draft-ietf-smime-cmsalg-08.txt   rfc3370.txt 
S/MIME Working Group R. Housley Network Working Group R. Housley
Internet Draft RSA Laboratories Request for Comments: 3370 RSA Laboratories
expires in six months February 2002 Obsoletes: 2630, 3211 August 2002
Category: Standards Track
Cryptographic Message Syntax (CMS) Algorithms Cryptographic Message Syntax (CMS) Algorithms
<draft-ietf-smime-cmsalg-08.txt>
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Abstract Abstract
This document describes several cryptographic algorithms for use with This document describes the conventions for using several
the Cryptographic Message Syntax (CMS) [CMS]. The CMS is used to cryptographic algorithms with the Cryptographic Message Syntax (CMS).
digitally sign, digest, authenticate, or encrypt arbitrary message The CMS is used to digitally sign, digest, authenticate, or encrypt
contents. arbitrary message contents.
Table of Contents Table of Contents
Status of this Memo .............................................. 1 1 Introduction ............................................... 2
Abstract ......................................................... 1 1.1 Changes Since RFC 2630 ..................................... 2
Table of Contents ................................................ 2 1.2 Terminology ................................................ 2
1 Introduction ................................................. 3 2 Message Digest Algorithms .................................. 3
1.1 Changes Since RFC 2630 ................................ 4 2.1 SHA-1 ...................................................... 3
1.2 Terminology ........................................... 4 2.2 MD5 ........................................................ 3
2 Message Digest Algorithms .................................... 3 3 Signature Algorithms ....................................... 4
2.1 SHA-1 ................................................. 4 3.1 DSA ........................................................ 4
2.2 MD5 ................................................... 4 3.2 RSA ........................................................ 5
3 Signature Algorithms ......................................... 4 4 Key Management Algorithms .................................. 6
3.1 DSA ................................................... 5 4.1 Key Agreement Algorithms ................................... 6
3.2 RSA ................................................... 6 4.1.1 X9.42 Ephemeral-Static Diffie-Hellman ...................... 7
4 Key Management Algorithms .................................... 7 4.1.2 X9.42 Static-Static Diffie-Hellman ......................... 8
4.1 Key Agreement Algorithms .............................. 7 4.2 Key Transport Algorithms ................................... 9
4.1.1 X9.42 Ephemeral-Static Diffie-Hellman ........ 8 4.2.1 RSA (PKCS #1 v1.5) ......................................... 10
4.1.2 X9.42 Static-Static Diffie-Hellman ........... 9 4.3 Symmetric Key-Encryption Key Algorithms .................... 10
4.2 Key Transport Algorithms .............................. 10 4.3.1 Triple-DES Key Wrap ........................................ 11
4.2.1 RSA (PKCS #1 v1.5) ........................... 10 4.3.2 RC2 Key Wrap ............................................... 12
4.3 Symmetric Key-Encryption Key Algorithms ............... 11 4.4 Key Derivation Algorithms .................................. 12
4.3.1 Triple-DES Key Wrap .......................... 11 4.4.1 PBKDF2 ..................................................... 13
4.3.2 RC2 Key Wrap ................................. 12 5 Content Encryption Algorithms .............................. 13
4.4 Key Derivation Algorithms ............................. 13 5.1 Triple-DES CBC ............................................. 14
4.4.1 PBKDF2 ....................................... 13 5.2 RC2 CBC .................................................... 14
5 Content Encryption Algorithms ................................ 14 6 Message Authentication Code (MAC) Algorithms ............... 15
5.1 Triple-DES CBC ........................................ 14 6.1 HMAC with SHA-1 ............................................ 15
5.2 RC2 CBC ............................................... 14 7 ASN.1 Module ............................................... 16
6 Message Authentication Code (MAC) Algorithms ................. 15 8 References ................................................. 18
6.1 HMAC with SHA-1 ....................................... 15 9 Security Considerations .................................... 20
7 ASN.1 Module ................................................. 15 10 Acknowledgments ............................................ 22
8 References ................................................... 19 11 Author's Address ........................................... 23
9 Security Considerations ...................................... 20 12 Full Copyright Statement ................................... 24
10 Acknowledgments .............................................. 23
11 Author's Address ............................................. 23
12 Full Copyright Statement ..................................... 23
1 Introduction 1 Introduction
The Cryptographic Message Syntax (CMS) [CMS] is used to digitally The Cryptographic Message Syntax (CMS) [CMS] is used to digitally
sign, digest, authenticate, or encrypt arbitrary message contents. sign, digest, authenticate, or encrypt arbitrary message contents.
This companion specification describes the use of common This companion specification describes the use of common
cryptographic algorithms with the CMS. Implementations of the CMS cryptographic algorithms with the CMS. Implementations of the CMS
may support these algorithms; implementations of the CMS may also may support these algorithms; implementations of the CMS may also
support other algorithms as well. However, if an implementation support other algorithms as well. However, if an implementation
chooses to support one of the algorithms discussed in this document, chooses to support one of the algorithms discussed in this document,
then the implementation MUST do so as described in this document. then the implementation MUST do so as described in this document.
The CMS values are generated using ASN.1 [X.208-88], using BER- The CMS values are generated using ASN.1 [X.208-88], using BER-
encoding [X.209-88]. Algorithm identifiers (which include ASN.1 encoding [X.209-88]. Algorithm identifiers (which include ASN.1
object identifiers) identify cryptographic algorithms, and some object identifiers) identify cryptographic algorithms, and some
algorithms require additional parameters. When needed, parameters algorithms require additional parameters. When needed, parameters
are specified with an ASN.1 structure. The algorithm identifier for are specified with an ASN.1 structure. The algorithm identifier for
each algorithm is specified, and, when needed, the parameter each algorithm is specified, and when needed, the parameter structure
structure is specified. The fields in the CMS employed by each is specified. The fields in the CMS employed by each algorithm are
algorithm are identified. identified.
1.1 Changes Since RFC 2630 1.1 Changes Since RFC 2630
This document obsoletes section 12 of RFC 2630 [OLDCMS]. RFC <TBD> This document obsoletes section 12 of RFC 2630 [OLDCMS]. RFC 3369
[CMS] obsoletes the rest of RFC 2630. Separation of the protocol and [CMS] obsoletes the rest of RFC 2630. Separation of the protocol and
algorithm specifications allows each one to be updated without algorithm specifications allows each one to be updated without
impacting the other. However, the conventions for using additional impacting the other. However, the conventions for using additional
algorithms with the CMS are likely to be specified in separate algorithms with the CMS are likely to be specified in separate
documents. documents.
