draft-ietf-smime-cms-rsaes-oaep-02.txt   draft-ietf-smime-cms-rsaes-oaep-03.txt 
S/MIME Working Group R. Housley S/MIME Working Group R. Housley
Internet Draft SPYRUS Internet Draft RSA Laboratories
expires in six months November 2000 expires in six months June 2002
Use of the RSAES-OAEP Key Transport Algorithm in CMS Use of the RSAES-OAEP Key Transport Algorithm in CMS
<draft-ietf-smime-cms-rsaes-oaep-02.txt> <draft-ietf-smime-cms-rsaes-oaep-03.txt>
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract Abstract
This document describes the use of the RSAES-OAEP key transport This document describes the use of the RSAES-OAEP key transport
method of key management within the Cryptographic Message Syntax method of key management within the Cryptographic Message Syntax.
[CMS].
1 Introduction
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smime/>. smime/>.
1 Introduction PKCS #1 Version 1.5 [PKCS#1v1.5] specifies a widely deployed variant
of the RSA key transport algorithm. PKCS #1 Version 1.5 key
When the variant of the RSA key transport algorithm specified in PKCS transport is vulnerable to adaptive chosen ciphertext attacks,
#1 Version 1.5 [PKCS#1v1.5] is used for key management, it is especially when it is used to for key management in interactive
vulnerable to adaptive chosen ciphertext attacks. This attack is applications. This attack is often referred to as the "Million
explained in [RSALAB] and [CRYPTO98]. The use of PKCS #1 Version 1.5 Message Attack," and it explained in [RSALABS] and [CRYPTO98].
key transport in interactive applications is especially vulnerable. Exploitation of this vulnerability, which reveals the result of a
Exploitation of this identified vulnerability, revealing the result particular RSA decryption, requires access to an oracle which will
of a particular RSA decryption, requires access to an oracle which respond to hundreds of thousands of ciphertexts, which are
will respond to hundreds of thousands of ciphertexts, which are constructed adaptively in response to previously received replies
constructed adaptively in response to previously-received replies that provide information on the successes or failures of attempted
providing information on the successes or failures of attempted
decryption operations. decryption operations.
The attack appears significantly less feasible in store-and-forward The attack is 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. RFC 3218 [MMA] discussed the
is applied as an intermediate encryption layer within an interactive countermeasures to this attack that are available when PKCS #1
request-response communications environment, exploitation could be Version 1.5 key transport is used in conjunction with the
more feasible. However, Secure Sockets Layer (SSL) [SSL] and Cryptographic Message Syntax (CMS) [CMS].
Transport Layer Security (TLS) [TLS] protocol implementations could
include countermeasures that detect and prevent Bleichenbacher's and When PKCS #1 Version 1.5 key transport is applied as an intermediate
other chosen-ciphertext attacks, without changing the way the RSA key encryption layer within an interactive request-response
transport algorithm is used. These countermeasures are performed communications environment, exploitation could be more feasible.
within the protocol level. In the interest of long-term security However, Secure Sockets Layer (SSL) [SSL] and Transport Layer
assurance, it is prudent to adopt an improved cryptographic technique Security (TLS) [TLS] protocol implementations could include
rather than embedding countermeasures within protocols. countermeasures that detect and prevent the Million Message Attack
and other chosen-ciphertext attacks. These countermeasures are
performed within the protocol level. In the interest of long-term
security assurance, it is prudent to adopt an improved cryptographic
technique 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 #1 [PKCS#1v2.0]. This new document supersedes RFC 2313. PKCS #1
Version 2.0 preserves support for the encryption padding format Version 2.0 preserves support for the encryption padding format
defined in PKCS #1 Version 1.5 [PKCS#1v1.5], and it also defines a defined in PKCS #1 Version 1.5 [PKCS#1v1.5], and it also defines a
new alternative. To resolve the adaptive chosen ciphertext 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) for RSA key
is used to provide confidentiality, such as key transport. 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 CMS. The CMS can be used in either a store-and-forward or an
either a store-and-forward or an interactive request-response interactive request-response environment.
environment.
CMS supports variety of architectures for certificate-based key The 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.
CMS values are generated using ASN.1 [X.208-88], using the Basic The CMS uses ASN.1 [X.208-88], the Basic Encoding Rules (BER)
Encoding Rules (BER) [X.209-88] and the Distinguished Encoding Rules [X.209-88], and the Distinguished Encoding Rules (DER) [X.509-88].
