST be id-rsa-kem (see Appendix
the RecipientInfo alternative for that recipient MUST be B)
KeyTransRecipientInfo. The algorithm-specific fields of the
KeyTransRecipientInfo value MUST have the following values:
o keyEncryptionAlgorithm.algorithm MUST be id-rsa-kem see Appendix o keyEncryptionAlgorithm.parameters MUST be a value of type
B) GenericHybridParameters, identifying the RSA-KEM key encapsulation
mechanism (see Appendix B)
o keyEncryptionAlgorithm.parameters MUST be a value of type o encryptedKey MUST be the encrypted keying data output by the
GenericHybridParameters, identifying the RSA-KEM key encapsulation algorithm, where the keying data is the content-encryption key. (see
mechanism (see Appendix B) Appendix A)
o encryptedKey MUST be the encrypted keying data output by the 2.3. Certificate Conventions
algorithm, where the keying data is the content-encryption
key.(see Appendix A)
2.3. Certificate Conventions The conventions specified in this section augment RFC 5280 [PROFILE].
The conventions specified in this section augment RFC 5280 [PROFILE]. A recipient who employs the RSA-KEM Key Transport Algorithm MAY
identify the public key in a certificate by the same
AlgorithmIdentifier as for the PKCS #1 v1.5 algorithm, i.e., using
the rsaEncryption object identifier [PKCS1]. The fact that the user
will accept RSA-KEM with this public key is not indicated by the use
of this identifier. This may be signed by the use of the appropriate
SMIME Capabilities either in a message or in the certificate.
A recipient who employs the RSA-KEM Key Transport Algorithm MAY If the recipient wishes only to employ the RSA-KEM Key Transport
identify the public key in a certificate by the same Algorithm with a given public key, the recipient MUST identify the
AlgorithmIdentifier as for the PKCS #1 v1.5 algorithm, i.e., using public key in the certificate using the id-rsa-kem object identifier
the rsaEncryption object identifier [PKCS1]. The fact that the user (see Appendix B). The parameters are absent.
will accept RSA-KEM with this public key is not indicated by the use
of this identifier. This may be signed by the use of the appropriate
SMIME Capabilities either in a message or in the certificate.
If the recipient wishes only to employ the RSA-KEM Key Transport Regardless of the AlgorithmIdentifier used, the RSA public key is
Algorithm with a given public key, the recipient MUST identify the encoded in the same manner in the subject public key information. The
public key in the certificate using the id-rsa-kem object identifier RSA public key MUST be encoded using the type RSAPublicKey type:
(see Appendix B). The parameters are absent.
Regardless of the AlgorithmIdentifier used, the RSA public key is RSAPublicKey ::= SEQUENCE {
encoded in the same manner in the subject public key information. The modulus INTEGER, -- n
RSA public key MUST be encoded using the type RSAPublicKey type: publicExponent INTEGER -- e
}
RSAPublicKey ::= SEQUENCE { Here, the modulus is the modulus n, and publicExponent is the public
modulus INTEGER, -- n exponent e. The DER encoded RSAPublicKey is carried in the
publicExponent INTEGER -- e subjectPublicKey BIT STRING within the subject public key
} information.
Here, the modulus is the modulus n, and publicExponent is the public The intended application for the key MAY be indicated in the key
exponent e. The DER encoded RSAPublicKey is carried in the usage certificate extension (see [PROFILE], Section 4.2.1.3). If the
subjectPublicKey BIT STRING within the subject public key keyUsage extension is present in a certificate that conveys an RSA
information. public key with the id-rsa-kem object identifier as discussed above,
then the key usage extension MUST contain the following value:
The intended application for the key MAY be indicated in the key keyEncipherment.
usage certificate extension (see [PROFILE], Section 4.2.1.3). If the
keyUsage extension is present in a certificate that conveys an RSA
public key with the id-rsa-kem object identifier as discussed above,
then the key usage extension MUST contain the following value:
keyEncipherment. dataEncipherment SHOULD NOT be present. That is, a key intended to be
employed only with the RSA-KEM Key Transport Algorithm SHOULD NOT
also be employed for data encryption or for authentication such as in
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 the other, and may be
essential to maintain provable security.
dataEncipherment SHOULD NOT be present. That is, a key intended to be 2.4. SMIMECapabilities Attribute Conventions
employed only with the RSA-KEM Key Transport Algorithm SHOULD NOT
also be employed for data encryption or for authentication such as in
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 the other, and may be
essential to maintain provable security.
2.4. SMIMECapabilities Attribute Conventions RFC 3851 [MSG], Section 2.5.2 defines the SMIMECapabilities signed
attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be
used to specify a partial list of algorithms that the software
announcing the SMIMECapabilities can support. When constructing a
signedData object, compliant software MAY include the
SMIMECapabilities signed attribute announcing that it supports the
RSA-KEM Key Transport algorithm.
RFC 3851 [MSG], Section 2.5.2 defines the SMIMECapabilities signed The SMIMECapability SEQUENCE representing the RSA-KEM Key Transport
attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be Algorithm MUST include the id-rsa-kem object identifier (see Appendix
used to specify a partial list of algorithms that the software B) in the capabilityID field and MUST include a
announcing the SMIMECapabilities can support. When constructing a GenericHybridParameters value in the parameters field identifying the
signedData object, compliant software MAY include the components with which the algorithm is to be employed.
SMIMECapabilities signed attribute announcing that it supports the
RSA-KEM Key Transport algorithm.
The SMIMECapability SEQUENCE representing the RSA-KEM Key Transport The DER encoding of a SMIMECapability SEQUENCE is the same as the DER
Algorithm MUST include the id-rsa-kem object identifier (see Appendix encoding of an AlgorithmIdentifier. Example DER encodings for typical
B) in the capabilityID field and MUST include a sets of components are given in Appendix B.4.
GenericHybridParameters value in the parameters field identifying the
components with which the algorithm is to be employed.
The DER encoding of a SMIMECapability SEQUENCE is the same as the DER 3. Security Considerations
encoding of an AlgorithmIdentifier. Example DER encodings for typical
sets of components are given in Appendix B.4.
3. Security Considerations The security of the RSA-KEM Key Transport Algorithm described in this
document can be shown to be tightly related to the difficulty of
either solving the RSA problem or breaking the underlying symmetric
key-wrapping scheme, if the underlying key derivation function is
modeled as a random oracle, and assuming that the symmetric key-
wrapping scheme satisfies the properties of a data encapsulation
mechanism [SHOUP]. While in practice a random-oracle result does not
provide an actual security proof for any particular key derivation
function, the result does provide assurance that the general
construction is reasonable; a key derivation function would need to
be particularly weak to lead to an attack that is not possible in the
random oracle model.
The security of the RSA-KEM Key Transport Algorithm described in this The RSA key size and the underlying components should be selected
document can be shown to be tightly related to the difficulty of consistent with the desired symmetric security level for an
either solving the RSA problem or breaking the underlying symmetric application. Several security levels have been identified in NIST
key-wrapping scheme, if the underlying key derivation function is FIPS PUB 800-57 [NIST-GUIDELINE]. For brevity, the first threelevels
modeled as a random oracle, and assuming that the symmetric key- are mentioned here:
wrapping scheme satisfies the properties of a data encapsulation
mechanism [SHOUP]. While in practice a random-oracle result does not
provide an actual security proof for any particular key derivation
function, the result does provide assurance that the general
construction is reasonable; a key derivation function would need to
be particularly weak to lead to an attack that is not possible in the
random oracle model.
The RSA key size and the underlying components should be selected o 80-bit security. The RSA key size SHOULD be at least 1024 bits,
consistent with the desired symmetric security level for an the hash function underlying the KDF SHOULD be SHA-1 or above, and
application. Several security levels have been identified in [NIST- the symmetric key-wrapping scheme SHOULD be AES Key Wrap, Triple-DES
FIPS PUB 800-57]. For brevity, the first three levels are mentioned Key Wrap, or Camellia Key Wrap.
here:
o 80-bit security. The RSA key size SHOULD be at least 1024 bits, o 112-bit security. The RSA key size SHOULD be at least 2048 bits,
the hash function underlying the KDF SHOULD be SHA-1 or above, and the hash function underlying the KDF SHOULD be SHA-224 or above, and
the symmetric key-wrapping scheme SHOULD be AES Key Wrap, Triple- the symmetric key-wrapping scheme SHOULD be AES Key Wrap, Triple-DES
DES Key Wrap, or Camellia Key Wrap. Key Wrap, or Camellia Key Wrap.
o 112-bit security. The RSA key size SHOULD be at least 2048 bits, o 128-bit security. The RSA key size SHOULD be at least 3072 bits,
the hash function underlying the KDF SHOULD be SHA-224 or above, the hash function underlying the KDF SHOULD be SHA-256 or above, and
and the symmetric key-wrapping scheme SHOULD be AES Key Wrap, the symmetric key-wrapping scheme SHOULD be AES Key Wrap or Camellia
Triple-DES Key Wrap, or Camellia Key Wrap. Key Wrap.
o 128-bit security. The RSA key size SHOULD be at least 3072 bits, Note that the AES Key Wrap or Camellia Key Wrap MAY be used at all
the hash function underlying the KDF SHOULD be SHA-256 or above, three of these levels; the use of AES or Camellia does not require a
and the symmetric key-wrapping scheme SHOULD be AES Key Wrap or 128-bit security level for other components.
