idea.c

00001 /* idea.c
00002  *
00003  * Copyright (C) 2006-2016 wolfSSL Inc.
00004  *
00005  * This file is part of wolfSSL.
00006  *
00007  * wolfSSL is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 2 of the License, or
00010  * (at your option) any later version.
00011  *
00012  * wolfSSL is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU General Public License
00018  * along with this program; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
00020  */
00021 
00022 
00023 #ifdef HAVE_CONFIG_H
00024     #include <config.h>
00025 #endif
00026 
00027 #include <wolfssl/wolfcrypt/settings.h>
00028 
00029 #ifdef HAVE_IDEA
00030 
00031 #include <wolfssl/wolfcrypt/idea.h>
00032 
00033 #include <wolfssl/wolfcrypt/error-crypt.h>
00034 #include <wolfssl/wolfcrypt/logging.h>
00035 
00036 #ifdef NO_INLINE
00037     #include <wolfssl/wolfcrypt/misc.h>
00038 #else
00039     #define WOLFSSL_MISC_INCLUDED
00040     #include <wolfcrypt/src/misc.c>
00041 #endif
00042 
00043 /* multiplication of x and y modulo 2^16+1
00044  * IDEA specify a special case when an entry value is 0 ( x or y)
00045  * then it must be replaced by 2^16
00046  */
00047 static INLINE word16 idea_mult(word16 x, word16 y)
00048 {
00049     long mul, res;
00050 
00051     mul = (long)x * (long)y;
00052     if (mul) {
00053         res = (mul & IDEA_MASK) - ((word32)mul >> 16);
00054         if (res <= 0)
00055             res += IDEA_MODULO;
00056 
00057         return (word16) (res & IDEA_MASK);
00058     }
00059 
00060     if (!x)
00061         return ((IDEA_MODULO - y) & IDEA_MASK);
00062 
00063     /* !y */
00064     return ((IDEA_MODULO - x) & IDEA_MASK);
00065 }
00066 
00067 /* compute 1/a modulo 2^16+1 using Extended euclidean algorithm
00068  * adapted from fp_invmod */
00069 static INLINE word16 idea_invmod(word16 x)
00070 {
00071     int   u, v, b, d;
00072 
00073     if (x <= 1)
00074         return x;
00075 
00076     u = IDEA_MODULO;
00077     v = x;
00078     d = 1;
00079     b = 0;
00080 
00081     do {
00082         while (!(u & 1)) {
00083             u >>= 1;
00084             if (b & 1)
00085                 b -= IDEA_MODULO;
00086             b >>= 1;
00087         }
00088 
00089         while (!(v & 1)) {
00090             v >>= 1;
00091             if (d & 1) {
00092                 d -= IDEA_MODULO;
00093             }
00094             d >>= 1;
00095         }
00096 
00097         if (u >= v) {
00098             u -= v;
00099             b -= d;
00100         } else {
00101             v -= u;
00102             d -= b;
00103         }
00104     } while (u != 0);
00105 
00106     /* d is now the inverse, put positive value if required */
00107     while (d < 0)
00108         d += IDEA_MODULO;
00109 
00110     /* d must be < IDEA_MODULO */
00111     while (d >= (int)IDEA_MODULO)
00112         d -= IDEA_MODULO;
00113 
00114     return (word16)(d & IDEA_MASK);
00115 }
00116 
00117 /* generate the 52 16-bits key sub-blocks from the 128 key */
00118 int wc_IdeaSetKey(Idea *idea, const byte* key, word16 keySz,
00119                   const byte *iv, int dir)
00120 {
00121     word16  idx = 0;
00122     word32  t;
00123     short   i;
00124 
00125     if (idea == NULL || key == NULL || keySz != IDEA_KEY_SIZE ||
00126         (dir != IDEA_ENCRYPTION && dir != IDEA_DECRYPTION))
00127         return BAD_FUNC_ARG;
00128 
00129     /* initial key schedule for 0 -> 7 */
00130     for (i = 0; i < IDEA_ROUNDS; i++) {
00131         idea->skey[i]  = (word16)key[idx++] << 8;
00132         idea->skey[i] |= (word16)key[idx++];
00133     }
00134 
00135     /* shift phase key schedule for 8 -> 51 */
00136     for (i = IDEA_ROUNDS; i < IDEA_SK_NUM; i++) {
00137         t  = (word32)idea->skey[((i+1) & 7) ? i-7 : i-15] << 9;
00138         t |= (word32)idea->skey[((i+2) & 7) < 2 ? i-14 : i-6] >> 7;
00139         idea->skey[i] = (word16)(t & IDEA_MASK);
00140     }
00141 
00142     /* compute decryption key from encryption key */
00143     if (dir == IDEA_DECRYPTION) {
00144         word16  enckey[IDEA_SK_NUM];
00145 
00146         /* put encryption key in tmp buffer */
00147         XMEMCPY(enckey, idea->skey, sizeof(idea->skey));
00148 
00149         idx = 0;
00150 
00151         idea->skey[6*IDEA_ROUNDS]   = idea_invmod(enckey[idx++]);
00152         idea->skey[6*IDEA_ROUNDS+1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00153         idea->skey[6*IDEA_ROUNDS+2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00154         idea->skey[6*IDEA_ROUNDS+3] = idea_invmod(enckey[idx++]);
