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Use of the SHAKE One-way Hash Functions in the Cryptographic Message Syntax (CMS)NIST100 Bureau DriveGaithersburg, MD 20899quynh.Dang@nist.govCisco Systemspkampana@cisco.com
General
LAMPS WGThis document describes the conventions for using the SHAKE family of
hash functions with the Cryptographic Message Syntax (CMS) as one-way hash
functions with the RSA Probabilistic signature and ECDSA signature algorithms,
as message digests and message authentication codes. The conventions for the
associated signer public keys in CMS are also described. [ EDNOTE: Remove this section before publication. ]draft-ietf-lamps-cms-shake-05:
Added informative references.Updated ASN.1 so it compiles.Updated IANA considerations.draft-ietf-lamps-cms-shake-04:
Added RFC8174 reference and text. Explicitly explained why RSASSA-PSS-params are omitted in section 4.2.1.Simplified Public Keys section by removing redundand info from RFCs.draft-ietf-lamps-cms-shake-03:
Removed paragraph suggesting KMAC to be used in generating k in Deterministric ECDSA. That should be RFC6979-bis. Removed paragraph from Security Considerations that talks about randomness of k because we are using deterministric ECDSA.Completed ASN.1 module and fixed KMAC ASN.1 based on Jim's feedback.Text fixes.draft-ietf-lamps-cms-shake-02:
Updates based on suggestions and clarifications by Jim. Started ASN.1 module.draft-ietf-lamps-cms-shake-01:
Significant reorganization of the sections to simplify the introduction, the new OIDs and their use in CMS.Added new OIDs for RSASSA-PSS that hardcodes hash, salt and MGF, according the WG consensus.Updated Public Key section to use the new RSASSA-PSS OIDs and clarify the algorithm identifier usage.Removed the no longer used SHAKE OIDs from section 3.1.draft-ietf-lamps-cms-shake-00:
Various updates to title and section names.Content changes filling in text and references.draft-dang-lamps-cms-shakes-hash-00:
Initial versionThe Cryptographic Message Syntax (CMS) is used to
digitally sign, digest, authenticate, or encrypt arbitrary message contents.
This specification describes the use of the SHAKE128 and SHAKE256
specified in as new hash functions in CMS. In addition,
it describes the use of these functions with the RSASSA-PSS signature
algorithm and the Elliptic Curve Digital Signature
Algorithm (ECDSA) with the CMS signed-data content type.In the SHA-3 family, two extendable-output functions (SHAKEs), SHAKE128 and SHAKE256,
are defined. Four other hash function instances, SHA3-224, SHA3-256,
SHA3-384, and SHA3-512 are also defined but are out of scope for this document.
A SHAKE is a variable length hash function. The output length, in bits, of a
SHAKE is defined by the d parameter. The corresponding collision and second
preimage resistance strengths for SHAKE128 are min(d/2,128) and min(d,128) bits
respectively. And, the corresponding collision and second preimage resistance
strengths for SHAKE256 are min(d/2,256) and min(d,256) bits respectively.A SHAKE can be used in CMS as the message digest function (to hash the
message to be signed) in RSASSA-PSS and deterministic ECDSA, message
authentication code and as the mask generating function in RSASSA-PSS.
This specification describes the identifiers for SHAKEs to be used in
CMS and their meaning. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14
when, and only when, they appear in all capitals, as shown here.This section defines six new OIDs for using SHAKE128 and SHAKE256 in CMS. EDNOTE: If PKIX draft is standardized first maybe we should not say the
identifiers are new for the RSASSA-PSS and ECDSA. Two object identifiers for SHAKE128 and SHAKE256 hash functions are defined
in and we include them here for convenience.In this specification, when using the id-shake128-len or id-shake256-len algorithm identifiers, the parameters
MUST be absent. That is, the identifier SHALL be a SEQUENCE of one component, the OID.
We define two new identifiers for RSASSA-PSS signatures using SHAKEs.The same RSASSA-PSS algorithm identifiers can be used for identifying
public keys and signatures.We define two new algorithm identifiers of ECDSA signatures using SHAKEs.The parameters for the four RSASSA-PSS and deterministic ECDSA identifiers
MUST be absent. That is, each identifier SHALL be a SEQUENCE of one component,
the OID.Two new object identifiers for KMACs using SHAKE128 and SHAKE256 are define elow.The parameters for id-KmacWithSHAKE128 and id-KmacWithSHAKE256 MUST be absent.