Camellia Key Wrap.
Note that the AES Key Wrap or Camellia Key Wrap MAY be used at all Implementations MUST protect the RSA private key and the content-
three of these levels; the use of AES or Camellia does not require a encryption key. Compromise of the RSA private key may result in the
128-bit security level for other components. disclosure of all messages protected with that key. Compromise of the
content-encryption key may result in disclosure of the associated
encrypted content.
Implementations MUST protect the RSA private key and the content- Additional considerations related to key management may be found in
encryption key. Compromise of the RSA private key may result in the [NIST-GUIDELINE].
disclosure of all messages protected with that key. Compromise of the
content-encryption key may result in disclosure of the associated
encrypted content.
Additional considerations related to key management may be found in The security of the algorithm also depends on the strength of the
[NIST-GUIDELINE]. random number generator, which SHOULD have a comparable security
level. For further discussion on random number generation, please see
[RANDOM].
The security of the algorithm also depends on the strength of the Implementations SHOULD NOT reveal information about intermediate
random number generator, which SHOULD have a comparable security values or calculations, whether by timing or other "side channels",
level. For further discussion on random number generation, please see or otherwise an opponent may be able to determine information about
[RANDOM]. 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.
Implementations SHOULD NOT reveal information about intermediate Generally, good cryptographic practice employs a given RSA key pair
values or calculations, whether by timing or other "side channels", in only one scheme. This practice avoids the risk that vulnerability
or otherwise an opponent may be able to determine information about in one scheme may compromise the security of the other, and may be
the keying data and/or the recipient's private key. Although not all essential to maintain provable security. While RSA public keys have
intermediate information may be useful to an opponent, it is often been employed for multiple purposes such as key transport and
preferable to conceal as much information as is practical, unless digital signature without any known bad interactions, for increased
analysis specifically indicates that the information would not be security assurance, such combined use of an RSA key pair is NOT
useful. RECOMMENDED in the future (unless the different schemes are
specifically designed to be used together).
Generally, good cryptographic practice employs a given RSA key pair Accordingly, an RSA key pair used for the RSA-KEM Key Transport
in only one scheme. This practice avoids the risk that vulnerability Algorithm SHOULD NOT also be used for digital signatures. (Indeed,
in one scheme may compromise the security of the other, and may be ASC X9 requires such a separation between key establishment key pairs
essential to maintain provable security. While RSA public keys have and digital signature key pairs.) Continuing this principle of key
often been employed for multiple purposes such as key transport and separation, a key pair used for the RSA-KEM Key Transport Algorithm
digital signature without any known bad interactions, for increased SHOULD NOT be used with other key establishment schemes, or for data
security assurance, such combined use of an RSA key pair is NOT encryption, or with more than one set of underlying algorithm
RECOMMENDED in the future (unless the different schemes are components.
specifically designed to be used together).
Accordingly, an RSA key pair used for the RSA-KEM Key Transport Parties MAY formalize the assurance that one another's
Algorithm SHOULD NOT also be used for digital signatures. (Indeed, implementations are correct through implementation validation, e.g.
ASC X9 requires such a separation between key establishment key pairs NIST's Cryptographic Module Validation Program (CMVP).
and digital signature key pairs.) Continuing this principle of key
separation, a key pair used for the RSA-KEM Key Transport Algorithm
SHOULD NOT be used with other key establishment schemes, or for data
encryption, or with more than one set of underlying algorithm
components.
Parties MAY formalize the assurance that one another's 4. References
implementations are correct through implementation validation, e.g.
NIST's Cryptographic Module Validation Program (CMVP).
4. References 4.1. Normative References
4.1. Normative References [3DES-WRAP] Housley, R. Triple-DES and RC2 Key Wrapping. RFC
3217. December 2001.
[3DES-WRAP] Housley, R. Triple-DES and RC2 Key Wrapping. RFC [AES-WRAP] Schaad, J. and R. Housley. Advanced Encryption
3217. December 2001. Standard (AES) Key Wrap Algorithm. RFC 3394.
September 2002.
[AES-WRAP] Schaad, J. and R. Housley. Advanced Encryption [ANS-X9.63] American National Standard X9.63-2002: Public Key
Standard (AES) Key Wrap Algorithm. RFC 3394. Cryptography for the Financial Services Industry:
September 2002. Key Agreement and Key Transport Using Elliptic
Curve Cryptography.
[ANS-X9.63] American National Standard X9.63-2002: Public Key [CAMELLIA] Kato, A., Moriai, S., and Kanda, M.: Use of the
Cryptography for the Financial Services Industry: Camellia Encryption Algorithm in Cryptographic
Key Agreement and Key Transport Using Elliptic Message Syntax. RFC 3657. December 2005.
Curve Cryptography.
[CAMELLIA] Kato, A., Moriai, S., and Kanda, M.: Use of the [CMS] Housley, R. Cryptographic Message Syntax. RFC
Camellia Encryption Algorithm in Cryptographic 5652. September 20009.
Message Syntax. RFC 3657. December 2005.
[CMS] Housley, R. Cryptographic Message Syntax. RFC [CMSALGS] Housley, R. Cryptographic Message Syntax (CMS)
3852. July 2004. Algorithms. RFC 3370. August 2002.
[CMSALGS] Housley, R. Cryptographic Message Syntax (CMS) [FIPS-180-2] National Institute of Standards and Technology
Algorithms. RFC 3370. August 2002. (NIST). FIPS 180-2: Secure Hash Standard. August
2002.
[FIPS-180-2] National Institute of Standards and Technology [MSG] Ramsdell, B. S/MIME Version 3 Message
(NIST). FIPS 180-2: Secure Hash Standard. August Specification. RFC 3851. July 2004.
2002.
[MSG] Ramsdell, B. S/MIME Version 3 Message [PROFILE] Cooper, D., Santesson, S., Farrell, S., Boeyen,
Specification. RFC 3851. July 2004. S., Housley, R., and W. Polk. Internet X.509
Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile. RFC
5280. May 2008.
[PROFILE] Cooper, D., Santesson, S., Farrell, S., [STDWORDS] Bradner, S. Key Words for Use in RFCs to Indicate
Boeyen, S., Housley, R., and W. Polk. Internet Requirement Levels. RFC 2119. March 1997.
X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile.
RFC 5280. May 2008.
[STDWORDS] Bradner, S. Key Words for Use in RFCs to Indicate 4.2. Informative References
Requirement Levels. RFC 2119. March 1997.
4.2. Informative References [ANS-X9.44] ASC X9F1 Working Group. American National Standard
X9.44: Public Key Cryptography for the Financial
Services Industry -- Key Establishment Using
Integer Factorization Cryptography. 2007
[ANS-X9.44] ASC X9F1 Working Group. American National [CMS-OAEP] Housley, R. Use of the RSAES-OAEP Key Transport
Standard X9.44: Public Key Cryptography for the Algorithm in the Cryptographic Message Syntax
Financial Services Industry -- Key Establishment (CMS). RFC 3560. July 2003.
Using Integer Factorization Cryptography. 2007
[CMS-OAEP] Housley, R. Use of the RSAES-OAEP Key Transport [IEEE-P1363a] IEEE Std 1363a-2004: Standard Specifications for
Algorithm in the Cryptographic Message Syntax Public Key Cryptography: Additional Techniques.
(CMS). RFC 3560. July 2003. IEEE, 2004.
[IEEE-P1363a] IEEE Std 1363a-2004: Standard Specifications for [ISO-IEC-18033-2] ISO/IEC 18033-2:2005 Information technology --
Public Key Cryptography: Additional Techniques. Security techniques -- Encryption algorithms --
IEEE, 2004. Part 2: Asymmetric Ciphers. ISO/IEC, 2005.
