1: /* Functions to compute SHA256 message digest of files or memory blocks.
    2:    according to the definition of SHA256 in FIPS 180-2.
    3:    Copyright (C) 2007 Free Software Foundation, Inc.
    4:    This file is part of the GNU C Library.
    5: 
    6:    The GNU C Library is free software; you can redistribute it and/or
    7:    modify it under the terms of the GNU Lesser General Public
    8:    License as published by the Free Software Foundation; either
    9:    version 2.1 of the License, or (at your option) any later version.
   10: 
   11:    The GNU C Library is distributed in the hope that it will be useful,
   12:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   13:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   14:    Lesser General Public License for more details.
   15: 
   16:    You should have received a copy of the GNU Lesser General Public
   17:    License along with the GNU C Library; if not, write to the Free
   18:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   19:    02111-1307 USA.  */
   20: 
   21: /* Written by Ulrich Drepper <drepper@redhat.com>, 2007.  */
   22: 
   23: #ifdef HAVE_CONFIG_H
   24: # include <config.h>
   25: #endif
   26: 
   27: #include <endian.h>
   28: #include <stdlib.h>
   29: #include <string.h>
   30: #include <sys/types.h>
   31: 
   32: #include "sha256.h"
   33: 
   34: #if __BYTE_ORDER == __LITTLE_ENDIAN
   35: # ifdef _LIBC
   36: #  include <byteswap.h>
   37: #  define SWAP(n) bswap_32 (n)
   38: # else
   39: #  define SWAP(n) \
   40:     (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
   41: # endif
   42: #else
   43: # define SWAP(n) (n)
   44: #endif
   45: 
   46: 
   47: /* This array contains the bytes used to pad the buffer to the next
   48:    64-byte boundary.  (FIPS 180-2:5.1.1)  */
   49: static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
   50: 
   51: 
   52: /* Constants for SHA256 from FIPS 180-2:4.2.2.  */
   53: static const uint32_t K[64] =
   54:   {
   55:     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
   56:     0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
   57:     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
   58:     0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
   59:     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
   60:     0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
   61:     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
   62:     0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
   63:     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
   64:     0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
   65:     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
   66:     0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
   67:     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
   68:     0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
   69:     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
   70:     0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
   71:   };
   72: 
   73: 
   74: /* Process LEN bytes of BUFFER, accumulating context into CTX.
   75:    It is assumed that LEN % 64 == 0.  */
   76: static void
   77: sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
   78: {
   79:   const uint32_t *words = buffer;
   80:   size_t nwords = len / sizeof (uint32_t);
   81:   uint32_t a = ctx->H[0];
   82:   uint32_t b = ctx->H[1];
   83:   uint32_t c = ctx->H[2];
   84:   uint32_t d = ctx->H[3];
   85:   uint32_t e = ctx->H[4];
   86:   uint32_t f = ctx->H[5];
   87:   uint32_t g = ctx->H[6];
   88:   uint32_t h = ctx->H[7];
   89: 
   90:   /* First increment the byte count.  FIPS 180-2 specifies the possible
   91:      length of the file up to 2^64 bits.  Here we only compute the
   92:      number of bytes.  Do a double word increment.  */
   93:   ctx->total[0] += len;
   94:   if (ctx->total[0] < len)
   95:     ++ctx->total[1];
   96: 
   97:   /* Process all bytes in the buffer with 64 bytes in each round of
   98:      the loop.  */
   99:   while (nwords > 0)
  100:     {
  101:       uint32_t W[64];
  102:       uint32_t a_save = a;
  103:       uint32_t b_save = b;
  104:       uint32_t c_save = c;
  105:       uint32_t d_save = d;
  106:       uint32_t e_save = e;
  107:       uint32_t f_save = f;
  108:       uint32_t g_save = g;
  109:       uint32_t h_save = h;
  110: 
  111:       /* Operators defined in FIPS 180-2:4.1.2.  */
  112: #define Ch(x, y, z) ((x & y) ^ (~x & z))
  113: #define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
  114: #define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
  115: #define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
  116: #define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
  117: #define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
  118: 
  119:       /* It is unfortunate that C does not provide an operator for
  120:          cyclic rotation.  Hope the C compiler is smart enough.  */
  121: #define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
  122: 
  123:       /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2.  */
  124:       for (unsigned int t = 0; t < 16; ++t)
  125:         {
  126:           W[t] = SWAP (*words);
  127:           ++words;
  128:         }
  129:       for (unsigned int t = 16; t < 64; ++t)
  130:         W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];
  131: 
  132:       /* The actual computation according to FIPS 180-2:6.2.2 step 3.  */
  133:       for (unsigned int t = 0; t < 64; ++t)
  134:         {
  135:           uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
  136:           uint32_t T2 = S0 (a) + Maj (a, b, c);
  137:           h = g;
  138:           g = f;
  139:           f = e;
  140:           e = d + T1;
  141:           d = c;
  142:           c = b;
  143:           b = a;
  144:           a = T1 + T2;
  145:         }
  146: 
  147:       /* Add the starting values of the context according to FIPS 180-2:6.2.2
  148:          step 4.  */
  149:       a += a_save;
  150:       b += b_save;
  151:       c += c_save;
  152:       d += d_save;
  153:       e += e_save;
  154:       f += f_save;
  155:       g += g_save;
  156:       h += h_save;
  157: 
  158:       /* Prepare for the next round.  */
  159:       nwords -= 16;
  160:     }
  161: 
  162:   /* Put checksum in context given as argument.  */
  163:   ctx->H[0] = a;
  164:   ctx->H[1] = b;
  165:   ctx->H[2] = c;
  166:   ctx->H[3] = d;
  167:   ctx->H[4] = e;
  168:   ctx->H[5] = f;
  169:   ctx->H[6] = g;
  170:   ctx->H[7] = h;
  171: }
  172: 
  173: 
  174: /* Initialize structure containing state of computation.
