Internet DRAFT - draft-housley-lamps-cms-kemri
draft-housley-lamps-cms-kemri
Network Working Group R. Housley
Internet-Draft Vigil Security
Intended status: Standards Track J. Gray
Expires: 24 August 2023 Entrust
T. Okubo
DigiCert
20 February 2023
Using Key Encapsulation Mechanism (KEM) Algorithms in the Cryptographic
Message Syntax (CMS)
draft-housley-lamps-cms-kemri-02
Abstract
The Cryptographic Message Syntax (CMS) supports key transport and key
agreement algorithms. In recent years, cryptographers have been
specifying Key Encapsulation Mechanism (KEM) algorithms, including
quantum-secure KEM algorithms. This document defines conventions for
the use of KEM algorithms by the originator and recipients to encrypt
CMS content.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 August 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. ASN.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. CMS Version Numbers . . . . . . . . . . . . . . . . . . . 3
2. KEM Processing Overview . . . . . . . . . . . . . . . . . . . 4
3. KEM Recipient Information . . . . . . . . . . . . . . . . . . 5
4. KEM Algorithm Identifier . . . . . . . . . . . . . . . . . . 7
5. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 7
6. ASN.1 Modules . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. KEMAlgorithmInformation-2023 ASN.1 Module . . . . . . . . 8
6.2. CMS-KEMRecipientInfo ASN.1 Module . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 14
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Normative References . . . . . . . . . . . . . . . . . . . . . 14
Informative References . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The Cryptographic Message Syntax (CMS) enveloped-data content type
[RFC5652] and the CMS authenticated-enveloped-data content type
[RFC5083] support both key transport and key agreement algorithms to
establish the key used to encrypt the content. In recent years,
cryptographers have be specifying Key Encapsulation Mechanism (KEM)
algorithms, including quantum-secure KEM algorithms. This document
defines conventions for the use of KEM algorithms for the CMS
enveloped-data content type and the CMS authenticated-enveloped-data
content type.
A KEM algorithm is a one-pass (store-and-forward) mechanism for
transporting random keying material to a recipient using the
recipient's public key. The recipient's private key is needed to
recover the random keying material, which is then treated as a
pairwise shared secret between the originator and recipient. A KEM
algorithm provides three functions:
* KeyGen() -> (pk, sk):
Generate the public key (pk) and a private key (sk).
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* Encapsulate(pk) -> (ct, ss):
Given the recipient's public key (pk), produce a ciphertext (ct)
to be passed to the recipient and shared secret (ss) for the
originator.
* Decapsulate(sk, ct) -> ss:
Given the private key (sk) and the ciphertext (ct), produce the
shared secret (ss) for the recipient.
To support a particular KEM algorithm, the CMS originator MUST
implement Encapsulate().
To support a particular KEM algorithm, the CMS recipient MUST
implement KeyGen() and Decapsulate(). The recipient's public key is
usually carried in a certificate [RFC5280].
1.1. Terminology
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. ASN.1
CMS values are generated using ASN.1 [X.680], which uses the Basic
Encoding Rules (BER) and the Distinguished Encoding Rules (DER)
[X.690].
1.3. CMS Version Numbers
The major data structures include a version number as the first item
in the data structure. The version number is intended to avoid ASN.1
decode errors. Some implementations do not check the version number
prior to attempting a decode, and then if a decode error occurs, the
version number is checked as part of the error handling routine.
This is a reasonable approach; it places error processing outside of
the fast path. This approach is also forgiving when an incorrect
version number is used by the sender.
Whenever the structure is updated, a higher version number will be
assigned. However, to ensure maximum interoperability, the higher
version number is only used when the new syntax feature is employed.
That is, the lowest version number that supports the generated syntax
is used.
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2. KEM Processing Overview
KEM algorithms can be used with three CMS content types: the
enveloped-data content type [RFC5652], the authenticated-data content
type [RFC5652], or the authenticated-enveloped-data content type
[RFC5083]. For simplicity, the terminology associated with the
enveloped-data content type will be used in this overview. Thus, the
content-encryption key is used to protect the in CMS content.
The originator randomly generates the content-encryption key, and
then all recipients obtain that key. All recipients use the
originator-generated symmetric key to decrypt the CMS message.
