< draft-ietf-lamps-cms-update-alg-id-protect-03.txt		draft-ietf-lamps-cms-update-alg-id-protect-04.txt >
	Network Working Group R. Housley		Network Working Group R. Housley
	Internet-Draft Vigil Security		Internet-Draft Vigil Security
	Updates: 5652 (if approved) August 07, 2020		Updates: 5652 (if approved) August 27, 2020
	Intended status: Standards Track		Intended status: Standards Track
	Expires: February 8, 2021		Expires: February 28, 2021
	Update to the Cryptographic Message Syntax (CMS) for Algorithm		Update to the Cryptographic Message Syntax (CMS) for Algorithm
	Identifier Protection		Identifier Protection
	draft-ietf-lamps-cms-update-alg-id-protect-03		draft-ietf-lamps-cms-update-alg-id-protect-04
	Abstract		Abstract
	This document updates the Cryptographic Message Syntax (CMS)		This document updates the Cryptographic Message Syntax (CMS)
	specified in RFC 5652 to ensure that algorithm identifiers in signed-		specified in RFC 5652 to ensure that algorithm identifiers in signed-
	data and authenticated-data content types are adequately protected.		data and authenticated-data content types are adequately protected.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	skipping to change at page 1, line 34 ¶		skipping to change at page 1, line 34 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on February 8, 2021.		This Internet-Draft will expire on February 28, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 15 ¶		skipping to change at page 2, line 15 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Required use the same hash algorithm . . . . . . . . . . . . 3		3. Required use the same hash algorithm . . . . . . . . . . . . 3
	3.1. RFC 5652, Section 5.3 . . . . . . . . . . . . . . . . . . 3		3.1. RFC 5652, Section 5.3 . . . . . . . . . . . . . . . . . . 3
	3.2. RFC 5652, Section 5.4 . . . . . . . . . . . . . . . . . . 4		3.2. RFC 5652, Section 5.4 . . . . . . . . . . . . . . . . . . 4
	3.3. RFC 5652, Section 5.6 . . . . . . . . . . . . . . . . . . 4		3.3. RFC 5652, Section 5.6 . . . . . . . . . . . . . . . . . . 4
	3.4. Backward Compatibility Considerations . . . . . . . . . . 5		3.4. Backward Compatibility Considerations . . . . . . . . . . 5
	3.5. Timestamp Compatibility Considerations . . . . . . . . . 5		3.5. Timestamp Compatibility Considerations . . . . . . . . . 5
	4. Recommend inclusion of the CMSAlgorithmProtection attribute . 5		4. Recommended inclusion of the CMSAlgorithmProtection attribute 6
	4.1. RFC 5652, Section 14 . . . . . . . . . . . . . . . . . . 6		4.1. RFC 5652, Section 14 . . . . . . . . . . . . . . . . . . 6
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 6		6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
	8.1. Normative References . . . . . . . . . . . . . . . . . . 7		8.1. Normative References . . . . . . . . . . . . . . . . . . 7
	8.2. Informative References . . . . . . . . . . . . . . . . . 7		8.2. Informative References . . . . . . . . . . . . . . . . . 8
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	This document updates the Cryptographic Message Syntax (CMS)		This document updates the Cryptographic Message Syntax (CMS)
	[RFC5652] to ensure that algorithm identifiers in signed-data and		[RFC5652] to ensure that algorithm identifiers in signed-data and
	authenticated-data content types are adequately protected.		authenticated-data content types are adequately protected.
	The CMS signed-data Content Type [RFC5652], unlike X.509 certificates		The CMS signed-data Content Type [RFC5652], unlike X.509 certificates
	[RFC5280], can be vulnerable to algorithm substitution attacks. In		[RFC5280], can be vulnerable to algorithm substitution attacks. In
	an algorithm substitution attack, the attacker changes either the		an algorithm substitution attack, the attacker changes either the
	algorithm identifier or the parameters associated with the algorithm		algorithm identifier or the parameters associated with the algorithm
	identifier to change the verification process used by the recipient.		identifier to change the verification process used by the recipient.
	The X.509 certificate structure protects the algorithm identifier and		The X.509 certificate structure protects the algorithm identifier and
	the associate parameters by signing them.		the associated parameters by signing them.
