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venv/lib/python3.12/site-packages/asyncssh/crypto/sntrup.py

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+# Copyright (c) 2022 by Ron Frederick <ronf@timeheart.net> and others.
+#
+# This program and the accompanying materials are made available under
+# the terms of the Eclipse Public License v2.0 which accompanies this
+# distribution and is available at:
+#
+#     http://www.eclipse.org/legal/epl-2.0/
+#
+# This program may also be made available under the following secondary
+# licenses when the conditions for such availability set forth in the
+# Eclipse Public License v2.0 are satisfied:
+#
+#    GNU General Public License, Version 2.0, or any later versions of
+#    that license
+#
+# SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
+#
+# Contributors:
+#     Ron Frederick - initial implementation, API, and documentation
+
+"""A shim around liboqs for Streamlined NTRU Prime post-quantum encryption"""
+
+import ctypes
+import ctypes.util
+from typing import Tuple
+
+
+sntrup761_available = False
+
+sntrup761_pubkey_bytes = 1158
+sntrup761_privkey_bytes = 1763
+sntrup761_ciphertext_bytes = 1039
+sntrup761_secret_bytes = 32
+
+
+for lib in ('oqs', 'liboqs'):
+    _oqs_lib = ctypes.util.find_library(lib)
+
+    if _oqs_lib: # pragma: no branch
+        break
+else: # pragma: no cover
+    _oqs_lib = None
+
+if _oqs_lib: # pragma: no branch
+    _oqs = ctypes.cdll.LoadLibrary(_oqs_lib)
+
+    _sntrup761_keypair = _oqs.OQS_KEM_ntruprime_sntrup761_keypair
+    _sntrup761_encaps = _oqs.OQS_KEM_ntruprime_sntrup761_encaps
+    _sntrup761_decaps = _oqs.OQS_KEM_ntruprime_sntrup761_decaps
+
+    sntrup761_available = True
+
+
+def sntrup761_keypair() -> Tuple[bytes, bytes]:
+    """Make a SNTRUP761 key pair"""
+
+    pubkey = ctypes.create_string_buffer(sntrup761_pubkey_bytes)
+    privkey = ctypes.create_string_buffer(sntrup761_privkey_bytes)
+    _sntrup761_keypair(pubkey, privkey)
+
+    return pubkey.raw, privkey.raw
+
+
+def sntrup761_encaps(pubkey: bytes) -> Tuple[bytes, bytes]:
+    """Generate a random secret and encrypt it with a public key"""
+
+    if len(pubkey) != sntrup761_pubkey_bytes:
+        raise ValueError('Invalid SNTRUP761 public key')
+
+    ciphertext = ctypes.create_string_buffer(sntrup761_ciphertext_bytes)
+    secret = ctypes.create_string_buffer(sntrup761_secret_bytes)
+
+    _sntrup761_encaps(ciphertext, secret, pubkey)
+
+    return secret.raw, ciphertext.raw
+
+
+def sntrup761_decaps(ciphertext: bytes, privkey: bytes) -> bytes:
+    """Decrypt an encrypted secret using a private key"""
+
+    if len(ciphertext) != sntrup761_ciphertext_bytes:
+        raise ValueError('Invalid SNTRUP761 ciphertext')
+
+    secret = ctypes.create_string_buffer(sntrup761_secret_bytes)
+
+    _sntrup761_decaps(secret, ciphertext, privkey)
+
+    return secret.raw