[ISO-IEC-18033-2] ISO/IEC 18033-2:2005 Information technology -- [NESSIE] NESSIE Consortium. Portfolio of Recommended
Security techniques -- Encryption algorithms -- Cryptographic Primitives. February 27, 2003.
Part 2: Asymmetric Ciphers. ISO/IEC, 2005. Available via http://www.cryptonessie.org/.
[NESSIE] NESSIE Consortium. Portfolio of Recommended [NIST-GUIDELINE] National Institute of Standards and Technology.
Cryptographic Primitives. February 27, 2003. Special Publication 800-57: Recommendation for
Available via http://www.cryptonessie.org/. Pairwise Key Establishment Schemes Using Discrete
Logarithm Cryptography March 2007. Available via:
http://csrc.nist.gov/publications/index.html.
[NIST-GUIDELINE] National Institute of Standards and Technology. [NIST-SP800-56A] National Institute of Standards and Technology.
Special Publication 800-57: Recommendation for Special Publication 800-56A: Recommendation for
Pairwise Key Establishment Schemes Using Discrete Key Management. Part 1: General Guideline. August
Logarithm Cryptography March 2007. Available via: 2005. Available via:
http://csrc.nist.gov/publications/index.html. http://csrc.nist.gov/publications/index.html.
[NIST-SP800-56A] National Institute of Standards and Technology. [PKCS1] Jonsson, J. and B. Kaliski. PKCS #1: RSA
Special Publication 800-56A: Recommendation for Cryptography Specifications Version 2.1. RFC 3447.
Key Management. Part 1: General Guideline. February 2003.
August 2005. Available via:
http://csrc.nist.gov/publications/index.html.
[PKCS1] Jonsson, J. and B. Kaliski. PKCS #1: RSA [RANDOM] Eastlake, D., S. Crocker, and J. Schiller.
Cryptography Specifications Version 2.1. RFC Randomness Recommendations for Security. RFC 4086.
3447. February 2003. June 2005.
[RANDOM] Eastlake, D., S. Crocker, and J. Schiller. [SHOUP] Shoup, V. A Proposal for an ISO Standard for
Randomness Recommendations for Security. RFC Public Key Encryption. Version 2.1, December 20,
4086. June 2005. 2001. Available via http://www.shoup.net/papers/.
[SHOUP] Shoup, V. A Proposal for an ISO Standard for Appendix A. RSA-KEM Key Transport Algorithm
Public Key Encryption. Version 2.1, December 20,
2001. Available via http://www.shoup.net/papers/.
Appendix A. The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward)
RSA-KEM Key Transport Algorithm mechanism for transporting keying data to a recipient using the
recipient's RSA public key.
The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward) With this type of algorithm, a sender encrypts the keying data using
mechanism for transporting keying data to a recipient using the the recipient's public key to obtain encrypted keying data. The
recipient's RSA public key. recipient decrypts the encrypted keying data using the recipient's
private key to recover the keying data.
With this type of algorithm, a sender encrypts the keying data using A.1. Underlying Components
the recipient's public key to obtain encrypted keying data. The
recipient decrypts the encrypted keying data using the recipient's
private key to recover the keying data.
A.1. Underlying Components The algorithm has the following underlying components:
The algorithm has the following underlying components: o KDF, a key derivation function, which derives keying data of a
specified length from a shared secret value
o KDF, a key derivation function, which derives keying data of a o Wrap, a symmetric key-wrapping scheme, which encrypts keying Data
specified length from a shared secret value using a key-encrypting key
o Wrap, a symmetric key-wrapping scheme, which encrypts keying Data In the following, kekLen denotes the length in bytes of the key-
using a key-encrypting key encrypting key for the underlying symmetric key-wrapping scheme.
In the following, kekLen denotes the length in bytes of the key- In this scheme, the length of the keying data to be transported MUST
encrypting key for the underlying symmetric key-wrapping scheme. be among the lengths supported by the underlying symmetric key-
wrapping scheme. (Both the AES and Camellia Key Wraps, for instance,
require the length of the keying data to be a multiple of 8 bytes,
and at least 16 bytes.) Usage and formatting of the keying data
(e.g., parity adjustment for Triple-DES keys) is outside the scope of
this algorithm. With some key derivation functions, it is possible to
include other information besides the shared secret value in the
input to the function. Also, with some symmetric key-wrapping
schemes, it is possible to associate a label with the keying data.
Such uses are outside the scope of this document, as they are not
directly supported by CMS.
In this scheme, the length of the keying data to be transported MUST A.2. Sender's Operation
be among the lengths supported by the underlying symmetric key-
wrapping scheme. (Both the AES and Camellia Key Wraps, for instance,
require the length of the keying data to be a multiple of 8 bytes,
and at least 16 bytes.) Usage and formatting of the keying data
(e.g., parity adjustment for Triple-DES keys) is outside the scope of
this algorithm. With some key derivation functions, it is possible to
include other information besides the shared secret value in the
input to the function. Also, with some symmetric key-wrapping
schemes, it is possible to associate a label with the keying data.
Such uses are outside the scope of this document, as they are not
directly supported by CMS.
A.2. Sender's Operations Let (n,e) be the recipient's RSA public key (see [PKCS1] for details)
and let K be the keying data to be transported.
Let (n,e) be the recipient's RSA public key (see [PKCS1] for Let nLen denote the length in bytes of the modulus n, i.e., the least
details) and let K be the keying data to be transported. integer such that 2^{8*nLen} > n.
Let nLen denote the length in bytes of the modulus n, i.e., the least The sender performs the following operations:
integer such that 2^{8*nLen} > n.
The sender performs the following operations: 1. Generate a random integer z between 0 and n-1 (see Note), and
convert z to a byte string Z of length nLen, most significant byte
first:
1. Generate a random integer z between 0 and n-1 (see Note), and z = RandomInteger (0, n-1)
convert z to a byte string Z of length nLen, most significant byte
first:
z = RandomInteger (0, n-1) Z = IntegerToString (z, nLen)
Z = IntegerToString (z, nLen)
2. Encrypt the random integer z using the recipient's public key n,e) 2. Encrypt the random integer z using the recipient's public key n,e)
and convert the resulting integer c to a ciphertext C, a byte and convert the resulting integer c to a ciphertext C, a byte string
string of length nLen: of length nLen:
c = z^e mod n c = z^e mod n
C = IntegerToString (c, nLen)
3. Derive a key-encrypting key KEK of length kekLen bytes from the C = IntegerToString (c, nLen)
byte string Z using the underlying key derivation function:
KEK = KDF (Z, kekLen) 3. Derive a key-encrypting key KEK of length kekLen bytes from the
byte string Z using the underlying key derivation function:
4. Wrap the keying data K with the key-encrypting key KEK using the KEK = KDF (Z, kekLen)
underlying key-wrapping scheme to obtain wrapped keying data WK:
WK = Wrap (KEK, K) 4. Wrap the keying data K with the key-encrypting key KEK using the
underlying key-wrapping scheme to obtain wrapped keying data WK:
5. Concatenate the ciphertext C and the wrapped keying data WK to WK = Wrap (KEK, K)
obtain the encrypted keying data EK:
EK = C || WK 5. Concatenate the ciphertext C and the wrapped keying data WK to
obtain the encrypted keying data EK:
6. Output the encrypted keying data EK. EK = C || WK
NOTE: The random integer z MUST be generated independently at random 6. Output the encrypted keying data EK.
for different encryption operations, whether for the same or
different recipients.
A.3. Recipient's Operations NOTE: The random integer z MUST be generated independently at random
for different encryption operations, whether for the same or
different recipients.
Let (n,d) be the recipient's RSA private key (see [PKCS1]; other A.3. Recipient's Operations
private key formats are allowed) and let EK be the encrypted keying
data.
Let nLen denote the length in bytes of the modulus n. Let (n,d) be the recipient's RSA private key (see [PKCS1]; other
private key formats are allowed) and let EK be the encrypted keying
data.
The recipient performs the following operations: Let nLen denote the length in bytes of the modulus n.
1. Separate the encrypted keying data EK into a ciphertext C of The recipient performs the following operations:
length nLen bytes and wrapped keying data WK:
C || WK = EK 1. Separate the encrypted keying data EK into a ciphertext C of
length nLen bytes and wrapped keying data WK:
If the length of the encrypted keying data is less than nLen C || WK = EK
bytes, output "decryption error" and stop.
