Migrate OCB3 to Rust

src/cryptography/hazmat/backends/openssl/aead.py

@@ -13,11 +13,10 @@
     from cryptography.hazmat.primitives.ciphers.aead import (
         AESCCM,
         AESGCM,
-        AESOCB3,
         ChaCha20Poly1305,
     )
 
-    _AEADTypes = typing.Union[AESCCM, AESGCM, AESOCB3, ChaCha20Poly1305]
+    _AEADTypes = typing.Union[AESCCM, AESGCM, ChaCha20Poly1305]
 
 
 def _is_evp_aead_supported_cipher(
@@ -220,16 +219,13 @@ def _evp_cipher_cipher_name(cipher: _AEADTypes) -> bytes:
     from cryptography.hazmat.primitives.ciphers.aead import (
         AESCCM,
         AESGCM,
-        AESOCB3,
         ChaCha20Poly1305,
     )
 
     if isinstance(cipher, ChaCha20Poly1305):
         return b"chacha20-poly1305"
     elif isinstance(cipher, AESCCM):
         return f"aes-{len(cipher._key) * 8}-ccm".encode("ascii")
-    elif isinstance(cipher, AESOCB3):
-        return f"aes-{len(cipher._key) * 8}-ocb".encode("ascii")
     else:
         assert isinstance(cipher, AESGCM)
         return f"aes-{len(cipher._key) * 8}-gcm".encode("ascii")

src/cryptography/hazmat/bindings/_rust/openssl/aead.pyi

@@ -16,3 +16,20 @@ class AESSIV:
         data: bytes,
         associated_data: list[bytes] | None,
     ) -> bytes: ...
+
+class AESOCB3:
+    def __init__(self, key: bytes) -> None: ...
+    @staticmethod
+    def generate_key(key_size: int) -> bytes: ...
+    def encrypt(
+        self,
+        nonce: bytes,
+        data: bytes,
+        associated_data: bytes | None,
+    ) -> bytes: ...
+    def decrypt(
+        self,
+        nonce: bytes,
+        data: bytes,
+        associated_data: bytes | None,
+    ) -> bytes: ...

src/cryptography/hazmat/primitives/ciphers/aead.py

@@ -21,6 +21,7 @@
 ]
 
 AESSIV = rust_openssl.aead.AESSIV
+AESOCB3 = rust_openssl.aead.AESOCB3
 
 
 class ChaCha20Poly1305:
@@ -242,72 +243,3 @@ def _check_params(
         utils._check_byteslike("associated_data", associated_data)
         if len(nonce) < 8 or len(nonce) > 128:
             raise ValueError("Nonce must be between 8 and 128 bytes")
-
-
-class AESOCB3:
-    _MAX_SIZE = 2**31 - 1
-
-    def __init__(self, key: bytes):
-        utils._check_byteslike("key", key)
-        if len(key) not in (16, 24, 32):
-            raise ValueError("AESOCB3 key must be 128, 192, or 256 bits.")
-
-        self._key = key
-
-        if not backend.aead_cipher_supported(self):
-            raise exceptions.UnsupportedAlgorithm(
-                "OCB3 is not supported by this version of OpenSSL",
-                exceptions._Reasons.UNSUPPORTED_CIPHER,
-            )
-
-    @classmethod
-    def generate_key(cls, bit_length: int) -> bytes:
-        if not isinstance(bit_length, int):
-            raise TypeError("bit_length must be an integer")
-
-        if bit_length not in (128, 192, 256):
-            raise ValueError("bit_length must be 128, 192, or 256")
-
-        return os.urandom(bit_length // 8)
-
-    def encrypt(
-        self,
-        nonce: bytes,
-        data: bytes,
-        associated_data: bytes | None,
-    ) -> bytes:
-        if associated_data is None:
-            associated_data = b""
-
-        if len(data) > self._MAX_SIZE or len(associated_data) > self._MAX_SIZE:
-            # This is OverflowError to match what cffi would raise
-            raise OverflowError(
-                "Data or associated data too long. Max 2**31 - 1 bytes"
-            )
-
-        self._check_params(nonce, data, associated_data)
-        return aead._encrypt(backend, self, nonce, data, [associated_data], 16)
-
-    def decrypt(
-        self,
-        nonce: bytes,
-        data: bytes,
-        associated_data: bytes | None,
-    ) -> bytes:
-        if associated_data is None:
-            associated_data = b""
-
-        self._check_params(nonce, data, associated_data)
-        return aead._decrypt(backend, self, nonce, data, [associated_data], 16)
-
-    def _check_params(
-        self,
-        nonce: bytes,
-        data: bytes,
-        associated_data: bytes,
-    ) -> None:
-        utils._check_byteslike("nonce", nonce)
-        utils._check_byteslike("data", data)
-        utils._check_byteslike("associated_data", associated_data)
-        if len(nonce) < 12 or len(nonce) > 15:
-            raise ValueError("Nonce must be between 12 and 15 bytes")

src/rust/Cargo.toml

@@ -9,6 +9,7 @@ rust-version = "1.63.0"
 
 [dependencies]
 once_cell = "1"
+cfg-if = "1"
 pyo3 = { version = "0.19", features = ["abi3-py37"] }
 asn1 = { version = "0.15.5", default-features = false }
 cryptography-cffi = { path = "cryptography-cffi" }