psi-verifier (Python)

Apex PSI is not a tool and not a product. It is the verification substrate — the layer beneath proof. It does not judge. It does not certify. It only remembers.

MIT. Free forever. Verify any APEX PSI seal. Zero dependencies, Python 3.8+.

from psi_verifier import verify, PsiSealInvalidError

try:
    result = verify(seal)          # enforce=True by default (v1.2.0)
except PsiSealInvalidError as e:
    print(e)                       # tells you exactly where to get a valid seal

v1.2.0 — enforcement release with cross-language parity

verify() now rejects non-conformant seals instead of merely reporting them. Invalid input raises PsiSealInvalidError with the canonical schema digest and a fix URL. Report-only inspection remains available:

from psi_verifier import verify_seal, is_conformant

verify(seal, enforce=False)   # legacy data only
verify_seal(seal)             # ConformanceResult, never raises
is_conformant(seal)           # bool

What it checks

The PSI-SEAL/1 canonical schema, byte for byte: closed field set (R2/R3), 64-char lowercase hex SHA-256 (R4/R5), RFC 3339 UTC with exactly three fractional digits (R6), exact octet length (R7), domain-separated leaf SHA-256("PSI1:" + hash) and promoted-odd Merkle assembly (R8/R9), seal_hash = SHA-256(JCS(core envelope)) (R10), and matching schema_digest (R12).

Licensing

• This verifier: MIT. Check seals forever, no cost, no permission.
• The generator (sealing engine): proprietary. Free for personal / non-commercial use; commercial sealing is licensed under PSI-05 royalty terms. Generate a conformant seal at https://ai-governance-standard.com/seal.

Schema: © 2026 APEX Infrastructure. Specification: https://ai-governance-standard.com/spec