swarmauri_signing_pep458

swarmauri_signing_pep458 packages a detached signature provider that implements PEP 458 style signing for The Update Framework (TUF) metadata. It brings canonical JSON, multi-algorithm support, and quorum-aware verification to the Swarmauri runtime so supply-chain aware components can produce and validate repository metadata with a uniform API.

Key Features

• PEP 458 compatible format ? Signatures emit the tuf/pep458 envelope with method, keyid, and base64-encoded payloads so the metadata aligns with the specification's detached signature requirements.
• Deterministic canonicalization ? Canonicalizes envelopes using TUF's lexicographically-sorted JSON encoding to guarantee byte-for-byte reproducibility.
• Multiple signature algorithms ? Supports Ed25519 for online roles and RSA-PSS-SHA256 for offline root-style metadata, allowing you to mix schemes per role.
• Quorum aware verification ? Enforces min_signers, explicit key-id allow lists, and algorithm restrictions during verification to help model offline threshold signing policies.
• Flexible key inputs ? Accepts cryptography key objects, PEM encoded key material, or Swarmauri KeyRef dictionaries for both signing and verification.

Installation

Using uv

uv add swarmauri_signing_pep458

Using pip

pip install swarmauri_signing_pep458

Quick Start

import asyncio
from cryptography.hazmat.primitives.asymmetric import ed25519
from swarmauri_signing_pep458 import Pep458Signer

async def main() -> None:
    signer = Pep458Signer()
    private = ed25519.Ed25519PrivateKey.generate()
    keyref = {"kind": "cryptography_obj", "obj": private, "alg": "Ed25519"}

    payload = b"release metadata"
    signatures = await signer.sign_bytes(keyref, payload)

    is_valid = await signer.verify_bytes(
        payload,
        signatures,
        opts={"pubkeys": [private.public_key()]},
    )
    print(f"Signature valid? {is_valid}")

asyncio.run(main())

Signature Format

Each signature returned by the signer follows this shape:

{
  "format": "tuf/pep458",
  "method": "ed25519",
  "alg": "Ed25519",
  "keyid": "base64(SHA256(method || SPKI))",
  "sig": "base64(signature-bytes)"
}

Use the method label when matching public keys and verifying thresholds for a particular TUF role.

Verification Policy Hints

The verify_bytes and verify_envelope APIs accept a require mapping with the following helpful keys:

• min_signers: Require at least n distinct key ids to validate.
• algs: Restrict verification to a subset of algorithms, e.g. ("Ed25519",). The values are normalized case-insensitively.
• kids: Whitelist key identifiers allowed to satisfy the policy.
• pubkeys: Explicit public key materials to use when verifying (PEM strings, cryptography objects, or {"kind": "pem", "pub": ...} dictionaries).

Relationship to the Cipher Suite

Pair this package with swarmauri_cipher_suite_pep458 to describe repository role policies, canonicalization settings, and default algorithm choices across the Swarmauri ecosystem.

Development

• Format the code with ruff format . and lint with ruff check . --fix.
• Run the asynchronous unit tests with pytest once cryptography dependencies are available.
• Contributions should include updates to documentation fragments and policy tables when new capabilities are added.

License

This project is licensed under the Apache License 2.0.