(DER) [X.509-88].
Throughout this document, when the terms MUST, MUST NOT, SHOULD and Throughout this document, when the terms MUST, MUST NOT, SHOULD and
MAY are used in capital letters, their use conforms to the MAY are used in capital letters, their use conforms to the
definitions in [MUSTSHOULD]. [MUSTSHOULD] defines these key words to definitions in [STDWORDS]. These key word definitions help make the
help make the intent of standards track documents as clear as intent of standards documents as clear as possible. These key words
possible. The same key words are used in this document to help are used in this document to help implementers achieve
implementers achieve interoperability. Implementations that claims interoperability.
compliance with this document MUST provide the capabilities as
indicated by the MUST, MUST NOT, SHOULD and MAY terms.
2 Enveloped-data Conventions 2 Enveloped-data Conventions
The CMS enveloped-data content type consists of encrypted content and The CMS enveloped-data content type consists of an encrypted content
wrapped content-encryption keys for one or more recipients. The and wrapped content-encryption keys for one or more recipients. The
RSAES-OAEP key transport algorithm is used to wrap the content- RSAES-OAEP key transport algorithm is used to wrap the content-
encryption key for one recipient. encryption key for one recipient.
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 encipher the content.
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 MUST be either 0 or 2. The EnvelopedData version MUST be 0, 2, or 3.
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 MUST be The EnvelopedData recipientInfos CHOICE MUST be
KeyTransRecipientInfo. See section 2.2 for further discussion of KeyTransRecipientInfo. See section 2.2 for further discussion of
KeyTransRecipientInfo. KeyTransRecipientInfo.
The EnvelopedData encryptedContentInfo contentEncryptionAlgorithm The EnvelopedData encryptedContentInfo contentEncryptionAlgorithm
field MUST be specify a symmetric encryption algorithm. field MUST be a symmetric encryption algorithm identifier.
Implementations MUST support the encryption of Triple-DES content-
encryption keys, but implementations MAY support other algorithms as
well.
The EnvelopedData unprotectedAttrs MAY be present. The EnvelopedData unprotectedAttrs MAY be present.
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 0 or 2. If the
RecipientIdentifier is the CHOICE issuerAndSerialNumber, then the RecipientIdentifier uses the issuerAndSerialNumber alternative, then
version MUST be 0. If the RecipientIdentifier is the version MUST be 0. If the RecipientIdentifier uses the
subjectKeyIdentifier, then the version MUST be 2. subjectKeyIdentifier alternative, 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 specifies that the The KeyTransRecipientInfo keyEncryptionAlgorithm specifies that the
RSAES-OAEP algorithm, and its associated parameters, was used to RSAES-OAEP algorithm, and its associated parameters, was used to
encrypt the content-encryption key for the recipient. The key- encrypt the content-encryption key for the recipient. The key-
encryption process is described in [PKCS#1v2.0]. See section 3 of encryption process is described in [PKCS#1v2.0]. See section 3 of
this document for the algorithm identifier and the parameter syntax. this document for the algorithm identifier and the parameter syntax.
The KeyTransRecipientInfo encryptedKey is the result of encrypting The KeyTransRecipientInfo encryptedKey is the result of encrypting
the content-encryption key in the recipient's RSA public key using the content-encryption key in the recipient's RSA public key using
the RSAES-OAEP algorithm. When using a Triple-DES content-encryption the RSAES-OAEP algorithm. When using a Triple-DES [3DES] content-
key, implementations MUST adjust the parity bits for each DES key encryption key, implementations MUST adjust the parity bits to ensure
comprising the Triple-DES key prior to RSAES-OAEP encryption. odd parity for each octet of each DES key comprising the Triple-DES
key prior to RSAES-OAEP encryption.
