draft-ietf-smime-aes-alg-02.txt   draft-ietf-smime-aes-alg-03.txt 
S/MIME Working Group J. Schaad S/MIME Working Group J. Schaad
Internet Draft Soaring Hawk Consulting Internet Draft Soaring Hawk Consulting
Document: draft-ietf-smime-aes-alg-02.txt R. Housley Document: draft-ietf-smime-aes-alg-03.txt R. Housley
Expires: December 20, 2001 RSA Laboratories Expires: May 2001 RSA Laboratories
July 2001 November 2001
Use of the AES Encryption Algorithm and RSA-OAEP Key Transport in CMS Use of the AES Encryption Algorithm and RSA-OAEP Key Transport in CMS
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 RFC 2026. all provisions of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Comments or suggestions for improvement may be made on the "ietf- Comments or suggestions for improvement may be made on the "ietf-
smime" mailing list, or directly to the author. smime" mailing list, or directly to the author.
Abstract Abstract
This document specifies how to incorporate the Advanced Encryption This document specifies the conventions for using the Advanced
Standard (AES) algorithm [AES] and RSAES-OAEP key transport method of Encryption Standard (AES) algorithm [AES] for encryption and the
key management into the S/MIME Cryptographic Message Syntax [CMS] as RSAES-OAEP key transport method [PKCS#1v2.0] for key management with
additional algorithms. the Cryptographic Message Syntax (CMS) [CMS].
Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119 this document are to be interpreted as described in RFC 2119
[MUSTSHOULD]. [MUSTSHOULD].
1 Overview 1 Overview
This document describes the conventions for using the RSAES-OAEP key This document specifies the conventions for using the RSAES-OAEP key
transport algorithm and Advanced Encryption Standard (AES) content transport algorithm and Advanced Encryption Standard (AES) content
encryption algorithm with the Cryptographic Message Syntax [CMS] encryption algorithm with the Cryptographic Message Syntax [CMS]
enveloped-data and encrypted-data content types. enveloped-data and encrypted-data content types.
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This document presents the use of the two algorithms together, and we This document presents the use of the two algorithms together, since
anticipate that they will be used together. However,the two we anticipate that they will be used together. However, the two
algorithms can be used independently. For example, RSA-OAEP could be algorithms can be used independently. For example, RSA-OAEP could be
used to transport Triple-DES keys, and AES keys could be distributed used to transport Triple-DES keys, and AES keys could be distributed
out-of-band for use with mail lists. The two algorithms are out-of-band for use with mail lists.
presented together simply because the initial usage of each will be
as a matched pair.
1.1 AES 1.1 AES
The Advanced Encryption Standard (AES) is being developed to replace The Advanced Encryption Standard (AES) is being developed to replace
DES [DES]. The AES will be a new Federal Information Processing DES [DES]. The AES will be a new Federal Information Processing
Standard (FIPS) Publication that will specify a cryptographic Standard (FIPS) Publication that will specify a cryptographic
algorithm for use by U.S. Government organizations. However, the AES algorithm for use by U.S. Government organizations. However, the AES
will also be widely used by organizations, institutions, and will also be widely used by organizations, institutions, and
individuals outside of the U.S. Government. individuals outside of the U.S. Government.
NIST has posted the Draft FIPS for the AES (see NIST has posted the Draft FIPS for the AES (see
http://csrc.nist.gov/encryption/aes). The AES will become official http://csrc.nist.gov/encryption/aes). The AES will become official
after a 90-day public comment period, NIST makes appropriate changes after a 90-day public comment period, NIST makes appropriate changes
to the Draft FIPS, and the Secretary of Commerce approves the FIPS. to the Draft FIPS, and the Secretary of Commerce approves the FIPS.
Current estimates place this sometime in the summer of 2001. In Current estimates place this sometime in late 2001. In other words,
other words, any day now. any day now.
The two researchers who developed and submitted the Rijndael Two researchers who developed and submitted the Rijndael algorithm
algorithm for the AES are both cryptographers from Belgium: Dr. Joan for consideration are both cryptographers from Belgium: Dr. Joan
Daemen of Proton World International and Dr. Vincent Rijmen, a Daemen of Proton World International and Dr. Vincent Rijmen, a
postdoctoral researcher in the Electrical Engineering Department of postdoctoral researcher in the Electrical Engineering Department of
Katholieke Universiteit Leuven. Katholieke Universiteit Leuven.
NIST selected the Rijndael algorithm for AES because it offers a NIST selected the Rijndael algorithm for AES because it offers a
combination of security, performance, efficiency, ease of combination of security, performance, efficiency, ease of
implementation, and flexibility. Specifically, Rijndael appears to implementation, and flexibility. Specifically, Rijndael appears to
be consistently a very good performer in both hardware and software be consistently a very good performer in both hardware and software
across a wide range of computing environments regardless of its use across a wide range of computing environments regardless of its use
in feedback or non-feedback modes. Its key setup time is excellent, in feedback or non-feedback modes. Its key setup time is excellent,
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postdoctoral researcher in the Electrical Engineering Department of postdoctoral researcher in the Electrical Engineering Department of
Katholieke Universiteit Leuven. Katholieke Universiteit Leuven.
NIST selected the Rijndael algorithm for AES because it offers a NIST selected the Rijndael algorithm for AES because it offers a
combination of security, performance, efficiency, ease of combination of security, performance, efficiency, ease of
implementation, and flexibility. Specifically, Rijndael appears to implementation, and flexibility. Specifically, Rijndael appears to
be consistently a very good performer in both hardware and software be consistently a very good performer in both hardware and software
across a wide range of computing environments regardless of its use across a wide range of computing environments regardless of its use
in feedback or non-feedback modes. Its key setup time is excellent, in feedback or non-feedback modes. Its key setup time is excellent,
and its key agility is good. The very low memory requirements of the and its key agility is good. The very low memory requirements of the
Rijndael algorithm make it very well suited for restricted-space Rijndael algorithm make it very well suited for restricted-space
environments, in which it also demonstrates excellent performance. environments, in which it also demonstrates excellent performance.
The Rijndael algorith operations are among the easiest to defend The Rijndael algorithm operations are among the easiest to defend
against power and timing attacks. Additionally, it appears that some against power and timing attacks. Additionally, it appears that some
defense can be provided against such attacks without significantly defense can be provided against such attacks without significantly
impacting the algorithm's performance. Finally, the algorithm's impacting the algorithm's performance. Finally, the algorithm's
internal round structure appears to have good potential to benefit internal round structure appears to have good potential to benefit
from instruction-level parallelism. from instruction-level parallelism.
The AES specifies three key sizes: 128, 192 and 256 bits. The AES specifies three key sizes: 128, 192 and 256 bits.
