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      1 /* sha256.c
      2 **
      3 ** Copyright 2013, The Android Open Source Project
      4 **
      5 ** Redistribution and use in source and binary forms, with or without
      6 ** modification, are permitted provided that the following conditions are met:
      7 **     * Redistributions of source code must retain the above copyright
      8 **       notice, this list of conditions and the following disclaimer.
      9 **     * Redistributions in binary form must reproduce the above copyright
     10 **       notice, this list of conditions and the following disclaimer in the
     11 **       documentation and/or other materials provided with the distribution.
     12 **     * Neither the name of Google Inc. nor the names of its contributors may
     13 **       be used to endorse or promote products derived from this software
     14 **       without specific prior written permission.
     15 **
     16 ** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
     17 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19 ** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21 ** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22 ** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23 ** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24 ** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25 ** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26 */
     27 
     28 // Optimized for minimal code size.
     29 
     30 #include "constrainedcrypto/sha256.h"
     31 
     32 #include <stdio.h>
     33 #include <string.h>
     34 #include <stdint.h>
     35 
     36 #define ror(value, bits) (((value) >> (bits)) | ((value) << (32 - (bits))))
     37 #define shr(value, bits) ((value) >> (bits))
     38 
     39 static const uint32_t K[64] = {
     40     0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
     41     0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
     42     0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
     43     0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
     44     0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
     45     0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
     46     0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
     47     0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
     48     0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
     49     0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
     50     0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
     51     0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
     52     0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
     53     0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
     54     0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
     55     0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 };
     56 
     57 static void SHA256_Transform(SHA256_CTX* ctx) {
     58     uint32_t W[64];
     59     uint32_t A, B, C, D, E, F, G, H;
     60     uint8_t* p = ctx->buf;
     61     int t;
     62 
     63     for(t = 0; t < 16; ++t) {
     64         uint32_t tmp =  *p++ << 24;
     65         tmp |= *p++ << 16;
     66         tmp |= *p++ << 8;
     67         tmp |= *p++;
     68         W[t] = tmp;
     69     }
     70 
     71     for(; t < 64; t++) {
     72         uint32_t s0 = ror(W[t-15], 7) ^ ror(W[t-15], 18) ^ shr(W[t-15], 3);
     73         uint32_t s1 = ror(W[t-2], 17) ^ ror(W[t-2], 19) ^ shr(W[t-2], 10);
     74         W[t] = W[t-16] + s0 + W[t-7] + s1;
     75     }
     76 
     77     A = ctx->state[0];
     78     B = ctx->state[1];
     79     C = ctx->state[2];
     80     D = ctx->state[3];
     81     E = ctx->state[4];
     82     F = ctx->state[5];
     83     G = ctx->state[6];
     84     H = ctx->state[7];
     85 
     86     for(t = 0; t < 64; t++) {
     87         uint32_t s0 = ror(A, 2) ^ ror(A, 13) ^ ror(A, 22);
     88         uint32_t maj = (A & B) ^ (A & C) ^ (B & C);
     89         uint32_t t2 = s0 + maj;
     90         uint32_t s1 = ror(E, 6) ^ ror(E, 11) ^ ror(E, 25);
     91         uint32_t ch = (E & F) ^ ((~E) & G);
     92         uint32_t t1 = H + s1 + ch + K[t] + W[t];
     93 
     94         H = G;
     95         G = F;
     96         F = E;
     97         E = D + t1;
     98         D = C;
     99         C = B;
    100         B = A;
    101         A = t1 + t2;
    102     }
    103 
    104     ctx->state[0] += A;
    105     ctx->state[1] += B;
    106     ctx->state[2] += C;
    107     ctx->state[3] += D;
    108     ctx->state[4] += E;
    109     ctx->state[5] += F;
    110     ctx->state[6] += G;
    111     ctx->state[7] += H;
    112 }
    113 
    114 static const HASH_VTAB SHA256_VTAB = {
    115     SHA256_init,
    116     SHA256_update,
    117     SHA256_final,
    118     SHA256_hash,
    119     SHA256_DIGEST_SIZE
    120 };
    121 
    122 void SHA256_init(SHA256_CTX* ctx) {
    123     ctx->f = &SHA256_VTAB;
    124     ctx->state[0] = 0x6a09e667;
    125     ctx->state[1] = 0xbb67ae85;
    126     ctx->state[2] = 0x3c6ef372;
    127     ctx->state[3] = 0xa54ff53a;
    128     ctx->state[4] = 0x510e527f;
    129     ctx->state[5] = 0x9b05688c;
    130     ctx->state[6] = 0x1f83d9ab;
    131     ctx->state[7] = 0x5be0cd19;
    132     ctx->count = 0;
    133 }
    134 
    135 
    136 void SHA256_update(SHA256_CTX* ctx, const void* data, int len) {
    137     int i = (int) (ctx->count & 63);
    138     const uint8_t* p = (const uint8_t*)data;
    139 
    140     ctx->count += len;
    141 
    142     while (len--) {
    143         ctx->buf[i++] = *p++;
    144         if (i == 64) {
    145             SHA256_Transform(ctx);
    146             i = 0;
    147         }
    148     }
    149 }
    150 
    151 
    152 const uint8_t* SHA256_final(SHA256_CTX* ctx) {
    153     uint8_t *p = ctx->buf;
    154     uint64_t cnt = ctx->count * 8;
    155     int i;
    156 
    157     SHA256_update(ctx, (uint8_t*)"\x80", 1);
    158     while ((ctx->count & 63) != 56) {
    159         SHA256_update(ctx, (uint8_t*)"\0", 1);
    160     }
    161     for (i = 0; i < 8; ++i) {
    162         uint8_t tmp = (uint8_t) (cnt >> ((7 - i) * 8));
    163         SHA256_update(ctx, &tmp, 1);
    164     }
    165 
    166     for (i = 0; i < 8; i++) {
    167         uint32_t tmp = ctx->state[i];
    168         *p++ = tmp >> 24;
    169         *p++ = tmp >> 16;
    170         *p++ = tmp >> 8;
    171         *p++ = tmp >> 0;
    172     }
    173 
    174     return ctx->buf;
    175 }
    176 
    177 /* Convenience function */
    178 const uint8_t* SHA256_hash(const void* data, int len, uint8_t* digest) {
    179     SHA256_CTX ctx;
    180     SHA256_init(&ctx);
    181     SHA256_update(&ctx, data, len);
    182     memcpy(digest, SHA256_final(&ctx), SHA256_DIGEST_SIZE);
    183     return digest;
    184 }
    185