3 RSAES-OAEP Algorithm Identifiers and Parameters 3 RSAES-OAEP Algorithm Identifiers and Parameters
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. The algorithm identifier for RSAES- is the content-encryption key. The algorithm identifier for RSAES-
OAEP is: OAEP is:
id-RSAES-OAEP OBJECT IDENTIFIER ::= { id-RSAES-OAEP OBJECT IDENTIFIER ::= { iso(1) member-body(2)
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 7 } us(840) rsadsi(113549) pkcs(1) pkcs-1(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 } pSourceFunc [2] AlgorithmIdentifier DEFAULT
pSpecifiedEmptyIdentifier }
sha1Identifier ::= AlgorithmIdentifier { 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, nullOctetString }
id-sha1 OBJECT IDENTIFIER ::= { nullOctetString OCTET STRING (SIZE (0)) ::= { ''H }
iso(1) identified-organization(3) oiw(14) secsig(3) algorithms(2) 26 }
id-mgf1 OBJECT IDENTIFIER ::= { id-sha1 OBJECT IDENTIFIER ::= { iso(1)
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 8 } identified-organization(3) oiw(14)
secsig(3) algorithms(2) 26 }
id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 9 } us(840) rsadsi(113549) pkcs(1) pkcs-1(1) }
id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 }
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 hashFunc identifies the one-way hash function. Implementations
MUST support SHA-1 [SHA1]. The SHA-1 algorithm identifier is MUST support SHA-1 [SHA1]. The SHA-1 algorithm identifier is
comprised of the id-sha1 object identifier and a parameter of comprised of the id-sha1 object identifier and a parameter of
NULL. Implementations that perform encryption MUST omit the NULL. Implementations that perform encryption MUST omit the
hashFunc field when SHA-1 is used, indicating that the default hashFunc field when SHA-1 is used, indicating that the default
algorithm was used. Implementations that perform decryption MUST algorithm was used. Implementations that perform decryption MUST
recognize both the id-sha1 object identifier and an absent recognize both the id-sha1 object identifier and an absent
skipping to change at page 6, line 23 skipping to change at page 6, line 25
Implementations MUST support a zero length P value. Implementations MUST support a zero length P value.
Implementations that perform encryption MUST omit the pSourceFunc Implementations that perform encryption MUST omit the pSourceFunc
field when a zero length P value is used, indicating that the field when a zero length P value is used, indicating that the
default value was used. Implementations that perform decryption default value was used. Implementations that perform decryption
MUST recognize both the id-pSpecified object identifier and an MUST recognize both the id-pSpecified object identifier and an
absent pSourceFunc field as an indication that a zero length P absent pSourceFunc field as an indication that a zero length P
value was used. value was used.
4 SMIMECapabilities Attribute Conventions 4 SMIMECapabilities Attribute Conventions
RFC 2633, 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. When constructing a announcing the SMIMECapabilities can support. When constructing a
signedData object, compliant software MAY include the 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. RSAES-OAEP algorithm.
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, { { id-RSAES-OAEP,
sha1Identifier, mgf1SHA1Identifier, 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 the following
hexadecimal string:
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
References 5 References
CMS Housley, R. Cryptographic Message Syntax. RFC 2630. This section provides normative and informative references.
June 1999.
5.1 Normative References
3DES American National Standards Institute. ANSI X9.52-1998,
Triple Data Encryption Algorithm Modes of Operation. 1998.
CMS Housley, R. Cryptographic Message Syntax. RFC <TBD>.
<TBD DATE>.
MSG Ramsdell, B. S/MIME Version 3 Message Specification.
RFC 2633. June 1999.
PKCS#1v2.0 Kaliski, B. PKCS #1: RSA Encryption, Version 2.0.
RFC 2437. October 1998.
PROFILE Housley, R., W. Polk, W. Ford, and D. Solo. Internet
X.509 Public Key Infrastructure: Certificate and
Certificate Revocation List (CRL) Profile. RFC 3280.
April 2002.
SHA1 National Institute of Standards and Technology.
FIPS Pub 180-1: Secure Hash Standard. 17 April 1995.
STDWORDS Bradner, S. Key Words for Use in RFCs to Indicate
Requirement Levels. BCP 14, RFC 2119. March 1997.
X.208-88 CCITT. Recommendation X.208: Specification of Abstract
Syntax Notation One (ASN.1). 1988.
X.209-88 CCITT. Recommendation X.209: Specification of Basic
Encoding Rules for Abstract Syntax Notation One
(ASN.1). 1988.
X.509-88 CCITT. Recommendation X.509: The Directory -
Authentication Framework. 1988.
5.2 Informative References
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 '98 in H. Krawczyk (editor), Advances in Cryptology - CRYPTO '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.
MUSTSHOULD Bradner, S. Key Words for Use in RFCs to Indicate MMA Rescorla, E. Preventing the Million Message Attack on
Requirement Levels. BCP 14, RFC 2119. March 1997. Cryptographic Message Syntax. RFC 3218. January 2002.
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.
RFC 2437. October 1998.
PROFILE Housley, R., W. Ford, W. Polk, and D. Solo. Internet
X.509 Public Key Infrastructure: Certificate and CRL
Profile. RFC 2459. January 1999.