A KEM algorithm and a key-derivation function are used to securely
establish a pairwise symmetric key-encryption key, which is used to
encrypt the originator-generated content-encryption key.
In advance, each recipient recipient uses KeyGen() to create a key
pair, and then obtains a certificate [RFC5280] that includes the
public key.
The originator establishes the content-encryption key using these
steps:
1. The content-encryption key, called CEK, is generated at random.
2. For each recipient:
* The recipient's public key is used with the Encapsulate()
function to obtain a pairwise shared secret and the ciphertext
for the recipient.
* The key-derivation function is used to derive a pairwise key-
encryption key, called KEK, from the pairwise shared secret
and other data that is send in the clear.
* The KEK is used to encrypt the CEK for this recipient.
The recipient obtains the content-encryption key using these steps:
1. The recipient's private key and the ciphertext are used with the
Decapsulate() function to obtain a pairwise shared secret.
2. The key-derivation function is used to derive a pairwise key-
encryption key, called KEK, from the pairwise shared secret and
other data that is send in the clear.
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3. The KEK is used to decrypt the content-encryption key, called
CEK.
3. KEM Recipient Information
This document defines KEMRecipientInfo for use with KEM algorithms.
As specified in Section 6.2.5 of [RFC5652], recipient information for
additional key management techniques are represented in the
OtherRecipientInfo type, and they are each identified by a unique
ASN.1 object identifier.
The object identifier associated with KEMRecipientInfo is:
id-ori OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) 13 }
id-ori-kem OBJECT IDENTIFIER ::= { id-ori TBD1 }
The KEMRecipientInfo type is:
KEMRecipientInfo ::= SEQUENCE {
version CMSVersion, -- always set to 0
rid RecipientIdentifier,
kem KEMAlgorithmIdentifier,
kemct OCTET STRING,
kdf KeyDerivationAlgorithmIdentifier,
kekLength INTEGER (1..MAX),
ukm [0] EXPLICIT UserKeyingMaterial OPTIONAL,
wrap KeyEncryptionAlgorithmIdentifier,
encryptedKey EncryptedKey }
The fields of the KEMRecipientInfo type have the following meanings:
version is the syntax version number. The version MUST be 0. The
CMSVersion type is described in Section 10.2.5 of [RFC5652].
rid specifies the recipient's certificate or key that was used by
the originator to with the Encapsulate() function. The
RecipientIdentifier provides two alternatives for specifying the
recipient's certificate [RFC5280], and thereby the recipient's
public key. The recipient's certificate MUST contain a KEM public
key. Therefore, a recipient X.509 version 3 certificate that
contains a key usage extension MUST assert the keyEncipherment
bit. The issuerAndSerialNumber alternative identifies the
recipient's certificate by the issuer's distinguished name and the
certificate serial number; the subjectKeyIdentifier identifies the
recipient's certificate by a key identifier. When an X.509
certificate is referenced, the key identifier matches the X.509
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subjectKeyIdentifier extension value. When other certificate
formats are referenced, the documents that specify the certificate
format and their use with the CMS must include details on matching
the key identifier to the appropriate certificate field. For
recipient processing, implementations MUST support both of these
alternatives for specifying the recipient's certificate. For
originator processing, implementations MUST support at least one
of these alternatives.
kem identifies the KEM algorithm, and any associated parameters,
used by the originator. The KEMAlgorithmIdentifier is described
in Section 4.
kemct is the ciphertext produced by the Encapsulate() function for
this recipient.
kdf identifies the key-derivation algorithm, and any associated
parameters, used by the originator to generate the key-encryption
key. The KeyDerivationAlgorithmIdentifier is described in
Section 10.1.6 of [RFC5652].
kekLength is the size of the key-encryption key in octets. This
value is one of the inputs to the key-derivation function.
Implementations MUST confirm that the value provided is consistent
with the key-encryption algorithm identified in the wrap field
below.
ukm is optional. When the ukm value is provided, it is used as an
input to the key-derivation function as a context input. For
example, user key material could include a nonce, an IV, or other
data required by the key-derivation function. Implementations
MUST accept a KEMRecipientInfo SEQUENCE that includes a ukm field.
