SQIsign is the only isogeny-based signature in Round 3. It produces the smallest signatures of any candidate (~200 B) by exploiting the Deuring correspondence between supersingular curves and quaternion orders.
Key parameters
spec snapshot- Hard problem
- Supersingular Endomorphism Ring Problem
- Public key size
- ≈ 64 B (SQIsign-I)
- Signature size
- ≈ 177 B (SQIsign-I) — smallest in PQC
- Sign cost
- ≈ 1–2 s (slow, but tiny on the wire)
- Verify cost
- ≈ 30 ms
- NIST security levels
- I, III, V
NIST citations
3 sourcesRound timeline
5 events · 2023 → 2027- Round 1
Submission accepted
Included in the 40-candidate cohort for the additional-signatures on-ramp.
- Round 2
Advanced to Round 2
NIST selected 14 candidates for continued analysis (IR 8528).
- Round 3
Advanced to Round 3
Down-selected to 9 candidates for the final evaluation round.
- Round 2
SQIsign2D-West variant proposed
Dimension-2 isogeny variant dramatically reduces signing time.
- Round 3
7th NIST PQC Standardization Conference
Scheduled late spring / early summer 2027, Gaithersburg, MD.
Source: NIST CSRC · IR 8610 (Round 3 advancement, May 14, 2026) · IR 8528 (Round 2 advancement, Oct 24, 2024).