Rewrite AES code with cryptography (drop pyaes)

pyproject.toml

@@ -11,10 +11,11 @@ requires-python = ">=3.7"
 license = {file = "LICENSE"}
 dependencies = [
     "chromalog==1.0.5",
-    "pyaes==1.6.1",
     "service-identity==21.1.0",
-    "txtorcon==23.0.0",
     "twisted==22.4.0",
+    "txtorcon==23.0.0",
+    'cryptography==3.3.2; platform_machine != "aarch64" and platform_machine != "amd64" and platform_machine != "x86_64"',
+    'cryptography==41.0.2; platform_machine == "aarch64" or platform_machine == "amd64" or platform_machine == "x86_64"',
 ]
 
 [project.optional-dependencies]
@@ -33,8 +34,6 @@ jmclient = [
 jmdaemon = [
     "libnacl==1.8.0",
     "pyopenssl==23.2.0",
-    'cryptography==3.3.2; platform_machine != "aarch64" and platform_machine != "amd64" and platform_machine != "x86_64"',
-    'cryptography==41.0.2; platform_machine == "aarch64" or platform_machine == "amd64" or platform_machine == "x86_64"',
 ]
 jmqtui = [
     "PyQt5!=5.15.0,!=5.15.1,!=5.15.2,!=6.0",

src/jmbase/crypto.py

@@ -1,15 +1,27 @@
-import pyaes
+from cryptography.hazmat.primitives import padding
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+
+def _pad(data: bytes) -> bytes:
+    if len(data) % 16 == 0:
+        return data
+    padder = padding.PKCS7(128).padder()
+    return padder.update(data) + padder.finalize()
+
+
+def _unpad(data: bytes) -> bytes:
+    try:
+        unpadder = padding.PKCS7(128).unpadder()
+        return unpadder.update(data) + unpadder.finalize()
+    except ValueError:
+        return data
+
 
 def aes_cbc_encrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
-    encrypter = pyaes.Encrypter(
-        pyaes.AESModeOfOperationCBC(key, iv=iv))
-    enc_data = encrypter.feed(data)
-    enc_data += encrypter.feed()
-    return enc_data
+    encrypter = Cipher(algorithms.AES(key), modes.CBC(iv)).encryptor()
+    return encrypter.update(_pad(data)) + encrypter.finalize()
+
 
 def aes_cbc_decrypt(key: bytes, data: bytes, iv: bytes) -> bytes:
-    decrypter = pyaes.Decrypter(
-        pyaes.AESModeOfOperationCBC(key, iv=iv))
-    dec_data = decrypter.feed(data)
-    dec_data += decrypter.feed()
-    return dec_data
+    decrypter = Cipher(algorithms.AES(key), modes.CBC(iv)).decryptor()
+    return _unpad(decrypter.update(data) + decrypter.finalize())

test/jmbase/test_crypto.py

@@ -0,0 +1,47 @@
+#! /usr/bin/env python
+import os
+from binascii import unhexlify
+
+import pytest
+
+from jmbase import crypto
+
+
+@pytest.mark.parametrize("data", [b"surely a secret message", b"joinmarket"])
+def test_aes_cbc_padding(data):
+    key, iv = os.urandom(32), os.urandom(16)
+    encrypted = crypto.aes_cbc_encrypt(key, data, iv)
+    assert crypto.aes_cbc_decrypt(key, encrypted, iv) == data
+
+
+@pytest.mark.parametrize(
+    "key, iv, ciphertext, plaintext",
+    [
+        (
+            "2b7e151628aed2a6abf7158809cf4f3c",
+            "000102030405060708090a0b0c0d0e0f",
+            "7649abac8119b246cee98e9b12e9197d5086cb9b507219ee95db113a917678b273bed6b8e3c1743b7116e69e222295163ff1caa1681fac09120eca307586e1a7",
+            "6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
+        ),
+        (
+            "8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b",
+            "000102030405060708090a0b0c0d0e0f",
+            "4f021db243bc633d7178183a9fa071e8b4d9ada9ad7dedf4e5e738763f69145a571b242012fb7ae07fa9baac3df102e008b0e27988598881d920a9e64f5615cd",
+            "6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
+        ),
+        (
+            "603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4",
+            "000102030405060708090a0b0c0d0e0f",
+            "f58c4c04d6e5f1ba779eabfb5f7bfbd69cfc4e967edb808d679f777bc6702c7d39f23369a9d9bacfa530e26304231461b2eb05e2c39be9fcda6c19078c6a9d1b",
+            "6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710",
+        ),
+    ],
+)
+def test_aes_cbc_nist_vectors(key, iv, ciphertext, plaintext):
+    _key = unhexlify(key)
+    _iv = unhexlify(iv)
+    ct = unhexlify(ciphertext)
+    pt = unhexlify(plaintext)
+
+    assert crypto.aes_cbc_encrypt(_key, pt, _iv) == ct
+    assert crypto.aes_cbc_decrypt(_key, ct, _iv) == pt