Note that this expands of the original purpose of the ukm
described in Section 10.2.6 of [RFC5652]; it is not limited to
being used with key agreement algorithms.
wrap identifies a key-encryption algorithm used to encrypt the
content-encryption key. The KeyEncryptionAlgorithmIdentifier is
described in Section 10.1.3 of [RFC5652].
encryptedKey is the result of encrypting the content-encryption
key or the content-authenticated-encryption key with the key-
encryption key. EncryptedKey is an OCTET STRING.
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4. KEM Algorithm Identifier
The KEMAlgorithmIdentifier type identifies a KEM algorithm used to
establish a pairwise shared secret. The details of establishment
depend on the KEM algorithm used. A Key derivation algorithm is used
to transform the pairwise shared secret value into a key-encryption
key.
KEMAlgorithmIdentifier ::= AlgorithmIdentifier
5. Key Derivation
This section describes the conventions of using the KDF to compute
the key-encryption key for KEMRecipientInfo. For simplicity, the
terminology used in the HKDF specification [RFC5869] is used here.
Many KDFs internally employ a one-way hash function. When this is
the case, the hash function that is used is indirectly indicated by
the KeyDerivationAlgorithmIdentifier. Other KDFs internally employ
an encryption algorithm. When this is the case, the encryption that
is used is indirectly indicated by the
KeyDerivationAlgorithmIdentifier.
The KDF inputs are:
IKM is the input key material. It is a symmetric secret input to
the KDF which may use a hash function or an encryption algorithm
to generate a pseudorandom key. The algorithm used to derive the
IKM is dependent on the algorithm identified in the
KeyDerivationAlgorithmIdentifier.
L is the length of the output keying material in octets which is
identified in the keklength of the KEMRecipientInfo. The value is
dependent on the key-encryption algorithm that is used which is
identified in the KeyEncryptionAlgorithmIdentifier.
info is the context used as in additional input to the KDF; it is
the DER-encoded CMSORIforKEMOtherInfo structure defined as:
CMSORIforKEMOtherInfo ::= SEQUENCE {
wrap KeyEncryptionAlgorithmIdentifier,
kekLength INTEGER (1..MAX),
ukm [0] EXPLICIT UserKeyingMaterial OPTIONAL
}
The CMSORIforKEMOtherInfo structure contains:
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wrap identifies a key-encryption algorithm; the output of the key-
derivation function will be used as a key for this algorithm.
kekLength is the length of the key-encryption key in octets; the
output of the key-derivation function will be exactly this size.
ukm is optional user keying material, which may be useful for some
key-derivation functions. For example, user keying material could
include a nonce, an IV, or additional key binding information.
The KDF output is:
OKM is the output keying material with the exact length of L
octets. The OKM is the key-encryption key that is used to encrypt
the content-encryption key or the content-authenticated-encryption
key.
An acceptable KDF MUST accept an IKM and L as inputs; an acceptable
KDF MAY also accept salt and other inputs identified in the
UserKeyingMaterial. All of these inputs MUST influence the output of
the KDF. If the KDF requires a salt or other inputs, then those
input MUST be provided as parameters of the
KeyDerivationAlgorithmIdentifier.
6. ASN.1 Modules
This section provides two ASN.1 modules [X.680]. The first ASN.1
module is an extension to the AlgorithmInformation-2009 module in
[RFC5912], and it defines the KEM-ALGORITHM CLASS. The second ASN.1
module defines the structures needed to use KEM Algorithms with CMS
[RFC5652].
The first ASN.1 module uses EXPLICIT tagging, and the second ASN.1
module uses IMPLICIT tagging.
Both ASN.1 modules follow the conventions established in [RFC5911],
[RFC5912], and [RFC6268].
