draft-ietf-smime-cmsalg-00.txt   draft-ietf-smime-cmsalg-01.txt 
S/MIME Working Group R. Housley S/MIME Working Group R. Housley
Internet Draft RSA Laboratories Internet Draft RSA Laboratories
expires in six months April 2001 expires in six months July 2001
Cryptographic Message Syntax (CMS) Algorithms Cryptographic Message Syntax (CMS) Algorithms
<draft-ietf-smime-cmsalg-00.txt> <draft-ietf-smime-cmsalg-01.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific
Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast).
Abstract Abstract
This document describes cryptographic algorithms for use with the This document describes cryptographic algorithms for use with the
Cryptographic Message Syntax (CMS) [CMS]. CMS is used to digitally Cryptographic Message Syntax (CMS) [CMS]. CMS is used to digitally
sign, digest, authenticate, or encrypt arbitrary messages. sign, digest, authenticate, or encrypt arbitrary messages.
Once approved, this draft will obsolete section 12 of RFC 2630. The Once approved, this draft will obsolete section 12 of RFC 2630. The
companion document (draft-ietf-smime-rfc2630bis-00.txt) will obsolete companion document (draft-ietf-smime-rfc2630bis-02.txt) will obsolete
the rest of RFC 2630. Separation of the protocol and algorithm the rest of RFC 2630. Separation of the protocol and algorithm
specifications allows the IETF to select different mandatory to specifications allows the IETF to select different mandatory to
implement algorithms in the future without reissuing the protocol implement algorithms in the future without reissuing the protocol
document. document.
This draft is being discussed on the "ietf-smime" mailing list. To This draft is being discussed on the "ietf-smime" mailing list. To
join the list, send a message to <ietf-smime-request@imc.org> with join the list, send a message to <ietf-smime-request@imc.org> with
the single word "subscribe" in the body of the message. Also, there the single word "subscribe" in the body of the message. Also, there
is a Web site for the mailing list at <http://www.imc.org/ietf- is a Web site for the mailing list at <http://www.imc.org/ietf-
smime/>. smime/>.
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3.1 DSA ................................................... 36 3.1 DSA ................................................... 36
3.2 RSA ................................................... 36 3.2 RSA ................................................... 36
4 Key Management Algorithms .................................... 36 4 Key Management Algorithms .................................... 36
4.1 Key Agreement Algorithms .............................. 36 4.1 Key Agreement Algorithms .............................. 36
4.1.1 X9.42 Ephemeral-Static Diffie-Hellman ........ 37 4.1.1 X9.42 Ephemeral-Static Diffie-Hellman ........ 37
4.2 Key Transport Algorithms .............................. 38 4.2 Key Transport Algorithms .............................. 38
4.2.1 RSA .......................................... 39 4.2.1 RSA .......................................... 39
4.3 Symmetric Key-Encryption Key Algorithms ............... 39 4.3 Symmetric Key-Encryption Key Algorithms ............... 39
4.3.1 Triple-DES Key Wrap .......................... 40 4.3.1 Triple-DES Key Wrap .......................... 40
4.3.2 RC2 Key Wrap ................................. 41 4.3.2 RC2 Key Wrap ................................. 41
4.4 Key Derivation Algorithms ............................. 41
4.4.1 PBKDF2 ....................................... 41
5 Content Encryption Algorithms ................................ 41 5 Content Encryption Algorithms ................................ 41
5.1 Triple-DES CBC ........................................ 42 5.1 Triple-DES CBC ........................................ 42
5.2 RC2 CBC ............................................... 42 5.2 RC2 CBC ............................................... 42
6 Message Authentication Code (MAC) Algorithms ................. 42 6 Message Authentication Code (MAC) Algorithms ................. 42
6.1 HMAC with SHA-1 ....................................... 43 6.1 HMAC with SHA-1 ....................................... 43
7 Triple-DES and RC2 Key Wrap Algorithms ....................... 43 7 Triple-DES and RC2 Key Wrap Algorithms ....................... 43
7.1 Key Checksum .......................................... 44 7.1 Key Checksum .......................................... 44
7.2 Triple-DES Key Wrap ................................... 44 7.2 Triple-DES Key Wrap ................................... 44
7.3 Triple-DES Key Unwrap ................................. 44 7.3 Triple-DES Key Unwrap ................................. 44
7.4 RC2 Key Wrap .......................................... 45 7.4 RC2 Key Wrap .......................................... 45
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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 messages. This sign, digest, authenticate, or encrypt arbitrary messages. This
companion specification lists the algorithms that MUST be supported companion specification lists the algorithms that MUST be supported
by CMS implementations. It also lists algorithms that SHOULD be by CMS implementations. It also lists algorithms that SHOULD be
supported by CMS implementations. Of course, CMS implementations MAY supported by CMS implementations. Of course, CMS implementations MAY
support other algorithms as well. support other algorithms as well.
Table 1 summarizes the algorithms that CMS implantations MUST support Table 1 summarizes the algorithms that CMS implementations MUST
and SHOULD support. support and SHOULD support.
