81 lines
2.5 KiB
Python
81 lines
2.5 KiB
Python
import base64
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import json
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import secrets
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from typing import Optional
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import secp256k1
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from cffi import FFI
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from cryptography.hazmat.primitives import padding
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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def get_shared_secret(privkey: str, pubkey: str):
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point = secp256k1.PublicKey(bytes.fromhex("02" + pubkey), True)
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return point.ecdh(bytes.fromhex(privkey), hashfn=copy_x)
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def decrypt_message(encoded_message: str, encryption_key) -> str:
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encoded_data = encoded_message.split("?iv=")
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encoded_content, encoded_iv = encoded_data[0], encoded_data[1]
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iv = base64.b64decode(encoded_iv)
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cipher = Cipher(algorithms.AES(encryption_key), modes.CBC(iv))
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encrypted_content = base64.b64decode(encoded_content)
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decryptor = cipher.decryptor()
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decrypted_message = decryptor.update(encrypted_content) + decryptor.finalize()
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unpadder = padding.PKCS7(128).unpadder()
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unpadded_data = unpadder.update(decrypted_message) + unpadder.finalize()
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return unpadded_data.decode()
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def encrypt_message(message: str, encryption_key, iv: Optional[bytes]) -> str:
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padder = padding.PKCS7(128).padder()
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padded_data = padder.update(message.encode()) + padder.finalize()
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iv = iv if iv else secrets.token_bytes(16)
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cipher = Cipher(algorithms.AES(encryption_key), modes.CBC(iv))
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encryptor = cipher.encryptor()
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encrypted_message = encryptor.update(padded_data) + encryptor.finalize()
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return f"{base64.b64encode(encrypted_message).decode()}?iv={base64.b64encode(iv).decode()}"
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def sign_message_hash(private_key: str, hash: bytes) -> str:
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privkey = secp256k1.PrivateKey(bytes.fromhex(private_key))
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sig = privkey.schnorr_sign(hash, None, raw=True)
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return sig.hex()
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def test_decrypt_encrypt(encoded_message: str, encryption_key):
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msg = decrypt_message(encoded_message, encryption_key)
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# ecrypt using the same initialisation vector
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iv = base64.b64decode(encoded_message.split("?iv=")[1])
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ecrypted_msg = encrypt_message(msg, encryption_key, iv)
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assert (
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encoded_message == ecrypted_msg
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), f"expected '{encoded_message}', but got '{ecrypted_msg}'"
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print("### test_decrypt_encrypt", encoded_message == ecrypted_msg)
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ffi = FFI()
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@ffi.callback(
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"int (unsigned char *, const unsigned char *, const unsigned char *, void *)"
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)
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def copy_x(output, x32, y32, data):
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ffi.memmove(output, x32, 32)
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return 1
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def is_json(string: str):
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try:
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json.loads(string)
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except ValueError as e:
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return False
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return True
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