00155 
00156         for (i = 6*(IDEA_ROUNDS-1); i >= 0; i -= 6) {
00157             idea->skey[i+4] = enckey[idx++];
00158             idea->skey[i+5] = enckey[idx++];
00159 
00160             idea->skey[i] = idea_invmod(enckey[idx++]);
00161             if (i) {
00162                 idea->skey[i+2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00163                 idea->skey[i+1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00164             }
00165             else {
00166                 idea->skey[1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00167                 idea->skey[2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00168             }
00169 
00170             idea->skey[i+3] = idea_invmod(enckey[idx++]);
00171         }
00172 
00173         /* erase temporary buffer */
00174         ForceZero(enckey, sizeof(enckey));
00175     }
00176 
00177     /* set the iv */
00178     return wc_IdeaSetIV(idea, iv);
00179 }
00180 
00181 /* set the IV in the Idea key structure */
00182 int wc_IdeaSetIV(Idea *idea, const byte* iv)
00183 {
00184     if (idea == NULL)
00185         return BAD_FUNC_ARG;
00186 
00187     if (iv != NULL)
00188         XMEMCPY(idea->reg, iv, IDEA_BLOCK_SIZE);
00189     else
00190         XMEMSET(idea->reg, 0, IDEA_BLOCK_SIZE);
00191 
00192     return 0;
00193 }
00194 
00195 /* encryption/decryption for a block (64 bits)
00196  */
00197 void wc_IdeaCipher(Idea *idea, byte* out, const byte* in)
00198 {
00199     word32 t1, t2;
00200     word16 i, skey_idx = 0, idx = 0;
00201     word16 x[4];
00202 
00203     /* put input byte block in word16 */
00204     for (i = 0; i < IDEA_BLOCK_SIZE/2; i++) {
00205         x[i]  = (word16)in[idx++] << 8;
00206         x[i] |= (word16)in[idx++];
00207     }
00208 
00209     for (i = 0; i < IDEA_ROUNDS; i++) {
00210         x[0] = idea_mult(x[0], idea->skey[skey_idx++]);
00211         x[1] = ((word32)x[1] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00212         x[2] = ((word32)x[2] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00213         x[3] = idea_mult(x[3], idea->skey[skey_idx++]);
00214 
00215         t2 = x[0] ^ x[2];
00216         t2 = idea_mult((word16)t2, idea->skey[skey_idx++]);
00217         t1 = (t2 + (x[1] ^ x[3])) & IDEA_MASK;
00218         t1 = idea_mult((word16)t1, idea->skey[skey_idx++]);
00219         t2 = (t1 + t2) & IDEA_MASK;
00220 
00221         x[0] ^= t1;
00222         x[3] ^= t2;
00223 
00224         t2 ^= x[1];
00225         x[1] = x[2] ^ (word16)t1;
00226         x[2] = (word16)t2;
00227     }
00228 
00229     x[0] = idea_mult(x[0], idea->skey[skey_idx++]);
00230     out[0] = (x[0] >> 8) & 0xFF;
00231     out[1] = x[0] & 0xFF;
00232 
00233     x[2] = ((word32)x[2] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00234     out[2] = (x[2] >> 8) & 0xFF;
00235     out[3] = x[2] & 0xFF;
00236 
00237     x[1] = ((word32)x[1] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00238     out[4] = (x[1] >> 8) & 0xFF;
00239     out[5] = x[1] & 0xFF;
00240 
00241     x[3] = idea_mult(x[3], idea->skey[skey_idx++]);
00242     out[6] = (x[3] >> 8) & 0xFF;
00243     out[7] = x[3] & 0xFF;
00244 }
00245 
00246 int wc_IdeaCbcEncrypt(Idea *idea, byte* out, const byte* in, word32 len)
00247 {
00248     int  blocks;
00249 
00250     if (idea == NULL || out == NULL || in == NULL)
00251         return BAD_FUNC_ARG;
00252 
00253     blocks = len / IDEA_BLOCK_SIZE;
00254     while (blocks--) {
00255         xorbuf((byte*)idea->reg, in, IDEA_BLOCK_SIZE);
00256         wc_IdeaCipher(idea, (byte*)idea->reg, (byte*)idea->reg);
00257         XMEMCPY(out, idea->reg, IDEA_BLOCK_SIZE);
00258 
00259         out += IDEA_BLOCK_SIZE;
00260         in  += IDEA_BLOCK_SIZE;
00261     }
00262 
00263     return 0;
00264 }
00265 
00266 int wc_IdeaCbcDecrypt(Idea *idea, byte* out, const byte* in, word32 len)
00267 {
00268     int  blocks;
00269 
00270     if (idea == NULL || out == NULL || in == NULL)
00271         return BAD_FUNC_ARG;
00272 
00273     blocks = len / IDEA_BLOCK_SIZE;
00274     while (blocks--) {
00275         XMEMCPY((byte*)idea->tmp, in, IDEA_BLOCK_SIZE);
00276         wc_IdeaCipher(idea, out, (byte*)idea->tmp);
00277         xorbuf(out, (byte*)idea->reg, IDEA_BLOCK_SIZE);
00278         XMEMCPY(idea->reg, idea->tmp, IDEA_BLOCK_SIZE);
00279 
00280         out += IDEA_BLOCK_SIZE;
00281         in  += IDEA_BLOCK_SIZE;
00282     }
00283 
00284     return 0;
00285 }
00286 
00287 #endif /* HAVE_IDEA */
00288