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 are be identified by algorithm encoding [X.209-88]. Algorithm are identified by algorithm
identifiers (ASN.1 object identifiers), and some algorithms require identifiers (ASN.1 object identifiers), and some algorithms require
additional parameters. When needed, parameters are specified with an additional parameters. When needed, parameters are specified with an
ASN.1 structure. The algorithm identifiers for each algorithm are ASN.1 structure. The algorithm identifier for each algorithm is
specified, and, when needed, the parameter structure is specified. specified, and, when needed, the parameter structure is specified.
The fields in the CMS employed by each algorithm are identified. The fields in the CMS employed by each algorithm are identified.
In this document, the key words MUST, MUST NOT, REQUIRED, SHOULD, Table 1. CMS Implementation Algorithm Requirements
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL are to be interpreted as
described by Scott Bradner in [STDWORDS].
Table 1. CMS Implantation Algorithm Requirements
Algorithm Type MUST implement SHOULD implement Algorithm Type MUST implement SHOULD implement
----------------------------------------------------------------- -----------------------------------------------------------------
Message Digest SHA-1 MD5 Message Digest SHA-1 MD5
Signature DSA and RSA (*) -- Signature DSA and RSA (1,2) --
Key Management Key Management
Key Agreement -- X9.42 E-S D-H Key Agreement -- X9.42 E-S D-H
Key Transport RSA -- Key Transport RSA --
Symmetric KEK Wrap Triple-DES Key Wrap RC2 Key Wrap Symmetric KEK Wrap Triple-DES Key Wrap RC2 Key Wrap
Key Derivation PBKDF2 (3) --
Content Encryption Triple-DES CBC RC2 CBC Content Encryption Triple-DES CBC RC2 CBC
Message Authentication HMAC with SHA-1 -- Message Authentication HMAC with SHA-1 (4) --
(*) Note: CMS implementations MUST be able to verify signatures Note 1: CMS implementations MUST be able to verify signatures
with both DSA and RSA, and they MUST be able to with both DSA and RSA (PKCS #1 v1.5), and they MUST be
generate signatures with at least one of them. able to generate signatures with at least one of them.
Note 2: CMS implementations MUST support RSA (PKCS #1 v1.5) with
SHA-1. CMS implementations SHOULD support RSA
(PKCS #1 v1.5) with MD5.
Note 3: Only those CMS implementations that support password-
based key management MUST implement the PBKDF2 key
derivation algorithm as specified in RFC 2898 [PKCS#5].
Note 4: Only those CMS implementations that support
authenticated-data MUST implement the HMAC with SHA-1
algorithm as specified in RFC 2104 [HMAC].
In this document, the key words MUST, MUST NOT, REQUIRED, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL are to be interpreted as
described by Scott Bradner in [STDWORDS].
2 Message Digest Algorithms 2 Message Digest Algorithms
CMS implementations MUST support SHA-1. CMS implementations SHOULD CMS implementations MUST support SHA-1. CMS implementations SHOULD
support MD5. support 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.
Digest values are located in the DigestedData digest field, and Digest values are located in the DigestedData digest field the
digest values are located in the Message Digest authenticated Message Digest authenticated attribute. In addition, digest values
attribute. In addition, digest values are input to signature are input to signature algorithms.
algorithms.
2.1 SHA-1 2.1 SHA-1
The SHA-1 digest algorithm is defined in FIPS Pub 180-1 [SHA1]. The The SHA-1 digest algorithm is defined in FIPS Pub 180-1 [SHA1]. The
algorithm identifier for SHA-1 is: 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 }
The AlgorithmIdentifier parameters field is OPTIONAL. If present, The AlgorithmIdentifier parameters field is OPTIONAL. If present,
the parameters field MUST contain an ASN.1 NULL. Implementations the parameters field MUST contain an ASN.1 NULL. Implementations
SHOULD accept SHA-1 AlgorithmIdentifiers with absent parameters as SHOULD accept SHA-1 AlgorithmIdentifiers with absent parameters as
well as NULL parameters. Implementations SHOULD generate SHA-1 well as NULL parameters. Implementations SHOULD generate SHA-1
AlgorithmIdentifiers with NULL parameters. AlgorithmIdentifiers with absent parameters.
2.2 MD5 2.2 MD5
The MD5 digest algorithm is defined in RFC 1321 [MD5]. The algorithm The MD5 digest algorithm is defined in RFC 1321 [MD5]. The algorithm
identifier for MD5 is: identifier for MD5 is:
md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) digestAlgorithm(2) 5 } rsadsi(113549) digestAlgorithm(2) 5 }
The AlgorithmIdentifier parameters field MUST be present, and the The AlgorithmIdentifier parameters field MUST be present, and the
parameters field MUST contain NULL. Implementations MAY accept the parameters field MUST contain NULL. Implementations MAY accept the
MD5 AlgorithmIdentifiers with absent parameters as well as NULL MD5 AlgorithmIdentifiers with absent parameters as well as NULL
parameters. parameters.
3 Signature Algorithms 3 Signature Algorithms
CMS implementations MUST support both DSA and RSA. CMS CMS implementations MUST support both DSA and RSA (PKCS #1 v1.5).
implementations MUST be able to verify signatures with both DSA and CMS implementations MUST be able to verify signatures with both DSA
RSA. CMS implementations MUST be able to generate signatures with and RSA (PKCS #1 v1.5). CMS implementations MUST be able to generate
either DSA or RSA. CMS implementations MAY be able to generate signatures with either DSA or RSA (PKCS #1 v1.5). CMS
signatures with both DSA and RSA. implementations MAY be able to generate signatures with both DSA and
RSA (PKCS #1 v1.5).
