< draft-pornin-deterministic-dsa-01.txt   draft-pornin-deterministic-dsa-02.txt >
Internet Engineering Task Force T. Pornin Internet Engineering Task Force T. Pornin
Internet-Draft August 27, 2012 Internet-Draft May 30, 2013
Intended status: Informational Intended status: Informational
Expires: February 28, 2013 Expires: December 1, 2013
Deterministic Usage of DSA and ECDSA Digital Signature Algorithms Deterministic Usage of DSA and ECDSA Digital Signature Algorithms
draft-pornin-deterministic-dsa-01 draft-pornin-deterministic-dsa-02
Abstract Abstract
This document defines a deterministic digital signature generation This document defines a deterministic digital signature generation
procedure. Such signatures are compatible with standard DSA and procedure. Such signatures are compatible with standard DSA and
ECDSA digital signatures, and can be processed with unmodified ECDSA digital signatures, and can be processed with unmodified
verifiers, which need not be aware of the procedure described verifiers, which need not be aware of the procedure described
therein. Deterministic signatures retain the cryptographic security therein. Deterministic signatures retain the cryptographic security
features associated with digital signatures, but can be more easily features associated with digital signatures, but can be more easily
implemented in various environments since they do not need access to implemented in various environments since they do not need access to
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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
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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 28, 2013. This Internet-Draft will expire on December 1, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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3.1. Building Blocks . . . . . . . . . . . . . . . . . . . . . 10 3.1. Building Blocks . . . . . . . . . . . . . . . . . . . . . 10
3.1.1. HMAC . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1.1. HMAC . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Generation of k . . . . . . . . . . . . . . . . . . . . . 11 3.2. Generation of k . . . . . . . . . . . . . . . . . . . . . 11
3.3. Alternate Description of the Generation of k . . . . . . . 12 3.3. Alternate Description of the Generation of k . . . . . . . 12
3.4. Usage Notes . . . . . . . . . . . . . . . . . . . . . . . 14 3.4. Usage Notes . . . . . . . . . . . . . . . . . . . . . . . 14
3.5. Rationale . . . . . . . . . . . . . . . . . . . . . . . . 14 3.5. Rationale . . . . . . . . . . . . . . . . . . . . . . . . 14
3.6. Variants . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.6. Variants . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6. Intellectual Property Status . . . . . . . . . . . . . . . . . 17 6. Intellectual Property Status . . . . . . . . . . . . . . . . . 17
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.1. Normative References . . . . . . . . . . . . . . . . . . . 17 7.1. Normative References . . . . . . . . . . . . . . . . . . . 18
7.2. Informative References . . . . . . . . . . . . . . . . . . 18 7.2. Informative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 20 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 20
A.1. Detailed Example . . . . . . . . . . . . . . . . . . . . . 20 A.1. Detailed Example . . . . . . . . . . . . . . . . . . . . . 20
A.1.1. Key Pair . . . . . . . . . . . . . . . . . . . . . . . 20 A.1.1. Key Pair . . . . . . . . . . . . . . . . . . . . . . . 20
A.1.2. Generation of k . . . . . . . . . . . . . . . . . . . 20 A.1.2. Generation of k . . . . . . . . . . . . . . . . . . . 20
A.1.3. signature . . . . . . . . . . . . . . . . . . . . . . 23 A.1.3. signature . . . . . . . . . . . . . . . . . . . . . . 23
A.2. Test Vectors . . . . . . . . . . . . . . . . . . . . . . . 24 A.2. Test Vectors . . . . . . . . . . . . . . . . . . . . . . . 24
A.2.1. DSA, 1024 bits . . . . . . . . . . . . . . . . . . . . 25 A.2.1. DSA, 1024 bits . . . . . . . . . . . . . . . . . . . . 25
A.2.2. DSA, 2048 bits . . . . . . . . . . . . . . . . . . . . 27 A.2.2. DSA, 2048 bits . . . . . . . . . . . . . . . . . . . . 27
A.2.3. ECDSA, 192 bits (prime field) . . . . . . . . . . . . 30 A.2.3. ECDSA, 192 bits (prime field) . . . . . . . . . . . . 30
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One remaining issue with deterministic (EC)DSA, as presented in this One remaining issue with deterministic (EC)DSA, as presented in this
document, is the "double use" of the private key 'x', both as private document, is the "double use" of the private key 'x', both as private
key in the signature generation algorithm itself, and as input to the key in the signature generation algorithm itself, and as input to the
HMAC_DRBG-based pseudo-random oracle for producing the 'k' value. HMAC_DRBG-based pseudo-random oracle for producing the 'k' value.
This requires HMAC_DRBG to keep on being a random oracle, even when This requires HMAC_DRBG to keep on being a random oracle, even when
the public key (which is computed from 'x') is also known. Given the the public key (which is computed from 'x') is also known. Given the
lack of common structure between HMAC and discrete logarithm, this lack of common structure between HMAC and discrete logarithm, this
seems a reasonable assumption. seems a reasonable assumption.
Side channel attacks are an important consideration whenever an
attacker can accurately measure aspects of an implementation such as
the length of time that it takes to perform a signing operation, or
the power consumed at each point of a signing operation. The
determinism of the algorithms described in this note may be useful to
an attacker in some forms of side channel attacks, so implementations
SHOULD use defensive measures to avoid leaking the private key
through a side channel.
6. Intellectual Property Status 6. Intellectual Property Status
To the best of our knowledge, deterministic (EC)DSA is not covered by To the best of our knowledge, deterministic (EC)DSA is not covered by
any active patent. The paper [BDLSY2011] points to two independent any active patent. The paper [BDLSY2011] points to two independent
publications of the idea of derandomization by Barwood and Wigley, publications of the idea of derandomization by Barwood and Wigley,
both in early 1997; then a patent application by Naccache, M'Raihi both in early 1997; then a patent application by Naccache, M'Raihi
and Levy-dit-Vehel a few months later [NML1997], but the application and Levy-dit-Vehel a few months later [NML1997], but the application
was withdrawn in 2003. We are not aware of any other patent on that was withdrawn in 2003. We are not aware of any other patent on that
subject. subject.
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