	In an algorithm substitution attack, the attacker looks for a		In an algorithm substitution attack, the attacker looks for a
	different algorithm that produces the same result as the algorithm		different algorithm that produces the same result as the algorithm
	used by the originator. As an example, if the signer of a message		used by the originator. As an example, if the signer of a message
	used SHA-256 [SHS] as the digest algorithm to hash the message		used SHA-256 [SHS] as the digest algorithm to hash the message
	content, then the attacker looks for a weaker hash algorithm that		content, then the attacker looks for a weaker hash algorithm that
	produces a result that is of the same length. The attacker's goal is		produces a result that is of the same length. The attacker's goal is
	to find a different message that results in the same hash value,		to find a different message that results in the same hash value,
	which is commonly called a collision. Today, there are many hash		which is called a cross-algorithm collision. Today, there are many
	functions that produce 256-bit results. One of them may be found to		hash functions that produce 256-bit results. One of them may be
	be weak in the future.		found to be weak in the future.
	Further, when a digest algorithm produces a larger result than is		Further, when a digest algorithm produces a larger result than is
	needed by a digital signature algorithm, the digest value is reduced		needed by a digital signature algorithm, the digest value is reduced
	to the size needed by the signature algorithm. This can be done both		to the size needed by the signature algorithm. This can be done both
	by truncation and modulo operations, with the simplest being		by truncation and modulo operations, with the simplest being
	straightforward truncation. In this situation, the attacker needs to		straightforward truncation. In this situation, the attacker needs to
	find a collision with the reduced digest value. As an example, if		find a collision with the reduced digest value. As an example, if
	the message signer uses SHA-512 [SHS] as the digest algorithm and		the message signer uses SHA-512 [SHS] as the digest algorithm and
	ECDSA with the P-256 curve [DSS] as the signature algorithm, then the		ECDSA with the P-256 curve [DSS] as the signature algorithm, then the
	attacker needs to find a collision with the first half of the digest.		attacker needs to find a collision with the first half of the digest.
	Similar attacks can be mounted against parameterized algorithm		Similar attacks can be mounted against parameterized algorithm
	identifiers. When looking at randomized hash functions, such as the		identifiers. When looking at randomized hash functions, such as the
	example in [RFC6210], the algorithm identifier parameter includes a		example in [RFC6210], the algorithm identifier parameter includes a
	random value that can be manipulated by an attacker looking for		random value that can be manipulated by an attacker looking for
	collisions. Some other algorithm identifiers include complex		collisions. Some other algorithm identifiers include complex
	parameter structures, and each value provides another opportunity for		parameter structures, and each value provides another opportunity for
	manipulation by an attacker.		manipulation by an attacker.
	This document makes two updates to CMS to provide similar protection		This document makes two updates to CMS to provide protection for the
	for the algorithm identifier. First, it mandates a convention		algorithm identifier. First, it mandates a convention followed by
	followed by many implementations by requiring the originator to use		many implementations by requiring the originator to use the same hash
	the same hash algorithm to compute the digest of the message content		algorithm to compute the digest of the message content and the digest
	and the digest of signed attributes. Second, it recommends that the		of signed attributes. Second, it recommends that the originator
	originator include the CMSAlgorithmProtection attribute [RFC6211].		include the CMSAlgorithmProtection attribute [RFC6211].
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
	BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	3. Required use the same hash algorithm		3. Required use the same hash algorithm
	skipping to change at page 4, line 17 ¶		skipping to change at page 4, line 17 ¶
	set.		set.
	NEW:		NEW:
	digestAlgorithm identifies the message digest algorithm, and any		digestAlgorithm identifies the message digest algorithm, and any
	associated parameters, used by the signer. The message digest is		associated parameters, used by the signer. The message digest is
	computed on either the content being signed or the content		computed on either the content being signed or the content
	together with the signedAttrs using the process described in		together with the signedAttrs using the process described in
	Section 5.4. The message digest algorithm SHOULD be among those		Section 5.4. The message digest algorithm SHOULD be among those
	listed in the digestAlgorithms field of the associated SignerData.		listed in the digestAlgorithms field of the associated SignerData.
	If signedAttrs field is present in the SignerInfo, then the same		If the signedAttrs field is present in the SignerInfo, then the
	digest algorithm MUST be used to compute both the digest of the		same digest algorithm MUST be used to compute both the digest of
	SignedData encapContentInfo eContent, which is carried in the		the SignedData encapContentInfo eContent, which is carried in the
	message-digest attribute, and the digest of the DER-encoded		message-digest attribute, and the digest of the DER-encoded
	signedAttrs, which is passed to the signature algorithm.		signedAttrs, which is passed to the signature algorithm.
