/*
 *  FIPS-180-1 compliant SHA-1 implementation
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  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.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org) and was downloaded from
 *  https://github.com/Secure-Embedded-Systems/RSA-example/tree/master/library/.
 */
/*
 *  The SHA-1 standard was published by NIST in 1993.
 *
 *  http://www.itl.nist.gov/fipspubs/fip180-1.htm
 */

#include "sha1.h"

#include <string.h>

/* Implementation that should never be optimized out by the compiler */
static void zeroize(void *v, size_t n) {
  volatile uint8_t *p = (uint8_t *)v;
  while (n--)
    *p++ = 0;
}

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n, b, i)                                                 \
  {                                                                            \
    (n) = ((uint32_t)(b)[(i)] << 24) | ((uint32_t)(b)[(i) + 1] << 16) |        \
          ((uint32_t)(b)[(i) + 2] << 8) | ((uint32_t)(b)[(i) + 3]);            \
  }
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n, b, i)                                                 \
  {                                                                            \
    (b)[(i)] = (uint8_t)((n) >> 24);                                           \
    (b)[(i) + 1] = (uint8_t)((n) >> 16);                                       \
    (b)[(i) + 2] = (uint8_t)((n) >> 8);                                        \
    (b)[(i) + 3] = (uint8_t)((n));                                             \
  }
#endif

void sha1_init(sha1_context *ctx) { memset(ctx, 0, sizeof(sha1_context)); }

void sha1_free(sha1_context *ctx) {
  if (ctx == NULL)
    return;

  zeroize(ctx, sizeof(sha1_context));
}

void sha1_clone(sha1_context *dst, const sha1_context *src) { *dst = *src; }

/*
 * SHA-1 context setup
 */
void sha1_starts(sha1_context *ctx) {
  ctx->total[0] = 0;
  ctx->total[1] = 0;

  ctx->state[0] = 0x67452301;
  ctx->state[1] = 0xEFCDAB89;
  ctx->state[2] = 0x98BADCFE;
  ctx->state[3] = 0x10325476;
  ctx->state[4] = 0xC3D2E1F0;
}

void sha1_process(sha1_context *ctx, const uint8_t data[64]) {
  uint32_t temp, W[16], A, B, C, D, E;

  GET_UINT32_BE(W[0], data, 0);
  GET_UINT32_BE(W[1], data, 4);
  GET_UINT32_BE(W[2], data, 8);
  GET_UINT32_BE(W[3], data, 12);
  GET_UINT32_BE(W[4], data, 16);
  GET_UINT32_BE(W[5], data, 20);
  GET_UINT32_BE(W[6], data, 24);
  GET_UINT32_BE(W[7], data, 28);
  GET_UINT32_BE(W[8], data, 32);
  GET_UINT32_BE(W[9], data, 36);
  GET_UINT32_BE(W[10], data, 40);
  GET_UINT32_BE(W[11], data, 44);
  GET_UINT32_BE(W[12], data, 48);
  GET_UINT32_BE(W[13], data, 52);
  GET_UINT32_BE(W[14], data, 56);
  GET_UINT32_BE(W[15], data, 60);

#define S(x, n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define R(t)                                                                   \
  (temp = W[(t - 3) & 0x0F] ^ W[(t - 8) & 0x0F] ^ W[(t - 14) & 0x0F] ^         \
          W[t & 0x0F],                                                         \
   (W[t & 0x0F] = S(temp, 1)))

#define P(a, b, c, d, e, x)                                                    \
  {                                                                            \
    e += S(a, 5) + F(b, c, d) + K + x;                                         \
    b = S(b, 30);                                                              \
  }

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

#define F(x, y, z) (z ^ (x & (y ^ z)))
#define K 0x5A827999

  P(A, B, C, D, E, W[0]);
  P(E, A, B, C, D, W[1]);
  P(D, E, A, B, C, W[2]);
  P(C, D, E, A, B, W[3]);
  P(B, C, D, E, A, W[4]);
  P(A, B, C, D, E, W[5]);
  P(E, A, B, C, D, W[6]);
  P(D, E, A, B, C, W[7]);
  P(C, D, E, A, B, W[8]);
  P(B, C, D, E, A, W[9]);
  P(A, B, C, D, E, W[10]);
  P(E, A, B, C, D, W[11]);
  P(D, E, A, B, C, W[12]);
  P(C, D, E, A, B, W[13]);
  P(B, C, D, E, A, W[14]);
  P(A, B, C, D, E, W[15]);
  P(E, A, B, C, D, R(16));
  P(D, E, A, B, C, R(17));
  P(C, D, E, A, B, R(18));
  P(B, C, D, E, A, R(19));