1.2 RSA-OAEP 1.2 RSA-OAEP
When the variant of the RSA key transport algorithm specified in PKCS When the variant of the RSA key transport algorithm specified in PKCS
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defense can be provided against such attacks without significantly defense can be provided against such attacks without significantly
impacting the algorithm's performance. Finally, the algorithm's impacting the algorithm's performance. Finally, the algorithm's
internal round structure appears to have good potential to benefit internal round structure appears to have good potential to benefit
from instruction-level parallelism. from instruction-level parallelism.
The AES specifies three key sizes: 128, 192 and 256 bits. The AES specifies three key sizes: 128, 192 and 256 bits.
1.2 RSA-OAEP 1.2 RSA-OAEP
When the variant of the RSA key transport algorithm specified in PKCS When the variant of the RSA key transport algorithm specified in PKCS
#1 Version 1.5 [PKCS#1v1.5] is used for key management, it is #1 Version 1.5 [PKCS#1v1.5] is used for key management, it is
vulnerable to adaptive chosen ciphertext attacks. This attack is vulnerable to adaptive chosen ciphertext attacks. This attack is
described in [RSALAB] and [CRYPTO98]. The use of PKCS #1 Version 1.5 described in [RSALAB] and [CRYPTO98]. The use of PKCS #1 Version 1.5
key transport in interactive applications is especially vulnerable,
but countermeasures are described in [MMA]. . Exploitation of this
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key transport in interactive applications is especially vulnerable. identified vulnerability, revealing the result of a particular RSA
Exploitation of this identified vulnerability, revealing the result decryption, requires access to an oracle which will respond to
of a particular RSA decryption, requires access to an oracle which hundreds of thousands of ciphertexts, which are constructed
will respond to hundreds of thousands of ciphertexts, which are adaptively in response to previously-received replies providing
constructed adaptively in response to previously-received replies information on the successes or failures of attempted decryption
providing information on the successes or failures of attempted operations.
decryption operations.
The attack appears significantly less feasible in store-and-forward The attack appears significantly less feasible in store-and-forward
environments, such as S/MIME. When PKCS #1 Version 1.5 key transport environments, such as S/MIME. When PKCS #1 Version 1.5 key transport
is applied as an intermediate encryption layer within an interactive is applied as an intermediate encryption layer within an interactive
request-response communications environment, exploitation could be request-response communications environment, exploitation could be
more feasible. However, Secure Sockets Layer (SSL) [SSL] and more feasible. However, Secure Sockets Layer (SSL) [SSL] and
Transport Layer Security (TLS) [TLS] protocol implementations could Transport Layer Security (TLS) [TLS] protocol implementations could
include countermeasures that detect and prevent Bleichenbacher's and include countermeasures that detect and prevent Bleichenbacher's and
other chosen-ciphertext attacks, without changing the way the RSA key other chosen-ciphertext attacks, without changing the way the RSA key
transport algorithm is used. These countermeasures are performed transport algorithm is used. These countermeasures are performed
within the protocol level. In the interest of long-term security within the protocol level. In the interest of long-term security
assurance, it is prudent to adopt an improved cryptographic technique assurance, it is prudent to adopt an improved cryptographic technique
rather than embedding countermeasures within protocols. rather than embedding countermeasures within protocols.
An updated version of PKCS #1 has been published, PKCS #1 Version 2.0 An updated version of PKCS #1 has been published, PKCS #1 Version 2.0
[PKCS#1v2.0]. This new document supersedes RFC 2313 [PKCS#1v1.5]. [PKCS#1v2.0]. This new document supersedes RFC 2313 [PKCS#1v1.5].
PKCS #1 Version 2.0 preserves support for the encryption padding PKCS #1 Version 2.0 preserves support for the encryption padding
format defined in PKCS #1 Version 1.5 [PKCS#1v1.5], and it also format defined in PKCS #1 Version 1.5 [PKCS#1v1.5], and it also
defines a new alternative. To resolve the adaptive chosen ciphertext defines a new alternative. To resolve the adaptive chosen ciphertext
vulnerability, the PKCS #1 Version 2.0 specifies and recommends use vulnerability, the PKCS #1 Version 2.0 specifies and recommends use
of Optimal Asymmetric Encryption Padding (OAEP) when RSA encryption of Optimal Asymmetric Encryption Padding (OAEP) when RSA encryption
is used to provide confidentiality, such as key transport. is used to provide confidentiality, such as key transport.
This document specifies the use of RSAES-OAEP key transport algorithm This document specifies the use of RSAES-OAEP key transport algorithm
in the Cryptographic Message Syntax (CMS) [CMS]. CMS can be used in in the Cryptographic Message Syntax (CMS) [CMS]. CMS can be used in
either a store-and-forward or an interactive request-response either a store-and-forward or an interactive request-response
environment. environment.
CMS supports variety of architectures for certificate-based key CMS supports variety of architectures for certificate-based key
management, particularly the one defined by the PKIX working group management, particularly the one defined by the PKIX working group
[PROFILE]. PKCS #1 Version 1.5 and PKCS #1 Version 2.0 require the [PROFILE]. PKCS #1 Version 1.5 and PKCS #1 Version 2.0 require the
same RSA public key information. Thus, a certified RSA public key same RSA public key information. Thus, a certified RSA public key
may be used with either RSA key transport technique. may be used with either RSA key transport technique.
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encrypt the content. encrypt the content.
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Compliant software MUST meet the requirements for constructing an Compliant software MUST meet the requirements for constructing an
enveloped-data content type stated in [CMS] Section 6, "Enveloped- enveloped-data content type stated in [CMS] Section 6, "Enveloped-
data Content Type". data Content Type".
A content-encryption key MUST be randomly generated for each instance A content-encryption key MUST be randomly generated for each instance
of an enveloped-data content type. The content-encryption key is of an enveloped-data content type. The content-encryption key is
used to encipher the content. used to encrypt the content.
AES can be used with the enveloped-data content type using any of the AES can be used with the enveloped-data content type using any of the
following key management techniques defined in [CMS] Section 6. following key management techniques defined in [CMS] Section 6.
1) Key Transport: The AES CEK is uniquely wrapped for each recipient 1) Key Transport: The AES CEK is uniquely wrapped for each recipient
using the recipient's public RSA key and other values. Section 2.2 using the recipient's public RSA key and other values. Section 2.2
provides additional details. provides additional details.