Signature algorithm identifiers are located in the SignerInfo Signature algorithm identifiers are located in the SignerInfo
signatureAlgorithm field. Also, signature algorithm identifiers are signatureAlgorithm field of SignedData. Also, signature algorithm
located in the SignerInfo signatureAlgorithm field of identifiers are located in the SignerInfo signatureAlgorithm field of
countersignature attributes. countersignature attributes.
Signature values are located in the SignerInfo signature field. Signature values are located in the SignerInfo signature field of
Also, signature values are located in the SignerInfo signature field SignedData. Also, signature values are located in the SignerInfo
of countersignature attributes. signature field of countersignature attributes.
3.1 DSA 3.1 DSA
The DSA signature algorithm is defined in FIPS Pub 186 [DSS]. DSA is The DSA signature algorithm is defined in FIPS Pub 186 [DSS]. DSA is
always used with the SHA-1 message digest algorithm. The algorithm always used with the SHA-1 message digest algorithm.
identifier for DSA is:
The algorithm identifier for DSA subject public keys in certificates
is:
id-dsa OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) x9-57 (10040) x9cm(4) 1 }
DSA signature validation requires three parameters, commonly called
p, q, and g. When the id-dsa algorithm identifier is used,
AlgorithmIdentifier parameters field is optional. If present, the
AlgorithmIdentifier parameters field MUST contain the three DSA
parameter values encoded using the Dss-Parms type. If absent, the
subject DSA public key uses the same DSA parameters as the
certificate issuer.
Dss-Parms ::= SEQUENCE {
p INTEGER,
q INTEGER,
g INTEGER }
When the id-dsa algorithm identifier is used, the DSA public key, commonly called Y, MUST be encoded as an INTEGER. The output of this encoding is carried in the certificate subject public key.
Dss-Pub-Key ::= INTEGER -- Y
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 }
The AlgorithmIdentifier parameters field MUST NOT be present. When the id-dsa-with-sha1 algorithm identifier is used,
AlgorithmIdentifier parameters field MUST be absent.
When signing, the DSA algorithm generates two values, commonly called
r and s. To transfer these two values as one signature, they MUST be
encoded using the Dss-Sig-Value type:
Dss-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER }
3.2 RSA 3.2 RSA
The RSA signature algorithm is defined in RFC 2437 [NEWPKCS#1]. RFC The RSA signature algorithm is defined in RFC 2437 [NEWPKCS#1]. RFC
2437 specifies the use of the RSA signature algorithm with the SHA-1 2437 specifies the use of the RSA signature algorithm with the SHA-1
and MD5 message digest algorithms. The algorithm identifier for RSA and MD5 message digest algorithms.
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 }
CMS implementations MUST support RSA with SHA-1. CMS implementations When the rsaEncryption algorithm identifier is used,
SHOULD support RSA with MD5. AlgorithmIdentifier parameters field MUST contain NULL.
When the rsaEncryption algorithm identifier is used, the RSA public
key, which is composed of a modulus and a public exponent, MUST be
encoded using the RSAPublicKey type. The output of this encoding is
carried in the certificate subject public key.
RSAPublicKey ::= SEQUENCE {
modulus INTEGER, -- n
publicExponent INTEGER } - e
CMS implementations MUST support RSA (PKCS #1 v1.5) with SHA-1. CMS implementations SHOULD support RSA (PKCS #1 v1.5) with MD5.
The algorithm identifier for RSA (PKCS #1 v1.5) with SHA-1 signature values is:
sha1WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) 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 values is:
md5WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 4 }
When either the sha1WithRSAEncryption algorithm identifier or the md5WithRSAEncryption algorithm identifier is used, AlgorithmIdentifier parameters field MUST be NULL.
When signing, the RSA algorithm generates a single value, and that value is used directly as the signature value.
4 Key Management Algorithms 4 Key Management Algorithms
CMS accommodates three general key management techniques: key CMS accommodates the following general key management techniques: key agreement, key transport, previously distributed symmetric key-encryption keys, and passwords.
agreement, key transport, and previously distributed symmetric key-
encryption keys.
4.1 Key Agreement Algorithms 4.1 Key Agreement Algorithms
CMS implementations SHOULD support key agreement using X9.42 CMS implementations SHOULD support key agreement using X9.42 Ephemeral-Static Diffie-Hellman (X9.42 E-S D-H).
Ephemeral-Static Diffie-Hellman (X9.42 E-S D-H).
Any symmetric encryption algorithm that a CMS implementation includes Any symmetric encryption algorithm that a CMS implementation includes as a content-encryption algorithm MUST also be included as a key-encryption algorithm. CMS implementations SHOULD include key agreement of Triple-DES pairwise key-encryption keys. CMS implementations SHOULD include key agreement of RC2 pairwise key-encryption keys. CMS implementations MUST include Triple-DES wrapping of Triple-DES content-encryption keys, and CMS implementations SHOULD include RC2 wrapping of RC2 content-encryption keys. The key wrap algorithms for Triple-DES and RC2 are described in section 7.
as a content-encryption algorithm MUST also be included as a key-
encryption algorithm. CMS implementations SHOULD include key
agreement of Triple-DES pairwise key-encryption keys. CMS
implementations SHOULD include key agreement of RC2 pairwise key-
encryption keys. CMS implementations MUST include Triple-DES
wrapping of Triple-DES content-encryption keys and RC2 wrapping of
RC2 content-encryption keys. The key wrap algorithms for Triple-DES
and RC2 are described in section 7.
