dependencies: rm pyaes from requirements

Since #6014, pyaes is not really needed anymore.

As we currently require either one of pycryptodomex or cryptography,
even if pyaes is available, it will not be used.
We could strip it out completely from crypto.py...

In any case, pyaes is still pulled in by some hw wallet dependencies indirectly;
but the core library no longer depends on it.

contrib/requirements/requirements.txt

@@ -1,4 +1,3 @@
-pyaes>=0.1a1
 ecdsa>=0.14
 qrcode
 protobuf>=3.12

electrum/crypto.py

@@ -30,12 +30,18 @@ import hashlib
 import hmac
 from typing import Union
 
-import pyaes
-
 from .util import assert_bytes, InvalidPassword, to_bytes, to_string, WalletFileException
 from .i18n import _
 
 
+HAS_PYAES = False
+try:
+    import pyaes
+except:
+    pass
+else:
+    HAS_PYAES = True
+
 HAS_CRYPTODOME = False
 try:
     from Cryptodome.Cipher import ChaCha20_Poly1305 as CD_ChaCha20_Poly1305
@@ -97,10 +103,12 @@ def aes_encrypt_with_iv(key: bytes, iv: bytes, data: bytes) -> bytes:
         cipher = CG_Cipher(CG_algorithms.AES(key), CG_modes.CBC(iv), backend=CG_default_backend())
         encryptor = cipher.encryptor()
         e = encryptor.update(data) + encryptor.finalize()
-    else:
+    elif HAS_PYAES:
         aes_cbc = pyaes.AESModeOfOperationCBC(key, iv=iv)
         aes = pyaes.Encrypter(aes_cbc, padding=pyaes.PADDING_NONE)
         e = aes.feed(data) + aes.feed()  # empty aes.feed() flushes buffer
+    else:
+        raise Exception("no AES backend found")
     return e
 
 
@@ -113,10 +121,12 @@ def aes_decrypt_with_iv(key: bytes, iv: bytes, data: bytes) -> bytes:
         cipher = CG_Cipher(CG_algorithms.AES(key), CG_modes.CBC(iv), backend=CG_default_backend())
         decryptor = cipher.decryptor()
         data = decryptor.update(data) + decryptor.finalize()
-    else:
+    elif HAS_PYAES:
         aes_cbc = pyaes.AESModeOfOperationCBC(key, iv=iv)
         aes = pyaes.Decrypter(aes_cbc, padding=pyaes.PADDING_NONE)
         data = aes.feed(data) + aes.feed()  # empty aes.feed() flushes buffer
+    else:
+        raise Exception("no AES backend found")
     try:
         return strip_PKCS7_padding(data)
     except InvalidPadding:

electrum/tests/test_bitcoin.py

@@ -46,18 +46,21 @@ def needs_test_with_all_aes_implementations(func):
             return
         has_cryptodome = crypto.HAS_CRYPTODOME
         has_cryptography = crypto.HAS_CRYPTOGRAPHY
+        has_pyaes = crypto.HAS_PYAES
         try:
-            (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY) = False, False
+            if has_pyaes:
+                (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY, crypto.HAS_PYAES) = False, False, True
                 func(*args, **kwargs)  # pyaes
             if has_cryptodome:
-                (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY) = True, False
+                (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY, crypto.HAS_PYAES) = True, False, False
                 func(*args, **kwargs)  # cryptodome
             if has_cryptography:
-                (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY) = False, True
+                (crypto.HAS_CRYPTODOME, crypto.HAS_CRYPTOGRAPHY, crypto.HAS_PYAES) = False, True, False
                 func(*args, **kwargs)  # cryptography
         finally:
             crypto.HAS_CRYPTODOME = has_cryptodome
             crypto.HAS_CRYPTOGRAPHY = has_cryptography
+            crypto.HAS_PYAES = has_pyaes
     return run_test
 
 
@@ -101,6 +104,10 @@ class Test_bitcoin(ElectrumTestCase):
         # we want the unit testing framework to test with cryptography available.
         self.assertTrue(bool(crypto.HAS_CRYPTOGRAPHY))
 
+    def test_pyaes_is_available(self):
+        # we want the unit testing framework to test with pyaes available.
+        self.assertTrue(bool(crypto.HAS_PYAES))
+
     @needs_test_with_all_aes_implementations
     def test_crypto(self):
         for message in [b"Chancellor on brink of second bailout for banks", b'\xff'*512]:

run_electrum

@@ -60,7 +60,6 @@ def check_imports():
     # pure-python dependencies need to be imported here for pyinstaller
     try:
         import dns
-        import pyaes
         import ecdsa
         import certifi
         import qrcode

setup.py

@@ -54,7 +54,7 @@ extras_require = {
     'hardware': requirements_hw,
     'gui': ['pyqt5'],
     'crypto': ['cryptography>=2.1'],
-    'tests': ['pycryptodomex>=3.7', 'cryptography>=2.1'],
+    'tests': ['pycryptodomex>=3.7', 'cryptography>=2.1', 'pyaes>=0.1a1'],
 }
 # 'full' extra that tries to grab everything an enduser would need (except for libsecp256k1...)
 extras_require['full'] = [pkg for sublist in