  175:    (FIPS 180-2:5.3.2)  */
  176: void
  177: __sha256_init_ctx (ctx)
  178:      struct sha256_ctx *ctx;
  179: {
  180:   ctx->H[0] = 0x6a09e667;
  181:   ctx->H[1] = 0xbb67ae85;
  182:   ctx->H[2] = 0x3c6ef372;
  183:   ctx->H[3] = 0xa54ff53a;
  184:   ctx->H[4] = 0x510e527f;
  185:   ctx->H[5] = 0x9b05688c;
  186:   ctx->H[6] = 0x1f83d9ab;
  187:   ctx->H[7] = 0x5be0cd19;
  188: 
  189:   ctx->total[0] = ctx->total[1] = 0;
  190:   ctx->buflen = 0;
  191: }
  192: 
  193: 
  194: /* Process the remaining bytes in the internal buffer and the usual
  195:    prolog according to the standard and write the result to RESBUF.
  196: 
  197:    IMPORTANT: On some systems it is required that RESBUF is correctly
  198:    aligned for a 32 bits value.  */
  199: void *
  200: __sha256_finish_ctx (ctx, resbuf)
  201:      struct sha256_ctx *ctx;
  202:      void *resbuf;
  203: {
  204:   /* Take yet unprocessed bytes into account.  */
  205:   uint32_t bytes = ctx->buflen;
  206:   size_t pad;
  207: 
  208:   /* Now count remaining bytes.  */
  209:   ctx->total[0] += bytes;
  210:   if (ctx->total[0] < bytes)
  211:     ++ctx->total[1];
  212: 
  213:   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
  214:   memcpy (&ctx->buffer[bytes], fillbuf, pad);
  215: 
  216:   /* Put the 64-bit file length in *bits* at the end of the buffer.  */
  217:   *(uint32_t *) &ctx->buffer[bytes + pad + 4] = SWAP (ctx->total[0] << 3);
  218:   *(uint32_t *) &ctx->buffer[bytes + pad] = SWAP ((ctx->total[1] << 3) |
  219:                                                   (ctx->total[0] >> 29));
  220: 
  221:   /* Process last bytes.  */
  222:   sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
  223: 
  224:   /* Put result from CTX in first 32 bytes following RESBUF.  */
  225:   for (unsigned int i = 0; i < 8; ++i)
  226:     ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
  227: 
  228:   return resbuf;
  229: }
  230: 
  231: 
  232: void
  233: __sha256_process_bytes (buffer, len, ctx)
  234:      const void *buffer;
  235:      size_t len;
  236:      struct sha256_ctx *ctx;
  237: {
  238:   /* When we already have some bits in our internal buffer concatenate
  239:      both inputs first.  */
  240:   if (ctx->buflen != 0)
  241:     {
  242:       size_t left_over = ctx->buflen;
  243:       size_t add = 128 - left_over > len ? len : 128 - left_over;
  244: 
  245:       memcpy (&ctx->buffer[left_over], buffer, add);
  246:       ctx->buflen += add;
  247: 
  248:       if (ctx->buflen > 64)
  249:         {
  250:           sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
  251: 
  252:           ctx->buflen &= 63;
  253:           /* The regions in the following copy operation cannot overlap.  */
  254:           memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
  255:                   ctx->buflen);
  256:         }
  257: 
  258:       buffer = (const char *) buffer + add;
  259:       len -= add;
  260:     }
  261: 
  262:   /* Process available complete blocks.  */
  263:   if (len >= 64)
  264:     {
  265: #if !_STRING_ARCH_unaligned
  266: /* To check alignment gcc has an appropriate operator.  Other
  267:    compilers don't.  */
  268: # if __GNUC__ >= 2
  269: #  define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
  270: # else
  271: #  define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
  272: # endif
  273:       if (UNALIGNED_P (buffer))
  274:         while (len > 64)
  275:           {
  276:             sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
  277:             buffer = (const char *) buffer + 64;
  278:             len -= 64;
  279:           }
  280:       else
  281: #endif
  282:         {
  283:           sha256_process_block (buffer, len & ~63, ctx);
  284:           buffer = (const char *) buffer + (len & ~63);
  285:           len &= 63;
  286:         }
  287:     }
  288: 
  289:   /* Move remaining bytes into internal buffer.  */
  290:   if (len > 0)
  291:     {
  292:       size_t left_over = ctx->buflen;
  293: 
  294:       memcpy (&ctx->buffer[left_over], buffer, len);
  295:       left_over += len;
  296:       if (left_over >= 64)
  297:         {
  298:           sha256_process_block (ctx->buffer, 64, ctx);
  299:           left_over -= 64;
  300:           memcpy (ctx->buffer, &ctx->buffer[64], left_over);
  301:         }
  302:       ctx->buflen = left_over;
  303:     }
  304: }