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 key MAY be wrapped with 168-bit Triple-DES key-encryption key. Similarly, a 40-bit RC2 content-encryption key MAY be wrapped with 128-bit RC2 key-encryption key.
encryption algorithms. For example, a 128-bit RC2 content-encryption
key MAY be wrapped with 168-bit Triple-DES key-encryption key.
Similarly, a 40-bit RC2 content-encryption key MAY be wrapped with
128-bit RC2 key-encryption key.
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 RC2 effective key [RC2].
generated as input to the key expansion process used to compute the
RC2 effective key [RC2].
Key agreement algorithm identifiers are located in the EnvelopedData Key agreement algorithm identifiers are located in the EnvelopedData RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm and AuthenticatedData RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm fields.
RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm and
AuthenticatedData RecipientInfos KeyAgreeRecipientInfo
keyEncryptionAlgorithm fields.
Key wrap algorithm identifiers are located in the KeyWrapAlgorithm Key wrap algorithm identifiers are located in the KeyWrapAlgorithm parameters within the EnvelopedData RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm and AuthenticatedData RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm fields.
parameters within the EnvelopedData RecipientInfos
KeyAgreeRecipientInfo keyEncryptionAlgorithm and AuthenticatedData
RecipientInfos KeyAgreeRecipientInfo keyEncryptionAlgorithm fields.
Wrapped content-encryption keys are located in the EnvelopedData Wrapped content-encryption keys are located in the EnvelopedData RecipientInfos KeyAgreeRecipientInfo RecipientEncryptedKeys encryptedKey field. Wrapped message-authentication keys are located in the AuthenticatedData RecipientInfos KeyAgreeRecipientInfo RecipientEncryptedKeys encryptedKey field.
RecipientInfos KeyAgreeRecipientInfo RecipientEncryptedKeys
encryptedKey field. Wrapped message-authentication keys are located
in the AuthenticatedData RecipientInfos KeyAgreeRecipientInfo
RecipientEncryptedKeys encryptedKey field.
4.1.1 X9.42 Ephemeral-Static Diffie-Hellman 4.1.1 X9.42 Ephemeral-Static Diffie-Hellman
Ephemeral-Static Diffie-Hellman key agreement is defined in RFC 2631 Ephemeral-Static Diffie-Hellman key agreement is defined in RFC 2631 [DH-X9.42]. When using Ephemeral-Static Diffie-Hellman, the EnvelopedData RecipientInfos KeyAgreeRecipientInfo and AuthenticatedData RecipientInfos KeyAgreeRecipientInfo fields are used as follows:
[DH-X9.42]. When using Ephemeral-Static Diffie-Hellman, the
EnvelopedData RecipientInfos KeyAgreeRecipientInfo and
AuthenticatedData RecipientInfos KeyAgreeRecipientInfo fields are
used as follows:
version MUST be 3. version MUST be 3.
originator MUST be the originatorKey alternative. The originator MUST be the originatorKey alternative. The originatorKey algorithm field MUST contain the dh-public-number object identifier with absent parameters. The originatorKey publicKey field MUST contain the sender's ephemeral public key. The dh-public-number object identifier is:
originatorKey algorithm field MUST contain the dh-public-number
object identifier with absent parameters. The originatorKey
publicKey field MUST contain the sender's ephemeral public key.
The dh-public-number object identifier is:
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 MAY be absent. When present, the ukm is used to ensure that a ukm MAY be absent. When present, the ukm is used to ensure that a
different key-encryption key is generated when the ephemeral different key-encryption key is generated when the ephemeral
private key might be used more than once. private key 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-
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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 content-
encryption key encrypted with the X9.42 Ephemeral-Static Diffie- encryption key encrypted with the X9.42 Ephemeral-Static Diffie-
Hellman generated pairwise key-encryption key using the algorithm Hellman generated pairwise key-encryption key using the algorithm
specified by the KeyWrapAlgortihm. specified by the KeyWrapAlgortihm.
4.2 Key Transport Algorithms 4.2 Key Transport Algorithms
CMS implementations MUST support key transport using RSA. RSA CMS implementations MUST support key transport using RSA (PKCS #1
implementations MUST support key transport of Triple-DES content- v1.5). RSA implementations MUST support key transport of Triple-DES
encryption keys. RSA implementations SHOULD support key transport of content-encryption keys. RSA implementations SHOULD support key
RC2 content-encryption keys. transport of RC2 content-encryption keys.
Key transport algorithm identifiers are located in the EnvelopedData Key transport algorithm identifiers are located in the EnvelopedData
RecipientInfos KeyTransRecipientInfo keyEncryptionAlgorithm and RecipientInfos KeyTransRecipientInfo keyEncryptionAlgorithm and
AuthenticatedData RecipientInfos KeyTransRecipientInfo AuthenticatedData RecipientInfos KeyTransRecipientInfo
keyEncryptionAlgorithm fields. keyEncryptionAlgorithm fields.