2) Key Agreement: The AES CEK is uniquely wrapped for each recipient 2) Key Agreement: The AES CEK is uniquely wrapped for each recipient
using a pairwise symmetric key-encryption key (KEK) generated using using a pairwise symmetric key-encryption key (KEK) generated using
DH-ES using the a randomly generated private key value for the DH-ES using the a randomly generated private key value for the
originator, the recipient's public DH key and other values. Section originator, the recipient's public DH key and other values. Section
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distributed are beyond the scope of this document. Section 2.4 distributed are beyond the scope of this document. Section 2.4
provides additional details. provides additional details.
4) Password Encryption: The AES CEK is wrapped using a KEK derived 4) Password Encryption: The AES CEK is wrapped using a KEK derived
from a password or other shared-secret value. Section 2.5 provides from a password or other shared-secret value. Section 2.5 provides
additional details. additional details.
2.1 EnvelopedData Fields 2.1 EnvelopedData Fields
The enveloped-data content type is ASN.1 encoded using the The enveloped-data content type is ASN.1 encoded using the
EnvelopedData syntax. The fields of the EnvelopedData syntax must be EnvelopedData syntax. The fields of the EnvelopedData syntax MUST be
populated as follows: populated as follows:
The EnvelopedData version is determined based on a number of factors. The EnvelopedData version is determined based on a number of factors.
See [CMS] section 6.1 for the algorithm to determine this value. See [CMS] section 6.1 for the algorithm to determine this value.
The EnvelopedData originatorInfo field is not used for the RSAES-OAEP The EnvelopedData originatorInfo field is not used for the RSAES-OAEP
key transport algorithm. However, this field MAY be present to key transport algorithm. However, this field MAY be present to
support recipients using other key management algorithms. support recipients using other key management algorithms.
The EnvelopedData recipientInfos CHOICE is dependent on the key The EnvelopedData recipientInfos CHOICE is dependent on the key
management technique used. Section 2.2, 2.3 and 2.4 provide management technique used. Section 2.2, 2.3 and 2.4 provide
additional information. additional information.
The EnvelopedData encryptedContentInfo contentEncryptionAlgorithm The EnvelopedData encryptedContentInfo contentEncryptionAlgorithm
field MUST specify a symmetric encryption algorithm. Implementations field MUST specify a symmetric encryption algorithm. Implementations
MUST support the encryption of AES keys, but implementations MAY MUST support the encryption of AES keys, but implementations MAY
support other algorithms as well. support other algorithms as well.
The EnvelopedData unprotectedAttrs MAY be present. The EnvelopedData unprotectedAttrs MAY be present.
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2.2 KeyTransRecipientInfo Fields 2.2 KeyTransRecipientInfo Fields
The enveloped-data content type is ASN.1 encoded using the The enveloped-data content type is ASN.1 encoded using the
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support other algorithms as well. support other algorithms as well.
The EnvelopedData unprotectedAttrs MAY be present. The EnvelopedData unprotectedAttrs MAY be present.
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2.2 KeyTransRecipientInfo Fields 2.2 KeyTransRecipientInfo Fields
The enveloped-data content type is ASN.1 encoded using the The enveloped-data content type is ASN.1 encoded using the
EnvelopedData syntax. The fields of the EnvelopedData syntax MUST be EnvelopedData syntax. The fields of the EnvelopedData syntax MUST be
populated as follows: populated as follows:
The KeyTransRecipientInfo version MUST be either 0 or 2. If the The KeyTransRecipientInfo version MUST be either 0 or 2. If the
RecipientIdentifier is the CHOICE issuerAndSerialNumber, then the RecipientIdentifier is the CHOICE issuerAndSerialNumber, then the
version MUST be 0. If the RecipientIdentifier is version MUST be 0. If the RecipientIdentifier is
subjectKeyIdentifier, then the version MUST be 2. subjectKeyIdentifier, then the version MUST be 2.
The KeyTransRecipientInfo RecipientIdentifier provides two The KeyTransRecipientInfo RecipientIdentifier provides two
alternatives for specifying the recipient's certificate, and thereby alternatives for specifying the recipient's certificate, and thereby
the recipient's public key. The recipient's certificate must contain the recipient's public key. The recipient's certificate MUST contain
a RSA public key. The content-encryption key is encrypted with the a RSA public key. The content-encryption key is encrypted with the
recipient's RSA public key. The issuerAndSerialNumber alternative recipient's RSA public key. The issuerAndSerialNumber alternative
identifies the recipient's certificate by the issuer's distinguished identifies the recipient's certificate by the issuer's distinguished
name and the certificate serial number; the subjectKeyIdentifier name and the certificate serial number; the subjectKeyIdentifier
identifies the recipient's certificate by the X.509 identifies the recipient's certificate by the X.509
subjectKeyIdentifier extension value. subjectKeyIdentifier extension value.
The KeyTransRecipientInfo keyEncryptionAlgorithm field specifies the The KeyTransRecipientInfo keyEncryptionAlgorithm field specifies the
RSAES-OAEP algorithm, and the associated parameters used to encrypt RSAES-OAEP algorithm, and the associated parameters used to encrypt
the content-encryption key for the recipient. The key-encryption the content-encryption key for the recipient. The key-encryption
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This section describes the conventions for using ES-DH and AES with This section describes the conventions for using ES-DH and AES with
the CMS enveloped-data content type to support key agreement. When the CMS enveloped-data content type to support key agreement. When
key agreement is used, then the RecipientInfo keyAgreeRecipientInfo key agreement is used, then the RecipientInfo keyAgreeRecipientInfo
CHOICE MUST be used. CHOICE MUST be used.
The KeyAgreeRecipient version MUST be 3. The KeyAgreeRecipient version MUST be 3.
The EnvelopedData originatorInfo field must be the originatorKey The EnvelopedData originatorInfo field must be the originatorKey
alternative. The originatoryKey algorithm fields MUST contain the alternative. The originatoryKey algorithm fields MUST contain the
dh-public-number object identifier with absent parameters. The dh-public-number object identifier with absent parameters. The
originatorKey publicKey MUST contain the senderĂs ephemeral public originatorKey publicKey MUST contain the sender's ephemeral public
key. key.
The EnvelopedData ukm MAY be absent. The EnvelopedData ukm MAY be absent.
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The EnvelopedData keyEncrytionAlgorithm MUST be the id-alg-ESDH The EnvelopedData keyEncrytionAlgorithm MUST be the id-alg-ESDH
algorithm identifier. algorithm identifier.
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0a 0b 0c 0d 0e 0f 10 11 12 13 0a 0b 0c 0d 0e 0f 10 11 12 13
The key wrap algorithm is AES-128 wrap, so we need 128 bits (20 The key wrap algorithm is AES-128 wrap, so we need 128 bits (20
bytes) of keying material. bytes) of keying material.
No partyAInfo is used. No partyAInfo is used.
