sha.cpp

/*
 Copyright (C) 2008 The Android Open Source Project

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

// Copyright 2008 Google Inc. All Rights Reserved.
// Author: mschilder@google.com (Marius Schilder)
//
// Optimized for minimal code size.

#include "sha.h"

#define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))

static void SHA1_Transform(SHA_CTX* ctx) {
  uint32_t W[80];
  uint32_t A, B, C, D, E;
  uint8_t* p = ctx->buf.b;
  int t;

  for(t = 0; t < 16; ++t) {
    uint32_t tmp =  *p++ << 24;
    tmp |= *p++ << 16;
    tmp |= *p++ << 8;
    tmp |= *p++;
    W[t] = tmp;
  }

  for(; t < 80; t++) {
    W[t] = rol(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
  }

  A = ctx->state[0];
  B = ctx->state[1];
  C = ctx->state[2];
  D = ctx->state[3];
  E = ctx->state[4];

  for(t = 0; t < 80; t++) {
    uint32_t tmp = rol(5,A) + E + W[t];

    if (t < 20)
      tmp += (D^(B&(C^D))) + 0x5A827999;
    else if ( t < 40)
      tmp += (B^C^D) + 0x6ED9EBA1;
    else if ( t < 60)
      tmp += ((B&C)|(D&(B|C))) + 0x8F1BBCDC;
    else
      tmp += (B^C^D) + 0xCA62C1D6;

    E = D;
    D = C;
    C = rol(30,B);
    B = A;
    A = tmp;
  }

  ctx->state[0] += A;
  ctx->state[1] += B;
  ctx->state[2] += C;
  ctx->state[3] += D;
  ctx->state[4] += E;
}

void SHA_init(SHA_CTX* ctx) {
  ctx->state[0] = 0x67452301;
  ctx->state[1] = 0xEFCDAB89;
  ctx->state[2] = 0x98BADCFE;
  ctx->state[3] = 0x10325476;
  ctx->state[4] = 0xC3D2E1F0;
  ctx->count = 0;
}


void SHA_update(SHA_CTX* ctx, const void* data, int len) {
  int i = ctx->count % sizeof(ctx->buf);
  const uint8_t* p = (const uint8_t*)data;

  ctx->count += len;

  while (len--) {
    ctx->buf.b[i++] = *p++;
    if (i == sizeof(ctx->buf)) {
      SHA1_Transform(ctx);
      i = 0;
    }
  }
}


const uint8_t* SHA_final(SHA_CTX* ctx) {
  uint8_t *p = ctx->buf.b;
  uint64_t cnt = ctx->count * 8;
  int i;

  SHA_update(ctx, (uint8_t*)"\x80", 1);
  while ((ctx->count % sizeof(ctx->buf)) != (sizeof(ctx->buf) - 8)) {
    SHA_update(ctx, (uint8_t*)"\0", 1);
  }
  for (i = 0; i < 8; ++i) {
    uint8_t tmp = cnt >> ((7 - i) * 8);
    SHA_update(ctx, &tmp, 1);
  }

  for (i = 0; i < 5; i++) {
    uint32_t tmp = ctx->state[i];
    *p++ = tmp >> 24;
    *p++ = tmp >> 16;
    *p++ = tmp >> 8;
    *p++ = tmp >> 0;
  }

  return ctx->buf.b;
}

/* Convenience function */
const uint8_t* SHA(const void* data, int len, uint8_t* digest) {
  const uint8_t* p;
  int i;
  SHA_CTX ctx;
  SHA_init(&ctx);
  SHA_update(&ctx, data, len);
  p = SHA_final(&ctx);
  for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
    digest[i] = *p++;
  }
  return digest;
}