Key transport encrypted content-encryption keys are located in the Key transport encrypted content-encryption keys are located in the
EnvelopedData RecipientInfos KeyTransRecipientInfo encryptedKey EnvelopedData RecipientInfos KeyTransRecipientInfo encryptedKey
field. Key transport encrypted message-authentication keys are field. Key transport encrypted message-authentication keys are
located in the AuthenticatedData RecipientInfos KeyTransRecipientInfo located in the AuthenticatedData RecipientInfos KeyTransRecipientInfo
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4.2.1 RSA 4.2.1 RSA
The RSA key transport algorithm is the RSA encryption scheme defined The RSA key transport algorithm is the RSA encryption scheme defined
in RFC 2313 [PKCS#1], block type is 02, where the message to be in RFC 2313 [PKCS#1], block type is 02, where the message to be
encrypted is the content-encryption key. The algorithm identifier encrypted is the content-encryption key. The algorithm identifier
for RSA is: for RSA 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 }
The AlgorithmIdentifier parameters field must be present, and the The AlgorithmIdentifier parameters field must be present, and the
parameters field must contain NULL. parameters field must contain NULL.
When using a Triple-DES content-encryption key, CMS implementations When using a Triple-DES content-encryption key, CMS implementations
MUST adjust the parity bits for each DES key comprising the Triple- MUST adjust the parity bits for each DES key comprising the Triple-
DES key prior to RSA encryption. DES key prior to RSA (PKCS #1 v1.5) encryption.
The use of RSA encryption, as defined in RFC 2313 [PKCS#1], to The use of RSA encryption, as defined in RFC 2313 [PKCS#1], to
provide confidentiality has a known vulnerability. The vulnerability provide confidentiality has a known vulnerability. The vulnerability
is primarily relevant to usage in interactive applications rather is primarily relevant to usage in interactive applications rather
than to store-and-forward environments. Further information and than to store-and-forward environments. Further information and
proposed countermeasures are discussed in the Security Considerations proposed countermeasures are discussed in the Security Considerations
section of this document and RFC <TBD> [MMA]. section of this document and RFC <TBD> [MMA].
Note that the same encryption scheme is also defined in RFC 2437 Note that the same encryption scheme is also defined in RFC 2437
[NEWPKCS#1]. Within RFC 2437, this scheme is called RSAES- [NEWPKCS#1]. Within RFC 2437, this scheme is called RSAES-
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encrypt the Triple-DES content-encryption key is beyond of the scope encrypt the Triple-DES content-encryption key is beyond of the scope
of this document. of this document.
4.3.2 RC2 Key Wrap 4.3.2 RC2 Key Wrap
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
RC2ParameterVersion ::= INTEGER RC2ParameterVersion ::= INTEGER
The RC2 effective-key-bits (key size) greater than 32 and less than The RC2 effective-key-bits (key size) greater than 32 and less than
256 is encoded in the RC2ParameterVersion. For the effective-key- 256 is encoded in the RC2ParameterVersion. For the effective-key-
bits of 40, 64, and 128, the rc2ParameterVersion values are 160, 120, bits of 40, 64, and 128, the rc2ParameterVersion values are 160, 120,
and 58 respectively. These values are not simply the RC2 key length. and 58 respectively. These values are not simply the RC2 key length.
Note that the value 160 must be encoded as two octets (00 A0), Note that the value 160 must be encoded as two octets (00 A0),
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be used with the RC2ParameterVersion parameter set to 58. be used with the RC2ParameterVersion parameter set to 58.
The key wrap algorithm used to encrypt a RC2 content-encryption key The key wrap algorithm used to encrypt a RC2 content-encryption key
with a RC2 key-encryption key is specified in section 7.4. The with a RC2 key-encryption key is specified in section 7.4. The
corresponding key unwrap algorithm is specified in section 7.5. corresponding key unwrap algorithm is specified in section 7.5.
Out-of-band distribution of the RC2 key-encryption key used to Out-of-band distribution of the RC2 key-encryption key used to
encrypt the RC2 content-encryption key is beyond of the scope of this encrypt the RC2 content-encryption key is beyond of the scope of this
document. document.
4.4 Key Derivation Algorithms
Key derivation algorithms are used to convert a password into a key-
encryption key as part of the password-based key management
technique. CMS implementations that support the password-based key
management technique MUST implement the PBKDF2 key derivation
algorithm specified in RFC 2898 [PKCS#5].
Key derivation algorithm identifiers are located in the EnvelopedData
RecipientInfos PasswordRecipientInfo keyDerivationAlgorithm and
AuthenticatedData RecipientInfos PasswordRecipientInfo
keyDerivationAlgorithm fields.
The key-encryption key that is derived from the password is used to
encrypt the content-encryption key
The content-encryption keys encrypted with password-derived key-
encryption keys are located in the EnvelopedData RecipientInfos
PasswordRecipientInfo encryptedKey field. The message-authentication
keys encrypted with password-derived key-encryption keys are located
in the AuthenticatedData RecipientInfos PasswordRecipientInfo
encryptedKey field.
4.4.1 PBKDF2
The PBKDF2 key derivation algorithm specified in RFC 2898 [PKCS#5].