	Implementations MAY fail to validate signatures that use a digest		Implementations MAY fail to validate signatures that use a digest
	algorithm that is not included in the SignedData digestAlgorithms		algorithm that is not included in the SignedData digestAlgorithms
	set.		set.
	3.2. RFC 5652, Section 5.4		3.2. RFC 5652, Section 5.4
	Add the following paragraph as the second paragraph in Section 5.4:		Add the following paragraph as the second paragraph in Section 5.4:
	ADD:		ADD:
	When the signedAttrs field is present, the same digest algorithm		When the signedAttrs field is present, the same digest algorithm
	MUST be used to compute the digest of the encapContentInfo		MUST be used to compute the digest of the encapContentInfo
	eContent OCTET STRING, which is carried in the message-digest		eContent OCTET STRING, which is carried in the message-digest
	attribute, and the collection of attributes that are signed.		attribute, and the digest of the collection of attributes that are
			signed.
			nit: there may be a grammar nit here, relating to the parallelism of
			"compute the digest of" - I think "the collection of attributes that
			are signed" should also have an "of" or "digest of" prefix.
	3.3. RFC 5652, Section 5.6		3.3. RFC 5652, Section 5.6
	Change the paragraph discussing the signed attributes as follows:		Change the paragraph discussing the signed attributes as follows:
	OLD:		OLD:
	The recipient MUST NOT rely on any message digest values computed		The recipient MUST NOT rely on any message digest values computed
	by the originator. If the SignedData signerInfo includes		by the originator. If the SignedData signerInfo includes
	signedAttributes, then the content message digest MUST be		signedAttributes, then the content message digest MUST be
	skipping to change at page 5, line 36 ¶		skipping to change at page 5, line 40 ¶
	3.5. Timestamp Compatibility Considerations		3.5. Timestamp Compatibility Considerations
	The new requirement introduced above might lead to compatibility		The new requirement introduced above might lead to compatibility
	issues for timestamping systems when the originator does not wish to		issues for timestamping systems when the originator does not wish to
	share the message content with the Time Stamp Authority (TSA)		share the message content with the Time Stamp Authority (TSA)
	[RFC3161]. In this situation, the originator sends a TimeStampReq to		[RFC3161]. In this situation, the originator sends a TimeStampReq to
	the TSA that includes a MessageImprint, which consists of a digest		the TSA that includes a MessageImprint, which consists of a digest
	algorithm identifier and a digest value, then the TSA uses the		algorithm identifier and a digest value, then the TSA uses the
	originator-provided digest in the MessageImprint.		originator-provided digest in the MessageImprint.
	When producing the TimeStampToken, the TSA MUST use same digest		When producing the TimeStampToken, the TSA MUST use the same digest
	algorithm to compute the digest of the encapContentInfo eContent,		algorithm to compute the digest of the encapContentInfo eContent,
	which is an OCTET STRING that contains the TSTInfo, and the message-		which is an OCTET STRING that contains the TSTInfo, and the message-
	digest attribute within the SignerInfo.		digest attribute within the SignerInfo.
	To ensure that TimeStampToken values that were generated before this		To ensure that TimeStampToken values that were generated before this
	update remain valid, no requirement is placed on a TSA to ensure that		update remain valid, no requirement is placed on a TSA to ensure that
	the digest algorithm for the TimeStampToken matches the digest		the digest algorithm for the TimeStampToken matches the digest
	algorithm for the MessageImprint embedded within the TSTTokenInfo.		algorithm for the MessageImprint embedded within the TSTInfo.
	4. Recommend inclusion of the CMSAlgorithmProtection attribute		4. Recommended inclusion of the CMSAlgorithmProtection attribute
	This section updates [RFC5652] to recommend that the originator		This section updates [RFC5652] to recommend that the originator
	include the CMSAlgorithmProtection attribute [RFC6211] whenever		include the CMSAlgorithmProtection attribute [RFC6211] whenever
	signed attributes or authenticated attributes are present.		signed attributes or authenticated attributes are present.