That is, each identifier SHALL be a SEQUENCE of one component, the OID., ,
and specify the required output length for each use
of SHAKE128 or SHAKE256 in message digests, RSASSA-PSS, determinstic ECDSA
and KMAC.The id-shake128-len and id-shake256-len OIDs () can
be used as the digest algorithm identifiers located in the SignedData,
SignerInfo, DigestedData, and the AuthenticatedData digestAlgorithm fields
in CMS . The encoding MUST omit the parameters field
and the output size, d, for the SHAKE128 or SHAKE256 message digest MUST be
256 or 512 bits respectively.The digest values are located in the DigestedData field and the Message
Digest authenticated attribute included in the signedAttributes of the
SignedData signerInfo. In addition, digest values are input to
signature algorithms. The digest algorithm MUST be the same as the
message hash algorithms used in signatures.In CMS, signature algorithm identifiers are located in the SignerInfo
signatureAlgorithm field of SignedData content type and countersignature attribute.
Signature values are located in the SignerInfo signature field of SignedData and
countersignature.Conforming implementations that process RSASSA-PSS and deterministic
ECDSA with SHAKE signatures when processing CMS data MUST recognize the
corresponding OIDs specified in .The RSASSA-PSS algorithm is defined in .
When id-RSASSA-PSS-SHAKE128 or id-RSASSA-PSS-SHAKE256 specified in
is used, the encoding MUST omit the parameters field. That is,
the AlgorithmIdentifier SHALL be a SEQUENCE of one component,
id-RSASSA-PSS-SHAKE128 or id-RSASSA-PSS-SHAKE256.
defines RSASSA-PSS-params that are used to define the algorithms and inputs
to the algorithm. This specification does not use parameters because the
hash and mask generating algorithsm and trailer and salt are embedded in
the OID definition.The hash algorithm to hash a message being signed and the hash and the hash
algorithm as the mask generation function used in RSASSA-PSS MUST be
the same, SHAKE128 or SHAKE256 respectively. The output-length of
the hash algorithm which hashes the message SHALL be 32 or 64 bytes
respectively. The mask generation function takes an octet string of variable length
and a desired output length as input, and outputs an octet string of
the desired length. In RSASSA-PSS with SHAKES, the SHAKEs MUST be
used natively as the MGF function, instead of the MGF1 algorithm that
uses the hash function in multiple iterations as specified in
Section B.2.1 of [RFC8017]. In other words, the MGF is defined as
the SHAKE128 or SHAKE256 output of the mgfSeed for id-RSASSA-PSS-
SHAKE128 and id-RSASSA-PSS-SHAKE256 respectively. The mgfSeed is the
seed from which mask is generated, an octet string [RFC8017]. The
output length is (n - 264)/8 or (n - 520)/8 bytes respectively, where
n is the RSA modulus in bits. For example, when RSA modulus n is
2048, the output length of SHAKE128 or SHAKE256 as the MGF will be
223 or 191-bits when id-RSASSA-PSS-SHAKE128 or id-RSASSA-PSS-SHAKE256
is used respectively.The RSASSA-PSS saltLength MUST be 32 or 64 bytes respectively.
Finally, the trailerField MUST be 1, which represents the trailer
field with hexadecimal value 0xBC .The Elliptic Curve Digital Signature Algorithm (ECDSA) is defined in
. When the id-ecdsa-with-SHAKE128 or id-ecdsa-with-SHAKE256
(specified in ) algorithm identifier appears, the
respective SHAKE function is used as the hash.
The encoding MUST omit the parameters field. That is, the AlgorithmIdentifier
SHALL be a SEQUENCE of one component, the OID id-ecdsa-with-SHAKE128 or
id-ecdsa-with-SHAKE256.For simplicity and compliance with the ECDSA standard specification,
the output size of the hash function must be explicitly determined.
The output size, d, for SHAKE128 or SHAKE256 used in ECDSA MUST be 256
or 512 bits respectively. Conforming implementations that generate ECDSA with SHAKE signatures
in CMS MUST generate such signatures with a deterministicly
generated, non-random k in accordance
with all the requirements specified in .
