144 lines
3.6 KiB
Python
144 lines
3.6 KiB
Python
# standard imports
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import os
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import hashlib
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import logging
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import json
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import uuid
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# external imports
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import coincurve
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from Crypto.Cipher import AES
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from Crypto.Util import Counter
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import sha3
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# local imports
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from crypto_dev_signer.encoding import private_key_to_address
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logg = logging.getLogger()
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algo_keywords = [
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'aes-128-ctr',
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]
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hash_keywords = [
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'scrypt'
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]
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default_kdfparams = {
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'dklen': 32,
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'n': 1 << 18,
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'p': 1,
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'r': 8,
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'salt': os.urandom(32).hex(),
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}
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def to_mac(mac_key, ciphertext_bytes):
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h = sha3.keccak_256()
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h.update(mac_key)
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h.update(ciphertext_bytes)
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return h.digest()
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class Hashes:
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@staticmethod
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def from_scrypt(kdfparams=default_kdfparams, passphrase=''):
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dklen = int(kdfparams['dklen'])
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n = int(kdfparams['n'])
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p = int(kdfparams['p'])
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r = int(kdfparams['r'])
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salt = bytes.fromhex(kdfparams['salt'])
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return hashlib.scrypt(passphrase.encode('utf-8'), salt=salt,n=n, p=p, r=r, maxmem=1024*1024*1024, dklen=dklen)
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class Ciphers:
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aes_128_block_size = 1 << 7
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aes_iv_len = 16
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@staticmethod
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def decrypt_aes_128_ctr(ciphertext, decryption_key, iv):
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ctr = Counter.new(Ciphers.aes_128_block_size, initial_value=iv)
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cipher = AES.new(decryption_key, AES.MODE_CTR, counter=ctr)
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plaintext = cipher.decrypt(ciphertext)
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return plaintext
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@staticmethod
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def encrypt_aes_128_ctr(plaintext, encryption_key, iv):
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ctr = Counter.new(Ciphers.aes_128_block_size, initial_value=iv)
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cipher = AES.new(encryption_key, AES.MODE_CTR, counter=ctr)
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ciphertext = cipher.encrypt(plaintext)
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return ciphertext
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def to_dict(private_key_bytes, passphrase=''):
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private_key = coincurve.PrivateKey(secret=private_key_bytes)
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encryption_key = Hashes.from_scrypt(passphrase=passphrase)
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address_hex = private_key_to_address(private_key)
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iv_bytes = os.urandom(Ciphers.aes_iv_len)
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iv = int.from_bytes(iv_bytes, 'big')
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ciphertext_bytes = Ciphers.encrypt_aes_128_ctr(private_key.secret, encryption_key[:16], iv)
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mac = to_mac(encryption_key[16:], ciphertext_bytes)
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crypto_dict = {
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'cipher': 'aes-128-ctr',
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'ciphertext': ciphertext_bytes.hex(),
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'cipherparams': {
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'iv': iv_bytes.hex(),
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},
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'kdf': 'scrypt',
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'kdfparams': default_kdfparams,
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'mac': mac.hex(),
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}
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uu = uuid.uuid1()
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o = {
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'address': address_hex,
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'version': 3,
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'crypto': crypto_dict,
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'id': str(uu),
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}
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return o
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def from_dict(o, passphrase=''):
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cipher = o['crypto']['cipher']
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if cipher not in algo_keywords:
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raise NotImplementedError('cipher "{}" not implemented'.format(cipher))
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kdf = o['crypto']['kdf']
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if kdf not in hash_keywords:
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raise NotImplementedError('kdf "{}" not implemented'.format(kdf))
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m = getattr(Hashes, 'from_{}'.format(kdf.replace('-', '_')))
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decryption_key = m(o['crypto']['kdfparams'], passphrase)
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control_mac = bytes.fromhex(o['crypto']['mac'])
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iv_bytes = bytes.fromhex(o['crypto']['cipherparams']['iv'])
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iv = int.from_bytes(iv_bytes, "big")
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ciphertext_bytes = bytes.fromhex(o['crypto']['ciphertext'])
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# check mac
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calculated_mac = to_mac(decryption_key[16:], ciphertext_bytes)
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assert control_mac == calculated_mac
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m = getattr(Ciphers, 'decrypt_{}'.format(cipher.replace('-', '_')))
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pk = m(ciphertext_bytes, decryption_key[:16], iv)
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return pk
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def from_file(filepath, passphrase=''):
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f = open(filepath, 'r')
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o = json.load(f)
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f.close()
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return from_dict(o, passphrase)
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