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] [http://www.rsasecurity.com/rsalabs/bulletins]
SHA1 National Institute of Standards and Technology.
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] [http://wp.netscape.com/eng/ssl3/draft302.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 6 Security Considerations
Syntax Notation One (ASN.1). 1988.
X.209-88 CCITT. Recommendation X.209: Specification of Basic Encoding
Rules for Abstract Syntax Notation One (ASN.1). 1988.
X.509-88 CCITT. Recommendation X.509: The Directory - Authentication
Framework. 1988.
Security Considerations
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
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 Implementations must protect the key management private key and the
message-authentication key. Compromise of the key management private message-authentication key. Compromise of the key management private
key permits masquerade of authenticated data. Compromise of the key permits masquerade of authenticated data. Compromise of the
skipping to change at page 8, line 23 skipping to change at page 8, line 47
The generation of RSA public/private key pairs relies on a random The generation of RSA public/private key pairs relies on a random
numbers. The use of inadequate pseudo-random number generators numbers. The use of inadequate pseudo-random number generators
(PRNGs) to generate cryptographic keys can result in little or no (PRNGs) to generate cryptographic keys can result in little or no
security. An attacker may find it much easier to reproduce the PRNG security. An attacker may find it much easier to reproduce the PRNG
environment that produced the keys, searching the resulting small set environment that produced the keys, searching the resulting small set
of possibilities, rather than brute force searching the whole key of possibilities, rather than brute force searching the whole key
space. The generation of quality random numbers is difficult. RFC space. The generation of quality random numbers is difficult. RFC
1750 [RANDOM] offers important guidance in this area. 1750 [RANDOM] offers important guidance in this area.
Acknowledgments 7 Acknowledgments
This document is the result of contributions from many professionals. This document is the result of contributions from many professionals.
I appreciate the hard work of all members of the IETF S/MIME Working I appreciate the hard work of all members of the IETF S/MIME Working
Group. I wish to extend a special thanks to Burt Kaliski. Group. Further, I extend a special thanks to Burt Kaliski.
Author Address 8 Author Address
Russell Housley Russell Housley
SPYRUS RSA Laboratories
381 Elden Street 918 Spring Knoll Drive
Suite 1120
Herndon, VA 20170 Herndon, VA 20170
USA USA
housley@spyrus.com rhousley@rsasecurity.com
Appendix A ASN.1 Module
CMS-RSAES-OAEP {iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0) cms-rsaes-oaep(20) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
-- From PKIX Certificate and CRL Profile
AlgorithmIdentifier
FROM PKIXExplicit88 { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-explicit(18) };
pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-1(1) }
id-RSAES-OAEP OBJECT IDENTIFIER ::= { pkcs-1 7 }
RSAES-OAEP-params ::= SEQUENCE {
hashFunc [0] AlgorithmIdentifier DEFAULT sha1Identifier,
maskGenFunc [1] AlgorithmIdentifier DEFAULT mgf1SHA1Identifier,
pSourceFunc [2] AlgorithmIdentifier DEFAULT
pSpecifiedEmptyIdentifier }
sha1Identifier AlgorithmIdentifier ::= { id-sha1, NULL }
mgf1SHA1Identifier AlgorithmIdentifier ::=
{ id-mgf1, sha1Identifier }
pSpecifiedEmptyIdentifier AlgorithmIdentifier ::=
{ id-pSpecified, nullOctetString }
nullOctetString OCTET STRING (SIZE (0)) ::= { ''H }
id-sha1 OBJECT IDENTIFIER ::= { iso(1)
identified-organization(3) oiw(14)
secsig(3) algorithms(2) 26 }
id-mgf1 OBJECT IDENTIFIER ::= { pkcs-1 8 }
id-pSpecified OBJECT IDENTIFIER ::= { pkcs-1 9 }
rSAES-OAEP-Default-Identifier AlgorithmIdentifier ::=
{ id-RSAES-OAEP,
{ sha1Identifier,
mgf1SHA1Identifier,
pSpecifiedEmptyIdentifier } }
END
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. In addition, the included on all such copies and derivative works. In addition, the
ASN.1 module presented in Appendix A may be used in whole or in part ASN.1 module presented in Appendix A may be used in whole or in part
without inclusion of the copyright notice. However, this document without inclusion of the copyright notice. However, this document
itself may not be modified in any way, such as by removing the itself may not be modified in any way, such as by removing the
 End of changes. 

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