slight update

env/lib/python3.12/site-packages/Crypto/PublicKey/_openssh.py

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+# ===================================================================
+#
+# Copyright (c) 2019, Helder Eijs <helderijs@gmail.com>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+# ===================================================================
+
+import struct
+
+from Crypto.Cipher import AES
+from Crypto.Hash import SHA512
+from Crypto.Protocol.KDF import _bcrypt_hash
+from Crypto.Util.strxor import strxor
+from Crypto.Util.py3compat import tostr, bchr, bord
+
+
+def read_int4(data):
+    if len(data) < 4:
+        raise ValueError("Insufficient data")
+    value = struct.unpack(">I", data[:4])[0]
+    return value, data[4:]
+
+
+def read_bytes(data):
+    size, data = read_int4(data)
+    if len(data) < size:
+        raise ValueError("Insufficient data (V)")
+    return data[:size], data[size:]
+
+
+def read_string(data):
+    s, d = read_bytes(data)
+    return tostr(s), d
+
+
+def check_padding(pad):
+    for v, x in enumerate(pad):
+        if bord(x) != ((v + 1) & 0xFF):
+            raise ValueError("Incorrect padding")
+
+
+def import_openssh_private_generic(data, password):
+    # https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.key?annotate=HEAD
+    # https://github.com/openssh/openssh-portable/blob/master/sshkey.c
+    # https://coolaj86.com/articles/the-openssh-private-key-format/
+    # https://coolaj86.com/articles/the-ssh-public-key-format/
+
+    if not data.startswith(b'openssh-key-v1\x00'):
+        raise ValueError("Incorrect magic value")
+    data = data[15:]
+
+    ciphername, data = read_string(data)
+    kdfname, data = read_string(data)
+    kdfoptions, data = read_bytes(data)
+    number_of_keys, data = read_int4(data)
+
+    if number_of_keys != 1:
+        raise ValueError("We only handle 1 key at a time")
+
+    _, data = read_string(data)             # Public key
+    encrypted, data = read_bytes(data)
+    if data:
+        raise ValueError("Too much data")
+
+    if len(encrypted) % 8 != 0:
+        raise ValueError("Incorrect payload length")
+
+    # Decrypt if necessary
+    if ciphername == 'none':
+        decrypted = encrypted
+    else:
+        if (ciphername, kdfname) != ('aes256-ctr', 'bcrypt'):
+            raise ValueError("Unsupported encryption scheme %s/%s" % (ciphername, kdfname))
+
+        salt, kdfoptions = read_bytes(kdfoptions)
+        iterations, kdfoptions = read_int4(kdfoptions)
+
+        if len(salt) != 16:
+            raise ValueError("Incorrect salt length")
+        if kdfoptions:
+            raise ValueError("Too much data in kdfoptions")
+
+        pwd_sha512 = SHA512.new(password).digest()
+        # We need 32+16 = 48 bytes, therefore 2 bcrypt outputs are sufficient
+        stripes = []
+        constant = b"OxychromaticBlowfishSwatDynamite"
+        for count in range(1, 3):
+            salt_sha512 = SHA512.new(salt + struct.pack(">I", count)).digest()
+            out_le = _bcrypt_hash(pwd_sha512, 6, salt_sha512, constant, False)
+            out = struct.pack("<IIIIIIII", *struct.unpack(">IIIIIIII", out_le))
+            acc = bytearray(out)
+            for _ in range(1, iterations):
+                out_le = _bcrypt_hash(pwd_sha512, 6, SHA512.new(out).digest(), constant, False)
+                out = struct.pack("<IIIIIIII", *struct.unpack(">IIIIIIII", out_le))
+                strxor(acc, out, output=acc)
+            stripes.append(acc[:24])
+
+        result = b"".join([bchr(a)+bchr(b) for (a, b) in zip(*stripes)])
+
+        cipher = AES.new(result[:32],
+                         AES.MODE_CTR,
+                         nonce=b"",
+                         initial_value=result[32:32+16])
+        decrypted = cipher.decrypt(encrypted)
+
+    checkint1, decrypted = read_int4(decrypted)
+    checkint2, decrypted = read_int4(decrypted)
+    if checkint1 != checkint2:
+        raise ValueError("Incorrect checksum")
+    ssh_name, decrypted = read_string(decrypted)
+
+    return ssh_name, decrypted