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Use of the SHAKE One-way Hash
Functions in the Cryptographic Message Syntax (CMS)Cisco Systemspkampana@cisco.comNIST100 Bureau DriveGaithersburg, MD 20899quynh.Dang@nist.gov
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-08:
id-shake128-len and id-shake256-len were replaced with id-sha128 with 32 bytes output length and id-shake256 with 64 bytes output length.Fixed a discrepancy between section 3 and 4.4 about the KMAC OIDs that have parameters as optional. draft-ietf-lamps-cms-shake-07:
Small nit from Russ while in WGLC.draft-ietf-lamps-cms-shake-06:
Incorporated Eric's suggestion from WGLC.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 defined as SHAKE(M, d) where the
output is a d-bits long digest of message M. 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 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 object identifiers (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 or id-shake256 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 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 defined below.The parameters for id-KmacWithSHAKE128 and id-KmacWithSHAKE256 are OPTIONAL., ,
and specify the required output length for each use
of SHAKE128 or SHAKE256 in message digests, RSASSA-PSS, ECDSA
and KMAC.The id-shake128 and id-shake256 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
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 .
As explained in Step 9 of section 9.1.1 of , the output
length of the MGF is emLen - hLen - 1 bytes. emLen is the maximum message
length ceil((n-1)/8), where n is the RSA modulus in bits. hLen is 32 and
64-bytes for id-RSASSA-PSS-SHAKE128 and id-RSASSA-PSS-SHAKE256 respectively.
Thus when SHAKE is used as the MGF, the SHAKE output length maskLen is
(n - 264) or (n - 520) bits respectively. For example, when RSA modulus n is 2048,
the output length of SHAKE128 or SHAKE256 as the MGF will be 1784 or 1528-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. It is RECOMMENDED that conforming implementations that generate
ECDSA with SHAKE signatures in CMS generate such signatures with a
deterministically 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.
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 .
Traditionally, the rsaEncryption object identifier is used to
identify RSA public keys. The rsaEncryption object identifier
continues to identify the public key when the RSA private
key owner does not wish to limit the use of the public key
exclusively to RSASSA-PSS with SHAKEs. 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 SHOULD be used as the algorithm attribute
in the OriginatorPublicKey sequence. Conforming client
implementations that process RSASSA-PSS with SHAKE public keys
in CMS message MUST recognize the corresponding OIDs in .Conforming implementations MUST specify and process the
algorithms explicitly by using the OIDs specified in
when encoding ECDSA with SHAKE
public keys in CMS messages. The identifier parameters, as explained in ,
MUST be absent. 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 OID
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.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.When using ECDSA with SHAKEs, the ECDSA curve order SHOULD be
chosen in line with the SHAKE output length. NIST has defined appropriate
use of the hash functions in terms of the algorithm strengths and
expected time frames for secure use in Special Publications (SPs)
and .
These documents can be used as guides to choose appropriate key sizes
for various security scenarios. In the context of this document
id-ecdsa-with-shake128 is RECOMMENDED for curves with group order
of 256-bits. id-ecdsa-with-shake256 is RECOMMENDED for curves
with group order of 384-bits or more.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. Valuable
feedback was also provided by Eric Rescorla.
&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)SP800-78-4: Cryptographic Algorithms and Key Sizes for Personal Identity VerificationNational Institute of Standards and Technology (NIST)SP800-107: Recommendation for Applications Using Approved Hash AlgorithmsNational Institute of Standards and Technology (NIST)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.