2. Convert the ciphertext C to an integer c, most significant byte If the length of the encrypted keying data is less than nLen
first. Decrypt the integer c using the recipient's private key bytes, output "decryption error" and stop.
(n,d) to recover an integer z (see Note):
c = StringToInteger (C) 2. Convert the ciphertext C to an integer c, most significant byte
z = c^d mod n first. Decrypt the integer c using the recipient's private key
(n,d) to recover an integer z (see Note):
If the integer c is not between 0 and n-1, output "decryption c = StringToInteger (C)
error" and stop.
3. Convert the integer z to a byte string Z of length nLen, most z = c^d mod n
significant byte first (see Note):
Z = IntegerToString (z, nLen) If the integer c is not between 0 and n-1, output "decryption
error" and stop.
4. Derive a key-encrypting key KEK of length kekLen bytes from 3. Convert the integer z to a byte string Z of length nLen, most
the byte string Z using the underlying key derivation function significant byte first (see Note):
(see Note):
KEK = KDF (Z, kekLen) Z = IntegerToString (z, nLen)
5. Unwrap the wrapped keying data WK with the key-encrypting key 4. Derive a key-encrypting key KEK of length kekLen bytes from the
KEK using the underlying key-wrapping scheme to recover the byte string Z using the underlying key derivation function (see
keying data K: Note):
K = Unwrap (KEK, WK) KEK = KDF (Z, kekLen)
If the unwrapping operation outputs an error, output "decryption 5. Unwrap the wrapped keying data WK with the key-encrypting key KEK
error" and stop. using the underlying key-wrapping scheme to recover the keying
data K:
6. Output the keying data K. K = Unwrap (KEK, WK)
NOTE: Implementations SHOULD NOT reveal information about the integer If the unwrapping operation outputs an error, output "decryption
z and the string Z, nor about the calculation of the exponentiation error" and stop.
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 SHOULD 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 MUST be securely deleted when they are no longer
needed.
Appendix B. 6. Output the keying data K.
ASN.1 Syntax
The ASN.1 syntax for identifying the RSA-KEM Key Transport Algorithm NOTE: Implementations SHOULD NOT reveal information about the integer
is an extension of the syntax for the "generic hybrid cipher" in z and the string Z, nor about the calculation of the exponentiation
ISO/IEC 18033-2 [ISO-IEC-18033-2], and is the same as employed in ANS in Step 2, the conversion in Step 3, or the key derivation in Step 4,
X9.44 [ANS-X9.44]. The syntax for the scheme is given in Section B.1. whether by timing or other "side channels". The observable behavior
The syntax for selected underlying components including those of the implementation SHOULD be the same at these steps for all
mentioned above is given in B.2. 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 MUST be securely deleted when they are no longer
needed.
The following object identifier prefixes are used in the definitions Appendix B. ASN.1 Syntax
below:
is18033-2 OID ::= { iso(1) standard(0) is18033(18033) part2(2) } The ASN.1 syntax for identifying the RSA-KEM Key Transport Algorithm
is an extension of the syntax for the "generic hybrid cipher" in
ISO/IEC 18033-2 [ISO-IEC-18033-2], and is the same as employed in ANS
X9.44 [ANS-X9.44]. The syntax for the scheme is given in Section B.1.
The syntax for selected underlying components including those
mentioned above is given in B.2.
nistAlgorithm OID ::= { The following object identifier prefixes are used in the definitions
joint-iso-itu-t(2) country(16) us(840) organization(1) below:
gov(101) csor(3) nistAlgorithm(4)
}
pkcs-1 OID ::= { is18033-2 OID ::= { iso(1) standard(0) is18033(18033) part2(2) }
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1)
}
NullParms is a more descriptive synonym for NULL when an algorithm nistAlgorithm OID ::= {
identifier has null parameters: joint-iso-itu-t(2) country(16) us(840) organization(1)
gov(101) csor(3) nistAlgorithm(4)
}
NullParms ::= NULL pkcs-1 OID ::= {
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1)
}
The material in this Appendix is based on ANS X9.44. NullParms is a more descriptive synonym for NULL when an algorithm
identifier has null parameters:
B.1 RSA-KEM Key Transport Algorithm NullParms ::= NULL
The object identifier for the RSA-KEM Key Transport Algorithm is id- The material in this Appendix is based on ANS X9.44.
rsa-kem, which is defined in the draft as:
id-rsa-kem OID ::= { B.1. RSA-KEM Key Transport Algorithm
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs-9(9) smime(16) alg(3) TBA
}
When id-rsa-kem is used in an AlgorithmIdentifier, the parameters The object identifier for the RSA-KEM Key Transport Algorithm is id-
MUST employ the GenericHybridParameters syntax. The parameters MUST rsa-kem, which is defined in the draft as:
be absent when used in the subjectPublicKeyInfo field The syntax for
GenericHybridParameters is as follows:
GenericHybridParameters ::= { id-rsa-kem OID ::= {
kem KeyEncapsulationMechanism, iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
dem DataEncapsulationMechanism pkcs-9(9) smime(16) alg(3) TBA
} }
The fields of type GenericHybridParameters have the following When id-rsa-kem is used in an AlgorithmIdentifier, the parameters
meanings: MUST employ the GenericHybridParameters syntax. The parameters MUST
be absent when used in the subjectPublicKeyInfo field The syntax for
GenericHybridParameters is as follows:
o kem identifies the underlying key encapsulation mechanism. For the GenericHybridParameters ::= {
RSA-KEM Key Transport Algorithm, the scheme is RSA-KEM from kem KeyEncapsulationMechanism,
ISO/IEC 18033-2. dem DataEncapsulationMechanism
}
The object identifier for RSA-KEM (as a key encapsulation The fields of type GenericHybridParameters have the following
mechanism) is id-kem-rsa, which is defined in ISO/IEC 18033-2 as meanings:
id-kem-rsa OID ::= { o kem identifies the underlying key encapsulation mechanism. For the
is18033-2 key-encapsulation-mechanism(2) rsa(4) RSA-KEM Key Transport Algorithm, the scheme is RSA-KEM from
} ISO/IEC 18033-2.
The associated parameters for id-kem-rsa have type The object identifier for RSA-KEM (as a key encapsulation
RsaKemParameters: mechanism) is id-kem-rsa, which is defined in ISO/IEC 18033-2 as:
RsaKemParameters ::= { id-kem-rsa OID ::= {
keyDerivationFunction KeyDerivationFunction, is18033-2 key-encapsulation-mechanism(2) rsa(4)
keyLength KeyLength }
}
The fields of type RsaKemParameters have the following meanings: The associated parameters for id-kem-rsa have type
RsaKemParameters:
* keyDerivationFunction identifies the underlying key RsaKemParameters ::= {
derivation function. For alignment with ANS X9.44, it keyDerivationFunction KeyDerivationFunction,
MUST be KDF2 or KDF3. However, other key derivation keyLength KeyLength
functions MAY be used with CMS. Please see B.2.1 for }
the syntax for KDF2 and KDF3.
KeyDerivationFunction ::= The fields of type RsaKemParameters have the following meanings:
AlgorithmIdentifier {{KDFAlgorithms}}
KDFAlgorithms ALGORITHM ::= { * keyDerivationFunction identifies the underlying key derivation
kdf2 | kdf3, function. For alignment with ANS X9.44, it MUST be KDF2 or KDF3.
... -- implementations may define other methods However, other key derivation functions MAY be used with CMS.
} Please see B.2.1 for the syntax for KDF2 and KDF3.
* keyLength is the length in bytes of the key-encrypting KeyDerivationFunction ::= AlgorithmIdentifier {{KDFAlgorithms}}
key, which depends on the underlying symmetric key-
wrapping scheme.
KeyLength ::= INTEGER (1..MAX) KDFAlgorithms ALGORITHM ::= {
kdf2 | kdf3,
... -- implementations may define other methods
}
o dem identifies the underlying data encapsulation mechanism. For * keyLength is the length in bytes of the key-encrypting key,
alignment with ANS X9.44, it MUST be an X9-approved symmetric key- which depends on the underlying symmetric key-wrapping scheme.
wrapping scheme. (See Note.) However, other symmetric key-wrapping
schemes MAY be used with CMS. Please see B.2.2 for the syntax for
the AES, Triple-DES, and Camellia Key Wraps.
