Migrate x25519 to use rust-openssl

src/_cffi_src/openssl/nid.py

@@ -15,7 +15,6 @@
 static const int NID_undef;
 static const int NID_aes_256_cbc;
 static const int NID_pbe_WithSHA1And3_Key_TripleDES_CBC;
-static const int NID_X25519;
 static const int NID_X448;
 static const int NID_ED25519;
 static const int NID_ED448;

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

@@ -53,10 +53,6 @@
     _X448PrivateKey,
     _X448PublicKey,
 )
-from cryptography.hazmat.backends.openssl.x25519 import (
-    _X25519PrivateKey,
-    _X25519PublicKey,
-)
 from cryptography.hazmat.bindings._rust import openssl as rust_openssl
 from cryptography.hazmat.bindings.openssl import binding
 from cryptography.hazmat.primitives import hashes, serialization
@@ -715,7 +711,9 @@ def _evp_pkey_to_private_key(
             # EVP_PKEY_X448 is not present in CRYPTOGRAPHY_IS_LIBRESSL
             return _X448PrivateKey(self, evp_pkey)
         elif key_type == self._lib.EVP_PKEY_X25519:
-            return _X25519PrivateKey(self, evp_pkey)
+            return rust_openssl.x25519.private_key_from_ptr(
+                int(self._ffi.cast("intptr_t", evp_pkey))
+            )
         elif key_type == getattr(self._lib, "EVP_PKEY_ED448", None):
             # EVP_PKEY_ED448 is not present in CRYPTOGRAPHY_IS_LIBRESSL
             return _Ed448PrivateKey(self, evp_pkey)
@@ -772,7 +770,9 @@ def _evp_pkey_to_public_key(self, evp_pkey) -> PublicKeyTypes:
             # EVP_PKEY_X448 is not present in CRYPTOGRAPHY_IS_LIBRESSL
             return _X448PublicKey(self, evp_pkey)
         elif key_type == self._lib.EVP_PKEY_X25519:
-            return _X25519PublicKey(self, evp_pkey)
+            return rust_openssl.x25519.public_key_from_ptr(
+                int(self._ffi.cast("intptr_t", evp_pkey))
+            )
         elif key_type == getattr(self._lib, "EVP_PKEY_ED448", None):
             # EVP_PKEY_ED448 is not present in CRYPTOGRAPHY_IS_LIBRESSL
             return _Ed448PublicKey(self, evp_pkey)
@@ -1860,30 +1860,12 @@ def dh_x942_serialization_supported(self) -> bool:
         return self._lib.Cryptography_HAS_EVP_PKEY_DHX == 1
 
     def x25519_load_public_bytes(self, data: bytes) -> x25519.X25519PublicKey:
-        if len(data) != 32:
-            raise ValueError("An X25519 public key is 32 bytes long")
-
-        data_ptr = self._ffi.from_buffer(data)
-        evp_pkey = self._lib.EVP_PKEY_new_raw_public_key(
-            self._lib.NID_X25519, self._ffi.NULL, data_ptr, len(data)
-        )
-        self.openssl_assert(evp_pkey != self._ffi.NULL)
-        evp_pkey = self._ffi.gc(evp_pkey, self._lib.EVP_PKEY_free)
-        return _X25519PublicKey(self, evp_pkey)
+        return rust_openssl.x25519.from_public_bytes(data)
 
     def x25519_load_private_bytes(
         self, data: bytes
     ) -> x25519.X25519PrivateKey:
-        if len(data) != 32:
-            raise ValueError("An X25519 private key is 32 bytes long")
-
-        data_ptr = self._ffi.from_buffer(data)
-        evp_pkey = self._lib.EVP_PKEY_new_raw_private_key(
-            self._lib.NID_X25519, self._ffi.NULL, data_ptr, len(data)
-        )
-        self.openssl_assert(evp_pkey != self._ffi.NULL)
-        evp_pkey = self._ffi.gc(evp_pkey, self._lib.EVP_PKEY_free)
-        return _X25519PrivateKey(self, evp_pkey)
+        return rust_openssl.x25519.from_private_bytes(data)
 
     def _evp_pkey_keygen_gc(self, nid):
         evp_pkey_ctx = self._lib.EVP_PKEY_CTX_new_id(nid, self._ffi.NULL)
@@ -1899,8 +1881,7 @@ def _evp_pkey_keygen_gc(self, nid):
         return evp_pkey
 
     def x25519_generate_key(self) -> x25519.X25519PrivateKey:
-        evp_pkey = self._evp_pkey_keygen_gc(self._lib.NID_X25519)
-        return _X25519PrivateKey(self, evp_pkey)
+        return rust_openssl.x25519.generate_key()
 
     def x25519_supported(self) -> bool:
         if self._fips_enabled:

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

@@ -4,6 +4,10 @@
 
 import typing
 
+from cryptography.hazmat.bindings._rust.openssl import x25519
+
+__all__ = ["openssl_version", "raise_openssl_error", "x25519"]
+
 def openssl_version() -> int: ...
 def raise_openssl_error() -> typing.NoReturn: ...
 def capture_error_stack() -> typing.List[OpenSSLError]: ...

src/cryptography/hazmat/bindings/_rust/openssl/x25519.pyi

@@ -0,0 +1,14 @@
+# 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.
+
+from cryptography.hazmat.primitives.asymmetric import x25519
+
+class X25519PrivateKey: ...
+class X25519PublicKey: ...
+
+def generate_key() -> x25519.X25519PrivateKey: ...
+def private_key_from_ptr(ptr: int) -> x25519.X25519PrivateKey: ...
+def public_key_from_ptr(ptr: int) -> x25519.X25519PublicKey: ...
+def from_private_bytes(data: bytes) -> x25519.X25519PrivateKey: ...
+def from_public_bytes(data: bytes) -> x25519.X25519PublicKey: ...

src/cryptography/hazmat/primitives/asymmetric/x25519.py

@@ -6,6 +6,7 @@
 import abc
 
 from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
+from cryptography.hazmat.bindings._rust import openssl as rust_openssl
 from cryptography.hazmat.primitives import _serialization
 
 
@@ -32,14 +33,17 @@ def public_bytes(
         The serialized bytes of the public key.
         """
 
+    @abc.abstractmethod
     def public_bytes_raw(self) -> bytes:
         """
         The raw bytes of the public key.
         Equivalent to public_bytes(Raw, Raw).
         """
-        return self.public_bytes(
-            _serialization.Encoding.Raw, _serialization.PublicFormat.Raw
-        )
+
+
+# For LibreSSL
+if hasattr(rust_openssl, "x25519"):
+    X25519PublicKey.register(rust_openssl.x25519.X25519PublicKey)
 
 
 class X25519PrivateKey(metaclass=abc.ABCMeta):
@@ -83,19 +87,20 @@ def private_bytes(
         The serialized bytes of the private key.
         """
 
+    @abc.abstractmethod
     def private_bytes_raw(self) -> bytes:
         """
         The raw bytes of the private key.
         Equivalent to private_bytes(Raw, Raw, NoEncryption()).
         """
-        return self.private_bytes(
-            _serialization.Encoding.Raw,
-            _serialization.PrivateFormat.Raw,
-            _serialization.NoEncryption(),
-        )
 
     @abc.abstractmethod
     def exchange(self, peer_public_key: X25519PublicKey) -> bytes:
         """
         Performs a key exchange operation using the provided peer's public key.
         """
+
+
+# For LibreSSL
+if hasattr(rust_openssl, "x25519"):
+    X25519PrivateKey.register(rust_openssl.x25519.X25519PrivateKey)

src/rust/Cargo.toml

@@ -16,6 +16,7 @@ chrono = { version = "0.4.24", default-features = false, features = ["alloc", "c
 ouroboros = "0.15"
 openssl = "0.10.48"
 openssl-sys = "0.9.72"
+foreign-types-shared = "0.1"
 
 [build-dependencies]
 cc = "1.0.72"

src/rust/build.rs

@@ -3,6 +3,7 @@ use std::io::Write;
 use std::path::Path;
 use std::process::{Command, Stdio};
 
+#[allow(clippy::unusual_byte_groupings)]
 fn main() {
     let target = env::var("TARGET").unwrap();
     let openssl_static = env::var("OPENSSL_STATIC")
@@ -71,6 +72,15 @@ fn main() {
     }
 
     build.compile("_openssl.a");
+
+    if let Ok(version) = env::var("DEP_OPENSSL_LIBRESSL_VERSION_NUMBER") {
+        let version = u64::from_str_radix(&version, 16).unwrap();
+
+        println!("cargo:rustc-cfg=CRYPTOGRAPHY_IS_LIBRESSL");
+        if version >= 0x3_07_00_00_0 {
+            println!("cargo:rustc-cfg=CRYPTOGRAPHY_LIBRESSL_370_OR_GREATER")
+        }
+    }
 }
 
 /// Run a python script using the specified interpreter binary.

src/rust/src/backend/mod.rs

@@ -0,0 +1,13 @@
+// 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.
+
+#[cfg(any(not(CRYPTOGRAPHY_IS_LIBRESSL), CRYPTOGRAPHY_LIBRESSL_370_OR_GREATER))]
+pub(crate) mod x25519;
+
+pub(crate) fn add_to_module(module: &pyo3::prelude::PyModule) -> pyo3::PyResult<()> {
+    #[cfg(any(not(CRYPTOGRAPHY_IS_LIBRESSL), CRYPTOGRAPHY_LIBRESSL_370_OR_GREATER))]
+    module.add_submodule(x25519::create_module(module.py())?)?;
+
+    Ok(())
+}