< draft-ietf-smime-pss-02.txt		draft-ietf-smime-pss-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-pss-02.txt November 2003		Document: draft-ietf-smime-pss-03.txt December 2003
	Category: Standards		Category: Standards
	Use of the RSA PSS Signature Algorithm in CMS		Use of the RSA PSS Signature Algorithm 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 RFC2026 [1].		all provisions of Section 10 of RFC2026 [1].
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	skipping to change at line 53 ¶		skipping to change at line 53 ¶
	[STDWORDS].		[STDWORDS].
	1. Overview		1. Overview
	This document specifies the conventions for using the RSASSA-PSS (RSA		This document specifies the conventions for using the RSASSA-PSS (RSA
	Signature Scheme with Appendix - Probabilistic Signature Scheme)		Signature Scheme with Appendix - Probabilistic Signature Scheme)
	[P1v2.1] digital signature algorithm with the Cryptographic Message		[P1v2.1] digital signature algorithm with the Cryptographic Message
	Syntax [CMS] signed-data content type.		Syntax [CMS] signed-data content type.
	CMS and PSS Signature February 2003		CMS and PSS Signature December 2003
	CMS values are generated using ASN.1 [X.208-88], using the Basic		CMS values are generated using ASN.1 [X.208-88], using the Basic
	Encoding Rules (BER) [X.209-88] and the Distinguished Encoding Rules		Encoding Rules (BER) [X.209-88] and the Distinguished Encoding Rules
	(DER) [X.509-88].		(DER) [X.509-88].
			This document is written to be used in conjunction with RFC XXX [RSA-
			ALGS]. All of the ASN.1 structures referenced in this document are
			defined in RFC XXX.
	1.1 PSS Algorithm		1.1 PSS Algorithm
	Although there are no known defects with the PKCS #1 v1.5 [P1v1.5]		Although there are no known defects with the PKCS #1 v1.5 [P1v1.5]
	signature algorithm, RSASSA-PSS [P1v2.1] was developed in an effort		signature algorithm, RSASSA-PSS [P1v2.1] was developed in an effort
	to have more mathematically provable security. PKCS #1 v1.5		to have more mathematically provable security. PKCS #1 v1.5
	signatures were developed in an ad hoc manner, RSASSA-PSS was		signatures were developed in an ad hoc manner, RSASSA-PSS was
	developed based on mathematical foundations.		developed based on mathematical foundations.
	2. Algorithm Identifiers and Parameters		2. Algorithm Identifiers and Parameters
	skipping to change at line 103 ¶		skipping to change at line 107 ¶
	In both cases, the RSA public key, which is composed of a modulus		In both cases, the RSA public key, which is composed of a modulus
	and a public exponent, MUST be encoded using the RSAPublicKey type.		and a public exponent, MUST be encoded using the RSAPublicKey type.
	The output of this encoding is carried in the certificate subject		The output of this encoding is carried in the certificate subject
	public key.		public key.
	RSAPublicKey ::= SEQUENCE {		RSAPublicKey ::= SEQUENCE {
	modulus INTEGER, -- n		modulus INTEGER, -- n
	publicExponent INTEGER } -- e		publicExponent INTEGER } -- e
	2.2 Signature Identifiers		2.2 Signature Identifiers
			CMS and PSS Signature December 2003
	The algorithm identifier for RSASAA-PSS signatures is:		The algorithm identifier for RSASAA-PSS signatures is:
	id-RSASSA-PSS OBJECT IDENTIFER ::= {pkcs-1 10 }		id-RSASSA-PSS OBJECT IDENTIFER ::= {pkcs-1 10 }
	CMS and PSS Signature February 2003
	When the id-RSASSA-PSS algorithm identifier is used for a signature,		When the id-RSASSA-PSS algorithm identifier is used for a signature,
	the AlgorithmIdentifier parameters field MUST contain RSASSA-PSS-		the AlgorithmIdentifier parameters field MUST contain RSASSA-PSS-
	params. Information about RSASSA-PSS-params can be found in [RSA-		params. Information about RSASSA-PSS-params can be found in [RSA-
	ALGS].		ALGS].
