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     #include <wolfcrypt/src/misc.c>
00040 #endif
00041 
00042 /* multiplication of x and y modulo 2^16+1
00043  * IDEA specify a special case when an entry value is 0 ( x or y)
00044  * then it must be replaced by 2^16
00045  */
00046 static INLINE word16 idea_mult(word16 x, word16 y)
00047 {
00048     long mul, res;
00049 
00050     mul = (long)x * (long)y;
00051     if (mul) {
00052         res = (mul & IDEA_MASK) - ((word32)mul >> 16);
00053         if (res <= 0)
00054             res += IDEA_MODULO;
00055 
00056         return (word16) (res & IDEA_MASK);
00057     }
00058 
00059     if (!x)
00060         return ((IDEA_MODULO - y) & IDEA_MASK);
00061 
00062     /* !y */
00063     return ((IDEA_MODULO - x) & IDEA_MASK);
00064 }
00065 
00066 /* compute 1/a modulo 2^16+1 using Extended euclidean algorithm
00067  * adapted from fp_invmod */
00068 static INLINE word16 idea_invmod(word16 x)
00069 {
00070     int   u, v, b, d;
00071 
00072     if (x <= 1)
00073         return x;
00074 
00075     u = IDEA_MODULO;
00076     v = x;
00077     d = 1;
00078     b = 0;
00079 
00080     do {
00081         while (!(u & 1)) {
00082             u >>= 1;
00083             if (b & 1)
00084                 b -= IDEA_MODULO;
00085             b >>= 1;
00086         }
00087 
00088         while (!(v & 1)) {
00089             v >>= 1;
00090             if (d & 1) {
00091                 d -= IDEA_MODULO;
00092             }
00093             d >>= 1;
00094         }
00095 
00096         if (u >= v) {
00097             u -= v;
00098             b -= d;
00099         } else {
00100             v -= u;
00101             d -= b;
00102         }
00103     } while (u != 0);
00104 
00105     /* d is now the inverse, put positive value if required */
00106     while (d < 0)
00107         d += IDEA_MODULO;
00108 
00109     /* d must be < IDEA_MODULO */
00110     while (d >= (int)IDEA_MODULO)
00111         d -= IDEA_MODULO;
00112 
00113     return (word16)(d & IDEA_MASK);
00114 }
00115 
00116 /* generate the 52 16-bits key sub-blocks from the 128 key */
00117 int wc_IdeaSetKey(Idea *idea, const byte* key, word16 keySz,
00118                   const byte *iv, int dir)
00119 {
00120     word16  idx = 0;
00121     word32  t;
00122     short   i;
00123 
00124     if (idea == NULL || key == NULL || keySz != IDEA_KEY_SIZE ||
00125         (dir != IDEA_ENCRYPTION && dir != IDEA_DECRYPTION))
00126         return BAD_FUNC_ARG;
00127 
00128     /* initial key schedule for 0 -> 7 */
00129     for (i = 0; i < IDEA_ROUNDS; i++) {
00130         idea->skey[i]  = (word16)key[idx++] << 8;
00131         idea->skey[i] |= (word16)key[idx++];
00132     }
00133 
00134     /* shift phase key schedule for 8 -> 51 */
00135     for (i = IDEA_ROUNDS; i < IDEA_SK_NUM; i++) {
00136         t  = (word32)idea->skey[((i+1) & 7) ? i-7 : i-15] << 9;
00137         t |= (word32)idea->skey[((i+2) & 7) < 2 ? i-14 : i-6] >> 7;
00138         idea->skey[i] = (word16)(t & IDEA_MASK);
00139     }
00140 
00141     /* compute decryption key from encryption key */
00142     if (dir == IDEA_DECRYPTION) {
00143         word16  enckey[IDEA_SK_NUM];
00144 
00145         /* put encryption key in tmp buffer */
00146         XMEMCPY(enckey, idea->skey, sizeof(idea->skey));
00147 
00148         idx = 0;
00149 
00150         idea->skey[6*IDEA_ROUNDS]   = idea_invmod(enckey[idx++]);
00151         idea->skey[6*IDEA_ROUNDS+1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00152         idea->skey[6*IDEA_ROUNDS+2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00153         idea->skey[6*IDEA_ROUNDS+3] = idea_invmod(enckey[idx++]);
00154 
00155         for (i = 6*(IDEA_ROUNDS-1); i >= 0; i -= 6) {
00156             idea->skey[i+4] = enckey[idx++];
00157             idea->skey[i+5] = enckey[idx++];
00158 
00159             idea->skey[i] = idea_invmod(enckey[idx++]);
00160             if (i) {
00161                 idea->skey[i+2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00162                 idea->skey[i+1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00163             }