Consequently, the input to the first invocation of SHA-256 is: Consequently, the input to the first invocation of SHA-256 is:
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 ; ZZ 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 ; ZZ
30 1d 30 1b
30 13 30 11
06 0b TBS ; AES-128 wrap OID 06 09 60 86 48 01 65 03 04 01 05 ; AES-128 wrap OID
04 04 04 04
00 00 00 01 ; Counter 00 00 00 01 ; Counter
a2 06 a2 06
04 04 04 04
00 00 00 80 ; key length 00 00 00 80 ; key length
And the output is the 32 bytes: And the output is the 32 bytes:
TBS 79 66 a0 38 22 28 1e a3 eb 08 d9 bc 69 5b d8 ff
89 23 26 4d 2b ef ee 73 99 c0 a7 91 18 60 44 c1
Consenquently, Consenquently,
K=TBS K=79 66 a0 38 22 28 1e a3 eb 08 d9 bc 69 5b d8 ff 89 23 26 4d
2.3.1.2 Example 2 2.3.1.2 Example 2
ZZ is the 20 bytes 00 01 02 03 04 05 06 07 08 09 ZZ is the 20 bytes 00 01 02 03 04 05 06 07 08 09
0a 0b 0c 0d 0e 0f 10 11 12 13 0a 0b 0c 0d 0e 0f 10 11 12 13
The key wrap algorithm is AES-256 key wrap, so we need 256 bits (32 The key wrap algorithm is AES-256 key wrap, so we need 256 bits (32
bytes) of keying material. bytes) of keying material.
The partyAInfo used is the 64 bytes The partyAInfo used is the 64 bytes
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
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01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
Consequently, the input to SHA-256 is: Consequently, the input to SHA-256 is:
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 ; ZZ 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 ; ZZ
30 61 30 5f
30 13 30 11
06 0b TBS ; AES-256 wrap OID 06 09 60 86 48 01 65 03 04 01 2c ; AES-256 wrap OID
04 04 04 04
00 00 00 01 ; Counter 00 00 00 01 ; Counter
a0 42 a0 42
04 40 04 40
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 ; partyAInfo 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 ; partyAInfo
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 01
a2 06 a2 06
04 04 04 04
00 00 01 00 ; key length 00 00 01 00 ; key length
And the output is the 32 bytes: And the output is the 32 bytes:
TBS 4f cd e4 58 60 0b 85 fb 47 f4 5a c8 1c 23 a9 4a
3e 64 4b 79 82 9d 98 66 df a5 ee 80 2c 80 99 bb
Consequently, Consequently,
K=TBS K=4f cd e4 58 60 0b 85 fb 47 f4 5a c8 1c 23 a9 4a
3e 64 4b 79 82 9d 98 66 df a5 ee 80 2c 80 99 bb
2.3.2 AES CEK Wrap Process 2.3.2 AES CEK Wrap Process
To be supplied. The AES key-wrap algorithm encrypts one AES key in another AES key.
The algorithm inputs are a value in a multiple of 64-bits (in this
case, the AES CEK) and an AES KEK of standard size. The algorithm
produces an output 64-bits longer than the input, the additional bits
acting as a checksum for the original data. The algorithm uses 6*n
AES encryption/decryption operations where n is number of 64-bit
blocks. Full details of the AES key-wrap algorithm are available at
[AES-KEYWRAP].
NIST has assigned the following OIDs to define the key-wrap
algorithm.
id-aes128-wrap OBJECT IDENTIFIER ::= { aes 5 }
id-aes192-wrap OBJECT IDENTIFIER ::= { aes 25 }
id-aes256-wrap OBJECT IDENTIFIER ::= { aes 45 }
In all cases the parameters field MUST be absent. The OID gives the
KEK key size, but does not make any statements as to the size of the
wrapped CEK. Implementations MAY use different size KEK and CEK
values. Implements MUST support the CEK and the KEK having the same
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length. If different lengths are supported, the KEK MUST be of equal
or greater length then the CEK.
2.4 KEKRecipientInfo Fields 2.4 KEKRecipientInfo Fields
This section describes the conventions for using AES with the CMS This section describes the conventions for using AES with the CMS
enveloped-data content type to support previously distributed enveloped-data content type to support previously distributed
symmetric KEKs. When a previously distributed symmetric KEK is used symmetric KEKs. When a previously distributed symmetric KEK is used
to wrap the AES CEK, then the RecipientInfo KEKRecipientInfo CHOICE to wrap the AES CEK, then the RecipientInfo KEKRecipientInfo CHOICE
MUST be used. The methods used to generate and distribute the MUST be used. The methods used to generate and distribute the
symmetric KEK are beyond the scope of this document. One possible symmetric KEK are beyond the scope of this document. One possible
method of distributing keys is documented in [SYMKEYDIST]. method of distributing keys is documented in [SYMKEYDIST].
The KEKRecipientInfo fields MUST be populated as specified in [CMS] The KEKRecipientInfo fields MUST be populated as specified in [CMS]
Section 6.2.3, KEKRecipientInfo Type. Section 6.2.3, KEKRecipientInfo Type.
The KEKRecipientInfo keyEncryptionAlgorithm algorithm field MUST be The KEKRecipientInfo keyEncryptionAlgorithm algorithm field MUST be
the id-NIST-AES-KEY-WRAP OID indicating that the AES wrap function is one of the OIDs defined in section 2.3.2 indicating that the AES wrap
used to wrap the AES CEK. The KEKRecipientInfo keyEncryptionAlgorithm
parameters field MUST be absent. function is used to wrap the AES CEK. The KEKRecipientInfo
keyEncryptionAlgorithm parameters field MUST be absent.
The KEKRecipientInfo encryptedKey field MUST include the AES CEK The KEKRecipientInfo encryptedKey field MUST include the AES CEK
wrapped using the previously distributed symmetric KEK as input to wrapped using the previously distributed symmetric KEK as input to
the AES wrap function. the AES wrap function.
To Be Decided ű Do we have multiple sizes of key wrap algorithms.
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2.5 PasswordRecipientInfo Fields 2.5 PasswordRecipientInfo Fields
To Be Provided This section describes the conventions for using AES with the CMS
enveloped-data content type to support password-based key management.
When a password derived KEK is used to wrap the AES CEK, then the
RecipientInfo PasswordRecipientInfo CHOICE MUST be used.
The keyEncryptionAlgorithm algorithm field MUST be one of the OIDs
defined in section 2.3.2 indicating the AES wrap function is used to
wrap the AES CEK. The keyEncryptionAlgorithm parameters field MUST
be absent.
The encryptedKey field MUST be the result of the AES key wrap
algorithm applied to the AES CEK value.
