libavutil: Added twofish symmetric block cipher

Signed-off-by: Supraja Meedinti <supraja0493@gmail.com>
Reviewed-by: Giorgio Vazzana <mywing81@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Changelog

@@ -16,6 +16,7 @@ version <next>:
 - Closed caption Decoder
 - fspp, uspp, pp7 MPlayer postprocessing filters ported to native filters
 - showpalette filter
+- Twofish symmetric block cipher
 
 
 version 2.5:

libavutil/Makefile

@@ -60,6 +60,7 @@ HEADERS = adler32.h                                                     \
           time.h                                                        \
           timecode.h                                                    \
           timestamp.h                                                   \
+          twofish.h                                                     \
           version.h                                                     \
           xtea.h                                                        \
 
@@ -129,6 +130,7 @@ OBJS = adler32.o                                                        \
        time.o                                                           \
        timecode.o                                                       \
        tree.o                                                           \
+       twofish.o                                                        \
        utils.o                                                          \
        xga_font_data.o                                                  \
        xtea.o                                                           \
@@ -184,6 +186,7 @@ TESTPROGS = adler32                                                     \
             sha512                                                      \
             softfloat                                                   \
             tree                                                        \
+            twofish                                                     \
             utf8                                                        \
             xtea                                                        \
 

libavutil/twofish.h

+/*
+ * An implementation of the TwoFish algorithm
+ * Copyright (c) 2015 Supraja Meedinti
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_TWOFISH_H
+#define AVUTIL_TWOFISH_H
+
+#include <stdint.h>
+
+
+/**
+  * @file
+  * @brief Public header for libavutil TWOFISH algorithm
+  * @defgroup lavu_twofish TWOFISH
+  * @ingroup lavu_crypto
+  * @{
+  */
+
+extern const int av_twofish_size;
+
+struct AVTWOFISH;
+
+/**
+  * Allocate an AVTWOFISH context
+  * To free the struct: av_free(ptr)
+  */
+struct AVTWOFISH *av_twofish_alloc(void);
+
+/**
+  * Initialize an AVTWOFISH context.
+  *
+  * @param ctx an AVTWOFISH context
+  * @param key a key of size ranging from 1 to 32 bytes used for encryption/decryption
+  * @param key_bits number of keybits: 128, 192, 256 If less than the required, padded with zeroes to nearest valid value; return value is 0 if key_bits is 128/192/256, -1 if less than 0, 1 otherwise
+ */
+int av_twofish_init(struct AVTWOFISH *ctx, const uint8_t *key, int key_bits);
+
+/**
+  * Encrypt or decrypt a buffer using a previously initialized context
+  *
+  * @param ctx an AVTWOFISH context
+  * @param dst destination array, can be equal to src
+  * @param src source array, can be equal to dst
+  * @param count number of 16 byte blocks
+  * @paran iv initialization vector for CBC mode, NULL for ECB mode
+  * @param decrypt 0 for encryption, 1 for decryption
+ */
+void av_twofish_crypt(struct AVTWOFISH *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t* iv, int decrypt);
+
+/**
+ * @}
+ */
+#endif /* AVUTIL_TWOFISH_H */