refactor verifier VPs
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Cayo Puigdefabregas
parent
8ebd824bed
commit
4bcb0911a7
160
verify_vp.py
160
verify_vp.py
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@ -1,141 +1,37 @@
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import sys
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import json
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import hashlib
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import multicodec
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import multiformats
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import nacl.signing
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import nacl.encoding
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from pyld import jsonld
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from jwcrypto import jwk
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from nacl.signing import SigningKey, VerifyKey
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from collections import OrderedDict
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from nacl.encoding import RawEncoder
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from datetime import datetime, timezone
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.asymmetric import ec
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
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def key_to_did(public_key_bytes):
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"""did-key-format :=
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did:key:MULTIBASE(base58-btc, MULTICODEC(public-key-type, raw-public-key-bytes))"""
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mc = multicodec.add_prefix('ed25519-pub', public_key_bytes)
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# Multibase encode the hashed bytes
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did = multiformats.multibase.encode(mc, 'base58btc')
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return f"did:key:{did}"
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def get_signing_input(payload):
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header = b'{"alg":"EdDSA","crit":["b64"],"b64":false}'
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header_b64 = nacl.encoding.URLSafeBase64Encoder.encode(header)
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signing_input = header_b64 + b"." + payload
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return header_b64, signing_input
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def urdna2015_normalize(document, proof):
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doc_dataset = jsonld.compact(document, "https://www.w3.org/2018/credentials/v1")
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sigopts_dataset = jsonld.compact(proof, "https://w3id.org/security/v2")
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doc_normalized = jsonld.normalize(
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doc_dataset,
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{'algorithm': 'URDNA2015', 'format': 'application/n-quads'}
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)
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sigopts_normalized = jsonld.normalize(
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sigopts_dataset,
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{'algorithm': 'URDNA2015', 'format': 'application/n-quads'}
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)
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return doc_normalized, sigopts_normalized
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def sha256_normalized(doc_normalized, sigopts_normalized):
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doc_digest = hashlib.sha256(doc_normalized.encode('utf-8')).digest()
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sigopts_digest = hashlib.sha256(sigopts_normalized.encode('utf-8')).digest()
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message = sigopts_digest + doc_digest
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return message
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def to_jws_payload(document, proof):
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doc_normalized, sigopts_normalized = urdna2015_normalize(document, proof)
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return sha256_normalized(doc_normalized, sigopts_normalized)
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def get_message(vc):
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document = vc.copy()
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proof = document.pop("proof", {})
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jws = proof.pop("jws", None)
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proof['@context'] = 'https://w3id.org/security/v2'
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if not jws:
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return None, False
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return jws+"==", to_jws_payload(document, proof)
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def get_verify_key(vc):
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did = vc["proof"]["verificationMethod"].split("#")[0]
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pub = did.split(":")[-1]
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mc = multiformats.multibase.decode(pub)
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public_key_bytes = multicodec.remove_prefix(mc)
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return VerifyKey(public_key_bytes)
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def jws_split(jws):
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header, sig_b64 = jws.split("..")
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signature = nacl.encoding.URLSafeBase64Encoder.decode(sig_b64.encode())
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return header.encode(), signature
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def verify_vc(vc):
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header = {"alg": "EdDSA", "crit": ["b64"], "b64": False}
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jws, message = get_message(vc)
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if not message:
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return False
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header_b64, signature = get_signing_input(message)
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header_jws, signature_jws = jws_split(jws)
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if header_jws != header_b64:
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return False
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header_jws_json = json.loads(
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nacl.encoding.URLSafeBase64Encoder.decode(header_jws)
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)
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for k, v in header.items():
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if header_jws_json.get(k) != v:
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return False
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verify_key = get_verify_key(vc)
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data_verified = verify_key.verify(signature_jws+signature)
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return data_verified == signature
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def verify_vp(presentation):
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result_presentation = verify_vc(presentation)
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if not result_presentation:
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return False
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for vc in presentation.get("verifiableCredential", []):
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if not verify_vc(vc):
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return False
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return True
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import argparse
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from verify import verify_vc
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def get_presentation(path_presentation):
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with open(path_presentation, "r") as f:
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vc = f.read()
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return json.loads(vc)
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return vc
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def main():
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parser=argparse.ArgumentParser(description='Verify a presentation')
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parser.add_argument("presentation_path")
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args=parser.parse_args()
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if args.presentation_path:
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presentation = get_presentation(args.presentation_path)
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presentation_verified = verify_vc(presentation)
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if not presentation_verified:
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print(presentation_verified)
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return
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vp = json.loads(presentation)
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for vc in vp['verifiableCredential']:
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vc_str = json.dumps(vc)
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verified = verify_vc(vc_str)
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if not verified:
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print(verified)
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return
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print(True)
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return
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if __name__ == "__main__":
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if len(sys.argv) > 1:
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path_presentation = sys.argv[1]
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presentation = get_presentation(path_presentation)
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print(verify_vp(presentation))
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else:
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print("You need pass a presentation.")
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main()
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