3 Encrypted-data Conventions 3 Encrypted-data Conventions
The encrypted-data content type is ASN.1 encoded using the The encrypted-data content type is ASN.1 encoded using the
EncryptededData syntax. The fields of the EncryptedData syntax MUST EncryptededData syntax. The fields of the EncryptedData syntax MUST
be populated as follows: be populated as follows:
The EncryptedData version is determined based on a number of factors. The EncryptedData version is determined based on a number of factors.
See [CMS] section 9.1 for the algorithm to determine this value. See [CMS] section 9.1 for the algorithm to determine this value.
The EncryptedData encryptedContentInfo contentEncryptionAlgorithm The EncryptedData encryptedContentInfo contentEncryptionAlgorithm
field MUST specify a symmetric encryption algorithm. Implementations field MUST specify a symmetric encryption algorithm. Implementations
MUST support the encryption of AES keys, but implementations MAY
support other algorithms as well. MUST support encryption using AES, but implementations MAY support
other algorithms as well.
Schaad, Housley 8
Use of the AES Algorithm in CMS November 2000
The EncryptedData unprotectedAttrs MAY be present. The EncryptedData unprotectedAttrs MAY be present.
4 Algorithm Identifiers and Parameters 4 Algorithm Identifiers and Parameters
This section specified algorithm identifiers for the AES encryption
algorithm and the RSAES-OAEP key transport algorithm.
4.1 AES Algorithm Identifiers and Parameters 4.1 AES Algorithm Identifiers and Parameters
The AES algorithm is defined in [AES]. RSA #1 v1.5 MUST NOT be used The AES algorithm is defined in [AES]. RSA #1 v1.5 [PKCS#1v1.5]
to transport AES keys. MUST NOT be used to transport AES keys. RSAES-OAEP [PKCS#1v2.0] MAY
be used to transport AES keys.
AES is added to the set of symmetric content encryption algorithms in AES is added to the set of symmetric content encryption algorithms in
CMS. The AES content-encryption algorithm in Cipher Block Chaining CMS. The AES content-encryption algorithm in Cipher Block Chaining
(CBC) mode for the three different key sizes are identified by the (CBC) mode for the three different key sizes are identified by the
OID: following object identifiers:
id-aes128-CBC OBJECT IDENTIFIER ::= { aes 2 } id-aes128-CBC OBJECT IDENTIFIER ::= { aes 2 }
id-aes192-CBC OBJECT IDENTIFIER ::= { aes 22 } id-aes192-CBC OBJECT IDENTIFIER ::= { aes 22 }
id-aes256-CBC OBJECT IDENTIFIER ::= { aes 42 } id-aes256-CBC OBJECT IDENTIFIER ::= { aes 42 }
The AlgorithmIdentifier parameters field MUST be present, and the The AlgorithmIdentifier parameters field MUST be present, and the
parameters field MUST contain a AES-IV associated with this OID parameters field MUST contain a AES-IV:
contains the initialization vector IV:
AES-IV ::= OCTET STRING (SIZE(16)) AES-IV ::= OCTET STRING (SIZE(16))
Content encryption algorithm 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 encrypt the content located
located in the EnvelopedData EncryptedContentInfo encryptedContent
and the EncryptedData EncryptedContentInfo encryptedContent fields.
4.2 RSAES-OAEP Algorithm Identifiers and Parameters in the EnvelopedData EncryptedContentInfo encryptedContent and the
EncryptedData EncryptedContentInfo encryptedContent fields.
Schaad, Housley 8 4.2 RSAES-OAEP Algorithm Identifiers and Parameters
Use of the AES Algorithm in CMS November 2000
The RSAES-OAEP key transport algorithm is the RSA encryption scheme The RSAES-OAEP key transport algorithm is the RSA encryption scheme
defined in RFC 2437 [PKCS#1v2.0], where the message to be encrypted defined in RFC 2437 [PKCS#1v2.0], where the message to be encrypted
is the content-encryption key. is the content-encryption key.
The RSA key is identified in a certificate using the OID The RSA key is identified in a certificate using the rsaEncryption
rsaEncryption. object identifier:
pkcs-1 OBJECT IDENTIFIER ::=
pkcs-1 OBJECT IDENTIFIER ::= {
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) } iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) }
rsaEncryption OBJECT IDENTIFIER ::= { pkcs-1 1 } rsaEncryption OBJECT IDENTIFIER ::= { pkcs-1 1 }
Note: This is the same algorithm identifier used by RSAES-PKCS1-v1_5. Note: This is the same algorithm identifier used by RSAES-PKCS1-v1_5.
This means that the existence of an RSA key in a certificate cannot This means that the existence of an RSA key in a certificate cannot
be used to infer that a recipient can decrypt an RSAES-OAEP encrypted be used to infer that a recipient can decrypt an RSAES-OAEP encrypted
content-encryption key. content-encryption key.
Schaad, Housley 9
Use of the AES Algorithm in CMS November 2000
The algorithm identifier for RSAES-OAEP is: The object identifier for RSAES-OAEP is:
id-RSAES-OAEP OBJECT IDENTIFIER ::= { pkcs-1 7 } id-RSAES-OAEP OBJECT IDENTIFIER ::= { pkcs-1 7 }
The AlgorithmIdentifier parameters field MUST be present, and the The AlgorithmIdentifier parameters field MUST be present, and the
parameters field MUST contain RSAES-OAEP-params. RSAES-OAEP-params parameters field MUST contain RSAES-OAEP-params. RSAES-OAEP-params
have the following syntax: have the following syntax:
RSAES-OAEP-params ::= SEQUENCE RSAES-OAEP-params ::= SEQUENCE {
hashFunc [0] AlgorithmIdentifier DEFAULT sha1Identifier, hashFunc [0] AlgorithmIdentifier DEFAULT sha1Identifier,
maskGenFunc [1] AlgorithmIdentifier DEFAULT mgf1SHA1Identifier, maskGenFunc [1] AlgorithmIdentifier DEFAULT mgf1SHA1Identifier,
pSourceFunc [2] AlgorithmIdentifier DEFAULT
pSpecifiedEmptyIdentifier }
sha1Identifier ::= AlgorithmIdentifier pSourceFunc [2] AlgorithmIdentifier
DEFAULT pSpecifiedEmptyIdentifier }
sha1Identifier ::= AlgorithmIdentifier {
id-sha1, NULL } id-sha1, NULL }
mgf1SHA1Identifier ::= AlgorithmIdentifier mgf1SHA1Identifier ::= AlgorithmIdentifier {
id-mgf1, sha1Identifier } id-mgf1, sha1Identifier }
pSpecifiedEmptyIdentifier ::= AlgorithmIdentifier pSpecifiedEmptyIdentifier ::= AlgorithmIdentifier {
id-pSpecified, OCTET STRING SIZE (0) } id-pSpecified, OCTET STRING SIZE (0) }
id-sha1 OBJECT IDENTIFIER ::= id-sha1 OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) oiw(14) secsig(3) iso(1) identified-organization(3) oiw(14) secsig(3)
algorithms(2) 26 } algorithms(2) 26 }
id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 } id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 }
id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 9 } id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 9 }
The fields of type RSAES-OAEP-params have the following meanings: The fields of type RSAES-OAEP-params have the following meanings:
hashFunc identifies the one-way hash function. Implementations MUST hashFunc identifies the one-way hash function. Implementations MUST
skipping to change at line 507 skipping to change at line 578
algorithms(2) 26 } algorithms(2) 26 }
id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 } id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 }
id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 9 } id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 9 }
The fields of type RSAES-OAEP-params have the following meanings: The fields of type RSAES-OAEP-params have the following meanings:
hashFunc identifies the one-way hash function. Implementations MUST hashFunc identifies the one-way hash function. Implementations MUST
support SHA-1 [SHA1]. The SHA-1 algorithm identifier is comprised of support SHA-1 [SHA1]. The SHA-1 algorithm identifier is comprised of
the id-sha1 object identifier and a parameter of NULL. the id-sha1 object identifier and a parameter of NULL.
