Add support for AES-GCM-SIV using OpenSSL>=3.2.0

CHANGELOG.rst

@@ -46,6 +46,9 @@ Changelog
 * In the next release (43.0.0) of cryptography, loading an X.509 certificate
   with a negative serial number will raise an exception. This has been
   deprecated since 36.0.0.
+* Added support for
+  :class:`~cryptography.hazmat.primitives.ciphers.aead.AESGCMSIV` when using
+  OpenSSL 3.2.0+.
 
 .. _v41-0-5:
 

docs/development/custom-vectors/aes-192-gcm-siv.rst

@@ -0,0 +1,28 @@
+AES-GCM-SIV vector creation
+===========================
+
+This page documents the code that was used to generate the AES-GCM-SIV test
+vectors for key lengths not available in the OpenSSL test vectors. All the
+vectors were generated using OpenSSL and verified with Rust.
+
+Creation
+--------
+
+The following Python script was run to generate the vector files. The OpenSSL
+test vectors were used as a base and modified to have 192-bit key length.
+
+.. literalinclude:: /development/custom-vectors/aes-192-gcm-siv/generate_aes192gcmsiv.py
+
+Download link: :download:`generate_aes192gcmsiv.py
+</development/custom-vectors/aes-192-gcm-siv/generate_aes192gcmsiv.py>`
+
+
+Verification
+------------
+
+The following Rust program was used to verify the vectors.
+
+.. literalinclude:: /development/custom-vectors/aes-192-gcm-siv/verify-aes192gcmsiv/src/main.rs
+
+Download link: :download:`main.rs
+</development/custom-vectors/aes-192-gcm-siv/verify-aes192gcmsiv/src/main.rs>`

docs/development/custom-vectors/aes-192-gcm-siv/generate_aes192gcmsiv.py

@@ -0,0 +1,86 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+import binascii
+
+from cryptography.hazmat.primitives.ciphers.aead import AESGCMSIV
+
+
+def convert_key_to_192_bits(key: str) -> str:
+    """
+    This takes existing 128 and 256-bit keys from test vectors from OpenSSL
+    and makes them 192-bit by either appending 0 or truncating the key.
+    """
+    new_key = binascii.unhexlify(key)
+    if len(new_key) == 16:
+        new_key += b"\x00" * 8
+    elif len(new_key) == 32:
+        new_key = new_key[0:24]
+    else:
+        raise RuntimeError(
+            "Unexpected key length. OpenSSL AES-GCM-SIV test vectors only "
+            "contain 128-bit and 256-bit keys"
+        )
+
+    return binascii.hexlify(new_key).decode("ascii")
+
+
+def encrypt(key: str, iv: str, plaintext: str, aad: str) -> (str, str):
+    aesgcmsiv = AESGCMSIV(binascii.unhexlify(key))
+    encrypted_output = aesgcmsiv.encrypt(
+        binascii.unhexlify(iv),
+        binascii.unhexlify(plaintext),
+        binascii.unhexlify(aad) if aad else None,
+    )
+    ciphertext, tag = encrypted_output[:-16], encrypted_output[-16:]
+
+    return (
+        binascii.hexlify(ciphertext).decode("ascii"),
+        binascii.hexlify(tag).decode("ascii"),
+    )
+
+
+def build_vectors(filename):
+    count = 0
+    output = []
+    key = None
+    iv = None
+    aad = None
+    plaintext = None
+
+    with open(filename) as vector_file:
+        for line in vector_file:
+            line = line.strip()
+            if line.startswith("Key"):
+                if count != 0:
+                    ciphertext, tag = encrypt(key, iv, plaintext, aad)
+                    output.append(f"Tag = {tag}\nCiphertext = {ciphertext}\n")
+                output.append(f"\nCOUNT = {count}")
+                count += 1
+                aad = None
+                _, key = line.split(" = ")
+                key = convert_key_to_192_bits(key)
+                output.append(f"Key = {key}")
+            elif line.startswith("IV"):
+                _, iv = line.split(" = ")
+                output.append(f"IV = {iv}")
+            elif line.startswith("AAD"):
+                _, aad = line.split(" = ")
+                output.append(f"AAD = {aad}")
+            elif line.startswith("Plaintext"):
+                _, plaintext = line.split(" = ")
+                output.append(f"Plaintext = {plaintext}")
+
+        ciphertext, tag = encrypt(key, iv, plaintext, aad)
+        output.append(f"Tag = {tag}\nCiphertext = {ciphertext}\n")
+        return "\n".join(output)
+
+
+def write_file(data, filename):
+    with open(filename, "w") as f:
+        f.write(data)
+
+
+path = "vectors/cryptography_vectors/ciphers/AES/GCM-SIV/openssl.txt"
+write_file(build_vectors(path), "aes-192-gcm-siv.txt")

docs/development/custom-vectors/aes-192-gcm-siv/verify-aes192gcmsiv/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "verify-aes192gcmsiv"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+aes-gcm-siv = "0.11.1"
+aes = "0.8.1"
+hex = "0.4.3"