PyPI Attestation Models

A library to convert between Sigstore Bundles and PEP 740 Attestation objects

Installation

python -m pip install pypi-attestation-models

Usage

See the full API documentation here.

Signing and verification

Use these APIs to create a PEP 740-compliant Attestation object by signing a Python artifact (i.e: sdist or wheel files), and to verify an Attestation object against a Python artifact.

from pathlib import Path

from pypi_attestation_models import Attestation, AttestationPayload
from sigstore.oidc import Issuer
from sigstore.sign import SigningContext
from sigstore.verify import Verifier, policy

artifact_path = Path("test_package-0.0.1-py3-none-any.whl")

# Sign a Python artifact
issuer = Issuer.production()
identity_token = issuer.identity_token()
signing_ctx = SigningContext.production()
with signing_ctx.signer(identity_token, cache=True) as signer:
    attestation = AttestationPayload.from_dist(artifact_path).sign(signer)

print(attestation.model_dump_json())

# Verify an attestation against a Python artifact
attestation_path = Path("test_package-0.0.1-py3-none-any.whl.attestation")
attestation = Attestation.model_validate_json(attestation_path.read_bytes())
verifier = Verifier.production()
policy = policy.Identity(identity="example@gmail.com", issuer="https://accounts.google.com")
attestation.verify(verifier, policy, attestation_path)

Low-level model conversions

These conversions assume that any Sigstore Bundle used as an input was created by signing an AttestationPayload object.

from pathlib import Path
from pypi_attestation_models import pypi_to_sigstore, sigstore_to_pypi, Attestation
from sigstore.models import Bundle

# Sigstore Bundle -> PEP 740 Attestation object
bundle_path = Path("test_package-0.0.1-py3-none-any.whl.sigstore")
with bundle_path.open("rb") as f:
    sigstore_bundle = Bundle.from_json(f.read())
attestation_object = sigstore_to_pypi(sigstore_bundle)
print(attestation_object.model_dump_json())


# PEP 740 Attestation object -> Sigstore Bundle
attestation_path = Path("attestation.json")
with attestation_path.open("rb") as f:
    attestation = Attestation.model_validate_json(f.read())
bundle = pypi_to_sigstore(attestation)
print(bundle.to_json())