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https://github.com/aljazceru/python-teos.git
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62 lines
2.4 KiB
Python
62 lines
2.4 KiB
Python
import re
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from hashlib import sha256
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from binascii import hexlify, unhexlify
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from cryptography.hazmat.primitives.ciphers.aead import AESGCM
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from apps.cli import SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
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from pisa.logger import Logger
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logger = Logger("Client")
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class Blob:
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def __init__(self, data, cipher, hash_function):
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if type(data) is not str or re.search(r'^[0-9A-Fa-f]+$', data) is None:
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raise ValueError("Non-Hex character found in txid.")
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self.data = data
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self.cipher = cipher
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self.hash_function = hash_function
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# FIXME: We only support SHA256 for now
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if self.hash_function.upper() not in SUPPORTED_HASH_FUNCTIONS:
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raise ValueError("Hash function not supported ({}). Supported Hash functions: {}"
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.format(self.hash_function, SUPPORTED_HASH_FUNCTIONS))
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# FIXME: We only support AES-GCM-128 for now
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if self.cipher.upper() not in SUPPORTED_CIPHERS:
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raise ValueError("Cipher not supported ({}). Supported ciphers: {}".format(self.hash_function,
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SUPPORTED_CIPHERS))
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def encrypt(self, tx_id):
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if len(tx_id) != 64:
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raise ValueError("txid does not matches the expected size (32-byte / 64 hex chars).")
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elif re.search(r'^[0-9A-Fa-f]+$', tx_id) is None:
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raise ValueError("Non-Hex character found in txid.")
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# Transaction to be encrypted
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# FIXME: The blob data should contain more things that just the transaction. Leaving like this for now.
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tx = unhexlify(self.data)
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tx_id = unhexlify(tx_id)
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# master_key = H(tx_id | tx_id)
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master_key = sha256(tx_id + tx_id).digest()
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# The 16 MSB of the master key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
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sk = master_key[:16]
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nonce = master_key[16:]
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# Encrypt the data
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aesgcm = AESGCM(sk)
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encrypted_blob = aesgcm.encrypt(nonce=nonce, data=tx, associated_data=None)
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encrypted_blob = hexlify(encrypted_blob).decode()
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logger.info("Creating new blob",
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master_key=hexlify(master_key).decode(),
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sk=hexlify(sk).decode(),
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nonce=hexlify(nonce).decode(),
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encrypted_blob=encrypted_blob)
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return encrypted_blob
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