DataEncapsulationMechanism ::= KeyLength ::= INTEGER (1..MAX)
AlgorithmIdentifier {{DEMAlgorithms}}
DEMAlgorithms ALGORITHM ::= { o dem identifies the underlying data encapsulation mechanism. For
X9-SymmetricKeyWrappingSchemes, alignment with ANS X9.44, it MUST be an X9-approved symmetric
Camellia-KeyWrappingSchemes, key-wrapping scheme. (See Note.) However, other symmetric key-
... -- implementations may define other methods wrapping schemes MAY be used with CMS. Please see B.2.2 for the
} syntax for the AES, Triple-DES, and Camellia Key Wraps.
X9-SymmetricKeyWrappingSchemes ALGORITHM ::= { DataEncapsulationMechanism ::=
aes128-Wrap | aes192-Wrap | aes256-Wrap | tdes-Wrap, AlgorithmIdentifier {{DEMAlgorithms}}
... -- allows for future expansion
}
Camellia-KeyWrappingSchemes ALGORITHM ::= { DEMAlgorithms ALGORITHM ::= {
Camellia128-Wrap | Camellia192-Wrap | Camellia256-Wrap X9-SymmetricKeyWrappingSchemes,
} Camellia-KeyWrappingSchemes,
... -- implementations may define other methods
}
NOTE: The generic hybrid cipher in ISO/IEC 18033-2 can encrypt X9-SymmetricKeyWrappingSchemes ALGORITHM ::= {
arbitrary data, hence the term "data encapsulation mechanism". The aes128-Wrap | aes192-Wrap | aes256-Wrap | tdes-Wrap,
symmetric key-wrapping schemes take the role of data encapsulation ... -- allows for future expansion
mechanisms in the RSA-KEM Key Transport Algorithm. ISO/IEC 18033-2 }
allows only three specific data encapsulation mechanisms, not
including any of these symmetric key-wrapping schemes. However, the
ASN.1 syntax in that document expects that additional algorithms will
be allowed.
B.2 Camellia-KeyWrappingSchemes ALGORITHM ::= {
Camellia128-Wrap | Camellia192-Wrap | Camellia256-Wrap
}
B.2.1 Key Derivation Functions NOTE: The generic hybrid cipher in ISO/IEC 18033-2 can encrypt
arbitrary data, hence the term "data encapsulation mechanism". The
symmetric key-wrapping schemes take the role of data encapsulation
mechanisms in the RSA-KEM Key Transport Algorithm. ISO/IEC 18033-2
allows only three specific data encapsulation mechanisms, not
including any of these symmetric key-wrapping schemes. However, the
ASN.1 syntax in that document expects that additional algorithms will
be allowed.
The object identifier for KDF2 (see [ANS X9.44]) is: B.2 Selected Underlying Components
id-kdf-kdf2 OID ::= { x9-44-components kdf2(1) } B.2.1. Key Derivation Functions
The associated parameters identify the underlying hash function. For The object identifier for KDF2 (see [ANS X9.44]) is:
alignment with ANS X9.44, the hash function MUST be an ASC X9-
approved hash function. However, other hash functions MAY be used
with CMS.
kdf2 ALGORITHM ::= { OID id-kdf-kdf2 PARMS KDF2-HashFunction } id-kdf-kdf2 OID ::= { x9-44-components kdf2(1) }
KDF2-HashFunction ::= AlgorithmIdentifier {{KDF2-
HashFunctions}}
KDF2-HashFunctions ALGORITHM ::= { The associated parameters identify the underlying hash function. For
X9-HashFunctions, alignment with ANS X9.44, the hash function MUST be an ASC X9-
... -- implementations may define other methods approved hash function. However, other hash functions MAY be used
} with CMS.
X9-HashFunctions ALGORITHM ::= { kdf2 ALGORITHM ::= { OID id-kdf-kdf2 PARMS KDF2-HashFunction }
sha1 | sha224 | sha256 | sha384 | sha512,
... -- allows for future expansion
}
The object identifier for SHA-1 is KDF2-HashFunction ::= AlgorithmIdentifier {{KDF2-HashFunctions}}
id-sha1 OID ::= { KDF2-HashFunctions ALGORITHM ::= {
iso(1) identified-organization(3) oiw(14) secsig(3) X9-HashFunctions,
algorithms(2) sha1(26) ... -- implementations may define other methods
} }
The object identifiers for SHA-224, SHA-256, SHA-384 and SHA-512 are X9-HashFunctions ALGORITHM ::= {
sha1 | sha224 | sha256 | sha384 | sha512,
... -- allows for future expansion
}
id-sha224 OID ::= { nistAlgorithm hashAlgs(2) sha224(4) } The object identifier for SHA-1 is:
id-sha256 OID ::= { nistAlgorithm hashAlgs(2) sha256(1) }
id-sha384 OID ::= { nistAlgorithm hashAlgs(2) sha384(2) }
id-sha512 OID ::= { nistAlgorithm hashAlgs(2) sha512(3) }
There has been some confusion over whether the various SHA object id-sha1 OID ::= {
identifiers have a NULL parameter, or no associated parameters. As iso(1) identified-organization(3) oiw(14) secsig(3)
also discussed in [PKCS1], implementations SHOULD generate algorithm algorithms(2) sha1(26)
identifiers without parameters, and MUST accept algorithm identifiers }
either without parameters, or with NULL parameters.
sha1 ALGORITHM ::= { OID id-sha1 } -- NULLParms MUST be The object identifiers for SHA-224, SHA-256, SHA-384 and SHA-512 are
sha224 ALGORITHM ::= { OID id-sha224 } -- accepted for these
sha256 ALGORITHM ::= { OID id-sha256 } -- OIDs
sha384 ALGORITHM ::= { OID id-sha384 } -- ""
sha512 ALGORITHM ::= { OID id-sha512 } -- ""
The object identifier for KDF3 (see [ANS X9.44]) is: id-sha224 OID ::= { nistAlgorithm hashAlgs(2) sha224(4) }
id-sha256 OID ::= { nistAlgorithm hashAlgs(2) sha256(1) }
id-sha384 OID ::= { nistAlgorithm hashAlgs(2) sha384(2) }
id-sha512 OID ::= { nistAlgorithm hashAlgs(2) sha512(3) }
id-kdf-kdf3 OID ::= { x9-44-components kdf3(2) } There has been some confusion over whether the various SHA object
identifiers have a NULL parameter, or no associated parameters. As
also discussed in [PKCS1], implementations SHOULD generate algorithm
identifiers without parameters, and MUST accept algorithm identifiers
either without parameters, or with NULL parameters.
The associated parameters identify the underlying hash function. For sha1 ALGORITHM ::= { OID id-sha1 } -- NULLParms MUST be
alignment with the draft ANS X9.44, the hash function MUST be an ASC sha224 ALGORITHM ::= { OID id-sha224 } -- accepted for these
X9-approved hash function. (See Note.) However, other hash functions sha256 ALGORITHM ::= { OID id-sha256 } -- OIDs
MAY be used with CMS. sha384 ALGORITHM ::= { OID id-sha384 } -- ""
sha512 ALGORITHM ::= { OID id-sha512 } -- ""
kdf3 ALGORITHM ::= { OID id-kdf-kdf3 PARMS KDF3-HashFunction } The object identifier for KDF3 (see [ANS X9.44]) is:
KDF3-HashFunction ::= AlgorithmIdentifier { KDF3-HashFunctions } id-kdf-kdf3 OID ::= { x9-44-components kdf3(2) }
KDF3-HashFunctions ALGORITHM ::= { The associated parameters identify the underlying hash function. For
X9-HashFunctions, alignment with the draft ANS X9.44, the hash function MUST be an ASC
... -- implementations may define other methods X9-approved hash function. (See Note.) However, other hash functions
} MAY be used with CMS.