The KeyDerivationAlgorithmIdentifer identifies the key-derivation
algorithm, and any associated parameters, used to derive the key-
encryption key from the user-supplied password. The algorithm
identifier for the PBKDF2 key derivation algorithm is:
id-PBKDF2 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-5(5) 12 }
The AlgorithmIdentifier parameter field MUST be PBKDF2-params:
PBKDF2-params ::= SEQUENCE {
salt CHOICE {
specified OCTET STRING,
otherSource AlgorithmIdentifier },
iterationCount INTEGER (1..MAX),
keyLength INTEGER (1..MAX) OPTIONAL,
prf AlgorithmIdentifier DEFAULT hMAC-SHA1 }
5 Content Encryption Algorithms 5 Content Encryption Algorithms
CMS implementations MUST support Three-Key Triple-DES in CBC mode. CMS implementations MUST support Three-Key Triple-DES in CBC mode.
MS implementations SHOULD support Two-Key Triple-DES in CBC mode. CMS implementations SHOULD support Two-Key Triple-DES in CBC mode.
CMS implementations SHOULD support RC2 in CBC mode. CMS implementations SHOULD support RC2 in CBC mode.
Content encryption algorithms identifiers are located in the Content encryption algorithms 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.
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7.2 Triple-DES Key Wrap 7.2 Triple-DES Key Wrap
The Triple-DES key wrap algorithm encrypts a Triple-DES content- The Triple-DES key wrap algorithm encrypts a Triple-DES content-
encryption key with a Triple-DES key-encryption key. The Triple-DES encryption key with a Triple-DES key-encryption key. The Triple-DES
key wrap algorithm is: key wrap algorithm is:
1. Set odd parity for each of the DES key octets comprising 1. Set odd parity for each of the DES key octets comprising
the content-encryption key, call the result CEK. the content-encryption key, call the result CEK.
2. Compute an 8 octet key checksum value on CEK as described above 2. Compute an 8 octet key checksum value on CEK as described above
in Section 12.6.1, call the result ICV. in Section 7.1, call the result ICV.
3. Let CEKICV = CEK || ICV. 3. Let CEKICV = CEK || ICV.
4. Generate 8 octets at random, call the result IV. 4. Generate 8 octets at random, call the result IV.
5. Encrypt CEKICV in CBC mode using the key-encryption key. Use 5. Encrypt CEKICV in CBC mode using the key-encryption key. Use
the random value generated in the previous step as the the random value generated in the previous step as the
initialization vector (IV). Call the ciphertext TEMP1. initialization vector (IV). Call the ciphertext TEMP1.
6. Let TEMP2 = IV || TEMP1. 6. Let TEMP2 = IV || TEMP1.
7. Reverse the order of the octets in TEMP2. That is, the most 7. Reverse the order of the octets in TEMP2. That is, the most
significant (first) octet is swapped with the least significant significant (first) octet is swapped with the least significant
(last) octet, and so on. Call the result TEMP3. (last) octet, and so on. Call the result TEMP3.
8. Encrypt TEMP3 in CBC mode using the key-encryption key. Use 8. Encrypt TEMP3 in CBC mode using the key-encryption key. Use
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(last) octet, and so on. Call the result TEMP2. (last) octet, and so on. Call the result TEMP2.
4. Decompose the TEMP2 into IV and TEMP1. IV is the most 4. Decompose the TEMP2 into IV and TEMP1. IV is the most
significant (first) 8 octets, and TEMP1 is the least significant significant (first) 8 octets, and TEMP1 is the least significant
(last) 32 octets. (last) 32 octets.
5. Decrypt TEMP1 in CBC mode using the key-encryption key. Use 5. Decrypt TEMP1 in CBC mode using the key-encryption key. Use
the IV value from the previous step as the initialization vector. the IV value from the previous step as the initialization vector.
Call the ciphertext CEKICV. Call the ciphertext CEKICV.
6. Decompose the CEKICV into CEK and ICV. CEK is the most significant 6. Decompose the CEKICV into CEK and ICV. CEK is the most significant
(first) 24 octets, and ICV is the least significant (last) 8 octets. (first) 24 octets, and ICV is the least significant (last) 8 octets.
7. Compute an 8 octet key checksum value on CEK as described above 7. Compute an 8 octet key checksum value on CEK as described above
in Section 12.6.1. If the computed key checksum value does not in Section 7.1. If the computed key checksum value does not
match the decrypted key checksum value, ICV, then error. match the decrypted key checksum value, ICV, then error.
8. Check for odd parity each of the DES key octets comprising CEK. 8. Check for odd parity each of the DES key octets comprising CEK.
If parity is incorrect, then there is an error. If parity is incorrect, then there is an error.
9. Use CEK as the content-encryption key. 9. Use CEK as the content-encryption key.
7.4 RC2 Key Wrap 7.4 RC2 Key Wrap
The RC2 key wrap algorithm encrypts a RC2 content-encryption key with The RC2 key wrap algorithm encrypts a RC2 content-encryption key with
a RC2 key-encryption key. The RC2 key wrap algorithm is: a RC2 key-encryption key. The RC2 key wrap algorithm is:
1. Let the content-encryption key be called CEK, and let the length 1. Let the content-encryption key be called CEK, and let the length
of the content-encryption key in octets be called LENGTH. LENGTH of the content-encryption key in octets be called LENGTH. LENGTH
is a single octet. is a single octet.