6.1. KEMAlgorithmInformation-2023 ASN.1 Module
<CODE BEGINS>
KEMAlgorithmInformation-2023
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-kemAlgorithmInformation-2023(TBD3) }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
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-- EXPORTS ALL;
IMPORTS
ParamOptions, PUBLIC-KEY, SMIME-CAPS
FROM AlgorithmInformation-2009
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58) } ;
-- KEM-ALGORITHM
--
-- Describes the basic properties of a KEM algorithm
--
-- Suggested prefixes for KEM algorithm objects is: kema-
--
-- &id - contains the OID identifying the KEM algorithm
-- &Value - if present, contains a type definition for the kemct;
-- if absent, implies that no ASN.1 encoding is
-- performed on the kemct value
-- &Params - if present, contains the type for the algorithm
-- parameters; if absent, implies no parameters
-- ¶mPresence - parameter presence requirement
-- &PublicKeySet - specifies which public keys are used with
-- this algorithm
-- &Ukm - if absent, type for user keying material
-- &ukmPresence - specifies the requirements to define the UKM field
-- &smimeCaps - contains the object describing how the S/MIME
-- capabilities are presented.
--
-- Example:
-- kema-kem-rsa KEM-ALGORITHM ::= {
-- IDENTIFIER id-kem-rsa
-- PARAMS TYPE RsaKemParameters ARE optional
-- PUBLIC-KEYS { pk-rsa | pk-rsa-kem }
-- UKM ARE optional
-- SMIME-CAPS { TYPE GenericHybridParameters
-- IDENTIFIED BY id-rsa-kem }
-- }
KEM-ALGORITHM ::= CLASS {
&id OBJECT IDENTIFIER UNIQUE,
&Value OPTIONAL,
&Params OPTIONAL,
¶mPresence ParamOptions DEFAULT absent,
&PublicKeySet PUBLIC-KEY OPTIONAL,
&Ukm OPTIONAL,
&ukmPresence ParamOptions DEFAULT absent,
&smimeCaps SMIME-CAPS OPTIONAL
} WITH SYNTAX {
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IDENTIFIER &id
[VALUE &Value]
[PARAMS [TYPE &Params] ARE ¶mPresence]
[PUBLIC-KEYS &PublicKeySet]
[UKM [TYPE &Ukm] ARE &ukmPresence]
[SMIME-CAPS &smimeCaps]
}
END
<CODE ENDS>
6.2. CMS-KEMRecipientInfo ASN.1 Module
RFC Editor: Please replace "[THISRFC]" with the the number assigned
to this document.
<CODE BEGINS>
CMS-KEMRecipientInfo-2023
{ iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0)
id-mod-cms-kemri-2023(TBD2) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL;
IMPORTS
OTHER-RECIPIENT, CMSVersion, RecipientIdentifier,
EncryptedKey, KeyDerivationAlgorithmIdentifier,
KeyEncryptionAlgorithmIdentifier, UserKeyingMaterial
FROM CryptographicMessageSyntax-2010 -- [RFC6268]
{ iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-9(9) smime(16) modules(0)
id-mod-cms-2009(58) }
KEM-ALGORITHM
FROM KEMAlgorithmInformation-2023 -- [THISRFC]
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-kemAlgorithmInformation-2023(TBD3) }
AlgorithmIdentifier{}
FROM AlgorithmInformation-2009 -- [RFC5912]
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58) } ;
--
-- OtherRecipientInfo Types (ori-)
--
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SupportedOtherRecipInfo OTHER-RECIPIENT ::= { ori-KEM, ... }
ori-KEM OTHER-RECIPIENT ::= {
KEMRecipientInfo IDENTIFIED BY id-ori-kem }
id-ori OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) 13 }
id-ori-kem OBJECT IDENTIFIER ::= { id-ori TBD1 }
--
-- KEMRecipientInfo
--
KEMRecipientInfo ::= SEQUENCE {
version CMSVersion, -- always set to 0
rid RecipientIdentifier,
kem KEMAlgorithmIdentifier,
kemct OCTET STRING,
kdf KeyDerivationAlgorithmIdentifier,
kekLength INTEGER (1..MAX),
ukm [0] EXPLICIT UserKeyingMaterial OPTIONAL,
wrap KeyEncryptionAlgorithmIdentifier,
encryptedKey EncryptedKey }
KEMAlgSet KEM-ALGORITHM ::= { ... }
KEMAlgorithmIdentifier ::=
AlgorithmIdentifier{ KEM-ALGORITHM, {KEMAlgSet} }
--
-- CMSORIforKEMOtherInfo
--
CMSORIforKEMOtherInfo ::= SEQUENCE {
wrap KeyEncryptionAlgorithmIdentifier,
kekLength INTEGER (1..MAX),
ukm [0] EXPLICIT UserKeyingMaterial OPTIONAL
}
END
<CODE ENDS>
7. Security Considerations
The Security Considerations of [RFC5652] are applicable to this
document.