	When signing, the RSA algorithm generates a single value, and that		When signing, the RSA algorithm generates a single value, and that
	value is used directly as the signature value.		value is used directly as the signature value.
	3. Signed-data Conventions		3. Signed-data Conventions
	digestAlgorithms SHOULD contain the one-way hash function used to		digestAlgorithms SHOULD contain the one-way hash function used to
	compute the message digest on the eContent value.		compute the message digest on the eContent value.
	The same one-way hash function SHOULD be used for computing the		The same one-way hash function SHOULD be used for computing the
	message digest on both the eContent and the signedAttributes value		message digest on both the eContent and the signedAttributes value
	if signedAttributes exist.		if signedAttributes exist.
	The same one-way hash function SHOULD be used for computing the		The same one-way hash function MUST be used for computing the
	message digest on the signedAttributes and as the hashAlgorithm in		message digest on the signedAttributes and as the hashAlgorithm in
	the RSA-PSS-params structure.		the RSA-PSS-params structure.
	signatureAlgorithm MUST contain id-RSASSA-PSS. The algorithm		signatureAlgorithm MUST contain id-RSASSA-PSS. The algorithm
	parameters field MUST contain RSASSA-PSS-params.		parameters field MUST contain RSASSA-PSS-params.
	signature contains the single value resulting from the signing		signature contains the single value resulting from the signing
	operation.		operation.
	If the subjectPublicKeyInfo algorithm identifier for the public key		If the subjectPublicKeyInfo algorithm identifier for the public key
	skipping to change at line 157 ¶		skipping to change at line 161 ¶
	3. The saltLength in the signatureAlgorithm parameters MUST be		3. The saltLength in the signatureAlgorithm parameters MUST be
	greater or equal to the saltLength in the certificate		greater or equal to the saltLength in the certificate
	subjectPublicKey.algorithm parameters.		subjectPublicKey.algorithm parameters.
	4. The trailerField in the certificate subjectPublicKey.algorithm		4. The trailerField in the certificate subjectPublicKey.algorithm
	parameters and signatureAlgorithm parameters MUST be the same.		parameters and signatureAlgorithm parameters MUST be the same.
	In doing the above comparisons, default values are considered to be		In doing the above comparisons, default values are considered to be
	the same as extant values. If any of the above four steps is not		the same as extant values. If any of the above four steps is not
	true, the signature checking algorithm MUST fail validation.		true, the signature checking algorithm MUST fail validation.
			CMS and PSS Signature December 2003
	4. Security Considerations		4. Security Considerations
	CMS and PSS Signature February 2003
	Implementations must protect the RSA private key. Compromise of the		Implementations must protect the RSA private key. Compromise of the
	RSA private key may result in the ability to forge signatures.		RSA private key may result in the ability to forge signatures.
	The generation of RSA private key relies on random numbers. The use		The generation of RSA private key relies on random numbers. The use
	of inadequate pseudo-random number generators (PRNGs) to generate		of inadequate pseudo-random number generators (PRNGs) to generate
	these values can result in little or no security. An attacker may		these values can result in little or no security. An attacker may
	find it much easier to reproduce the PRNG environment that produced		find it much easier to reproduce the PRNG environment that produced
	the keys, searching the resulting small set of possibilities, rather		the keys, searching the resulting small set of possibilities, rather
	than brute force searching the whole key space. The generation of		than brute force searching the whole key space. The generation of
	skipping to change at line 183 ¶		skipping to change at line 188 ¶
	of allowing an attacker to get extra information about the key. It		of allowing an attacker to get extra information about the key. It
	is strongly suggested that the same key not be used for both the PKCS		is strongly suggested that the same key not be used for both the PKCS
	#1 v1.5 and RSASSA-PSS signature algorithms.		#1 v1.5 and RSASSA-PSS signature algorithms.
	When computing signatures, the same hash function should be used for		When computing signatures, the same hash function should be used for
	all operations. This reduces the number of failure points in the		all operations. This reduces the number of failure points in the
	signature process.		signature process.