2. Let LCEK = LENGTH || CEK. 2. Let LCEK = LENGTH || CEK.
3. Let LCEKPAD = LCEK || PAD. If the length of LCEK is a multiple 3. Let LCEKPAD = LCEK || PAD. If the length of LCEK is a multiple
of 8, the PAD has a length of zero. If the length of LCEK is of 8, the PAD has a length of zero. If the length of LCEK is
not a multiple of 8, then PAD contains the fewest number of not a multiple of 8, then PAD contains the fewest number of
random octets to make the length of LCEKPAD a multiple of 8. random octets to make the length of LCEKPAD a multiple of 8.
4. Compute an 8 octet key checksum value on LCEKPAD as described 4. Compute an 8 octet key checksum value on LCEKPAD as described
above in Section 12.6.1, call the result ICV. above in Section 7.1, call the result ICV.
5. Let LCEKPADICV = LCEKPAD || ICV. 5. Let LCEKPADICV = LCEKPAD || ICV.
6. Generate 8 octets at random, call the result IV. 6. Generate 8 octets at random, call the result IV.
7. Encrypt LCEKPADICV in CBC mode using the key-encryption key. 7. Encrypt LCEKPADICV in CBC mode using the key-encryption key.
Use the random value generated in the previous step as the Use the random value generated in the previous step as the
initialization vector (IV). Call the ciphertext TEMP1. initialization vector (IV). Call the ciphertext TEMP1.
8. Let TEMP2 = IV || TEMP1. 8. Let TEMP2 = IV || TEMP1.
9. Reverse the order of the octets in TEMP2. That is, the most 9. Reverse the order of the octets in TEMP2. That is, the most
significant (first) octet is swapped with the least significant significant (first) octet is swapped with the least significant
(last) octet, and so on. Call the result TEMP3. (last) octet, and so on. Call the result TEMP3.
10. Encrypt TEMP3 in CBC mode using the key-encryption key. Use 10. Encrypt TEMP3 in CBC mode using the key-encryption key. Use
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(last) octet, and so on. Call the result TEMP2. (last) octet, and so on. Call the result TEMP2.
4. Decompose the TEMP2 into IV and TEMP1. IV is the most 4. Decompose the TEMP2 into IV and TEMP1. IV is the most
significant (first) 8 octets, and TEMP1 is the remaining octets. significant (first) 8 octets, and TEMP1 is the remaining octets.
5. Decrypt TEMP1 in CBC mode using the key-encryption key. Use 5. Decrypt TEMP1 in CBC mode using the key-encryption key. Use
the IV value from the previous step as the initialization vector. the IV value from the previous step as the initialization vector.
Call the plaintext LCEKPADICV. Call the plaintext LCEKPADICV.
6. Decompose the LCEKPADICV into LCEKPAD, and ICV. ICV is the 6. Decompose the LCEKPADICV into LCEKPAD, and ICV. ICV is the
least significant (last) octet 8 octets. LCEKPAD is the least significant (last) octet 8 octets. LCEKPAD is the
remaining octets. remaining octets.
7. Compute an 8 octet key checksum value on LCEKPAD as described 7. Compute an 8 octet key checksum value on LCEKPAD as described
above in Section 12.6.1. If the computed key checksum value above in Section 7.1. If the computed key checksum value does
does not match the decrypted key checksum value, ICV, then error. not match the decrypted key checksum value, ICV, then error.
8. Decompose the LCEKPAD into LENGTH, CEK, and PAD. LENGTH is the 8. Decompose the LCEKPAD into LENGTH, CEK, and PAD. LENGTH is the
most significant (first) octet. CEK is the following LENGTH most significant (first) octet. CEK is the following LENGTH
octets. PAD is the remaining octets, if any. octets. PAD is the remaining octets, if any.