1.2 Terminology 1.2 Terminology
In this document, the key words MUST, MUST NOT, REQUIRED, SHOULD, In this document, the key words MUST, MUST NOT, REQUIRED, SHOULD,
SHOULD NOT, RECOMMENDED, and MAY are to be interpreted as described SHOULD NOT, RECOMMENDED, and MAY are to be interpreted as described
by Scott Bradner in [STDWORDS]. in [STDWORDS].
2 Message Digest Algorithms 2 Message Digest Algorithms
This section specifies the conventions employed by CMS This section specifies the conventions employed by CMS
implementations that support SHA-1 or MD5. implementations that support SHA-1 or MD5.
Digest algorithm identifiers are located in the SignedData Digest algorithm identifiers are located in the SignedData
digestAlgorithms field, the SignerInfo digestAlgorithm field, the digestAlgorithms field, the SignerInfo digestAlgorithm field, the
DigestedData digestAlgorithm field, and the AuthenticatedData DigestedData digestAlgorithm field, and the AuthenticatedData
digestAlgorithm field. digestAlgorithm field.
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The SHA-1 message digest algorithm is defined in FIPS Pub 180-1 The SHA-1 message digest algorithm is defined in FIPS Pub 180-1
[SHA1]. The algorithm identifier for SHA-1 is: [SHA1]. The algorithm identifier for SHA-1 is:
sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
oiw(14) secsig(3) algorithm(2) 26 } oiw(14) secsig(3) algorithm(2) 26 }
There are two possible encodings for the SHA-1 AlgorithmIdentifier There are two possible encodings for the SHA-1 AlgorithmIdentifier
parameters field. The two alternatives arise from the fact that when parameters field. The two alternatives arise from the fact that when
the 1988 syntax for AlgorithmIdentifier was translated into the 1997 the 1988 syntax for AlgorithmIdentifier was translated into the 1997
syntax the OPTIONAL associated with the AlgorithmIdentifier syntax, the OPTIONAL associated with the AlgorithmIdentifier
parameters got lost. Later the OPTIONAL was recovered via a defect parameters got lost. Later the OPTIONAL was recovered via a defect
report, but by then many people thought that algorithm parameters report, but by then many people thought that algorithm parameters
were mandatory. Because of this history some implementations encode were mandatory. Because of this history some implementations encode
parameters as a NULL element and others omit them entirely. The parameters as a NULL element and others omit them entirely. The
correct encoding is to omit the parameters field; however, correct encoding is to omit the parameters field; however,
implementations MUST also handle a SHA-1 AlgorithmIdentifier implementations MUST also handle a SHA-1 AlgorithmIdentifier
parameters field which contains a NULL. parameters field which contains a NULL.
The AlgorithmIdentifier parameters field is OPTIONAL. If present, The AlgorithmIdentifier parameters field is OPTIONAL. If present,
the parameters field MUST contain a NULL. Implementations MUST the parameters field MUST contain a NULL. Implementations MUST
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The DSA signature algorithm is defined in FIPS Pub 186 [DSS]. DSA The DSA signature algorithm is defined in FIPS Pub 186 [DSS]. DSA
MUST be used with the SHA-1 message digest algorithm. MUST be used with the SHA-1 message digest algorithm.
The algorithm identifier for DSA subject public keys in certificates The algorithm identifier for DSA subject public keys in certificates
is: is:
id-dsa OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-dsa OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) x9-57 (10040) x9cm(4) 1 } us(840) x9-57 (10040) x9cm(4) 1 }
DSA signature validation requires three parameters, commonly called DSA signature validation requires three parameters, commonly called
p, q, and g. When the id-dsa algorithm identifier is used, p, q, and g. When the id-dsa algorithm identifier is used, the
AlgorithmIdentifier parameters field is optional. If present, the AlgorithmIdentifier parameters field is optional. If present, the
AlgorithmIdentifier parameters field MUST contain the three DSA AlgorithmIdentifier parameters field MUST contain the three DSA
parameter values encoded using the Dss-Parms type. If absent, the parameter values encoded using the Dss-Parms type. If absent, the
subject DSA public key uses the same DSA parameters as the subject DSA public key uses the same DSA parameters as the
certificate issuer. certificate issuer.
Dss-Parms ::= SEQUENCE { Dss-Parms ::= SEQUENCE {
p INTEGER, p INTEGER,
q INTEGER, q INTEGER,
g INTEGER } g INTEGER }
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commonly called Y, MUST be encoded as an INTEGER. The output of this commonly called Y, MUST be encoded as an INTEGER. The output of this
encoding is carried in the certificate subject public key. encoding is carried in the certificate subject public key.
Dss-Pub-Key ::= INTEGER -- Y Dss-Pub-Key ::= INTEGER -- Y
The algorithm identifier for DSA with SHA-1 signature values is: The algorithm identifier for DSA with SHA-1 signature values is:
id-dsa-with-sha1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-dsa-with-sha1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) x9-57 (10040) x9cm(4) 3 } us(840) x9-57 (10040) x9cm(4) 3 }
When the id-dsa-with-sha1 algorithm identifier is used, When the id-dsa-with-sha1 algorithm identifier is used, the
AlgorithmIdentifier parameters field MUST be absent. AlgorithmIdentifier parameters field MUST be absent.
When signing, the DSA algorithm generates two values, commonly called When signing, the DSA algorithm generates two values, commonly called
r and s. To transfer these two values as one signature, they MUST be r and s. To transfer these two values as one signature, they MUST be
encoded using the Dss-Sig-Value type: encoded using the Dss-Sig-Value type:
Dss-Sig-Value ::= SEQUENCE { Dss-Sig-Value ::= SEQUENCE {
r INTEGER, r INTEGER,
s INTEGER } s INTEGER }
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The RSA (PKCS #1 v1.5) signature algorithm is defined in RFC 2437 The RSA (PKCS #1 v1.5) signature algorithm is defined in RFC 2437
[NEWPKCS#1]. RFC 2437 specifies the use of the RSA signature [NEWPKCS#1]. RFC 2437 specifies the use of the RSA signature
algorithm with the SHA-1 and MD5 message digest algorithms. algorithm with the SHA-1 and MD5 message digest algorithms.