	4.1. RFC 5652, Section 14		4.1. RFC 5652, Section 14
	Add the following paragraph as the eighth paragraph in Section 14:		Add the following paragraph as the eighth paragraph in Section 14:
	ADD:		ADD:
	While no known algorithm substitution attacks are known at this		While there are no known algorithm substitution attacks today, the
	time, the inclusion of the algorithm identifiers used by the		inclusion of the algorithm identifiers used by the originator as a
	originator as a signed attribute or an authenticated attribute		signed attribute or an authenticated attribute makes such an
	makes such an attack significantly more difficult. Therefore, the		attack significantly more difficult. Therefore, the originator of
	originator of a signed-data content type that includes signed		a signed-data content type that includes signed attributes SHOULD
			include the CMSAlgorithmProtection attribute [RFC6211] as one of
			the signed attributes. Likewise, the originator of an
			authenticated-data content type that includes authenticated
	attributes SHOULD include the CMSAlgorithmProtection attribute		attributes SHOULD include the CMSAlgorithmProtection attribute
	[RFC6211] as one of the signed attributes. Likewise, the		[RFC6211] as one of the authenticated attributes.
	originator of an authenticated-data content type that includes
	authenticated attributes SHOULD include the CMSAlgorithmProtection
	attribute [RFC6211] as one of the authenticated attributes.
	5. IANA Considerations		5. IANA Considerations
	This document makes no requests of the IANA.		This document makes no requests of the IANA.
	6. Security Considerations		6. Security Considerations
	The security properties of the CMS [RFC5652] signed-data and		The security properties of the CMS [RFC5652] signed-data and
	authenticated-data content types are updated to ensure that algorithm		authenticated-data content types are updated to offer protection for
	identifiers are adequately protected, which makes algorithm		algorithm identifiers, which makes algorithm substitution attacks
	substitution attacks significantly more difficult.		significantly more difficult.
	For the signed-data content type, the improvements specified in this		For the signed-data content type, the improvements specified in this
	document force an attacker to mount a hash algorithm substitution		document force an attacker to mount a hash algorithm substitution
	attack on the overall signature, not just on the message digest of		attack on the overall signature, not just on the message digest of
	the encapContentInfo eContent.		the encapContentInfo eContent.
	Some digital signature algorithms have prevented hash function		Some digital signature algorithms have prevented hash function
	substitutions by including a digest algorithm identifier as an input		substitutions by including a digest algorithm identifier as an input
	to the signature algorithm. As discussed in [HASHID], such a		to the signature algorithm. As discussed in [HASHID], such a
	"firewall" may not be effective or even possible with newer signature		"firewall" may not be effective or even possible with newer signature
	algorithms. For example, RSASSA-PKCS1-v1_5 [RFC8017] protects the		algorithms. For example, RSASSA-PKCS1-v1_5 [RFC8017] protects the
	digest algorithm identifier, but RSASSA-PSS [RFC8017] does not.		digest algorithm identifier, but RSASSA-PSS [RFC8017] does not.
	Therefore, it remains important that a signer have a way to signal to		Therefore, it remains important that a signer have a way to signal to
	a recipient which digest algorithms are allowed to be used in		a recipient which digest algorithms are allowed to be used in
	conjunction with the verification of an overall signature. This		conjunction with the verification of an overall signature. This
	signalling can be done as part of the specification of the signature		signaling can be done as part of the specification of the signature
	algorithm in an X.509v3 certificate extension [RFC5280], or some		algorithm, in an X.509v3 certificate extension [RFC5280], or some
	other means. The Digital Signature Standard (DSS) [DSS] takes the		other means. The Digital Signature Standard (DSS) [DSS] takes the
	first approach by requiring the use of an "approved" one-way hash		first approach by requiring the use of an "approved" one-way hash
	algorithm.		algorithm.
	For the authenticated-data content type, the improvements specified		For the authenticated-data content type, the improvements specified
	in this document force an attacker to mount a MAC algorithm		in this document force an attacker to mount a MAC algorithm
	substitution attack, which is difficult because the attacker does not		substitution attack, which is difficult because the attacker does not
	know the authentication key.		know the authentication key.