Schaad, Housley 9 Implementations that perform key encryption MUST omit the hashFunc
Use of the AES Algorithm in CMS November 2000 field when SHA-1 is used, indicating that the default algorithm was
used. Implementations that perform key decryption MUST recognize
both the id-sha1 object identifier and an absent hashFunc field as an
Implementations that perform encryption MUST omit the hashFunc field indication that SHA-1 was used.
when SHA-1 is used, indicating that the default algorithm was used.
Implementations that perform decryption MUST recognize both the id-
sha1 object identifier and an absent hashFunc field as an indication
that SHA-1 was used.
maskGenFunc identifies the mask generation function. Implementations maskGenFunc identifies the mask generation function. Implementations
MUST support MFG1 [PKCS#1v2.0]. MFG1 requires a one-way hash MUST support MFG1 [PKCS#1v2.0]. MFG1 requires a one-way hash
function, and it is identified in the parameter field of the MFG1 function, and it is identified in the parameter field of the MFG1
algorithm identifier. Implementations MUST support SHA-1 [SHA1]. algorithm identifier. Implementations MUST support SHA-1 [SHA1].
The MFG1 algorithm identifier is comprised of the id-mgf1 object The MFG1 algorithm identifier is comprised of the id-mgf1 object
identifier and a parameter that contains the algorithm identifier of identifier and a parameter that contains the algorithm identifier of
the one-way hash function employed with MFG1. The SHA-1 algorithm the one-way hash function employed with MFG1. The SHA-1 algorithm
identifier is comprised of the id-sha1 object identifier and a identifier is comprised of the id-sha1 object identifier and a
parameter of NULL. Implementations that perform encryption MUST omit parameter of NULL. Implementations that perform key encryption MUST
the maskGenFunc field when MFG1 with SHA-1 is used, indicating that omit the maskGenFunc field when MFG1 with SHA-1 is used, indicating
the default algorithm was used. Implementations that perform that the default algorithm was used. Implementations that perform
decryption MUST recognize both the id-mgf1 and id-sha1 object Schaad, Housley 10
Use of the AES Algorithm in CMS November 2000
key decryption MUST recognize both the id-mgf1 and id-sha1 object
identifiers as well as an absent maskGenFunc field as an indication identifiers as well as an absent maskGenFunc field as an indication
that MFG1 with SHA-1 was used. that MFG1 with SHA-1 was used.
pSourceFunc identifies the source (and possibly the value) of the pSourceFunc identifies the source (and possibly the value) of the
encoding parameters, commonly called P. Implementations MUST encoding parameters, commonly called P. Implementations MUST
represent P by an algorithm identifier, id-pSpecified, indicating represent P by an algorithm identifier, id-pSpecified, indicating
that P is explicitly provided as an OCTET STRING in the parameters. that P is explicitly provided as an OCTET STRING in the parameters.
The default value for P is an empty string. In this case, pHash in The default value for P is an empty string. In this case, pHash in
EME-OAEP contains the hash of a zero length string. Implementations EME-OAEP contains the hash of a zero length string. Implementations
MUST support a zero length P value. Implementations that perform MUST support a zero length P value. Implementations that perform key
encryption MUST omit the pSourceFunc field when a zero length P value encryption MUST omit the pSourceFunc field when a zero length P value
is used, indicating that the default value was used. Implementations is used, indicating that the default value was used. Implementations
that perform decryption MUST recognize both the id-pSpecified object
identifier and an absent pSourceFunc field as an indication that a that perform key decryption MUST recognize both the id-pSpecified
zero length P value was used. object identifier and an absent pSourceFunc field as an indication
that a zero length P value was used.
5 SMIMECapabilities Attribute Conventions 5 SMIMECapabilities Attribute Conventions
An S/MIME client SHOULD announce the set of cryptographic functions An S/MIME client SHOULD announce the set of cryptographic functions
it supports by using the S/MIME capabilities attribute. This it supports by using the S/MIME capabilities attribute. This
attribute provides a partial list of object identifiers of attribute provides a partial list of object identifiers of
cryptographic functions and MUST be signed by the client. The cryptographic functions and MUST be signed by the client. The
algorithm OIDs SHOULD be logically separated in functional categories algorithm OIDs SHOULD be logically separated in functional categories
and MUST be ordered with respect to their preference. and MUST be ordered with respect to their preference.
RFC 2633 [MSG], Section 2.5.2 defines the SMIMECapabilities signed RFC 2633 [MSG], Section 2.5.2 defines the SMIMECapabilities signed
attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be
used to specify a partial list of algorithms that the software used to specify a partial list of algorithms that the software
announcing the SMIMECapabilities can support. announcing the SMIMECapabilities can support.
5.1 RSAES-OEAP SMIMECapability Attribute 5.1 RSAES-OEAP SMIMECapability Attribute
When constructing a signedData object, compliant software MAY include When constructing a signedData object, compliant software MAY include
skipping to change at line 562 skipping to change at line 639
and MUST be ordered with respect to their preference. and MUST be ordered with respect to their preference.
