mirror of
https://github.com/aljazceru/python-teos.git
synced 2025-12-17 06:04:21 +01:00
50 lines
1.5 KiB
Python
50 lines
1.5 KiB
Python
from hashlib import sha256
|
|
from binascii import unhexlify, hexlify
|
|
from cryptography.exceptions import InvalidTag
|
|
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
|
|
|
|
from pisa.logger import Logger
|
|
|
|
logger = Logger("Cryptographer")
|
|
|
|
|
|
class Cryptographer:
|
|
@staticmethod
|
|
# ToDo: #20-test-tx-decrypting-edge-cases
|
|
def decrypt(encrypted_blob, key, rtype="hex"):
|
|
if rtype not in ["hex", "bytes"]:
|
|
raise ValueError("Wrong return type. Return type must be 'hex' or 'bytes'")
|
|
|
|
if len(encrypted_blob.data) % 2:
|
|
logger.info(
|
|
"Incorrect (Odd-length) value to be decrypted.", encrypted_blob=encrypted_blob.data, dispute_txid=key
|
|
)
|
|
return None
|
|
|
|
# sk is the H(txid) (32-byte) and nonce is set to 0 (12-byte)
|
|
sk = sha256(unhexlify(key)).digest()
|
|
nonce = bytearray(12)
|
|
|
|
logger.info(
|
|
"Creating new blob.",
|
|
sk=hexlify(sk).decode(),
|
|
nonce=hexlify(nonce).decode(),
|
|
encrypted_blob=encrypted_blob.data,
|
|
)
|
|
|
|
# Decrypt
|
|
cipher = ChaCha20Poly1305(sk)
|
|
data = unhexlify(encrypted_blob.data.encode())
|
|
|
|
try:
|
|
blob = cipher.decrypt(nonce=nonce, data=data, associated_data=None)
|
|
|
|
# Change the blob encoding to hex depending on the rtype (default)
|
|
if rtype == "hex":
|
|
blob = hexlify(blob).decode("utf8")
|
|
|
|
except InvalidTag:
|
|
blob = None
|
|
|
|
return blob
|