From ffb1cf483d2065703111ba36649b2fcebd3a137f Mon Sep 17 00:00:00 2001
From: Christian Stemmle <feodoran@online.de>
Date: Sun, 20 Aug 2017 01:21:11 +0200
Subject: [PATCH] Faster crypto by using libssl (closes #199)

---
 telethon/crypto/aes.py    |  6 ++-
 telethon/crypto/libssl.py | 85 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 telethon/crypto/libssl.py

diff --git a/telethon/crypto/aes.py b/telethon/crypto/aes.py
index 9a4459df..cf0994dc 100644
--- a/telethon/crypto/aes.py
+++ b/telethon/crypto/aes.py
@@ -1,6 +1,6 @@
 import os
 import pyaes
-
+from . import libssl
 
 class AES:
     @staticmethod
@@ -71,3 +71,7 @@ class AES:
             cipher_text.extend(cipher_text_block)
 
         return bytes(cipher_text)
+
+# use libssl if available
+if libssl.libssl:
+    AES = libssl.AES
diff --git a/telethon/crypto/libssl.py b/telethon/crypto/libssl.py
new file mode 100644
index 00000000..58437ced
--- /dev/null
+++ b/telethon/crypto/libssl.py
@@ -0,0 +1,85 @@
+import os
+import ctypes
+from ctypes.util import find_library
+
+# search and load libssl.so
+lib = find_library('ssl')
+if not lib:
+    libssl = None
+else:
+    libssl = ctypes.cdll.LoadLibrary(lib)
+
+""" <aes.h>
+# define AES_ENCRYPT     1
+# define AES_DECRYPT     0
+# define AES_MAXNR 14
+struct aes_key_st {
+# ifdef AES_LONG
+    unsigned long rd_key[4 * (AES_MAXNR + 1)];
+# else
+    unsigned int rd_key[4 * (AES_MAXNR + 1)];
+# endif
+    int rounds;
+};
+typedef struct aes_key_st AES_KEY;
+
+int AES_set_encrypt_key(const unsigned char *userKey, const int bits,
+                        AES_KEY *key);
+int AES_set_decrypt_key(const unsigned char *userKey, const int bits,
+                        AES_KEY *key);
+void AES_ige_encrypt(const unsigned char *in, unsigned char *out,
+                     size_t length, const AES_KEY *key,
+                     unsigned char *ivec, const int enc);
+"""
+
+AES_MAXNR = 14
+AES_ENCRYPT = ctypes.c_int(1)
+AES_DECRYPT = ctypes.c_int(0)
+
+class AES_KEY(ctypes.Structure):
+    _fields_ = [
+        ('rd_key', ctypes.c_uint32 * (4*(AES_MAXNR + 1))),
+        ('rounds', ctypes.c_uint),
+    ]
+
+class AES:
+    @staticmethod
+    def decrypt_ige(cipher_text, key, iv):
+
+        # declare types
+        aeskey = AES_KEY()
+        ckey = (ctypes.c_ubyte * len(key))(*key)
+        cklen = ctypes.c_int(len(key)*8)
+        cin = (ctypes.c_ubyte * len(cipher_text))(*cipher_text)
+        ctlen = ctypes.c_size_t(len(cipher_text))
+        cout = (ctypes.c_ubyte * len(cipher_text))()
+        civ = (ctypes.c_ubyte * len(iv))(*iv)
+
+        # decrypt
+        libssl.AES_set_decrypt_key(ckey, cklen,  ctypes.byref(aeskey))
+        libssl.AES_ige_encrypt(ctypes.byref(cin), ctypes.byref(cout), ctlen,  ctypes.byref(aeskey), ctypes.byref(civ), AES_DECRYPT)
+
+        return bytes(cout)
+
+    @staticmethod
+    def encrypt_ige(plain_text, key, iv):
+
+        # Add random padding if and only if it's not evenly divisible by 16 already
+        if len(plain_text) % 16 != 0:
+            padding_count = 16 - len(plain_text) % 16
+            plain_text += os.urandom(padding_count)
+
+        # declare types
+        aeskey = AES_KEY()
+        ckey = (ctypes.c_ubyte * len(key))(*key)
+        cklen = ctypes.c_int(len(key)*8)
+        cin = (ctypes.c_ubyte * len(plain_text))(*plain_text)
+        ctlen = ctypes.c_size_t(len(plain_text))
+        cout = (ctypes.c_ubyte * len(plain_text))()
+        civ = (ctypes.c_ubyte * len(iv))(*iv)
+
+        # encrypt
+        libssl.AES_set_encrypt_key(ckey, cklen,  ctypes.byref(aeskey))
+        libssl.AES_ige_encrypt(ctypes.byref(cin), ctypes.byref(cout), ctlen,  ctypes.byref(aeskey), ctypes.byref(civ), AES_ENCRYPT)
+
+        return bytes(cout)