The algorithm identifier for RSA subject public keys in certificates The algorithm identifier for RSA subject public keys in certificates
is: is:
rsaEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) rsaEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 1 } us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 1 }
When the rsaEncryption algorithm identifier is used, When the rsaEncryption algorithm identifier is used, the
AlgorithmIdentifier parameters field MUST contain NULL. AlgorithmIdentifier parameters field MUST contain NULL.
When the rsaEncryption algorithm identifier is used, the RSA public When the rsaEncryption algorithm identifier is used, the RSA public
key, which is composed of a modulus and a public exponent, MUST be key, which is composed of a modulus and a public exponent, MUST be
encoded using the RSAPublicKey type. The output of this encoding is encoded using the RSAPublicKey type. The output of this encoding is
carried in the certificate subject public key. carried in the certificate subject public key.
RSAPublicKey ::= SEQUENCE { RSAPublicKey ::= SEQUENCE {
modulus INTEGER, -- n modulus INTEGER, -- n
publicExponent INTEGER } -- e publicExponent INTEGER } -- e
CMS implementations that include the RSA (PKCS #1 v1.5) signature CMS implementations that include the RSA (PKCS #1 v1.5) signature
algorithm MUST also implement the SHA-1 message digest algorithm. algorithm MUST also implement the SHA-1 message digest algorithm.
Such implementations SHOULD also support MD5 message digest Such implementations SHOULD also support the MD5 message digest
algorithm. algorithm.
The rsaEncryption algorithm identifier is used to identify RSA (PKCS The rsaEncryption algorithm identifier is used to identify RSA (PKCS
#1 v1.5) signature values regardless of the message digest algorithm #1 v1.5) signature values regardless of the message digest algorithm
employed. CMS implementations that include the RSA (PKCS #1 v1.5) employed. CMS implementations that include the RSA (PKCS #1 v1.5)
signature algorithm MUST support the rsaEncryption signature value signature algorithm MUST support the rsaEncryption signature value
algorithm identifier, and CMS implementations MAY support RSA (PKCS algorithm identifier, and CMS implementations MAY support RSA (PKCS
#1 v1.5) signature value algorithm identifiers that specify both the #1 v1.5) signature value algorithm identifiers that specify both the
RSA (PKCS #1 v1.5) signature algorithm and the message digest RSA (PKCS #1 v1.5) signature algorithm and the message digest
algorithm. algorithm.
The algorithm identifier for RSA (PKCS #1 v1.5) with SHA-1 signature The algorithm identifier for RSA (PKCS #1 v1.5) with SHA-1 signature
values is: values is:
sha1WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) sha1WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1)
us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 5 } member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 5 }
The algorithm identifier for RSA (PKCS #1 v1.5) with MD5 signature The algorithm identifier for RSA (PKCS #1 v1.5) with MD5 signature
values is: values is:
md5WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2) md5WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1)
us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 4 } member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 4 }
When the rsaEncryption, sha1WithRSAEncryption, or When the rsaEncryption, sha1WithRSAEncryption, or
md5WithRSAEncryption signature value algorithm identifiers are used, md5WithRSAEncryption signature value algorithm identifiers are used,
the AlgorithmIdentifier parameters field MUST be NULL. the AlgorithmIdentifier parameters field MUST be NULL.
When signing, the RSA algorithm generates a single value, and that When signing, the RSA algorithm generates a single value, and that
value is used directly as the signature value. value is used directly as the signature value.
4 Key Management Algorithms 4 Key Management Algorithms
CMS accommodates the following general key management techniques: key CMS accommodates the following general key management techniques: key
agreement, key transport, previously distributed symmetric key- agreement, key transport, previously distributed symmetric key-
encryption keys, and passwords. encryption keys, and passwords.
4.1 Key Agreement Algorithms 4.1 Key Agreement Algorithms
This section specifies the conventions employed by CMS This section specifies the conventions employed by CMS
implementations that support key agreement using X9.42 Ephemeral- implementations that support key agreement using X9.42 Ephemeral-
Static Diffie-Hellman (X9.42 E-S D-H) and X9.42 Static-Static Diffie- Static Diffie-Hellman (X9.42 E-S D-H) and X9.42 Static-Static
Hellman (X9.42 S-S D-H). Diffie-Hellman (X9.42 S-S D-H).
When a key agreement algorithm is used, a key-encryption algorithm is When a key agreement algorithm is used, a key-encryption algorithm is
also needed. Therefore, when key agreement is supported, a key- also needed. Therefore, when key agreement is supported, a key-
encryption algorithm MUST be provided for each content-encryption encryption algorithm MUST be provided for each content-encryption
algorithm. The key wrap algorithms for Triple-DES and RC2 are algorithm. The key wrap algorithms for Triple-DES and RC2 are
described in RFC 3217 [WRAP]. described in RFC 3217 [WRAP].
For key agreement of RC2 key-encryption keys, 128 bits MUST be For key agreement of RC2 key-encryption keys, 128 bits MUST be
generated as input to the key expansion process used to compute the generated as input to the key expansion process used to compute the
RC2 effective key [RC2]. RC2 effective key [RC2].
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present. When present, the ukm is used to ensure that a different present. When present, the ukm is used to ensure that a different
key-encryption key is generated when the ephemeral private key key-encryption key is generated when the ephemeral private key
might be used more than once. might be used more than once.