B.2.2 Symmetric Key-Wrapping Schemes kdf3 ALGORITHM ::= { OID id-kdf-kdf3 PARMS KDF3-HashFunction }
The object identifiers for the AES Key Wrap depends on the size of KDF3-HashFunction ::= AlgorithmIdentifier { KDF3-HashFunctions }
the key encrypting key. There are three object identifiers (see
[AES-WRAP]):
id-aes128-Wrap OID ::= { nistAlgorithm aes(1) aes128-Wrap(5) } KDF3-HashFunctions ALGORITHM ::= {
id-aes192-Wrap OID ::= { nistAlgorithm aes(1) aes192-Wrap(25) } X9-HashFunctions,
id-aes256-Wrap OID ::= { nistAlgorithm aes(1) aes256-Wrap(45) } ... -- implementations may define other methods
}
These object identifiers have no associated parameters. B.2.2 Symmetric Key-Wrapping Schemes
aes128-Wrap ALGORITHM ::= { OID id-aes128-Wrap } The object identifiers for the AES Key Wrap depends on the size of
aes192-Wrap ALGORITHM ::= { OID id-aes192-Wrap } the key encrypting key. There are three object identifiers (see [AES-
aes256-Wrap ALGORITHM ::= { OID id-aes256-Wrap } WRAP]):
The object identifier for the Triple-DES Key Wrap (see [3DES-WRAP]) id-aes128-Wrap OID ::= { nistAlgorithm aes(1) aes128-Wrap(5) }
is id-aes192-Wrap OID ::= { nistAlgorithm aes(1) aes192-Wrap(25) }
id-aes256-Wrap OID ::= { nistAlgorithm aes(1) aes256-Wrap(45) }
id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= { These object identifiers have no associated parameters.
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) alg(3) 6
}
This object identifier has a NULL parameter. aes128-Wrap ALGORITHM ::= { OID id-aes128-Wrap }
aes192-Wrap ALGORITHM ::= { OID id-aes192-Wrap }
aes256-Wrap ALGORITHM ::= { OID id-aes256-Wrap }
tdes-Wrap ALGORITHM ::= The object identifier for the Triple-DES Key Wrap (see [3DES-WRAP])
{ OID id-alg-CMS3DESwrap PARMS NullParms } is:
NOTE: As of this writing, the AES Key Wrap and the Triple-DES Key id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= {
Wrap are in the process of being approved by ASC X9. iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) alg(3) 6
}
The object identifiers for the Camellia Key Wrap depend on the size This object identifier has a NULL parameter.
of the key encrypting key. There are three object identifiers:
id-camellia128-Wrap OBJECT IDENTIFIER ::= tdes-Wrap ALGORITHM ::=
{ iso(1) member-body(2) 392 200011 61 security(1) { OID id-alg-CMS3DESwrap PARMS NullParms }
algorithm(1) key-wrap-algorithm(3)
camellia128-wrap(2) }
id-camellia192-Wrap OBJECT IDENTIFIER ::= NOTE: As of this writing, the AES Key Wrap and the Triple-DES Key
{ iso(1) member-body(2) 392 200011 61 security(1) Wrap are in the process of being approved by ASC X9.
algorithm(1) key-wrap-algorithm(3)
camellia192-wrap(3) }
id-camellia256-Wrap OBJECT IDENTIFIER ::= The object identifiers for the Camellia Key Wrap depend on the size
{ iso(1) member-body(2) 392 200011 61 security(1) of the key encrypting key. There are three object identifiers:
algorithm(1) key-wrap-algorithm(3)
camellia256-wrap(4) }
These object identifiers have no associated parameters. id-camellia128-Wrap OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia128-wrap(2) }
camellia128-Wrap ALGORITHM ::= { OID id-camellia128-Wrap } id-camellia192-Wrap OBJECT IDENTIFIER ::=
camellia192-Wrap ALGORITHM ::= { OID id-camellia192-Wrap } { iso(1) member-body(2) 392 200011 61 security(1)
camellia256-Wrap ALGORITHM ::= { OID id-camellia256-Wrap } algorithm(1) key-wrap-algorithm(3)
camellia192-wrap(3) }
B.3 ASN.1 module id-camellia256-Wrap OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia256-wrap(4) }
CMS-RSA-KEM These object identifiers have no associated parameters.
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs-9(9) smime(16) modules(0) cms-rsa-kem(21) }
DEFINITIONS ::= camellia128-Wrap ALGORITHM ::= { OID id-camellia128-Wrap }
camellia192-Wrap ALGORITHM ::= { OID id-camellia192-Wrap }
camellia256-Wrap ALGORITHM ::= { OID id-camellia256-Wrap }
BEGIN B.3 ASN.1 module
-- EXPORTS ALL CMS-RSA-KEM
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs-9(9) smime(16) modules(0) cms-rsa-kem(21) }
-- IMPORTS None DEFINITIONS ::=
-- Useful types and definitions BEGIN
OID ::= OBJECT IDENTIFIER -- alias -- EXPORTS ALL
-- Unless otherwise stated, if an object identifier has associated -- IMPORTS None
-- parameters (i.e., the PARMS element is specified), the -- Useful types and definitions
-- parameters field shall be included in algorithm identifier
-- values. The parameters field shall be omitted if and only if
-- the object identifier does not have associated parameters
-- (i.e., the PARMS element is omitted), unless otherwise stated.
ALGORITHM ::= CLASS { OID ::= OBJECT IDENTIFIER -- alias
&id OBJECT IDENTIFIER UNIQUE,
&Type OPTIONAL
}
WITH SYNTAX { OID &id [PARMS &Type] }
AlgorithmIdentifier { ALGORITHM:IOSet } ::= SEQUENCE { -- Unless otherwise stated, if an object identifier has associated
algorithm ALGORITHM.&id( {IOSet} ), -- parameters (i.e., the PARMS element is specified), the
parameters ALGORITHM.&Type( {IOSet}{@algorithm} ) OPTIONAL -- parameters field shall be included in algorithm identifier
} -- values. The parameters field shall be omitted if and only if
-- the object identifier does not have associated parameters
-- (i.e., the PARMS element is omitted), unless otherwise stated.
NullParms ::= NULL ALGORITHM ::= CLASS {
&id OBJECT IDENTIFIER UNIQUE,
&Type OPTIONAL
}
WITH SYNTAX { OID &id [PARMS &Type] }
-- ISO/IEC 18033-2 arc AlgorithmIdentifier { ALGORITHM:IOSet } ::= SEQUENCE {
algorithm ALGORITHM.&id( {IOSet} ),
parameters ALGORITHM.&Type( {IOSet}{@algorithm} ) OPTIONAL
}
is18033-2 OID ::= { iso(1) standard(0) is18033(18033) part2(2) } NullParms ::= NULL
-- NIST algorithm arc -- ISO/IEC 18033-2 arc
nistAlgorithm OID ::= { is18033-2 OID ::= { iso(1) standard(0) is18033(18033) part2(2) }
joint-iso-itu-t(2) country(16) us(840) organization(1)
gov(101) csor(3) nistAlgorithm(4)
}
-- PKCS #1 arc -- NIST algorithm arc
pkcs-1 OID ::= { nistAlgorithm OID ::= {
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) joint-iso-itu-t(2) country(16) us(840) organization(1)
} gov(101) csor(3) nistAlgorithm(4)
}
-- RSA-KEM Key Transport Algorithm -- PKCS #1 arc
id-rsa-kem OID ::= { pkcs-1 OID ::= {
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1)
pkcs-9(9) smime(16) alg(3) TBA }
}
GenericHybridParameters ::= SEQUENCE { -- RSA-KEM Key Transport Algorithm
kem KeyEncapsulationMechanism,
dem DataEncapsulationMechanism
}
KeyEncapsulationMechanism ::= AlgorithmIdentifier {{KEMAlgorithms}} id-rsa-kem OID ::= {
id-kem-rsa OID ::= { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
is18033-2 key-encapsulation-mechanism(2) rsa(4) pkcs-9(9) smime(16) alg(3) TBA
} }
RsaKemParameters ::= SEQUENCE { GenericHybridParameters ::= SEQUENCE {
keyDerivationFunction KeyDerivationFunction, kem KeyEncapsulationMechanism,
keyLength KeyLength dem DataEncapsulationMechanism
} }
KeyDerivationFunction ::= AlgorithmIdentifier {{KDFAlgorithms}} KeyEncapsulationMechanism ::= AlgorithmIdentifier {{KEMAlgorithms}}