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To be appropriate for use with this specification, the KEM algorithm
MUST explicitly be designed to be secure when the public key is used
many times. For example, a KEM algorithm with a single-use public
key is not appropriate because the public key is expected to be
carried in a long-lived certificate [RFC5280] and used over and over.
Thus, KEM algorithms that offer indistinguishability under adaptive
chosen ciphertext attack (IND-CCA2) security are appropriate. A
common design pattern for obtaining IND-CCA2 security with public key
reuse is to apply the Fujisaki-Okamoto (FO) transform [FO] or a
variant of the FO transform [HHK].
The choice of the KDF SHOULD be made based on the security level
provided by the KEM. The KDF SHOULD at least have the security level
of the KEM.
KEM algorithms do not provide data origin authentication; therefore,
when a KEM algorithm is used to with the authenticated-data content
type, the contents are delivered with integrity from an unknown
source.
Implementations MUST protect the KEM private key, the key-encryption
key, the content-encryption key and the content-authenticated-
encryption. Compromise of the KEM private key may result in the
disclosure of all contents protected with that KEM private key.
However, compromise of the key-encryption key, the content-encryption
key, or the content-authenticated-encryption may result in disclosure
of the encrypted content of a single message.
The KEM produces the IKM input value for the KDF. This IKM value
MUST NOT be reused for any other purpose. Likewise, any random value
used to by the KEM algorithm to produce the shared secret or its
encapsulation MUST NOT be reused for any other purpose. That is, the
originator MUST generate a fresh KEM shared secret for each recipient
in the KEMRecipientInfo structure, including any random value used by
the KEM algorithm to produce the KEM shared secret. In addition, the
originator MUST discard the KEM shared secret, including any random
value used by the KEM algorithm to produce the KEM shared secret,
after constructing the entry in the KEMRecipientInfo structure for
the corresponding recipient. Similarly, the recipient MUST discard
the KEM shared secret, including any random value used by the KEM
algorithm to produce the KEM shared secret, after constructing the
key-encryption key from the KEMRecipientInfo structure.
Implementations MUST randomly generate content-encryption keys,
content-authenticated-encryption keys, and message-authentication
keys. Also, the generation of KEM key pairs relies on random
numbers. The use of inadequate pseudo-random number generators
(PRNGs) to generate these keys can result in little or no security.
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An attacker may find it much easier to reproduce the PRNG environment
that produced the keys, searching the resulting small set of
possibilities, rather than brute force searching the whole key space.
The generation of quality random numbers is difficult. [RFC4086]
offers important guidance in this area.
If the cipher and key sizes used for the key-encryption and the
content-encryption algorithms are different, the effective security
is determined by the weaker of the two algorithms. If, for example,
the content is encrypted with AES-CBC using a 128-bit content-
encryption key, and the content-encryption key is wrapped with AES-
KEYWRAP using a 256-bit key-encryption key, then at most 128 bits of
protection is provided.
If the cipher and key sizes used for the key-encryption and the
content-authenticated-encryption algorithms are different, the
effective security is determined by the weaker of the two algorithms.
If, for example, the content is encrypted with AES-GCM using a
128-bit content-authenticated-encryption key, and the content-
authenticated-encryption key is wrapped with AES-KEYWRAP using a
192-bit key-encryption key, then at most 128 bits of protection is
provided.
If the cipher and key sizes used for the key-encryption and the
message-authentication algorithms are different, the effective
security is determined by the weaker of the two algorithms. If, for
example, the content is authenticated with HMAC-SHA256 using a
512-bit message-authentication key, and the message-authentication
key is wrapped with AES-KEYWRAP using a 256-bit key-encryption key,
then at most 256 bits of protection is provided.