	The CMSAlgorithmProtection attribute [RFC6211] offers protection for		The CMSAlgorithmProtection attribute [RFC6211] offers protection for
	the algorithm identifiers used in the signed-data and authenticated-		the algorithm identifiers used in the signed-data and authenticated-
	data content types. However, no protection is provided for the		data content types. However, no protection is provided for the
	algorithm identifiers in the enveloped-data, digested-data, or		algorithm identifiers in the enveloped-data, digested-data, or
	encrypted-data content types. Likewise, The CMSAlgorithmProtection		encrypted-data content types. Likewise, The CMSAlgorithmProtection
	attribute provides no protection for the algorithm identifiers used		attribute provides no protection for the algorithm identifiers used
	in the authenticated-enveloped-data content type defined in		in the authenticated-enveloped-data content type defined in
	[RFC5083].		[RFC5083]. A mechanism for algorithm identifier protection for these
			content types is work for the future.
	7. Acknowledgements		7. Acknowledgements
	Many thanks to Jim Schaad and Peter Gutmann; without knowing it, they		Many thanks to Jim Schaad and Peter Gutmann; without knowing it, they
	motivated me to write this document. Thanks to Roman Danyliw for		motivated me to write this document. Thanks to Roman Danyliw, Ben
	careful review and editorial suggestions.		Kaduk, and Peter Yee for their careful review and editorial
			suggestions.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
			[RFC3161] Adams, C., Cain, P., Pinkas, D., and R. Zuccherato,
			"Internet X.509 Public Key Infrastructure Time-Stamp
			Protocol (TSP)", RFC 3161, DOI 10.17487/RFC3161, August
			2001, <https://www.rfc-editor.org/info/rfc3161>.
	[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,		[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
	RFC 5652, DOI 10.17487/RFC5652, September 2009,		RFC 5652, DOI 10.17487/RFC5652, September 2009,
	<https://www.rfc-editor.org/info/rfc5652>.		<https://www.rfc-editor.org/info/rfc5652>.
	[RFC6211] Schaad, J., "Cryptographic Message Syntax (CMS) Algorithm		[RFC6211] Schaad, J., "Cryptographic Message Syntax (CMS) Algorithm
	Identifier Protection Attribute", RFC 6211,		Identifier Protection Attribute", RFC 6211,
	DOI 10.17487/RFC6211, April 2011,		DOI 10.17487/RFC6211, April 2011,
	<https://www.rfc-editor.org/info/rfc6211>.		<https://www.rfc-editor.org/info/rfc6211>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	skipping to change at page 8, line 9 ¶		skipping to change at page 8, line 24 ¶
	8.2. Informative References		8.2. Informative References
	[DSS] National Institute of Standards and Technology (NIST),		[DSS] National Institute of Standards and Technology (NIST),
	"Digital Signature Standard (DSS)", FIPS		"Digital Signature Standard (DSS)", FIPS
	Publication 186-4, July 2013.		Publication 186-4, July 2013.
	[HASHID] Kaliski, B., "On Hash Function Firewalls in Signature		[HASHID] Kaliski, B., "On Hash Function Firewalls in Signature
	Schemes", Lecture Notes in Computer Science, Volume 2271,		Schemes", Lecture Notes in Computer Science, Volume 2271,
	DOI 10.1007/3-540-45760-7_1, February 2002.		DOI 10.1007/3-540-45760-7_1, February 2002.
	[RFC3161] Adams, C., Cain, P., Pinkas, D., and R. Zuccherato,
	"Internet X.509 Public Key Infrastructure Time-Stamp
	Protocol (TSP)", RFC 3161, DOI 10.17487/RFC3161, August
	2001, <https://www.rfc-editor.org/info/rfc3161>.
	[RFC5083] Housley, R., "Cryptographic Message Syntax (CMS)		[RFC5083] Housley, R., "Cryptographic Message Syntax (CMS)
	Authenticated-Enveloped-Data Content Type", RFC 5083,		Authenticated-Enveloped-Data Content Type", RFC 5083,
	DOI 10.17487/RFC5083, November 2007,		DOI 10.17487/RFC5083, November 2007,
	<https://www.rfc-editor.org/info/rfc5083>.		<https://www.rfc-editor.org/info/rfc5083>.
	[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,		[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
	Housley, R., and W. Polk, "Internet X.509 Public Key		Housley, R., and W. Polk, "Internet X.509 Public Key
	Infrastructure Certificate and Certificate Revocation List		Infrastructure Certificate and Certificate Revocation List
	(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,		(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
	<https://www.rfc-editor.org/info/rfc5280>.		<https://www.rfc-editor.org/info/rfc5280>.
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