00164             else {
00165                 idea->skey[1] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00166                 idea->skey[2] = (IDEA_2EXP16 - enckey[idx++]) & IDEA_MASK;
00167             }
00168 
00169             idea->skey[i+3] = idea_invmod(enckey[idx++]);
00170         }
00171 
00172         /* erase temporary buffer */
00173         ForceZero(enckey, sizeof(enckey));
00174     }
00175 
00176     /* set the iv */
00177     return wc_IdeaSetIV(idea, iv);
00178 }
00179 
00180 /* set the IV in the Idea key structure */
00181 int wc_IdeaSetIV(Idea *idea, const byte* iv)
00182 {
00183     if (idea == NULL)
00184         return BAD_FUNC_ARG;
00185 
00186     if (iv != NULL)
00187         XMEMCPY(idea->reg, iv, IDEA_BLOCK_SIZE);
00188     else
00189         XMEMSET(idea->reg, 0, IDEA_BLOCK_SIZE);
00190 
00191     return 0;
00192 }
00193 
00194 /* encryption/decryption for a block (64 bits)
00195  */
00196 void wc_IdeaCipher(Idea *idea, byte* out, const byte* in)
00197 {
00198     word32 t1, t2;
00199     word16 i, skey_idx = 0, idx = 0;
00200     word16 x[4];
00201 
00202     /* put input byte block in word16 */
00203     for (i = 0; i < IDEA_BLOCK_SIZE/2; i++) {
00204         x[i]  = (word16)in[idx++] << 8;
00205         x[i] |= (word16)in[idx++];
00206     }
00207 
00208     for (i = 0; i < IDEA_ROUNDS; i++) {
00209         x[0] = idea_mult(x[0], idea->skey[skey_idx++]);
00210         x[1] = ((word32)x[1] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00211         x[2] = ((word32)x[2] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00212         x[3] = idea_mult(x[3], idea->skey[skey_idx++]);
00213 
00214         t2 = x[0] ^ x[2];
00215         t2 = idea_mult((word16)t2, idea->skey[skey_idx++]);
00216         t1 = (t2 + (x[1] ^ x[3])) & IDEA_MASK;
00217         t1 = idea_mult((word16)t1, idea->skey[skey_idx++]);
00218         t2 = (t1 + t2) & IDEA_MASK;
00219 
00220         x[0] ^= t1;
00221         x[3] ^= t2;
00222 
00223         t2 ^= x[1];
00224         x[1] = x[2] ^ (word16)t1;
00225         x[2] = (word16)t2;
00226     }
00227 
00228     x[0] = idea_mult(x[0], idea->skey[skey_idx++]);
00229     out[0] = (x[0] >> 8) & 0xFF;
00230     out[1] = x[0] & 0xFF;
00231 
00232     x[2] = ((word32)x[2] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00233     out[2] = (x[2] >> 8) & 0xFF;
00234     out[3] = x[2] & 0xFF;
00235 
00236     x[1] = ((word32)x[1] + (word32)idea->skey[skey_idx++]) & IDEA_MASK;
00237     out[4] = (x[1] >> 8) & 0xFF;
00238     out[5] = x[1] & 0xFF;
00239 
00240     x[3] = idea_mult(x[3], idea->skey[skey_idx++]);
00241     out[6] = (x[3] >> 8) & 0xFF;
00242     out[7] = x[3] & 0xFF;
00243 }
00244 
00245 int wc_IdeaCbcEncrypt(Idea *idea, byte* out, const byte* in, word32 len)
00246 {
00247     int  blocks;
00248 
00249     if (idea == NULL || out == NULL || in == NULL)
00250         return BAD_FUNC_ARG;
00251 
00252     blocks = len / IDEA_BLOCK_SIZE;
00253     while (blocks--) {
00254         xorbuf((byte*)idea->reg, in, IDEA_BLOCK_SIZE);
00255         wc_IdeaCipher(idea, (byte*)idea->reg, (byte*)idea->reg);
00256         XMEMCPY(out, idea->reg, IDEA_BLOCK_SIZE);
00257 
00258         out += IDEA_BLOCK_SIZE;
00259         in  += IDEA_BLOCK_SIZE;
00260     }
00261 
00262     return 0;
00263 }
00264 
00265 int wc_IdeaCbcDecrypt(Idea *idea, byte* out, const byte* in, word32 len)
00266 {
00267     int  blocks;
00268 
00269     if (idea == NULL || out == NULL || in == NULL)
00270         return BAD_FUNC_ARG;
00271 
00272     blocks = len / IDEA_BLOCK_SIZE;
00273     while (blocks--) {
00274         XMEMCPY((byte*)idea->tmp, in, IDEA_BLOCK_SIZE);
00275         wc_IdeaCipher(idea, out, (byte*)idea->tmp);
00276         xorbuf(out, (byte*)idea->reg, IDEA_BLOCK_SIZE);
00277         XMEMCPY(idea->reg, idea->tmp, IDEA_BLOCK_SIZE);
00278 
00279         out += IDEA_BLOCK_SIZE;
00280         in  += IDEA_BLOCK_SIZE;
00281     }
00282 
00283     return 0;
00284 }
00285 
00286 #endif /* HAVE_IDEA */
00287