RFC 2633 [MSG], Section 2.5.2 defines the SMIMECapabilities signed RFC 2633 [MSG], Section 2.5.2 defines the SMIMECapabilities signed
attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be attribute (defined as a SEQUENCE of SMIMECapability SEQUENCEs) to be
used to specify a partial list of algorithms that the software used to specify a partial list of algorithms that the software
announcing the SMIMECapabilities can support. announcing the SMIMECapabilities can support.
5.1 RSAES-OEAP SMIMECapability Attribute 5.1 RSAES-OEAP SMIMECapability Attribute
When constructing a signedData object, compliant software MAY include When constructing a signedData object, compliant software MAY include
the SMIMECapabilities signed attribute announcing that it supports the SMIMECapabilities signed attribute announcing that it supports
the RSAES-OAEP algorithm. the RSAES-OAEP algorithm.
Schaad, Housley 10
Use of the AES Algorithm in CMS November 2000
The SMIMECapability SEQUENCE representing RSAES-OAEP MUST include the The SMIMECapability SEQUENCE representing RSAES-OAEP MUST include the
id-RSAES-OAEP object identifier in the capabilityID field and MUST id-RSAES-OAEP object identifier in the capabilityID field and MUST
include the RSAES-OAEP-Default-Identifier SEQUENCE in the parameters include the RSAES-OAEP-Default-Identifier SEQUENCE in the parameters
field. field.
RSAES-OAEP-Default-Identifier ::= AlgorithmIdentifier RSAES-OAEP-Default-Identifier ::= AlgorithmIdentifier {
id-RSAES-OAEP, { sha1Identifier, mgf1SHA1Identifier,
id-RSAES-OAEP, pSpecifiedEmptyIdentifier } }
sha1Identifier, mgf1SHA1Identifier, pSpecifiedEmptyIdentifier
} }
When all of the default settings are selected, the SMIMECapability When all of the default settings are selected, the SMIMECapability
SEQUENCE representing RSAES-OAEP MUST be DER-encoded as: SEQUENCE representing RSAES-OAEP MUST be DER-encoded as:
30 0D 06 09 2A 86 48 86 F7 0D 01 01 07 30 00 30 0D 06 09 2A 86 48 86 F7 0D 01 01 07 30 00
5.2 AES S/MIME Capability Attributes 5.2 AES S/MIME Capability Attributes
Schaad, Housley 11
Use of the AES Algorithm in CMS November 2000
If an S/MIME client is required to support symmetric encryption with If an S/MIME client is required to support symmetric encryption with
AES, the capabilities attribute MUST contain the AES object AES, the capabilities attribute MUST contain the AES object
identifier specified above in the category of symmetric algorithms. identifier specified above in the category of symmetric algorithms.
The parameter associated with this object identifier MUST is The parameter associated with this object identifier MUST is
AESSMimeCapability. AESSMimeCapability.
AESSMimeCapabilty ::= NULL AESSMimeCapabilty ::= NULL
The encodings for the mandatory key sizes are: The encodings for the mandatory key sizes are:
skipping to change at line 609 skipping to change at line 685
196 30 0D 06 09 60 86 48 01 65 03 04 01 16 30 00 196 30 0D 06 09 60 86 48 01 65 03 04 01 16 30 00
256 30 0D 06 09 60 86 48 01 65 03 04 01 2A 30 00 256 30 0D 06 09 60 86 48 01 65 03 04 01 2A 30 00
When a sending agent creates an encrypted message, it has to decide When a sending agent creates an encrypted message, it has to decide
which type of encryption algorithm to use. In general the decision which type of encryption algorithm to use. In general the decision
process involves information obtained from the capabilities lists process involves information obtained from the capabilities lists
included in messages received from the recipient, as well as other included in messages received from the recipient, as well as other
information such as private agreements, user preferences, legal information such as private agreements, user preferences, legal
restrictions, and so on. If users require AES for symmetric restrictions, and so on. If users require AES for symmetric
encryption, the S/MIME clients on both the sending and receiving side encryption, the S/MIME clients on both the sending and receiving side
MUST support it, and it MUST be set in the user preferences. MUST support it, and it MUST be set in the user preferences.
6 Security Considerations 6 Security Considerations
If RSA-OAEP and RSA #1 v1.5 are both used to transport the same If RSA-OAEP and RSA #1 v1.5 are both used to transport the same
content encryption key, then an attacker can still use the content-encryption key, then an attacker can still use the
Bleichenbacher attack against the RSA #1 v1.5 encrypted key. It is Bleichenbacher attack against the RSA #1 v1.5 encrypted key. It is
generally unadvisable to mix both RSA-OAEP and RSA #1 v1.5 in the generally unadvisable to mix both RSA-OAEP and RSA #1 v1.5 in the
same set of recipients. same set of recipients.
Implementations must protect the RSA private key and the content- Implementations must protect the RSA private key and the content-
encryption key. Compromise of the RSA private key may result in the encryption key. Compromise of the RSA private key may result in the
disclosure of all messages protected with that key. Compromise of disclosure of all messages protected with that key. Compromise of
Schaad, Housley 11
Use of the AES Algorithm in CMS November 2000
the content-encryption key may result in disclosure of the associated the content-encryption key may result in disclosure of the associated
encrypted content. encrypted content.
Implementations must protect the key management private key and the The generation of RSA public/private key pairs and MGF seeds rely on
message-authentication key. Compromise of the key management private random numbers. The use of inadequate pseudo-random number
key permits masquerade of authenticated data. Compromise of the generators (PRNGs) to generate these values can result in little or
message-authentication key may result in undetectable modification of no security. An attacker may find it much easier to reproduce the
the authenticated content. PRNG environment that produced the keys, searching the resulting
small set of possibilities, rather than brute force searching the
whole key space. The generation of quality random numbers is
difficult. RFC 1750 [RANDOM] offers important guidance in this area.
The generation of RSA public/private key pairs relies on a random When wrapping a content-encryption key with a key-encryption key, the
numbers. The use of inadequate pseudo-random number generators
(PRNGs) to generate cryptographic keys can result in little or no key-encryption key should always be at least the same length as the
security. An attacker may find it much easier to reproduce the PRNG content -encryption key. An attacker will generally work at the
environment that produced the keys, searching the resulting small set weakest point in an encryption system. This would be the smaller of
of possibilities, rather than brute force searching the whole key the two key sizes for a brute force attack.
space. The generation of quality random numbers is difficult. RFC
1750 [RANDOM] offers important guidance in this area. Schaad, Housley 12
Use of the AES Algorithm in CMS November 2000
7 Open Issues 7 Open Issues
- Key wrap algorithm is undetermined.
- Mandatory key sizes for Key Wrap
- Mandatory key sizes for AES algorithm
- References to each algorithm that would be acceptable to the RFC - References to each algorithm that would be acceptable to the RFC
editor. editor. We have a FIPS number for AES (but it is not yet officially
published). We have no document for the key wrap algorithm yet and
need to work out the details with NIST for publishing.