They MAY also generate such signatures
in accordance with all other recommendations in or
if they have a stated policy that requires
conformance to these standards. In CMS, the signer's public key algorithm identifiers are located in the
OriginatorPublicKey's algorithm attribute.Conforming implementations MUST specify the algorithms explicitly by
using the OIDs specified in when encoding RSASSA-PSS
with SHAKE public keys in CMS messages.
The conventions and encoding for RSASSA-PSS and ECDSA
public keys algorithm identifiers are as specified in
Section 2.3 of ,
Section 3.1 of
and Section 2.1 of .
When the RSA private key owner wishes to limit the use of
the public key exclusively to RSASSA-PSS, the AlgorithmIdentifier for
RSASSA-PSS defined in can be used as the algorithm
attribute in the OriginatorPublicKey sequence. The
identifier parameters, as explained in , MUST be
absent. The RSASSA-PSS algorithm functions and output lengths are the
same as defined in .KMAC message authentication code (KMAC) is specified in .
In CMS, KMAC algorithm identifiers are located in the AuthenticatedData
macAlgorithm field. The KMAC values are located in the AuthenticatedData mac field.When the id-KmacWithSHAKE128 or id-KmacWithSHAKE256 algorithm identifier
is used as the MAC algorithm identifier, the parameters field is optional
(absent or present). If absent, the SHAKE256 output length used in KMAC is
256 or 512 bits respectively and the customization string is an empty string by default.Conforming implementations that process KMACs with the SHAKEs
when processing CMS data MUST recognize these identifiers.When calculating the KMAC output, the variable N is 0xD2B282C2, S
is an empty string, and L, the integer representing the requested output
length in bits, is 256 or 512 for KmacWithSHAKE128 or KmacWithSHAKE256
respectively in this specification.One object identifier for the ASN.1 module in
was assigned in the SMI Security for S/MIME Module Identifiers
(1.2.840.113549.1.9.16.0) registry: The SHAKEs are deterministic functions. Like any other deterministic
function, executing each function with the same input multiple times
will produce the same output. Therefore, users should not expect
unrelated outputs (with the same or different output lengths) from
excuting a SHAKE function with the same input multiple times.
The shorter one of any 2 outputs produced from a SHAKE with the same
input is a prefix of the longer one. It is a similar situation as
truncating a 512-bit output of SHA-512 by taking its 256 left-most bits.
These 256 left-most bits are a prefix of the 512-bit output.Implementations must protect the signer's private key. Compromise of
the signer's private key permits masquerade.When more than two parties share the same message-authentication key,
data origin authentication is not provided. Any party that knows the
message-authentication key can compute a valid MAC, therefore the
content could originate from any one of the parties.Implementers should be aware that cryptographic algorithms may
become weaker with time. As new cryptanalysis techniques are developed
and computing power increases, the work factor or time required to break
a particular cryptographic algorithm may decrease. Therefore, cryptographic
algorithm implementations should be modular allowing new algorithms to
be readily inserted. That is, implementers should be prepared to
regularly update the set of algorithms in their implementations.This document is based on Russ Housley's draft
.
It replaces SHA3 hash functions by SHAKE128 and SHAKE256 as the LAMPS
WG agreed.The authors would like to thank Russ Housley for his guidance and
very valuable contributions with the ASN.1 module.
&RFC2119;
&RFC8174;
&RFC5652;
&RFC8017;
&RFC4055;
&RFC5480;
SHA-3 Standard - Permutation-Based Hash and Extendable-Output FunctionsNational Institute of Standards and Technology, U.S. Department of CommerceSHA-3 Derived Functions: cSHAKE, KMAC, TupleHash and ParallelHash. NIST SP 800-185National Institute of Standards and Technology
&RFC3279;
&RFC5753;
&RFC5911;
&RFC6268;
&RFC6979;
Computer Security Objects RegisterNational Institute of Standards and TechnologyX9.62-2005 Public Key Cryptography for the Financial Services Industry: The Elliptic Curve Digital Signature Standard (ECDSA)American National Standard for Financial Services (ANSI)SEC 1: Elliptic Curve CryptographyStandards for Efficient Cryptography GroupThis appendix includes the ASN.1 modules for SHAKEs in CMS.
This module includes some ASN.1 from other standards for reference.