65 lines
2.3 KiB
Python
65 lines
2.3 KiB
Python
import hashlib
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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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# https://github.com/spruceid/ssi/blob/main/ssi-jws/src/lib.rs#L75
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def sign_bytes(data, secret):
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# https://github.com/spruceid/ssi/blob/main/ssi-jws/src/lib.rs#L125
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return secret.sign(data)[:-len(data)]
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# https://github.com/spruceid/ssi/blob/main/ssi-jws/src/lib.rs#L248
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def sign_bytes_b64(data, key):
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signature = sign_bytes(data, key)
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sig_b64 = nacl.encoding.URLSafeBase64Encoder.encode(signature)
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return sig_b64
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# https://github.com/spruceid/ssi/blob/main/ssi-jws/src/lib.rs#L581
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def detached_sign_unencoded_payload(payload, key):
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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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sig_b64 = sign_bytes_b64(signing_input, key)
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jws = header_b64 + b".." + sig_b64
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return jws
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# https://github.com/spruceid/ssi/blob/main/ssi-ldp/src/lib.rs#L423
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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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# https://github.com/spruceid/ssi/blob/main/ssi-ldp/src/lib.rs#L456
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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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# https://github.com/spruceid/ssi/blob/main/ssi-ldp/src/lib.rs#L413
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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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# https://github.com/spruceid/ssi/blob/main/ssi-ldp/src/lib.rs#L498
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def sign_proof(document, proof, key):
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message = to_jws_payload(document, proof)
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jws = detached_sign_unencoded_payload(message, key)
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proof["jws"] = jws.decode('utf-8')[:-2]
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return proof
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