[Ffmpeg-cvslog] r7460 - trunk/libavutil/aes.c
michael
subversion
Sun Jan 14 10:06:14 CET 2007
Author: michael
Date: Sun Jan 14 10:06:13 2007
New Revision: 7460
Added:
trunk/libavutil/aes.c
Log:
aes support (unfinished)
Added: trunk/libavutil/aes.c
==============================================================================
--- (empty file)
+++ trunk/libavutil/aes.c Sun Jan 14 10:06:13 2007
@@ -0,0 +1,172 @@
+/*
+ * copyright (c) 2007 Michael Niedermayer <michaelni at gmx.at>
+ *
+ * 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
+ */
+
+#include "common.h"
+#include "log.h"
+#include "aes.h"
+
+typedef struct AVAES{
+ uint8_t state[4][4];
+ uint8_t round_key[15][4][4];
+ int rounds;
+}AVAES;
+
+static const uint8_t rcon[30] = {
+ 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
+ 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f,
+ 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4,
+ 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91
+};
+
+static uint8_t log8[256];
+static uint8_t alog8[512];
+static uint8_t sbox[256];
+static uint8_t inv_sbox[256];
+
+static inline void addkey(uint32_t state[4], uint32_t round_key[4]){
+ int i;
+ for(i=0; i<4; i++)
+ state[i] ^= round_key[i]; //partial memory stall? FIXME benchmark
+}
+
+#define SUBSHIFT0(s, box) s[0]=box[s[ 0]]; s[ 4]=box[s[ 4]]; s[ 8]=box[s[ 8]]; s[12]=box[s[12]];
+#define SUBSHIFT1(s, box) t=s[0]; s[0]=box[s[ 4]]; s[ 4]=box[s[ 8]]; s[ 8]=box[s[12]]; s[12]=box[t];
+#define SUBSHIFT2(s, box) t=s[0]; s[0]=box[s[ 8]]; s[ 8]=box[ t]; t=s[ 4]; s[ 4]=box[s[12]]; s[12]=box[t];
+#define SUBSHIFT3(s, box) t=s[0]; s[0]=box[s[12]]; s[12]=box[s[ 8]]; s[ 8]=box[s[ 4]]; s[ 4]=box[t];
+
+static inline int mul(int a, int b){
+ if(a==255) return 0;
+ else return alog8[a+b];
+}
+
+static inline void mix(uint8_t state[4][4], int c0, int c1, int c2, int c3){
+ uint8_t tmp[4][4];
+ int i, j;
+
+ for(i=0; i<16; i++)
+ tmp[0][i]= log8[ state[0][i] ];
+ for(j=0; j<4; j++)
+ for(i=0; i<4; i++)
+ state[j][i]= mul( tmp[j][ i ], c0 )
+ ^mul( tmp[j][(i+ 1)&3], c1 )
+ ^mul( tmp[j][(i+ 2)&3], c2 )
+ ^mul( tmp[j][(i+ 3)&3], c3 );
+}
+
+
+void av_aes_decrypt(AVAES *a){
+ int t, r;
+
+ for(r=a->rounds-1; r>=0; r--){
+ if(r==a->rounds-1)
+ addkey(a->state, a->round_key[r+1]);
+ else
+ mix(a->state, log8[0xe], log8[0xb], log8[0xd], log8[9]); //FIXME replace log8 by const
+ SUBSHIFT0((a->state[0]+0), inv_sbox)
+ SUBSHIFT3((a->state[0]+1), inv_sbox)
+ SUBSHIFT2((a->state[0]+2), inv_sbox)
+ SUBSHIFT1((a->state[0]+3), inv_sbox)
+ addkey(a->state, a->round_key[r]);
+ }
+}
+
+void av_aes_encrypt(AVAES *a){
+ int r, t;
+
+ for(r=0; r<a->rounds; r++){
+ addkey(a->state, a->round_key[r]);
+ SUBSHIFT0((a->state[0]+0), sbox)
+ SUBSHIFT1((a->state[0]+1), sbox)
+ SUBSHIFT2((a->state[0]+2), sbox)
+ SUBSHIFT3((a->state[0]+3), sbox)
+ if(r==a->rounds-1)
+ addkey(a->state, a->round_key[r+1]);
+ else
+ mix(a->state, log8[2], log8[3], 0, 0); //FIXME replace log8 by const / optimze mix as this can be simplified alot
+ }
+}
+
+// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
+AVAES *av_aes_init(uint8_t *key, int keyBits) {
+ AVAES *a= av_malloc(sizeof(AVAES));
+ int i, j, t, rconpointer = 0;
+ uint8_t tk[8][4];
+ int KC= keyBits/32;
+ int ROUNDS= KC + 6;
+
+ if(!sbox[255]){
+ j=1;
+ for(i=0; i<255; i++){
+ alog8[i]=
+ alog8[i+255]= j;
+ log8[j]= i;
+ j^= j+j;
+ if(j>255) j^= 0x11B;
+ }
+ log8[0]= 255;
+ for(i=0; i<256; i++){
+ j= i ? alog8[255-log8[i]] : 0;
+ j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4)
+ ^(j>>7) ^ (j>>6) ^ (j>>5) ^ (j>>4) ^ 99;
+ j&=255;
+ inv_sbox[j]= i;
+ sbox [i]= j;
+// av_log(NULL, AV_LOG_ERROR, "%d, ", log8[i]);
+ }
+ }
+
+ a->rounds= ROUNDS;
+
+ if(keyBits!=128 && keyBits!=192 && keyBits!=256)
+ return NULL;
+
+ memcpy(tk, key, KC*4);
+
+ for(t= 0; t < (ROUNDS+1)*4; ) {
+ for(j = 0; (j < KC) && (t < (ROUNDS+1)*4); j++, t++)
+ for(i = 0; i < 4; i++)
+ a->round_key[0][t][i] = tk[j][i];
+
+ for(i = 0; i < 4; i++)
+ tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
+ tk[0][0] ^= rcon[rconpointer++];
+
+ for(j = 1; j < KC; j++){
+ if(KC != 8 || j != KC/2)
+ for(i = 0; i < 4; i++) tk[j][i] ^= tk[j-1][i];
+ else
+ for(i = 0; i < 4; i++)
+ tk[KC/2][i] ^= sbox[tk[KC/2 - 1][i]];
+ }
+ }
+ return a;
+}
+
+#ifdef TEST
+
+int main(){
+ int i,j,k;
+ AVAES *a= av_aes_init("PI=3.141592654..", 128);
+
+ for(i=0; i<10000; i++){
+ }
+ return 0;
+}
+#endif
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