Implementers should be aware that cryptographic algorithms, including
KEM algorithms, become weaker with time. As new cryptoanalysis
techniques are developed and computing capabilities advance, the work
factor to break a particular cryptographic algorithm will be reduced.
As a result, cryptographic algorithm implementations should be
modular, allowing new algorithms to be readily inserted. That is,
implementers should be prepared for the set of supported algorithms
to change over time.
8. IANA Considerations
For KEMRecipientInfo in Section 3, IANA is requested to assign an
object identifier (OID) to replace TBD1. The OID for
KEMRecipientInfo should be allocated in the "SMI Security for S/MIME
Other Recipient Info Identifiers" registry
(1.2.840.113549.1.9.16.13).
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For the ASN.1 Module in Section 6.1, IANA is requested to assign an
object identifier (OID) for the module identifier to replace TBD3.
The OID for the module should be allocated in the "SMI Security for
PKIX Module Identifier" registry (1.3.6.1.5.5.7.0).
For the ASN.1 Module in Section 6.2, IANA is requested to assign an
object identifier (OID) for the module identifier to replace TBD2.
The OID for the module should be allocated in the "SMI Security for
S/MIME Module Identifier" registry (1.2.840.113549.1.9.16.0).
Acknowledgements
Our thanks to Burt Kaliski for his guidance and design review.
Our thanks to Carl Wallace for his careful review of the ASN.1
modules.
References
Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5083] Housley, R., "Cryptographic Message Syntax (CMS)
Authenticated-Enveloped-Data Content Type", RFC 5083,
DOI 10.17487/RFC5083, November 2007,
<https://www.rfc-editor.org/info/rfc5083>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<https://www.rfc-editor.org/info/rfc5652>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Housley, et al. Expires 24 August 2023 [Page 14]
Internet-Draft CMS KEMRecipientInfo February 2023
[X.680] ITU-T, "Information technology -- Abstract Syntax Notation
One (ASN.1): Specification of basic notation", ITU-T
Recommendation X.680, ISO/IEC 8824-1:2021, February 2021,
<https://www.itu.int/rec/T-REC-X.680>.
[X.690] ITU-T, "Information technology -- ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X.690, ISO/IEC 8825-1:2021,
February 2021, <https://www.itu.int/rec/T-REC-X.680>.
Informative References
[FO] Fujisaki, E., Okamoto, T., and Springer Science and
Business Media LLC, "Secure Integration of Asymmetric and
Symmetric Encryption Schemes", Journal of Cryptology, vol.
26, no. 1, pp. 80-101, DOI 10.1007/s00145-011-9114-1, 2
December 2011,
<http://dx.doi.org/10.1007/s00145-011-9114-1>.
[HHK] Hofheinz, D., Hövelmanns, K., Kiltz, E., and Springer
International Publishing, "A Modular Analysis of the
Fujisaki-Okamoto Transformation", Theory of Cryptography,
pp. 341-371, DOI 10.1007/978-3-319-70500-2_12, 2017,
<http://dx.doi.org/10.1007/978-3-319-70500-2_12>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010,
<https://www.rfc-editor.org/info/rfc5869>.
[RFC5911] Hoffman, P. and J. Schaad, "New ASN.1 Modules for
Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911,
DOI 10.17487/RFC5911, June 2010,
<https://www.rfc-editor.org/info/rfc5911>.
[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
DOI 10.17487/RFC5912, June 2010,
<https://www.rfc-editor.org/info/rfc5912>.
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Internet-Draft CMS KEMRecipientInfo February 2023
[RFC6268] Schaad, J. and S. Turner, "Additional New ASN.1 Modules
for the Cryptographic Message Syntax (CMS) and the Public
Key Infrastructure Using X.509 (PKIX)", RFC 6268,
DOI 10.17487/RFC6268, July 2011,
<https://www.rfc-editor.org/info/rfc6268>.
Authors' Addresses
Russ Housley
Vigil Security, LLC
Herndon, VA,
United States of America
Email: housley@vigilsec.com
John Gray
Entrust
Minneapolis, MN,
United States of America
Email: john.gray@entrust.com
Tomofumi Okubo
DigiCert, Inc.
Fairfax, VA,
United States of America
Email: tomofumi.okubo+ietf@gmail.com
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