KDFAlgorithms ALGORITHM ::= { KEMAlgorithms ALGORITHM ::= { kem-rsa, ... }
kdf2 | kdf3,
... -- implementations may define other methods
}
KeyLength ::= INTEGER (1..MAX) kem-rsa ALGORITHM ::= { OID id-kem-rsa PARMS RsaKemParameters }
id-kem-rsa OID ::= {
is18033-2 key-encapsulation-mechanism(2) rsa(4)
}
DataEncapsulationMechanism ::= RsaKemParameters ::= SEQUENCE {
AlgorithmIdentifier {{DEMAlgorithms}} keyDerivationFunction KeyDerivationFunction,
keyLength KeyLength
}
DEMAlgorithms ALGORITHM ::= { KeyDerivationFunction ::= AlgorithmIdentifier {{KDFAlgorithms}}
X9-SymmetricKeyWrappingSchemes |
Camellia-KeyWrappingSchemes,
... -- implementations may define other methods
}
X9-SymmetricKeyWrappingSchemes ALGORITHM ::= { KDFAlgorithms ALGORITHM ::= {
aes128-Wrap | aes192-Wrap | aes256-Wrap | tdes-Wrap, kdf2 | kdf3,
... -- allows for future expansion ... -- implementations may define other methods
} }
X9-SymmetricKeyWrappingScheme ::= KeyLength ::= INTEGER (1..MAX)
AlgorithmIdentifier {{ X9-SymmetricKeyWrappingSchemes }}
Camellia-KeyWrappingSchemes ALGORITHM ::= { DataEncapsulationMechanism ::= AlgorithmIdentifier {{DEMAlgorithms}}
camellia128-Wrap | camellia192-Wrap | camellia256-Wrap,
... -- allows for future expansion
}
Camellia-KeyWrappingScheme ::= DEMAlgorithms ALGORITHM ::= {
AlgorithmIdentifier {{ Camellia-KeyWrappingSchemes }} X9-SymmetricKeyWrappingSchemes |
Camellia-KeyWrappingSchemes,
... -- implementations may define other methods
}
-- Key Derivation Functions X9-SymmetricKeyWrappingSchemes ALGORITHM ::= {
aes128-Wrap | aes192-Wrap | aes256-Wrap | tdes-Wrap,
... -- allows for future expansion
}
id-kdf-kdf2 OID ::= { x9-44-components kdf2(1) } X9-SymmetricKeyWrappingScheme ::=
-- Base arc AlgorithmIdentifier {{ X9-SymmetricKeyWrappingSchemes }}
x9-44 OID ::= { Camellia-KeyWrappingSchemes ALGORITHM ::= {
iso(1) identified-organization(3) tc68(133) country(16) x9(840) camellia128-Wrap | camellia192-Wrap | camellia256-Wrap,
x9Standards(9) x9-44(44) ... -- allows for future expansion
} }
x9-44-components OID ::= { x9-44 components(1) } Camellia-KeyWrappingScheme ::=
AlgorithmIdentifier {{ Camellia-KeyWrappingSchemes }}
kdf2 ALGORITHM ::= { OID id-kdf-kdf2 PARMS KDF2-HashFunction } -- Key Derivation Functions
KDF2-HashFunction ::= AlgorithmIdentifier {{ KDF2-HashFunctions }} id-kdf-kdf2 OID ::= { x9-44-components kdf2(1) }
KDF2-HashFunctions ALGORITHM ::= { -- Base arc
X9-HashFunctions, x9-44 OID ::= {
... -- implementations may define other methods iso(1) identified-organization(3) tc68(133) country(16) x9(840)
} x9Standards(9) x9-44(44)
}
-- id-kdf-kdf3 OID ::= { x9-44-components kdf3(2) } kdf3 ALGORITHM x9-44-components OID ::= { x9-44 components(1) }
::= { OID id-kdf-kdf2 PARMS KDF3-HashFunction } KDF3-HashFunction
::= AlgorithmIdentifier {{ KDF3-HashFunctions }}
KDF3-HashFunctions ALGORITHM ::= { kdf2 ALGORITHM ::= { OID id-kdf-kdf2 PARMS KDF2-HashFunction }
X9-HashFunctions,
... -- implementations may define other methods
}
-- Hash Functions KDF2-HashFunction ::= AlgorithmIdentifier {{ KDF2-HashFunctions }}
X9-HashFunctions ALGORITHM ::= { KDF2-HashFunctions ALGORITHM ::= {
sha1 | sha224 | sha256 | sha384 | sha512, X9-HashFunctions,
... -- allows for future expansion ... -- implementations may define other methods
} }
id-sha1 OID ::= { id-kdf-kdf3 OID ::= { x9-44-components kdf3(2) }
iso(1) identified-organization(3) oiw(14) secsig(3)
algorithms(2) sha1(26)
}
id-sha224 OID ::= { nistAlgorithm hashAlgs(2) sha256(4) } kdf3 ALGORITHM ::= { OID id-kdf-kdf2 PARMS KDF3-HashFunction }
id-sha256 OID ::= { nistAlgorithm hashAlgs(2) sha256(1) }
id-sha384 OID ::= { nistAlgorithm hashAlgs(2) sha384(2) }
id-sha512 OID ::= { nistAlgorithm hashAlgs(2) sha512(3) }
sha1 ALGORITHM ::= { OID id-sha1 } -- NullParms MUST be
sha224 ALGORITHM ::= { OID id-sha224 } -- accepted for these
sha256 ALGORITHM ::= { OID id-sha256 } -- OIDs
sha384 ALGORITHM ::= { OID id-sha384 } -- ""
sha512 ALGORITHM ::= { OID id-sha512 } -- ""
-- Symmetric Key-Wrapping Schemes KDF3-HashFunction ::= AlgorithmIdentifier {{ KDF3-HashFunctions }}
id-aes128-Wrap OID ::= { nistAlgorithm aes(1) aes128-Wrap(5) } KDF3-HashFunctions ALGORITHM ::= {
id-aes192-Wrap OID ::= { nistAlgorithm aes(1) aes192-Wrap(25) } X9-HashFunctions,
id-aes256-Wrap OID ::= { nistAlgorithm aes(1) aes256-Wrap(45) } ... -- implementations may define other methods
}
aes128-Wrap ALGORITHM ::= { OID id-aes128-Wrap } -- Hash Functions
aes192-Wrap ALGORITHM ::= { OID id-aes192-Wrap }
aes256-Wrap ALGORITHM ::= { OID id-aes256-Wrap }
id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= { X9-HashFunctions ALGORITHM ::= {
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) sha1 | sha224 | sha256 | sha384 | sha512,
smime(16) alg(3) 6 ... -- allows for future expansion
} }
tdes-Wrap ALGORITHM ::= { OID id-alg-CMS3DESwrap PARMS NullParms } id-sha1 OID ::= {
iso(1) identified-organization(3) oiw(14) secsig(3)
algorithms(2) sha1(26)
}
id-camellia128-Wrap OBJECT IDENTIFIER ::= id-sha224 OID ::= { nistAlgorithm hashAlgs(2) sha256(4) }
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia128-wrap(2) }
id-camellia192-Wrap OBJECT IDENTIFIER ::= id-sha256 OID ::= { nistAlgorithm hashAlgs(2) sha256(1) }
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia192-wrap(3) }
id-camellia256-Wrap OBJECT IDENTIFIER ::= id-sha384 OID ::= { nistAlgorithm hashAlgs(2) sha384(2) }
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia256-wrap(4) }
camellia128-Wrap ALGORITHM ::= { OID id-camellia128-Wrap } id-sha512 OID ::= { nistAlgorithm hashAlgs(2) sha512(3) }
camellia192-Wrap ALGORITHM ::= { OID id-camellia192-Wrap } sha1 ALGORITHM ::= { OID id-sha1 } -- NullParms MUST be
camellia256-Wrap ALGORITHM ::= { OID id-camellia256-Wrap }
END sha224 ALGORITHM ::= { OID id-sha224 } -- accepted for these
B.4 Examples sha256 ALGORITHM ::= { OID id-sha256 } -- OIDs
As an example, if the key derivation function is KDF3 based on SHA- sha384 ALGORITHM ::= { OID id-sha384 } -- ""
256 and the symmetric key-wrapping scheme is the AES Key Wrap with a
128-bit KEK, the AlgorithmIdentifier for the RSA-KEM Key Transport
Algorithm will have the following value:
SEQUENCE { sha512 ALGORITHM ::= { OID id-sha512 } -- ""
id-rsa-kem, -- RSA-KEM cipher
SEQUENCE { -- GenericHybridParameters
SEQUENCE { -- key encapsulation mechanism
id-kem-rsa, -- RSA-KEM
SEQUENCE { -- RsaKemParameters
SEQUENCE { -- key derivation function
id-kdf-kdf3, -- KDF3
SEQUENCE { -- KDF2-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
}
}
}
This AlgorithmIdentifier value has the following DER encoding (?? -- Symmetric Key-Wrapping Schemes
indicates the algorithm number which is to be assigned):
30 53 id-aes128-Wrap OID ::= { nistAlgorithm aes(1) aes128-Wrap(5) }
06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? -- id-rsa-kem
30 44
30 25
06 07 28 81 8c 71 02 02 04 -- id-kem-rsa
30 1a
30 16
06 07 28 81 8c 71 02 05 02 -- id-kdf-kdf3
30 0b
06 09 60 86 48 01 65 03 04 02 01 -- id-sha256
02 10 -- 16 bytes
30 0b
06 09 60 86 48 01 65 03 04 01 05 -- id-aes128-Wrap
