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87 lines
2.9 KiB
Python
87 lines
2.9 KiB
Python
# libzot.py: crypto primitives to support Zot6/Nomad
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import hashlib
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import whirlpool
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import base64
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.asymmetric import rsa, padding
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from cryptography.hazmat.primitives import serialization, hashes
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from cryptography.exceptions import UnsupportedAlgorithm, AlreadyFinalized, InvalidSignature, NotYetFinalized, AlreadyUpdated, InvalidKey
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# base64url implementations which support "no padding"
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def base64urlnopad_encode(data: bytes) -> str:
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return base64.urlsafe_b64encode(data).decode("utf-8").replace("=","");
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def base64urlnopad_decode(data: str) -> bytes:
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# restore any missing padding before calling the (strict) base64 decoder
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if (data.find('=') == -1):
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data += "=" * (-len(data) % 4)
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return base64.urlsafe_b64decode(data)
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def generate_rsa_keypair() -> (str, str):
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key = rsa.generate_private_key(
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public_exponent = 65537,
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key_size = 4096,
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backend = default_backend()
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)
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prvkey_pem = key.private_bytes(
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encoding = serialization.Encoding.PEM,
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format = serialization.PrivateFormat.TraditionalOpenSSL,
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encryption_algorithm = serialization.NoEncryption()
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)
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pubkey = key.public_key()
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pubkey_pem = pubkey.public_bytes(
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encoding = serialization.Encoding.PEM,
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format = serialization.PublicFormat.SubjectPublicKeyInfo,
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)
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# convert bytes to str
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prvkey_pem = prvkey_pem.decode("utf-8")
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pubkey_pem = pubkey_pem.decode("utf-8")
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return prvkey_pem, pubkey_pem
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def zot_sign(data: str, prvkey: str) -> str:
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key = serialization.load_pem_private_key(prvkey.encode("ascii"),password = None)
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rawsig = key.sign(hashlib.sha256(data.encode("utf-8")).hexdigest().encode("utf-8"), padding.PKCS1v15(), hashes.SHA256())
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return 'sha256.' + base64.b64encode(rawsig).decode("utf-8")
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def zot_verify(data: str, sig: str, pubkey: str) -> bool:
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key = serialization.load_pem_public_key(pubkey.encode("ascii"))
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alg, signature = sig.split('.')
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if alg == 'sha256':
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hashed = hashlib.sha256(data.encode("utf-8")).hexdigest().encode("utf-8")
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algorithm = hashes.SHA256()
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elif alg == 'sha512':
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hashed = hashlib.sha256(data.encode("utf-8")).hexdigest().encode("utf-8")
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algorithm = hashes.SHA512()
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else:
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hashed = ""
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rawsig = base64.b64decode(signature)
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try:
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key.verify(rawsig, hashed, padding.PKCS1v15(), algorithm)
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return True
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except UnsupportedAlgorithm:
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pass
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except AlreadyFinalized:
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pass
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except InvalidSignature:
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pass
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except NotYetFinalized:
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pass
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except AlreadyUpdated:
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pass
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except InvalidKey:
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pass
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except BaseException:
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pass
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return False
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def make_xchan_hash(id_str: str,id_pubkey: str) -> str:
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wp = whirlpool.new(id_str.encode("utf-8") + id_pubkey.encode("utf-8"))
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return base64urlnopad_encode(wp.digest());
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