c8a04e144b
Clean-room reference implementation (Ed25519 certificate chain, AES-256-GCM envelope, three-rung revocation ladder, crypto-erasure) with runnable examples and 36 tests that reproduce each demonstrated claim on stand-in payloads. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
129 lines
3.9 KiB
Python
129 lines
3.9 KiB
Python
"""Claim 2: output provenance binding verifies and invalidates as stated."""
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import dataclasses
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import pytest
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from capability_licensing import (
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AXIS_CONTEXT_SOURCE,
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AXIS_WEIGHT_SOURCE,
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RevocationList,
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RUNG_CRYPTO_ERASURE,
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bind_output,
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verify_output_provenance,
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)
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OUTPUT = b"Stand-in generated output bound to its composition certificates."
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@pytest.fixture()
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def bound(chain):
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"""A second (context-source) certificate and a signed provenance record."""
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context_source, _ = chain.authority.issue_capability(
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chain.organisation.serial,
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"licensed-reference-corpus",
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claims={"axis": AXIS_CONTEXT_SOURCE},
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)
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record = bind_output(
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OUTPUT,
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sources=[
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(AXIS_WEIGHT_SOURCE, chain.capability),
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(AXIS_CONTEXT_SOURCE, context_source),
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],
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signer_certificate=chain.capability,
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signer_private_key=chain.capability_key,
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)
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return chain, context_source, record
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def _verify(bound, output=OUTPUT, revocations=None):
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chain, _context_source, record = bound
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return verify_output_provenance(
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output,
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record,
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chain.authority.registry(),
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[chain.organisation],
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[chain.root],
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revocations or RevocationList(),
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)
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def test_intact_composition_is_valid(bound):
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result = _verify(bound)
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assert result.valid, result.reason
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# One digest check, one signature check, one signer-chain check, and one
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# check per referenced source.
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assert len(result.checks) == 5
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def test_tampered_output_is_invalid(bound):
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result = _verify(bound, output=OUTPUT + b" [edited]")
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assert not result.valid
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assert "does not match the bound digest" in result.reason
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def test_forged_record_signature_is_invalid(bound):
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chain, context_source, record = bound
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forged = dataclasses.replace(record, output_sha256="0" * 64)
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result = verify_output_provenance(
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OUTPUT,
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forged,
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chain.authority.registry(),
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[chain.organisation],
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[chain.root],
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)
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assert not result.valid
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def test_revoked_source_certificate_invalidates_the_output(bound):
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_chain, context_source, _record = bound
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revocations = RevocationList()
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revocations.revoke(context_source.serial, "context licence terminated")
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result = _verify(bound, revocations=revocations)
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assert not result.valid
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assert "revoked" in result.reason
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assert context_source.serial in result.reason
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def test_erased_source_certificate_invalidates_the_output(bound):
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chain, _context_source, _record = bound
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revocations = RevocationList()
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revocations.revoke(
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chain.capability.serial,
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"capability unit crypto-erased",
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rung=RUNG_CRYPTO_ERASURE,
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)
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result = _verify(bound, revocations=revocations)
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assert not result.valid
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assert "crypto-erasure" in result.reason
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def test_reinstating_a_soft_revocation_restores_validity(bound):
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_chain, context_source, _record = bound
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revocations = RevocationList()
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revocations.revoke(context_source.serial, "temporary hold")
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assert not _verify(bound, revocations=revocations).valid
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revocations.reinstate(context_source.serial)
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assert _verify(bound, revocations=revocations).valid
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def test_substituted_source_certificate_is_detected(bound):
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chain, context_source, record = bound
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# An attacker replaces the registry's copy of the context-source
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# certificate with a different one under the same serial.
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substituted, _ = chain.authority.issue_capability(
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chain.organisation.serial, "look-alike-corpus", claims={}
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)
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registry = chain.authority.registry()
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registry[context_source.serial] = dataclasses.replace(
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substituted, serial=context_source.serial
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)
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result = verify_output_provenance(
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OUTPUT,
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record,
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registry,
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[chain.organisation],
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[chain.root],
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)
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assert not result.valid
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assert "substituted certificate" in result.reason
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