The DER encodings for other typical sets of underlying components are id-aes192-Wrap OID ::= { nistAlgorithm aes(1) aes192-Wrap(25) }
as follows:
o KDF3 based on SHA-384, AES Key Wrap with a 192-bit KEK id-aes256-Wrap OID ::= { nistAlgorithm aes(1) aes256-Wrap(45) }
30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02 aes128-Wrap ALGORITHM ::= { OID id-aes128-Wrap }
01 02 30 44 30 25 06 07 28 81 8c 71 02 02 04 30
1a 30 16 06 07 28 81 8c 71 02 05 02 30 0b 06 09
60 86 48 01 65 03 04 02 02 02 18 30 0b 06 09 60
86 48 01 65 03 04 01 19
o KDF3 based on SHA-512, AES Key Wrap with a 256-bit KEK aes192-Wrap ALGORITHM ::= { OID id-aes192-Wrap }
30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02 aes256-Wrap ALGORITHM ::= { OID id-aes256-Wrap }
01 02 30 44 30 25 06 07 28 81 8c 71 02 02 04 30
1a 30 16 06 07 28 81 8c 71 02 05 02 30 0b 06 09
60 86 48 01 65 03 04 02 03 02 20 30 0b 06 09 60
86 48 01 65 03 04 01 2d
o KDF2 based on SHA-1, Triple-DES Key Wrap with a 128-bit KEK (two- id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= {
key triple-DES) iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) alg(3) 6
}
30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02 tdes-Wrap ALGORITHM ::= { OID id-alg-CMS3DESwrap PARMS NullParms }
01 02 30 44 30 21 06 07 28 81 8c 71 02 01 04 30
16 30 12 06 07 28 81 8c 71 02 05 02 30 07 06 05
2b 0e 03 02 1a 02 10 30 0f 06 0b 2a 86 48 86 f7
0d 01 09 10 03 06 05 00
IANA Considerations id-camellia128-Wrap OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia128-wrap(2) }
Within the CMS, algorithms are identified by object identifiers id-camellia192-Wrap OBJECT IDENTIFIER ::=
(OIDs). With one exception, all of the OIDs used in this document { iso(1) member-body(2) 392 200011 61 security(1)
were assigned in other IETF documents, in ISO/IEC standards algorithm(1) key-wrap-algorithm(3)
documents, by the National Institute of Standards and Technology camellia192-wrap(3) }
(NIST), and in Public-Key Cryptography Standards (PKCS) documents.
The one exception is that the ASN.1 module's identifier (see Appendix
B.3) is assigned in this document. No further action by the IANA is
necessary for this document or any anticipated updates.
Acknowledgments id-camellia256-Wrap OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) 392 200011 61 security(1)
algorithm(1) key-wrap-algorithm(3)
camellia256-wrap(4) }
This document is one part of a strategy to align algorithm standards camellia128-Wrap ALGORITHM ::= { OID id-camellia128-Wrap }
produced by ASC X9, ISO/IEC JTC1 SC27, NIST, and the IETF. We would camellia192-Wrap ALGORITHM ::= { OID id-camellia192-Wrap }
like to thank the members of the ASC X9F1 working group for their
contributions to drafts of ANS X9.44 which led to this specification.
Our thanks to Russ Housley as well for his guidance and camellia256-Wrap ALGORITHM ::= { OID id-camellia256-Wrap }
encouragement. We also appreciate the helpful direction we've
received from Blake Ramsdell and Jim Schaad in bringing this document
to fruition. A special thanks to Magnus Nystrom for his assistance on
Appendix B. Thanks also to Bob Griffin and John Linn for both
editorial direction and procedural guidance.
Author Information END
James Randall B.4 Examples
Randall Consulting As an example, if the key derivation function is KDF3 based on SHA-
55 Sandpiper Drive 256 and the symmetric key-wrapping scheme is the AES Key Wrap with a
Dover, NH 03820 128-bit KEK, the AlgorithmIdentifier for the RSA-KEM Key Transport
USA Algorithm will have the following value:
Email: jdrandall@comcast.net SEQUENCE {
id-rsa-kem, -- RSA-KEM cipher
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
}
}
}
Burt Kaliski This AlgorithmIdentifier value has the following DER encoding (??
indicates the algorithm number which is to be assigned):
EMC 30 53
176 South Street 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? -- id-rsa-kem
Hopkinton, MA 01748 30 44
USA 30 25
06 07 28 81 8c 71 02 02 04 -- id-kem-rsa
30 1a
30 16
06 07 28 81 8c 71 02 05 02 -- id-kdf-kdf3
30 0b
06 09 60 86 48 01 65 03 04 02 01 -- id-sha256
02 10 -- 16 bytes
Email: kaliski_burt@emc.com 30 0b
06 09 60 86 48 01 65 03 04 01 05 -- id-aes128-Wrap
John Brainard The DER encodings for other typical sets of underlying components are
as follows:
RSA, The Security Division of EMC o KDF3 based on SHA-384, AES Key Wrap with a 192-bit KEK
174 Middlesex Turnpike
Bedford, MA 01730
USA
Email: jbrainard@rsa.com
Sean Turner 30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02
01 02 30 44 30 25 06 07 28 81 8c 71 02 02 04 30
1a 30 16 06 07 28 81 8c 71 02 05 02 30 0b 06 09
60 86 48 01 65 03 04 02 02 02 18 30 0b 06 09 60
86 48 01 65 03 04 01 19
IECA, Inc. o KDF3 based on SHA-512, AES Key Wrap with a 256-bit KEK
3057 Nutley Street, Suite 106
Fairfax, VA 22031
USA
Email: turners@ieca.com 30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02
01 02 30 44 30 25 06 07 28 81 8c 71 02 02 04 30
1a 30 16 06 07 28 81 8c 71 02 05 02 30 0b 06 09
60 86 48 01 65 03 04 02 03 02 20 30 0b 06 09 60
86 48 01 65 03 04 01 2d
o KDF2 based on SHA-1, Triple-DES Key Wrap with a 128-bit KEK (two-
key triple-DES)
30 46 06 0b 2a 86 48 86 f7 0d 01 09 10 03 ?? 02
01 02 30 44 30 21 06 07 28 81 8c 71 02 01 04 30
16 30 12 06 07 28 81 8c 71 02 05 02 30 07 06 05
2b 0e 03 02 1a 02 10 30 0f 06 0b 2a 86 48 86 f7
0d 01 09 10 03 06 05 00
IANA Considerations
Within the CMS, algorithms are identified by object identifiers
(OIDs). With one exception, all of the OIDs used in this document
were assigned in other IETF documents, in ISO/IEC standards
documents, by the National Institute of Standards and Technology
(NIST), and in Public-Key Cryptography Standards (PKCS) documents.
The one exception is that the ASN.1 module's identifier (see Appendix
B.3) is assigned in this document. No further action by the IANA is
necessary for this document or any anticipated updates.
Acknowledgements
This document is one part of a strategy to align algorithm standards
produced by ASC X9, ISO/IEC JTC1 SC27, NIST, and the IETF. We would
like to thank the members of the ASC X9F1 working group for their
contributions to drafts of ANS X9.44 which led to this specification.
Our thanks to Russ Housley as well for his guidance and
encouragement. We also appreciate the helpful direction we've
received from Blake Ramsdell and Jim Schaad in bringing this document
to fruition. A special thanks to Magnus Nystrom for his assistance on
Appendix B. Thanks also to Bob Griffin and John Linn for both
editorial direction and procedural guidance.
Authors' Addresses
James Randall
Randall Consulting
55 Sandpiper Drive
Dover, NH 03820
USA
Email: jdrandall@comcast.net
Burt Kaliski
EMC
176 South Street
Hopkinton, MA 01748
USA
Email: kaliski_burt@emc.com
John Brainard
RSA, The Security Division of EMC
174 Middlesex Turnpike
Bedford, MA 01730
USA
Email: jbrainard@rsa.com
Sean Turner
IECA, Inc.
3057 Nutley Street, Suite 106
Fairfax, VA 22031
USA
Email: turners@ieca.com
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