3
$\begingroup$

FIPS 186-4 Digital Signature Standard defers to ANSI X9.62-2005 for the specification of ECDSA, with additional requirements set out in Chapter 6 and Appendix D. However, X9.62-2005 has since been withdrawn and replaced by ANSI X9.142-2020. The FIPS 186-5 draft noted the withdrawal of X9.62-2005 and that X9.142 was under development (Appendix E, p. 78), and instead gives its own specification of ECDSA in Chapter 6 (with recommended curve parameters moved to SP 800-186).

I haven't scaled the ANSI paywall to read X9.142-2020 but the freely-available preview (PDF, p. xv) notes a number of technical changes from X9.62-2005:

  • New examples of elliptic curve domain parameters and signatures.
  • Provision for new hash functions.
  • New recommendations and requirements for elliptic curve domain parameters.
  • New specifications for assurance of domain parameter validity, assurance of public key validity, and assurance of private key possession.
  • New random number generation method.
  • New syntax.

It also notes that FIPS 186-4 "contains much in common with both this Standard and the previous ANSI X9.62-2005 version, particularly in regard to elliptic curve domain parameters and the elliptic curve digital signature algorithm", but is silent on FIPS 186-5.

My question is, how consistent are the FIPS 186-5 and X9.142-2020 specifications of ECDSA? Specifically, in a contractual or regulatory setting where detailed conformance matters (and pretending FIPS 186-5 has been approved as-is), is it true given an appropriate choice of parameters that:

  1. Conformance with the FIPS 186-5 specification of ECDSA implies conformance with X9.142-2020?
  2. Conformance with X9.142-2020 implies conformance with the FIPS 186-5 specification?

Or are the two specifications inconsistent no matter what parameters are chosen, meaning implementations need to choose between them?

$\endgroup$

1 Answer 1

0
$\begingroup$

Many FIPS standards are modified versions of standards used in broader communities, from my experience, conformance with the FIPS 186-5 specification of ECDSA implies conformance with X9.142-2020, and not backwards.

$\endgroup$
1
  • $\begingroup$ It would be useful to add an example of FIPS 186-5 requirement not in X9.142-2020 $\endgroup$
    – fgrieu
    Feb 18 at 16:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.