]>
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).[ EDNOTE: Remove this section before publication. ]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.The SHA-3 family of one-way hash functions is specified in .
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.
In of this document we define six new OIDs
using SHAKE128 and SHAKE256 in CMS. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .The 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.
The new identifiers for RSASSA-PSS signatures using SHAKEs are below.The new algorithm identifiers of ECDSA signatures using SHAKEs are below.The same RSASSA-PSS and deterministric ECDSA with SHAKEs algorithm identifiers
are used for identifying public keys and signatures.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.The new object identifiers for KMACs using SHAKE128 and SHAKE256 are below.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.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.The hash algorithm to hash a message being signed and the hash algorithm as the
mask generation function "MGF(H, emLen - hLen - 1)" used
in RSASSA-PSS MUST be the same, SHAKE128 or SHAKE256 respectively. The
output-length of the SHAKE which hashes the message SHALL be 32 or 64 bytes respectively.In RSASSA-PSS, a 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, instead of the MGF1 algorithm
that uses the hash function in multiple iterations as specified in Section B.2.1 of
. In other words, the MGF is defined as
and
respectively for id-RSASSA-PSS-SHAKE128 and id-RSASSA-PSS-SHAKE256. The mgfSeed is
the seed from which mask is generated, an octet string. The maskLen for SHAKE128 or SHAKE256 being used
as the MGF 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 bytes 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. The ECDSA message hash function is
SHAKE128 or SHAKE256 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 Section 3.2 "Generation of k" of , HMAC is used to derive
the deterministic k. Conforming implementations that generate deterministic
ECDSA with SHAKE signatures in X.509 MUST use KMAC with SHAKE128 or KMAC with
SHAKE256 as specfied in when SHAKE128 or SHAKE256 is
used as the message hashing algorithm, respectively. In this situation, KMAC with
SHAKE128 and KMAC with SHAKE256 have 256-bit and 512-bit outputs respectively,
and the optional customization bit string S is an empty string.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 and
ECDSA with SHAKE public keys in CMS messages.
The conventions for RSASSA-PSS and ECDSA public keys
algorithm identifiers are as specified in ,
and
,
but we include them below for convenience. defines the following OID for RSA AlgorithmIdentifier
in the SubjectPublicKeyInfo with NULL parameters.Additionally, 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 . Regardless of what public key algorithm identifier is used, the RSA public
key, which is composed of a modulus and a public exponent, MUST be encoded
using the RSAPublicKey type . The output of this
encoding is carried in the CMS publicKey bit string. When id-ecdsa-with-shake128 or id-ecdsa-with-shake256 are
used as the algorithm identitifier in the public key, the parameters,
as explained in , MUST be absent. The hash
function and its output-length are the same as in .Additionally, the mandatory EC
SubjectPublicKey is defined in Section 2.1.1 and its syntax in Section 2.2 of
. We also include them here for convenience: The ECParameters associated with the ECDSA public key in the signers
certificate SHALL apply to the verification of the signature.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 KMAC algorithm identifier, the parameters field MUST be absent.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.[ EDNOTE: Update here only if there are OID allocations by IANA. ]
This document has no IANA actions. SHAKE128 and SHAKE256 are one-way extensible-output functions. Their
output length depends on a required length of the consuming application.The SHAKEs are deterministic functions. Like any other deterministic
functions, 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.Implementations must randomly generate message-authentication keys
and one-time values, such as the k value when generating a ECDSA
signature. In addition, the generation of public/private key pairs
relies on random numbers. The use of inadequate pseudo-random
number generators (PRNGs) to generate such cryptographic values can
result in little or no security. The generation of quality random
numbers is difficult. offers important guidance
in this area, and series provide acceptable
PRNGs.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.
&RFC2119;
&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;
&RFC4086;
&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 GroupRecommendation for Random Number Generation Using Deterministic Random Bit Generators. NIST SP 800-90ANational Institute of Standards and Technology
[EDNOTE: Update. TBD. ]