9. If the length of PAD is more than 7 octets, then error. 9. If the length of PAD is more than 7 octets, then error.
10. Use CEK as the content-encryption key. 10. Use CEK as the content-encryption key.
Appendix A: ASN.1 Module Appendix A: ASN.1 Module
CryptographicMessageSyntaxAlgorithms CryptographicMessageSyntaxAlgorithms
{ iso(1) member-body(2) us(840) rsadsi(113549) { iso(1) member-body(2) us(840) rsadsi(113549)
skipping to change at page 16, line 29 skipping to change at page 19, line 29
-- IMPORTS None -- IMPORTS None
-- 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 }
md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) digestAlgorithm(2) 5 } rsadsi(113549) digestAlgorithm(2) 5 }
id-dsa OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
x9-57(10040) x9cm(4) 1 }
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 }
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 }
md5WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 4 }
sha1WithRSAEncryption OBJECT IDENTIFIER ::= { iso(1)
member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 5 }
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 }
id-alg-ESDH OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) id-alg-ESDH OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 5 } rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 5 }
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 }
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 }
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 }
rc2-cbc OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840) rc2-cbc OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) encryptionAlgorithm(3) 2 } rsadsi(113549) encryptionAlgorithm(3) 2 }
hMAC-SHA1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) hMAC-SHA1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) 8 1 2 } dod(6) internet(1) security(5) mechanisms(5) 8 1 2 }
-- Algorithm Parameters id-PBKDF2 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-5(5) 12 }
-- Public Key Types
Dss-Pub-Key ::= INTEGER -- Y
RSAPublicKey ::= SEQUENCE {
modulus INTEGER, -- n
publicExponent INTEGER } -- e
DHPublicKey ::= INTEGER -- y = g^x mod p
-- Signature Value Types
Dss-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER }
-- Algorithm Identifier Parameter Types
Dss-Parms ::= SEQUENCE {
p INTEGER,
q INTEGER,
g INTEGER }
DHDomainParameters ::= SEQUENCE {
p INTEGER, -- odd prime, p=jq +1
g INTEGER, -- generator, g
q INTEGER, -- factor of p-1
j INTEGER OPTIONAL, -- subgroup factor
validationParms ValidationParms OPTIONAL }
ValidationParms ::= SEQUENCE {
seed BIT STRING,
pgenCounter INTEGER }
KeyWrapAlgorithm ::= AlgorithmIdentifier KeyWrapAlgorithm ::= AlgorithmIdentifier
RC2wrapParameter ::= RC2ParameterVersion RC2wrapParameter ::= RC2ParameterVersion
RC2ParameterVersion ::= INTEGER RC2ParameterVersion ::= INTEGER
CBCParameter ::= IV CBCParameter ::= IV
IV ::= OCTET STRING -- exactly 8 octets IV ::= OCTET STRING -- exactly 8 octets
RC2CBCParameter ::= SEQUENCE { RC2CBCParameter ::= SEQUENCE {
rc2ParameterVersion INTEGER, rc2ParameterVersion INTEGER,
iv OCTET STRING } -- exactly 8 octets iv OCTET STRING } -- exactly 8 octets
PBKDF2-params ::= SEQUENCE {
salt CHOICE {
specified OCTET STRING,
otherSource AlgorithmIdentifier },
iterationCount INTEGER (1..MAX),
keyLength INTEGER (1..MAX) OPTIONAL,
prf AlgorithmIdentifier DEFAULT hMAC-SHA1 }
END -- of CryptographicMessageSyntaxAlgorithms END -- of CryptographicMessageSyntaxAlgorithms
References 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.
CMS Housley, R. Cryptographic Message Syntax. RFC <TBD>. <Date>. CMS Housley, R. Cryptographic Message Syntax. RFC <TBD>. <Date>.
{draft-ietf-smime-rfc2630bis-*.txt} {draft-ietf-smime-rfc2630bis-*.txt}
skipping to change at page 18, line 17 skipping to change at page 22, line 23
MODES National Institute of Standards and Technology. MODES National Institute of Standards and Technology.
FIPS Pub 81: DES Modes of Operation. 2 December 1980. FIPS Pub 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.
PKCS#1 Kaliski, B. PKCS #1: RSA Encryption, Version 1.5. PKCS#1 Kaliski, B. PKCS #1: RSA Encryption, Version 1.5.
RFC 2313. March 1998. RFC 2313. March 1998.
PKCS#5 Kaliski, B. PKCS #5: Password-Based Cryptography
Specification, Version 2.0. RFC 2898. September 2000.
RANDOM Eastlake, D., S. Crocker, and J. Schiller. Randomness RANDOM Eastlake, D., S. Crocker, 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 Algorithm.
RFC 2268. March 1998. RFC 2268. March 1998.
SHA1 National Institute of Standards and Technology. SHA1 National Institute of Standards and Technology.
FIPS Pub 180-1: Secure Hash Standard. 17 April 1995. FIPS Pub 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
skipping to change at page 20, line 20 skipping to change at page 24, line 29
support the additional ciphers. 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 cryptoanalysis techniques are developed and weaker with time. As new cryptoanalysis 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 for to be readily inserted. That is, implementers should be prepared for
the set of mandatory to implement algorithms to change over time. the set of mandatory to implement algorithms to change over time.
The countersignature unauthenticated attribute includes a digital
signature that is computed on the content signature value, thus the
countersigning process need not know the original signed content.
This structure permits implementation efficiency advantages; however,
this structure may also permit the countersigning of an inappropriate
signature value. Therefore, implementations that perform
countersignatures should either verify the original signature value
prior to countersigning it (this verification requires processing of
the original content), or implementations should perform
countersigning in a context that ensures that only appropriate
signature values are countersigned.
Users of CMS, particularly those employing CMS to support interactive Users of CMS, particularly those employing CMS to support interactive
applications, should be aware that PKCS #1 Version 1.5 as specified applications, should be aware that PKCS #1 Version 1.5 as specified
in RFC 2313 [PKCS#1] is vulnerable to adaptive chosen ciphertext in RFC 2313 [PKCS#1] is vulnerable to adaptive chosen ciphertext
attacks when applied for encryption purposes. Exploitation of this attacks when applied for encryption purposes. Exploitation of this
identified vulnerability, revealing the result of a particular RSA identified vulnerability, revealing the result of a particular RSA
decryption, requires access to an oracle which will respond to a decryption, requires access to an oracle which will respond to a
large number of ciphertexts (based on currently available results, large number of ciphertexts (based on currently available results,
hundreds of thousands or more), which are constructed adaptively in hundreds of thousands or more), which are constructed adaptively in
response to previously-received replies providing information on the response to previously-received replies providing information on the
successes or failures of attempted decryption operations. As a successes or failures of attempted decryption operations. As a
 End of changes. 

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