Port to cryptography.

Author: tomprince

requirements.txt

@@ -1,5 +1,5 @@
 six>=1.10.0
-pycryptodomex>=3.7.0
+cryptography>=3.1
 requests>=2.9.1
 vdf>=3.3
 gevent>=1.3.0

setup.py

@@ -16,7 +16,7 @@
 
 install_requires = [
     'six>=1.10',
-    'pycryptodomex>=3.7.0',
+    'cryptography>=3.1',
     'requests>=2.9.1',
     'vdf>=3.3',
     'cachetools>=3.0.0',

steam/core/crypto.py

@@ -1,21 +1,23 @@
 """
 All function in this module take and return :class:`bytes`
 """
+import hashlib
 import sys
+from base64 import b64decode
 from os import urandom as random_bytes
 from struct import pack
-from base64 import b64decode
 
-from Cryptodome.Hash import SHA1, HMAC
-from Cryptodome.PublicKey.RSA import import_key as rsa_import_key, construct as rsa_construct
-from Cryptodome.Cipher import PKCS1_OAEP, PKCS1_v1_5
-from Cryptodome.Cipher import AES as AES
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
+from cryptography.hazmat.primitives.hmac import HMAC
+from cryptography.hazmat.primitives.serialization import load_der_public_key
 
 
 class UniverseKey(object):
     """Public keys for Universes"""
 
-    Public = rsa_import_key(b64decode("""
+    Public = load_der_public_key(b64decode("""
 MIGdMA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQDf7BrWLBBmLBc1OhSwfFkRf53T
 2Ct64+AVzRkeRuh7h3SiGEYxqQMUeYKO6UWiSRKpI2hzic9pobFhRr3Bvr/WARvY
 gdTckPv+T1JzZsuVcNfFjrocejN1oWI0Rrtgt4Bo+hOneoo3S57G9F1fOpn5nsQ6
@@ -39,8 +41,14 @@ def generate_session_key(hmac_secret=b''):
     :rtype: :class:`tuple`
     """
     session_key = random_bytes(32)
-    encrypted_session_key = PKCS1_OAEP.new(UniverseKey.Public, SHA1)\
-                                      .encrypt(session_key + hmac_secret)
+    encrypted_session_key = UniverseKey.Public.encrypt(
+        session_key + hmac_secret,
+        padding.OAEP(
+            mgf=padding.MGF1(algorithm=hashes.SHA1()),
+            algorithm=hashes.SHA256(),
+            label=None
+        )
+    )
 
     return (session_key, encrypted_session_key)
 
@@ -49,7 +57,13 @@ def symmetric_encrypt(message, key):
     return symmetric_encrypt_with_iv(message, key, iv)
 
 def symmetric_encrypt_ecb(message, key):
-    return AES.new(key, AES.MODE_ECB).encrypt(pad(message))
+    padder = padding.PKCS7(algorithms.AES.block_size).padder()
+    plaintext = padder.update(message)
+    plaintext += padder.finalize()
+    encryptor = Cipher(algorithms.AES(key), modes.ECB()).encryptor()
+    cyphertext = encryptor.update(plaintext)
+    cyphertext += encryptor.finalize()
+    return cyphertext
 
 def symmetric_encrypt_HMAC(message, key, hmac_secret):
     prefix = random_bytes(3)
@@ -58,19 +72,33 @@ def symmetric_encrypt_HMAC(message, key, hmac_secret):
     return symmetric_encrypt_with_iv(message, key, iv)
 
 def symmetric_encrypt_iv(iv, key):
-    return AES.new(key, AES.MODE_ECB).encrypt(iv)
+    encryptor = Cipher(algorithms.AES(key), modes.ECB()).encryptor()
+    cyphertext = encryptor.update(iv)
+    cyphertext += encryptor.finalize()
+    return cyphertext
 
 def symmetric_encrypt_with_iv(message, key, iv):
     encrypted_iv = symmetric_encrypt_iv(iv, key)
-    cyphertext = AES.new(key, AES.MODE_CBC, iv).encrypt(pad(message))
+    padder = padding.PKCS7(algorithms.AES.block_size).padder()
+    plaintext = padder.update(message)
+    plaintext += padder.finalize()
+    encryptor = Cipher(algorithms.AES(key), modes.CBC(iv)).encryptor()
+    cyphertext = encryptor.update(plaintext)
+    cyphertext += encryptor.finalize()
     return encrypted_iv + cyphertext
 
 def symmetric_decrypt(cyphertext, key):
     iv = symmetric_decrypt_iv(cyphertext, key)
     return symmetric_decrypt_with_iv(cyphertext, key, iv)
 
 def symmetric_decrypt_ecb(cyphertext, key):
-    return unpad(AES.new(key, AES.MODE_ECB).decrypt(cyphertext))
+    decryptor = Cipher(algorithms.AES(key), modes.ECB()).decryptor()
+    plaintext = decryptor.update(cyphertext)
+    plaintext += decryptor.finalize()
+    unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
+    message = unpadder.update(plaintext)
+    message += unpadder.finalize()
+    return message
 
 def symmetric_decrypt_HMAC(cyphertext, key, hmac_secret):
     """:raises: :class:`RuntimeError` when HMAC verification fails"""
@@ -85,19 +113,33 @@ def symmetric_decrypt_HMAC(cyphertext, key, hmac_secret):
     return message
 
 def symmetric_decrypt_iv(cyphertext, key):
-    return AES.new(key, AES.MODE_ECB).decrypt(cyphertext[:BS])
+    decryptor = Cipher(algorithms.AES(key), modes.ECB()).decryptor()
+    iv = decryptor.update(cyphertext[:BS])
+    iv += decryptor.finalize()
+    return iv
 
 def symmetric_decrypt_with_iv(cyphertext, key, iv):
-    return unpad(AES.new(key, AES.MODE_CBC, iv).decrypt(cyphertext[BS:]))
+    decryptor = Cipher(algorithms.AES(key), modes.CBC(iv)).decryptor()
+    plaintext = decryptor.update(cyphertext[BS:])
+    plaintext += decryptor.finalize()
+    unpadder = padding.PKCS7(algorithms.AES.block_size).unpadder()
+    message = unpadder.update(plaintext)
+    message += unpadder.finalize()
+    return message
 
 def hmac_sha1(secret, data):
-    return HMAC.new(secret, data, SHA1).digest()
+    h = HMAC(secret, hashes.SHA1())
+    h.update(data)
+    return h.finalize()
 
 def sha1_hash(data):
-    return SHA1.new(data).digest()
+    return hashlib.sha1(data).digest()
 
 def rsa_publickey(mod, exp):
-    return rsa_construct((mod, exp))
+    return rsa.RSAPublicNumbers(e=exp, n=mod).public_key()
 
 def pkcs1v15_encrypt(key, message):
-    return PKCS1_v1_5.new(key).encrypt(message)
+    key.encrypt(
+        message,
+        padding.PKCS1v15,
+    )