keyEncryptionAlgorithm MUST be the id-alg-ESDH algorithm keyEncryptionAlgorithm MUST be the id-alg-ESDH algorithm
identifier. The algorithm identifier parameter field for id-alg- identifier. The algorithm identifier parameter field for id-alg-
ESDH is KeyWrapAlgorithm, and this parameter MUST be present. The ESDH is KeyWrapAlgorithm, and this parameter MUST be present. The
KeyWrapAlgorithm denotes the symmetric encryption algorithm used KeyWrapAlgorithm denotes the symmetric encryption algorithm used
to encrypt the content-encryption key with the pairwise key- to encrypt the content-encryption key with the pairwise key-
encryption key generated using the X9.42 Ephemeral-Static Diffie- encryption key generated using the X9.42 Ephemeral-Static Diffie-
Hellman key agreement algorithm. Triple-DES and RC2 key wrap Hellman key agreement algorithm. Triple-DES and RC2 key wrap
algorithms are described in RFC 3217 [WRAP]. The id-alg-ESDH algorithms are described in RFC 3217 [WRAP]. The id-alg-ESDH
algorithm identifier and parameter syntax is: algorithm identifier and parameter syntax is:
id-alg-ESDH OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-alg-ESDH OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16)
alg(3) 5 } alg(3) 5 }
KeyWrapAlgorithm ::= AlgorithmIdentifier KeyWrapAlgorithm ::= AlgorithmIdentifier
recipientEncryptedKeys contains an identifier and an encrypted key recipientEncryptedKeys contains an identifier and an encrypted key
for each recipient. The RecipientEncryptedKey for each recipient. The RecipientEncryptedKey
KeyAgreeRecipientIdentifier MUST contain either the KeyAgreeRecipientIdentifier MUST contain either the
issuerAndSerialNumber identifying the recipient's certificate or issuerAndSerialNumber identifying the recipient's certificate or
the RecipientKeyIdentifier containing the subject key identifier the RecipientKeyIdentifier containing the subject key identifier
from the recipient's certificate. In both cases, the recipient's from the recipient's certificate. In both cases, the recipient's
certificate contains the recipient's static public key. certificate contains the recipient's static public key.
RecipientEncryptedKey EncryptedKey MUST contain the content- RecipientEncryptedKey EncryptedKey MUST contain the
encryption key encrypted with the X9.42 Ephemeral-Static Diffie- content-encryption key encrypted with the X9.42 Ephemeral-Static
Hellman generated pairwise key-encryption key using the algorithm Diffie-Hellman generated pairwise key-encryption key using the
specified by the KeyWrapAlgorithm. algorithm specified by the KeyWrapAlgorithm.
4.1.2 X9.42 Static-Static Diffie-Hellman 4.1.2 X9.42 Static-Static Diffie-Hellman
Static-Static Diffie-Hellman key agreement is defined in RFC 2631 Static-Static Diffie-Hellman key agreement is defined in RFC 2631
[DH-X9.42]. When using Static-Static Diffie-Hellman, the [DH-X9.42]. When using Static-Static Diffie-Hellman, the
EnvelopedData RecipientInfos KeyAgreeRecipientInfo and EnvelopedData RecipientInfos KeyAgreeRecipientInfo and
AuthenticatedData RecipientInfos KeyAgreeRecipientInfo fields are AuthenticatedData RecipientInfos KeyAgreeRecipientInfo fields are
used as follows: used as follows:
version MUST be 3. version MUST be 3.
originator MUST be either the issuerAndSerialNumber or originator MUST be either the issuerAndSerialNumber or
subjectKeyIdentifier alternative. In both cases, the originator's subjectKeyIdentifier alternative. In both cases, the originator's
certificate contains the sender's static public key. RFC <TBD> certificate contains the sender's static public key. RFC 3279
[CERTALGS] specifies the AlgorithmIdentifier parameters syntax and [CERTALGS] specifies the AlgorithmIdentifier parameters syntax and
values that are included in the originator's certificate. The values that are included in the originator's certificate. The
originator's certificate subject public key information field MUST originator's certificate subject public key information field MUST
contain the dh-public-number object identifier: contain the dh-public-number object identifier:
dh-public-number OBJECT IDENTIFIER ::= { iso(1) member-body(2) dh-public-number OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) ansi-x942(10046) number-type(2) 1 } us(840) ansi-x942(10046) number-type(2) 1 }
ukm MUST be present. The ukm ensures that a different key- ukm MUST be present. The ukm ensures that a different key-
encryption key is generated for each message between the same encryption key is generated for each message between the same
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RSAES-PKCS1-v1_5. RSAES-PKCS1-v1_5.
4.3 Symmetric Key-Encryption Key Algorithms 4.3 Symmetric Key-Encryption Key Algorithms
This section specifies the conventions employed by CMS This section specifies the conventions employed by CMS
implementations that support symmetric key-encryption key management implementations that support symmetric key-encryption key management
using Triple-DES or RC2 key-encryption keys. When RC2 is supported, using Triple-DES or RC2 key-encryption keys. When RC2 is supported,
RC2 128-bit keys MUST be used as key-encryption keys, and they MUST RC2 128-bit keys MUST be used as key-encryption keys, and they MUST
be used with the RC2ParameterVersion parameter set to 58. A CMS be used with the RC2ParameterVersion parameter set to 58. A CMS
implementation MAY support mixed key-encryption and content- implementation MAY support mixed key-encryption and content-
encryption algorithms. For example, a 40-bit RC2 content-encryption encryptionalgorithms. For example, a 40-bit RC2 content-encryption
key MAY be wrapped with 168-bit Triple-DES key-encryption key or with key MAY be wrapped with a 168-bit Triple-DES key-encryption key or
a 128-bit RC2 key-encryption key. with a 128-bit RC2 key-encryption key.
Key wrap algorithm identifiers are located in the EnvelopedData Key wrap algorithm identifiers are located in the EnvelopedData
RecipientInfos KEKRecipientInfo keyEncryptionAlgorithm and RecipientInfos KEKRecipientInfo keyEncryptionAlgorithm and
AuthenticatedData RecipientInfos KEKRecipientInfo AuthenticatedData RecipientInfos KEKRecipientInfo
keyEncryptionAlgorithm fields. keyEncryptionAlgorithm fields.
Wrapped content-encryption keys are located in the EnvelopedData Wrapped content-encryption keys are located in the EnvelopedData
RecipientInfos KEKRecipientInfo encryptedKey field. Wrapped message- RecipientInfos KEKRecipientInfo encryptedKey field. Wrapped
authentication keys are located in the AuthenticatedData message-authentication keys are located in the AuthenticatedData
RecipientInfos KEKRecipientInfo encryptedKey field. RecipientInfos KEKRecipientInfo encryptedKey field.
