crypto.Crypto: new encrypt_aes_ctr() method

mmgen/altcoin/util.py

@@ -14,7 +14,7 @@ altcoin.util: various altcoin-related utilities
 
 from ..util import die
 
-def decrypt_keystore(data, passwd, *, mac_algo=None, mac_params={}):
+def decrypt_keystore(cfg, data, passwd, *, mac_algo=None, mac_params={}):
 	"""
 	Decrypt the encrypted data in a cross-chain keystore
 	Returns the decrypted data as a bytestring
@@ -70,12 +70,8 @@ def decrypt_keystore(data, passwd, *, mac_algo=None, mac_params={}):
 		die(1, 'incorrect password')
 
 	# Decrypt data:
-	from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-	from cryptography.hazmat.backends import default_backend
-	cipher_len = int(cipher.split('-')[1]) // 8
-	c = Cipher(
-		algorithms.AES(hashed_pw[:cipher_len]),
-		modes.CTR(bytes.fromhex(cdata['cipherparams']['iv'])),
-		backend = default_backend())
-	encryptor = c.encryptor()
-	return encryptor.update(bytes.fromhex(cdata['ciphertext'])) + encryptor.finalize()
+	from ..crypto import Crypto
+	return Crypto(cfg).encrypt_aes_ctr(
+		hashed_pw[:int(cipher.split('-')[1]) // 8],
+		bytes.fromhex(cdata['cipherparams']['iv']),
+		bytes.fromhex(cdata['ciphertext']))

mmgen/crypto.py

@@ -68,6 +68,16 @@ class Crypto:
 		self.cfg = cfg
 		self.util = cfg._util
 
+	@staticmethod
+	def get_aes_ctr(key, iv):
+		from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+		from cryptography.hazmat.backends import default_backend
+		return Cipher(algorithms.AES(key), modes.CTR(iv), backend=default_backend()).encryptor()
+
+	def encrypt_aes_ctr(self, key, iv, data):
+		encryptor = self.get_aes_ctr(key, iv)
+		return encryptor.update(data) + encryptor.finalize()
+
 	def get_hash_params(self, hash_preset):
 		if hash_preset in self.hash_presets:
 			return self.hash_presets[hash_preset] # N, r, p
@@ -126,20 +136,14 @@ class Crypto:
 			verify = True,
 			silent = False):
 
-		from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-		from cryptography.hazmat.backends import default_backend
 		if not silent:
 			self.util.vmsg(f'Encrypting {desc}')
-		c = Cipher(algorithms.AES(key), modes.CTR(iv), backend=default_backend())
-		encryptor = c.encryptor()
-		enc_data = encryptor.update(data) + encryptor.finalize()
+
+		enc_data = self.encrypt_aes_ctr(key, iv, data)
 
 		if verify:
 			self.util.vmsg_r(f'Performing a test decryption of the {desc}...')
-			c = Cipher(algorithms.AES(key), modes.CTR(iv), backend=default_backend())
-			encryptor = c.encryptor()
-			dec_data = encryptor.update(enc_data) + encryptor.finalize()
-			if dec_data != data:
+			if self.encrypt_aes_ctr(key, iv, enc_data) != data:
 				die(2, f'ERROR.\nDecrypted {desc} doesn’t match original {desc}')
 			if not silent:
 				self.util.vmsg('done')
@@ -154,12 +158,9 @@ class Crypto:
 			iv   = aesctr_dfl_iv,
 			desc = 'data'):
 
-		from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-		from cryptography.hazmat.backends import default_backend
 		self.util.vmsg_r(f'Decrypting {desc} with key...')
-		c = Cipher(algorithms.AES(key), modes.CTR(iv), backend=default_backend())
-		encryptor = c.encryptor()
-		return encryptor.update(enc_data) + encryptor.finalize()
+
+		return self.encrypt_aes_ctr(key, iv, enc_data)
 
 	def scrypt_hash_passphrase(
 			self,

mmgen/proto/eth/util.py

@@ -27,6 +27,7 @@ def decrypt_geth_keystore(cfg, wallet_fn, passwd, *, check_addr=True):
 
 	from ...altcoin.util import decrypt_keystore
 	key = decrypt_keystore(
+		cfg,
 		wallet_data,
 		passwd,
 		mac_algo = get_keccak())

mmgen/tool/fileutil.py

@@ -94,15 +94,12 @@ class tool_cmd(tool_cmd_base):
 		"""
 		from threading import Thread
 		from queue import Queue
-		from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-		from cryptography.hazmat.backends import default_backend
 
 		from ..util2 import parse_bytespec
+		from ..crypto import Crypto
 
 		def encrypt_worker():
-			ctr_init_val = os.urandom(Crypto.aesctr_iv_len)
-			c = Cipher(algorithms.AES(key), modes.CTR(ctr_init_val), backend=default_backend())
-			encryptor = c.encryptor()
+			encryptor = Crypto(self.cfg).get_aes_ctr(key, os.urandom(Crypto.aesctr_iv_len))
 			while True:
 				q2.put(encryptor.update(q1.get()))
 				q1.task_done()
@@ -161,7 +158,7 @@ class tool_cmd(tool_cmd_base):
 		with open(wallet_file) as fh:
 			data = json.loads(fh.read())
 		from ..altcoin.util import decrypt_keystore
-		ret = decrypt_keystore(data[0]['keystore'], passwd)
+		ret = decrypt_keystore(self.cfg, data[0]['keystore'], passwd)
 		return ret.hex() if output_hex else ret
 
 	def decrypt_geth_keystore(self, wallet_file: str, *, check_addr=True):

test/modtest_d/dep.py

@@ -75,11 +75,8 @@ class unit_tests:
 		return False
 
 	def cryptography(self, name, ut):
-		from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-		from cryptography.hazmat.backends import default_backend
-		c = Cipher(algorithms.AES(b'deadbeef'*4), modes.CTR(b'deadbeef'*2), backend=default_backend())
-		encryptor = c.encryptor()
-		encryptor.update(b'foo') + encryptor.finalize()
+		from mmgen.crypto import Crypto
+		Crypto(cfg).encrypt_aes_ctr(b'deadbeef' * 4, b'deadbeef' * 2, b'foo')
 		return True
 
 	def ecdsa(self, name, ut):