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On the Expected Number of Iterations in ML-DSA Signing: A Complete Accounting of the Rejection Conditions
eprint.iacr.orgpaper

On the Expected Number of Iterations in ML-DSA Signing: A Complete Accounting of the Rejection Conditions

ePrint paper showing that FIPS 204 Table 1's expected iteration counts for the ML-DSA signing loop cover only the line-23 validity checks (z and r0 norms). They omit the two line-28 encoding-correctness checks (‖c·t0‖∞ and hint weight). It accounts for all four conditions: z by exact counting, c·t0 by an Irwin-Hall tail, and hint weight by a closed-form conditioned per-coefficient probability with a Monte Carlo tail estimate. Corrected expected iterations are 4.36, 5.14 and 3.91 for ML-DSA-44, -65 and -87, within 0.14% of an end-to-end measurement and consistent with NIST's FIPS 204 errata.

TL;DR Corrects FIPS 204's ML-DSA expected signing iterations to 4.36/5.14/3.91 by counting all four rejection conditions, not just two.

Organisations named here

  • FIPS 204
  • Irwin-Hall distribution
  • ML-DSA

Technologies named here

  • ML-DSA-44
  • ML-DSA.Sign_internal
  • Monte Carlo estimation
  • ML-DSA-65
  • ML-DSA-87
  • FIPS 204 Table 1
  • NIST
  • CRYSTALS-Dilithium

Techniques named here

  • Rejection sampling