The output of a key agreement algorithm is a key-encryption key, and The output of a key agreement algorithm is a key-encryption key, and
this key-encryption key is used to encrypt the content-encryption this key-encryption key is used to encrypt the content-encryption
key. To support key agreement, key wrap algorithm identifiers are key. To support key agreement, key wrap algorithm identifiers are
located in the KeyWrapAlgorithm parameter of the EnvelopedData located in the KeyWrapAlgorithm parameter of the EnvelopedData
RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm and RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm and
AuthenticatedData RecipientInfos KeyAgreeRecipientInfo AuthenticatedData RecipientInfos KeyAgreeRecipientInfo
keyEncryptionAlgorithm fields. However, only key agreement keyEncryptionAlgorithm fields. However, only key agreement
algorithms that inherently provide authentication ought to be used algorithms that inherently provide authentication ought to be used
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in the EnvelopedData RecipientInfos KeyAgreeRecipientInfo in the EnvelopedData RecipientInfos KeyAgreeRecipientInfo
RecipientEncryptedKeys encryptedKey field, wrapped message- RecipientEncryptedKeys encryptedKey field, wrapped message-
authentication keys are located in the AuthenticatedData authentication keys are located in the AuthenticatedData
RecipientInfos KeyAgreeRecipientInfo RecipientEncryptedKeys RecipientInfos KeyAgreeRecipientInfo RecipientEncryptedKeys
encryptedKey field. encryptedKey field.
4.3.1 Triple-DES Key Wrap 4.3.1 Triple-DES Key Wrap
A CMS implementation MAY support mixed key-encryption and content- A CMS implementation MAY support mixed key-encryption and content-
encryption algorithms. For example, a 128-bit RC2 content-encryption encryption algorithms. For example, a 128-bit RC2 content-encryption
key MAY be wrapped with 168-bit Triple-DES key-encryption key. key MAY be wrapped with a 168-bit Triple-DES key-encryption key.
Triple-DES key encryption has the algorithm identifier: Triple-DES key encryption has the algorithm identifier:
id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-alg-CMS3DESwrap OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 6 } us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 6 }
The AlgorithmIdentifier parameter field MUST be NULL. The AlgorithmIdentifier parameter field MUST be NULL.
The key wrap algorithm used to encrypt a Triple-DES content- The key wrap algorithm used to encrypt a Triple-DES content-
encryption key with a Triple-DES key-encryption key is specified in encryption key with a Triple-DES key-encryption key is specified in
section 3.1 of RFC 3217 [WRAP]. The corresponding key unwrap section 3.1 of RFC 3217 [WRAP]. The corresponding key unwrap
algorithm is specified in section 3.2 of RFC 3217 [WRAP]. algorithm is specified in section 3.2 of RFC 3217 [WRAP].
Out-of-band distribution of the Triple-DES key-encryption key used to Out-of-band distribution of the Triple-DES key-encryption key used to
encrypt the Triple-DES content-encryption key is beyond of the scope encrypt the Triple-DES content-encryption key is beyond the scope of
of this document. this document.
4.3.2 RC2 Key Wrap 4.3.2 RC2 Key Wrap
A CMS implementation MAY support mixed key-encryption and content- A CMS implementation MAY support mixed key-encryption and content-
encryption algorithms. For example, a 128-bit RC2 content-encryption encryption algorithms. For example, a 128-bit RC2 content-encryption
key MAY be wrapped with 168-bit Triple-DES key-encryption key. key MAY be wrapped with a 168-bit Triple-DES key-encryption key.
Similarly, a 40-bit RC2 content-encryption key MAY be wrapped with Similarly, a 40-bit RC2 content-encryption key MAY be wrapped with a
128-bit RC2 key-encryption key. 128-bit RC2 key-encryption key.
RC2 key encryption has the algorithm identifier: RC2 key encryption has the algorithm identifier:
id-alg-CMSRC2wrap OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-alg-CMSRC2wrap OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 7 } us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 7 }
The AlgorithmIdentifier parameter field MUST be RC2wrapParameter: The AlgorithmIdentifier parameter field MUST be RC2wrapParameter:
RC2wrapParameter ::= RC2ParameterVersion RC2wrapParameter ::= RC2ParameterVersion
skipping to change at page 13, line 36 skipping to change at page 13, line 22
The content-encryption keys encrypted with password-derived key- The content-encryption keys encrypted with password-derived key-
encryption keys are located in the EnvelopedData RecipientInfos encryption keys are located in the EnvelopedData RecipientInfos
PasswordRecipientInfo encryptedKey field. The message-authentication PasswordRecipientInfo encryptedKey field. The message-authentication
keys encrypted with password-derived key-encryption keys are located keys encrypted with password-derived key-encryption keys are located
in the AuthenticatedData RecipientInfos PasswordRecipientInfo in the AuthenticatedData RecipientInfos PasswordRecipientInfo
encryptedKey field. encryptedKey field.
4.4.1 PBKDF2 4.4.1 PBKDF2
The PBKDF2 key derivation algorithm specified in RFC 2898 [PKCS#5]. The PBKDF2 key derivation algorithm is specified in RFC 2898
The KeyDerivationAlgorithmIdentifer identifies the key-derivation [PKCS#5]. The KeyDerivationAlgorithmIdentifer identifies the key-
algorithm, and any associated parameters, used to derive the key- derivation algorithm, and any associated parameters used to derive
encryption key from the user-supplied password. The algorithm the key-encryption key from the user-supplied password. The
identifier for the PBKDF2 key derivation algorithm is: algorithm identifier for the PBKDF2 key derivation algorithm is:
id-PBKDF2 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) id-PBKDF2 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-5(5) 12 } rsadsi(113549) pkcs(1) pkcs-5(5) 12 }
The AlgorithmIdentifier parameter field MUST be PBKDF2-params: The AlgorithmIdentifier parameter field MUST be PBKDF2-params:
PBKDF2-params ::= SEQUENCE { PBKDF2-params ::= SEQUENCE {
salt CHOICE { salt CHOICE {
specified OCTET STRING, specified OCTET STRING,
otherSource AlgorithmIdentifier }, otherSource AlgorithmIdentifier },
skipping to change at page 14, line 17 skipping to change at page 14, line 5
Within the PBKDF2-params, the salt MUST use the specified OCTET Within the PBKDF2-params, the salt MUST use the specified OCTET
STRING. STRING.
5 Content Encryption Algorithms 5 Content Encryption Algorithms
This section specifies the conventions employed by CMS This section specifies the conventions employed by CMS
implementations that support content encryption using Three-Key implementations that support content encryption using Three-Key
Triple-DES in CBC mode, Two-Key Triple-DES in CBC mode, or RC2 in CBC Triple-DES in CBC mode, Two-Key Triple-DES in CBC mode, or RC2 in CBC
mode. mode.