			The parameter checking procedures outlined in section 3 are of
			special importance. It is possible to forge signatures by changing
			(especially to weaker values) these parameter values. Signers using
			this algorithm should take care that only one set of parameter values
			is used as this decreases the possibility of leaking information.
	5. Normative References		5. Normative References
	CMS Housley, R, "Cryptographic Message Syntax",		CMS Housley, R, "Cryptographic Message Syntax",
	RFC 3369, August 2002.		RFC 3369, August 2002.
	P1v2.1 Jonsson, J., and B. Kaliski, "PKCS #1: RSA		P1v2.1 Jonsson, J., and B. Kaliski, "PKCS #1: RSA
	Cryptography Specification Version 2.1",		Cryptography Specification Version 2.1",
	RFC 3447, February 2003.		RFC 3447, February 2003.
	RSA-ALGS Schaad, J., B. Kaliski and R Housley, "Additional		RSA-ALGS Schaad, J., B. Kaliski and R Housley, "Additional
	skipping to change at line 207 ¶		skipping to change at line 219 ¶
	draft-ietf-pkix-rsa-pkalgs-01.txt,		draft-ietf-pkix-rsa-pkalgs-01.txt,
	November 2003.		November 2003.
	STDWORDS S. Bradner, "Key Words for Use in RFCs to		STDWORDS S. Bradner, "Key Words for Use in RFCs to
	Indicate Requirement Levels", RFC 2119, March		Indicate Requirement Levels", RFC 2119, March
	1997.		1997.
	X.208-88 CCITT Recommendation X.208: Specification of		X.208-88 CCITT Recommendation X.208: Specification of
	Abstract Syntax Notation One (ASN.1), 1998.		Abstract Syntax Notation One (ASN.1), 1998.
			CMS and PSS Signature December 2003
	X.209-88 CCITT Recommendation X.209: Specification of		X.209-88 CCITT Recommendation X.209: Specification of
	Basic Encoding Rules for Abstract Syntax		Basic Encoding Rules for Abstract Syntax
	Notation One (ASN.1), 1988.		Notation One (ASN.1), 1988.
	X.509-88 CCITT Recommendation X.509: The Directory		X.509-88 CCITT Recommendation X.509: The Directory
	Authentication Framework, 1988.		Authentication Framework, 1988.
	6. Informational References		6. Informational References
	CMS and PSS Signature February 2003
	P1v1.5 Kaliski, B. and J. Staddon, "PKCS #1: RSA Encryption,		P1v1.5 Kaliski, B. and J. Staddon, "PKCS #1: RSA Encryption,
	Version 2.0, RFC 2437, October 1998.		Version 2.0, RFC 2437, October 1998.
	PKALGS Polk, W, R Housley, L. Bassham, "Algorithms and Identifiers		PKALGS Polk, W, R Housley, L. Bassham, "Algorithms and Identifiers
	for the Internet X.509 Public Key Infrastructure		for the Internet X.509 Public Key Infrastructure
	Certificate and Certificate Revocation List (CRL) Profile",		Certificate and Certificate Revocation List (CRL) Profile",
	RFC 3279, April 2002.		RFC 3279, April 2002.
	RANDOM Eastlake, D., S. Crocker and J. Schiller		RANDOM Eastlake, D., S. Crocker and J. Schiller
	skipping to change at line 258 ¶		skipping to change at line 271 ¶
	document itself may not be modified in any way, such as by removing		document itself may not be modified in any way, such as by removing
	the copyright notice or references to the Internet Society or other		the copyright notice or references to the Internet Society or other
	Internet organizations, except as needed for the purpose of		Internet organizations, except as needed for the purpose of
	developing Internet standards in which case the procedures for		developing Internet standards in which case the procedures for
	copyrights defined in the Internet Standards process must be		copyrights defined in the Internet Standards process must be
	followed, or as required to translate it into languages other than		followed, or as required to translate it into languages other than
	English.		English.
	The limited permissions granted above are perpetual and will not be		The limited permissions granted above are perpetual and will not be
	revoked by the Internet Society or its successors or assigns.		revoked by the Internet Society or its successors or assigns.
			CMS and PSS Signature December 2003
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