- Does the oid for key derivation need to be changed since we are - Does the oid for key derivation need to be changed since we are
using SHA-256 not SHA-1? using SHA-256 not SHA-1?
- Need to provide an ASN.1 module as [PKCS#1v2.0] is not 1988 syntax.
References References
AES J. Daemen, V. Rijmen, "The Rijndael Block Cipher" AES J. Daemen, V. Rijmen, "The Rijndael Block Cipher", FIPS
http://csrc.nist.gov/encryption/aes/rijndael/Rijndael.pdf 197, <To Be Published>.
3rd September 1999.
AES-KEYWRAP NIST, "AES Key-Wrap Algorithm", TBD.
< http://www.nist.gov/kms/key-wrap.pdf>
CMS Housley, R. Cryptographic Message Syntax. RFC 2630. CMS Housley, R. Cryptographic Message Syntax. RFC 2630.
June 1999. June 1999.
CRYPTO98 Bleichenbacher, D. "Chosen Ciphertext Attacks Against CRYPTO98 Bleichenbacher, D. "Chosen Ciphertext Attacks Against
Protocols Based on the RSA Encryption Standard PKCS #1," Protocols Based on the RSA Encryption Standard PKCS #1,"
in H. Krawczyk (editor), Advances in Cryptology - CRYPTO in H. Krawczyk (editor), Advances in Cryptology - CRYPTO
'98 '98
Proceedings, Lecture Notes in Computer Science 1462 (1998), Proceedings, Lecture Notes in Computer Science 1462 (1998),
Springer-Verlag, pp. 1-12. Springer-Verlag, pp. 1-12.
DES National Institute of Standards and Technology. DES National Institute of Standards and Technology.
FIPS Pub 46: Data Encryption Standard. 15 January 1977. FIPS Pub 46: Data Encryption Standard. 15 January 1977.
DH E. Rescorla, ˘Diffie-Hellman Key Agreement Method÷, RFC DH Rescorla, E. Diffie-Hellman Key Agreement Method, RFC
2631, June 1999. 2631, June 1999.
MUSTSHOULD Bradner, S. Key Words for Use in RFCs to Indicate MUSTSHOULD Bradner, S. Key Words for Use in RFCs to Indicate
Requirement Levels. BCP 14, RFC 2119. March 1997. Requirement Levels. BCP 14, RFC 2119. March 1997.
MSG Ramsdell, B., Editor. S/MIME Version 3 Message MMA Rescorla, E. Preventing the Million Message Attack
Schaad, Housley 12 on CMS, RFC TBD, Date TBD.
Use of the AES Algorithm in CMS November 2000 <draft-ietf-smime-pkcs1-01.txt>
MSG Ramsdell, B., Editor. S/MIME Version 3 Message
Specification. RFC 2633. June 1999. Specification. RFC 2633. June 1999.
PKCS#1v1.5 Kaliski, B. PKCS #1: RSA Encryption, Version 1.5. PKCS#1v1.5 Kaliski, B. PKCS #1: RSA Encryption, Version 1.5.
RFC 2313. March 1998. RFC 2313. March 1998.
PKCS#1v2.0 Kaliski, B. PKCS #1: RSA Encryption, Version 2.0. PKCS#1v2.0 Kaliski, B. PKCS #1: RSA Encryption, Version 2.0.
RFC 2437. October 1998. RFC 2437. October 1998.
PROFILE Housley, R., W. Ford, W. Polk, and D. Solo. Internet PROFILE Housley, R., W. Ford, W. Polk, and D. Solo. Internet
X.509 Public Key Infrastructure: Certificate and CRL X.509 Public Key Infrastructure: Certificate and CRL
Profile. RFC 2459. January 1999. Profile. RFC 2459. January 1999.
Schaad, Housley 13
Use of the AES Algorithm in CMS November 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.
RSALABS Bleichenbacher, D., B. Kaliski, and J. Staddon. RSALABS Bleichenbacher, D., B. Kaliski, and J. Staddon.
Recent Results on PKCS #1: RSA Encryption Standard. Recent Results on PKCS #1: RSA Encryption Standard.
RSA Laboratories' Bulletin No. 7, June 26, 1998. RSA Laboratories' Bulletin No. 7, June 26, 1998.
[Available at http://www.rsasecurity.com/rsalabs/bulletins] [Available at http://www.rsasecurity.com/rsalabs/bulletins]
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.
SSL Freier, A., P. Karlton, and P. Kocher. The SSL Protocol, SSL Freier, A., P. Karlton, and P. Kocher. The SSL Protocol,
Version 3.0. Netscape Communications. November 1996. Version 3.0. Netscape Communications. November 1996.
[Available at http://draft-freier-ssl-version3-02.txt] [Available at http://draft-freier-ssl-version3-02.txt]
SYMKEYDIST TBS SYMKEYDIST Turner, S. CMS Symmetric Key Management and Distribution.
RFC TDB. Date TBD.
< draft-ietf-smime-symkeydist-06.txt>
TLS Dierks, T. and C. Allen. The TLS Protocol Version 1.0. TLS Dierks, T. and C. Allen. The TLS Protocol Version 1.0.
RFC 2246. January 1999. RFC 2246. January 1999.
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 X.209-88 CCITT. Recommendation X.209: Specification of Basic
Encoding Rules for Abstract Syntax Notation One (ASN.1). Encoding Rules for Abstract Syntax Notation One (ASN.1).
1988. 1988.
skipping to change at line 736 skipping to change at line 822
This document is the result of contributions from many This document is the result of contributions from many
professionals. We appreciate the hard work of all members of the professionals. We appreciate the hard work of all members of the
IETF S/MIME Working Group. We wish to extend a special thanks to IETF S/MIME Working Group. We wish to extend a special thanks to
Burt Kaliski. Burt Kaliski.
Author's Addresses Author's Addresses
Jim Schaad Jim Schaad
Soaring Hawk Consulting Soaring Hawk Consulting
Schaad, Housley 13
Use of the AES Algorithm in CMS November 2000
Email: jimsch@exmsft.com Email: jimsch@exmsft.com
Russell Housley Russell Housley
RSA Laboratories RSA Laboratories
918 Spring Knoll Drive 918 Spring Knoll Drive
Herndon, VA 20170 Herndon, VA 20170
USA USA
Schaad, Housley 14
Use of the AES Algorithm in CMS November 2000
Email: rhousley@rsasecurity.com Email: rhousley@rsasecurity.com
Schaad, Housley 14 Schaad, Housley 15
 End of changes. 

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