Content encryption algorithms identifiers are located in the Content encryption algorithm identifiers are located in the
EnvelopedData EncryptedContentInfo contentEncryptionAlgorithm and the EnvelopedData EncryptedContentInfo contentEncryptionAlgorithm and the
EncryptedData EncryptedContentInfo contentEncryptionAlgorithm fields. EncryptedData EncryptedContentInfo contentEncryptionAlgorithm fields.
Content encryption algorithms are used to encipher the content Content encryption algorithms are used to encipher the content
located in the EnvelopedData EncryptedContentInfo encryptedContent located in the EnvelopedData EncryptedContentInfo encryptedContent
field and the EncryptedData EncryptedContentInfo encryptedContent field and the EncryptedData EncryptedContentInfo encryptedContent
field. field.
5.1 Triple-DES CBC 5.1 Triple-DES CBC
The Triple-DES algorithm is described in ANSI X9.52 [3DES]. The The Triple-DES algorithm is described in ANSI X9.52 [3DES]. The
Triple-DES is composed from three sequential DES [DES] operations: Triple-DES is composed from three sequential DES [DES] operations:
encrypt, decrypt, and encrypt. Three-Key Triple-DES uses a different encrypt, decrypt, and encrypt. Three-Key Triple-DES uses a different
key for each DES operation. Two-Key Triple-DES uses one key for the key for each DES operation. Two-Key Triple-DES uses one key for the
two encrypt operations and different key for the decrypt operation. two encrypt operations and a different key for the decrypt operation.
The same algorithm identifiers are used for Three-Key Triple-DES and The same algorithm identifiers are used for Three-Key Triple-DES and
Two-Key Triple-DES. The algorithm identifier for Triple-DES in Two-Key Triple-DES. The algorithm identifier for Triple-DES in
Cipher Block Chaining (CBC) mode is: Cipher Block Chaining (CBC) mode is:
des-ede3-cbc OBJECT IDENTIFIER ::= { iso(1) member-body(2) des-ede3-cbc OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) encryptionAlgorithm(3) 7 } us(840) rsadsi(113549) encryptionAlgorithm(3) 7 }
The AlgorithmIdentifier parameters field MUST be present, and the The AlgorithmIdentifier parameters field MUST be present, and the
parameters field must contain a CBCParameter: parameters field must contain a CBCParameter:
skipping to change at page 15, line 38 skipping to change at page 15, line 28
MAC algorithm identifiers are located in the AuthenticatedData MAC algorithm identifiers are located in the AuthenticatedData
macAlgorithm field. macAlgorithm field.
MAC values are located in the AuthenticatedData mac field. MAC values are located in the AuthenticatedData mac field.
6.1 HMAC with SHA-1 6.1 HMAC with SHA-1
The HMAC with SHA-1 algorithm is described in RFC 2104 [HMAC]. The The HMAC with SHA-1 algorithm is described in RFC 2104 [HMAC]. The
algorithm identifier for HMAC with SHA-1 is: algorithm identifier for HMAC with SHA-1 is:
hMAC-SHA1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) hMAC-SHA1 OBJECT IDENTIFIER ::= { iso(1)
dod(6) internet(1) security(5) mechanisms(5) 8 1 2 } identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) 8 1 2 }
There are two possible encodings for the HMAC with SHA-1 There are two possible encodings for the HMAC with SHA-1
AlgorithmIdentifier parameters field. The two alternatives arise AlgorithmIdentifier parameters field. The two alternatives arise
from the fact that when the 1988 syntax for AlgorithmIdentifier was from the fact that when the 1988 syntax for the AlgorithmIdentifier
translated into the 1997 syntax the OPTIONAL associated with the type was translated into the 1997 syntax, the OPTIONAL associated
AlgorithmIdentifier parameters got lost. Later the OPTIONAL was with the AlgorithmIdentifier parameters got lost. Later the OPTIONAL
recovered via a defect report, but by then many people thought that was recovered via a defect report, but by then many people thought
algorithm parameters were mandatory. Because of this history some that algorithm parameters were mandatory. Because of this history
implementations may encode parameters as a NULL element and others some implementations may encode parameters as a NULL while others
omit them entirely. omit them entirely.
The AlgorithmIdentifier parameters field is OPTIONAL. If present, The AlgorithmIdentifier parameters field is OPTIONAL. If present,
the parameters field MUST contain a NULL. Implementations MUST the parameters field MUST contain a NULL. Implementations MUST
accept HMAC with SHA-1 AlgorithmIdentifiers with absent parameters. accept HMAC with SHA-1 AlgorithmIdentifiers with absent parameters.
Implementations MUST accept HMAC with SHA-1 AlgorithmIdentifiers with Implementations MUST accept HMAC with SHA-1 AlgorithmIdentifiers with
NULL parameters. Implementations SHOULD generate HMAC with SHA-1 NULL parameters. Implementations SHOULD generate HMAC with SHA-1
AlgorithmIdentifiers with absent parameters. AlgorithmIdentifiers with absent parameters.
7 ASN.1 Module 7 ASN.1 Module
CryptographicMessageSyntaxAlgorithms CryptographicMessageSyntaxAlgorithms
{ iso(1) member-body(2) us(840) rsadsi(113549) { iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0) cmsalg-2001(16) } pkcs(1) pkcs-9(9) smime(16) modules(0) cmsalg-2001(16) }
DEFINITIONS IMPLICIT TAGS ::= DEFINITIONS IMPLICIT TAGS ::=
BEGIN BEGIN
-- EXPORTS All -- EXPORTS All
-- The types and values defined in this module are exported for use in -- The types and values defined in this module are exported for use
-- the other ASN.1 modules. Other applications may use them for their -- in the other ASN.1 modules. Other applications may use them for
-- own purposes. -- their own purposes.
