78 lines
2.2 KiB
Python
78 lines
2.2 KiB
Python
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import base64
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import hashlib
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import typing
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from datetime import datetime
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from functools import lru_cache
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from typing import Any
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from Crypto.Hash import SHA256
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from Crypto.Signature import PKCS1_v1_5
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from pyld import jsonld # type: ignore
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if typing.TYPE_CHECKING:
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from app.key import Key
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_LOADER = jsonld.requests_document_loader()
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@lru_cache(256)
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def _caching_document_loader(url: str) -> Any:
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return _LOADER(url)
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jsonld.set_document_loader(_caching_document_loader)
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def _options_hash(doc):
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doc = dict(doc["signature"])
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for k in ["type", "id", "signatureValue"]:
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if k in doc:
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del doc[k]
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doc["@context"] = "https://w3id.org/identity/v1"
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normalized = jsonld.normalize(
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doc, {"algorithm": "URDNA2015", "format": "application/nquads"}
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)
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h = hashlib.new("sha256")
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h.update(normalized.encode("utf-8"))
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return h.hexdigest()
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def _doc_hash(doc):
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doc = dict(doc)
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if "signature" in doc:
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del doc["signature"]
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normalized = jsonld.normalize(
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doc, {"algorithm": "URDNA2015", "format": "application/nquads"}
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)
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h = hashlib.new("sha256")
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h.update(normalized.encode("utf-8"))
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return h.hexdigest()
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def verify_signature(doc, key: "Key"):
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to_be_signed = _options_hash(doc) + _doc_hash(doc)
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signature = doc["signature"]["signatureValue"]
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signer = PKCS1_v1_5.new(key.pubkey or key.privkey) # type: ignore
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digest = SHA256.new()
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digest.update(to_be_signed.encode("utf-8"))
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return signer.verify(digest, base64.b64decode(signature)) # type: ignore
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def generate_signature(doc, key: "Key"):
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options = {
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"type": "RsaSignature2017",
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"creator": doc["actor"] + "#main-key",
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"created": datetime.utcnow().replace(microsecond=0).isoformat() + "Z",
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}
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doc["signature"] = options
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to_be_signed = _options_hash(doc) + _doc_hash(doc)
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if not key.privkey:
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raise ValueError(f"missing privkey on key {key!r}")
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signer = PKCS1_v1_5.new(key.privkey)
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digest = SHA256.new()
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digest.update(to_be_signed.encode("utf-8"))
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sig = base64.b64encode(signer.sign(digest)) # type: ignore
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options["signatureValue"] = sig.decode("utf-8")
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