IMPORTS IMPORTS
-- Imports from RFC <TBD> [PROFILE], Appendix A.1 -- Imports from RFC 3280 [PROFILE], Appendix A.1
AlgorithmIdentifier AlgorithmIdentifier
FROM PKIX1Explicit88 { iso(1) FROM PKIX1Explicit88 { iso(1)
identified-organization(3) dod(6) internet(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) mod(0) security(5) mechanisms(5) pkix(7) mod(0)
pkix1-explicit(18) } ; pkix1-explicit(18) } ;
-- Algorithm Identifiers -- Algorithm Identifiers
sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) sha-1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
oiw(14) secsig(3) algorithm(2) 26 } oiw(14) secsig(3) algorithm(2) 26 }
skipping to change at page 19, line 7 skipping to change at page 18, line 43
otherSource AlgorithmIdentifier }, otherSource AlgorithmIdentifier },
iterationCount INTEGER (1..MAX), iterationCount INTEGER (1..MAX),
keyLength INTEGER (1..MAX) OPTIONAL, keyLength INTEGER (1..MAX) OPTIONAL,
prf AlgorithmIdentifier prf AlgorithmIdentifier
DEFAULT { algorithm hMAC-SHA1, parameters NULL } } DEFAULT { algorithm hMAC-SHA1, parameters NULL } }
END -- of CryptographicMessageSyntaxAlgorithms END -- of CryptographicMessageSyntaxAlgorithms
8 References 8 References
3DES American National Standards Institute. ANSI X9.52-1998, [3DES] American National Standards Institute. ANSI X9.52-1998,
Triple Data Encryption Algorithm Modes of Operation. 1998. Triple Data Encryption Algorithm Modes of Operation.
1998.
CERTALGS Bassham, L., R. Housley, and W. Polk. Algorithms and [CERTALGS] Bassham, L., Housley, R. and W. Polk, "Algorithms and
Identifiers for the Internet X.509 Public Key Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and CRL Profile. RFC <TBD>. Infrastructure Certificate and Certificate Revocation
<Date>. {draft-ietf-pkix-ipki-pkalgs-*.txt} List (CRL) Profile", RFC 3279, April 2002.
CMS Housley, R. Cryptographic Message Syntax. RFC <TBD>. [CMS] Housley, R., "Cryptographic Message Syntax", RFC 3269,
<Date>. {draft-ietf-smime-rfc2630bis-*.txt} August 2002.
DES American National Standards Institute. ANSI X3.106, [DES] American National Standards Institute. ANSI X3.106,
"American National Standard for Information Systems - Data "American National Standard for Information Systems -
Link Encryption". 1983. Data Link Encryption". 1983.
DH-X9.42 Rescorla, E. Diffie-Hellman Key Agreement Method. [DH-X9.42] Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC
RFC 2631. June 1999. 2631, June 1999.
DSS National Institute of Standards and Technology. [DSS] National Institute of Standards and Technology. FIPS Pub
FIPS Pub 186: Digital Signature Standard. 19 May 1994. 186: Digital Signature Standard. 19 May 1994.
HMAC Krawczyk, H. HMAC: Keyed-Hashing for Message Authentication. [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
RFC 2104. February 1997. Authentication", RFC 2104, February 1997.
MD5 Rivest, R. The MD5 Message-Digest Algorithm. RFC 1321. [MD5] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992. April 1992.
MMA Rescorla, E. Preventing the Million Message Attack on CMS. [MMA] Rescorla, E., "Preventing the Million Message Attack on
RFC 3218. December 2001. CMS", RFC 3218, January 2002.
MODES National Institute of Standards and Technology. [MODES] National Institute of Standards and Technology. FIPS Pub
FIPS Pub 81: DES Modes of Operation. 2 December 1980. 81: DES Modes of Operation. 2 December 1980.
NEWPKCS#1 Kaliski, B., and J. Staddon. PKCS #1: RSA Encryption, [NEWPKCS#1] Kaliski, B. and J. Staddon, "PKCS #1: RSA Encryption,
Version 2.0. RFC 2437. October 1998. Version 2.0, RFC 2437, October 1998.
OLDCMS Housley, R., Cryptographic Message Syntax, RFC 2630, [OLDCMS] Housley, R., "Cryptographic Message Syntax", RFC 2630,
June 1999. June 1999.
PKCS#1 Kaliski, B. PKCS #1: RSA Encryption, Version 1.5. [PKCS#1] Kaliski, B, "PKCS #1: RSA Encryption, Version 2.0", RFC
RFC 2313. March 1998. 2437, October, 1998.
PKCS#5 Kaliski, B. PKCS #5: Password-Based Cryptography [PKCS#5] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification, Version 2.0. RFC 2898. September 2000. Specification", RFC 2898, September 2000.
PROFILE Housley, R., W. Ford, W. Polk, and D. Solo. Internet [PROFILE] Housley, R., Ford, W., Polk, W. and D. Solo, "Internet
X.509 Public Key Infrastructure: Certificate and CRL X.509 Public Key Infrastructure Certificate and
Profile. RFC <TBD>. <Date>. Certificate Revocation List (CRL) Profile", RFC 3280,
{draft-ietf-pkix-new-part1-*.txt} April 2002.
RANDOM Eastlake, D., S. Crocker, and J. Schiller. Randomness [RANDOM] Eastlake, D., Crocker, S. and J. Schiller, "Randomness
Recommendations for Security. RFC 1750. December 1994. Recommendations for Security, RFC 1750, December 1994.
RC2 Rivest, R. A Description of the RC2 (r) Encryption Algorithm. [RC2] Rivest, R., "A Description of the RC2 (r) Encryption
RFC 2268. March 1998. Algorithm", RFC 2268, March 1998.
SHA1 National Institute of Standards and Technology. [SHA1] National Institute of Standards and Technology. FIPS Pub
FIPS Pub 180-1: Secure Hash Standard. 17 April 1995. 180-1: Secure Hash Standard. 17 April 1995.
STDWORDS Bradner, S. Key Words for Use in RFCs to Indicate [STDWORDS] Bradner, S., "Key Words for Use in RFCs to Indicate
Requirement Levels. RFC2119. March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
WRAP Housley, R. Triple-DES and RC2 Key Wrapping. RFC 3217. [WRAP] Housley, R., "Triple-DES and RC2 Key Wrapping", RFC 3217,
December 2001. December 2001.
X.208-88 CCITT. Recommendation X.208: Specification of Abstract [X.208-88] CCITT. Recommendation X.208: Specification of Abstract
Syntax Notation One (ASN.1). 1988. Syntax Notation One (ASN.1). 1988.
X.209-88 CCITT. Recommendation X.209: Specification of Basic Encoding [X.209-88] CCITT. Recommendation X.209: Specification of Basic
Rules for Abstract Syntax Notation One (ASN.1). 1988. Encoding Rules for Abstract Syntax Notation One (ASN.1).
1988.
9 Security Considerations 9 Security Considerations
The CMS provides a method for digitally signing data, digesting data, The CMS provides a method for digitally signing data, digesting data,
encrypting data, and authenticating data. This document identifies encrypting data, and authenticating data. This document identifies
the conventions for using several cryptographic algorithms for use the conventions for using several cryptographic algorithms for use
with the CMS. with the CMS.
Implementations must protect the signer's private key. Compromise of Implementations must protect the signer's private key. Compromise of
the signer's private key permits masquerade. the signer's private key permits masquerade.
Implementations must protect the key management private key, the key- Implementations must protect the key management private key, the
encryption key, and the content-encryption key. Compromise of the key-encryption key, and the content-encryption key. Compromise of
key management private key or the key-encryption key may result in the key management private key or the key-encryption key may result
the disclosure of all contents protected with that key. Similarly, in the disclosure of all contents protected with that key.
compromise of the content-encryption key may result in disclosure of Similarly, compromise of the content-encryption key may result in
the associated encrypted content. disclosure of the associated encrypted content.
Implementations must protect the key management private key and the Implementations must protect the key management private key and the
message-authentication key. Compromise of the key management private message-authentication key. Compromise of the key management private
key permits masquerade of authenticated data. Similarly, compromise key permits masquerade of authenticated data. Similarly, compromise
of the message-authentication key may result in undetectable of the message-authentication key may result in undetectable
modification of the authenticated content. modification of the authenticated content.
The key management technique employed to distribute message- The key management technique employed to distribute message-
authentication keys must itself provide authentication, otherwise the authentication keys must itself provide authentication, otherwise the
content is delivered with integrity from an unknown source. Neither content is delivered with integrity from an unknown source. Neither
skipping to change at page 21, line 49 skipping to change at page 21, line 39
content is encrypted with 168-bit Triple-DES and the Triple-DES content is encrypted with 168-bit Triple-DES and the Triple-DES
content-encryption key is wrapped with a 40-bit RC2 key, then at most content-encryption key is wrapped with a 40-bit RC2 key, then at most
40 bits of protection is provided. A trivial search to determine the 40 bits of protection is provided. A trivial search to determine the
value of the 40-bit RC2 key can recover Triple-DES key, and then the value of the 40-bit RC2 key can recover Triple-DES key, and then the
Triple-DES key can be used to decrypt the content. Therefore, Triple-DES key can be used to decrypt the content. Therefore,
implementers must ensure that key-encryption algorithms are as strong implementers must ensure that key-encryption algorithms are as strong
or stronger than content-encryption algorithms. or stronger than content-encryption algorithms.
RFC 3217 [WRAP] specifies key wrap algorithms used to encrypt a RFC 3217 [WRAP] specifies key wrap algorithms used to encrypt a
Triple-DES content-encryption key with a Triple-DES key-encryption Triple-DES content-encryption key with a Triple-DES key-encryption
key [3DES] or to encrypt a RC2 content-encryption key with a RC2 key- key [3DES] or to encrypt a RC2 content-encryption key with a RC2
encryption key [RC2]. The key wrap algorithms makes use of CBC mode key-encryption key [RC2]. The key wrap algorithms makes use of CBC
[MODES]. These key wrap algorithms have been reviewed for use with mode [MODES]. These key wrap algorithms have been reviewed for use
Triple-DES and RC2. They have not been reviewed for use with other with Triple-DES and RC2. They have not been reviewed for use with
cryptographic modes or other encryption algorithms. Therefore, if a other cryptographic modes or other encryption algorithms. Therefore,
CMS implementation wishes to support ciphers in addition to Triple- if a CMS implementation wishes to support ciphers in addition to
DES or RC2, then additional key wrap algorithms need to be defined to Triple-DES or RC2, then additional key wrap algorithms need to be
support the additional ciphers. defined to support the additional ciphers.
Implementers should be aware that cryptographic algorithms become Implementers should be aware that cryptographic algorithms become
weaker with time. As new cryptanalysis techniques are developed and weaker with time. As new cryptanalysis techniques are developed and
computing performance improves, the work factor to break a particular computing performance improves, the work factor to break a particular
cryptographic algorithm will reduce. Therefore, cryptographic cryptographic algorithm will reduce. Therefore, cryptographic
algorithm implementations should be modular allowing new algorithms algorithm implementations should be modular allowing new algorithms
to be readily inserted. That is, implementers should be prepared to to be readily inserted. That is, implementers should be prepared to
regularly update the set of algorithms in their implementations. regularly update the set of algorithms in their implementations.
Users of the CMS, particularly those employing the CMS to support Users of the CMS, particularly those employing the CMS to support
skipping to change at page 23, line 21 skipping to change at page 23, line 11
Stephen Henson, Paul Hoffman, Scott Hollenbeck, Don Johnson, Burt Stephen Henson, Paul Hoffman, Scott Hollenbeck, Don Johnson, Burt
Kaliski, John Linn, John Pawling, Blake Ramsdell, Francois Rousseau, Kaliski, John Linn, John Pawling, Blake Ramsdell, Francois Rousseau,
Jim Schaad, and Dave Solo for their efforts and support. Jim Schaad, and Dave Solo for their efforts and support.
11 Author Address 11 Author Address
Russell Housley Russell Housley
RSA Laboratories RSA Laboratories
918 Spring Knoll Drive 918 Spring Knoll Drive
Herndon, VA 20170 Herndon, VA 20170
USA EMail: rhousley@rsasecurity.com
rhousley@rsasecurity.com
12 Full Copyright Statement 12. Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. In addition, the included on all such copies and derivative works. However, this
ASN.1 module presented in Appendix A may be used in whole or in part document itself may not be modified in any way, such as by removing
without inclusion of the copyright notice. However, this document the copyright notice or references to the Internet Society or other
itself may not be modified in any way, such as by removing the
copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process shall be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. This revoked by the Internet Society or its successors or assigns.
document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK This document and the information contained herein is provided on an
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
OR FITNESS FOR A PARTICULAR PURPOSE. HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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