#undef K
#undef F

#define F(x, y, z) (x ^ y ^ z)
#define K 0x6ED9EBA1

  P(A, B, C, D, E, R(20));
  P(E, A, B, C, D, R(21));
  P(D, E, A, B, C, R(22));
  P(C, D, E, A, B, R(23));
  P(B, C, D, E, A, R(24));
  P(A, B, C, D, E, R(25));
  P(E, A, B, C, D, R(26));
  P(D, E, A, B, C, R(27));
  P(C, D, E, A, B, R(28));
  P(B, C, D, E, A, R(29));
  P(A, B, C, D, E, R(30));
  P(E, A, B, C, D, R(31));
  P(D, E, A, B, C, R(32));
  P(C, D, E, A, B, R(33));
  P(B, C, D, E, A, R(34));
  P(A, B, C, D, E, R(35));
  P(E, A, B, C, D, R(36));
  P(D, E, A, B, C, R(37));
  P(C, D, E, A, B, R(38));
  P(B, C, D, E, A, R(39));

#undef K
#undef F

#define F(x, y, z) ((x & y) | (z & (x | y)))
#define K 0x8F1BBCDC

  P(A, B, C, D, E, R(40));
  P(E, A, B, C, D, R(41));
  P(D, E, A, B, C, R(42));
  P(C, D, E, A, B, R(43));
  P(B, C, D, E, A, R(44));
  P(A, B, C, D, E, R(45));
  P(E, A, B, C, D, R(46));
  P(D, E, A, B, C, R(47));
  P(C, D, E, A, B, R(48));
  P(B, C, D, E, A, R(49));
  P(A, B, C, D, E, R(50));
  P(E, A, B, C, D, R(51));
  P(D, E, A, B, C, R(52));
  P(C, D, E, A, B, R(53));
  P(B, C, D, E, A, R(54));
  P(A, B, C, D, E, R(55));
  P(E, A, B, C, D, R(56));
  P(D, E, A, B, C, R(57));
  P(C, D, E, A, B, R(58));
  P(B, C, D, E, A, R(59));

#undef K
#undef F

#define F(x, y, z) (x ^ y ^ z)
#define K 0xCA62C1D6

  P(A, B, C, D, E, R(60));
  P(E, A, B, C, D, R(61));
  P(D, E, A, B, C, R(62));
  P(C, D, E, A, B, R(63));
  P(B, C, D, E, A, R(64));
  P(A, B, C, D, E, R(65));
  P(E, A, B, C, D, R(66));
  P(D, E, A, B, C, R(67));
  P(C, D, E, A, B, R(68));
  P(B, C, D, E, A, R(69));
  P(A, B, C, D, E, R(70));
  P(E, A, B, C, D, R(71));
  P(D, E, A, B, C, R(72));
  P(C, D, E, A, B, R(73));
  P(B, C, D, E, A, R(74));
  P(A, B, C, D, E, R(75));
  P(E, A, B, C, D, R(76));
  P(D, E, A, B, C, R(77));
  P(C, D, E, A, B, R(78));
  P(B, C, D, E, A, R(79));

#undef K
#undef F

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

/*
 * SHA-1 process buffer
 */
void sha1_update(sha1_context *ctx, const uint8_t *input, size_t ilen) {
  size_t fill;
  uint32_t left;

  if (ilen == 0)
    return;

  left = ctx->total[0] & 0x3F;
  fill = 64 - left;

  ctx->total[0] += (uint32_t)ilen;
  ctx->total[0] &= 0xFFFFFFFF;

  if (ctx->total[0] < (uint32_t)ilen)
    ctx->total[1]++;

  if (left && ilen >= fill) {
    memcpy((void *)(ctx->buffer + left), input, fill);
    sha1_process(ctx, ctx->buffer);
    input += fill;
    ilen -= fill;
    left = 0;
  }

  while (ilen >= 64) {
    sha1_process(ctx, input);
    input += 64;
    ilen -= 64;
  }

  if (ilen > 0)
    memcpy((void *)(ctx->buffer + left), input, ilen);
}

static const uint8_t sha1_padding[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

/*
 * SHA-1 final digest
 */
void sha1_finish(sha1_context *ctx, uint8_t output[SHA_DIGEST_LENGTH]) {
  uint32_t last, padn;
  uint32_t high, low;
  uint8_t msglen[8];

  high = (ctx->total[0] >> 29) | (ctx->total[1] << 3);
  low = (ctx->total[0] << 3);

  PUT_UINT32_BE(high, msglen, 0);
  PUT_UINT32_BE(low, msglen, 4);

  last = ctx->total[0] & 0x3F;
  padn = (last < 56) ? (56 - last) : (120 - last);

  sha1_update(ctx, sha1_padding, padn);
  sha1_update(ctx, msglen, 8);

  PUT_UINT32_BE(ctx->state[0], output, 0);
  PUT_UINT32_BE(ctx->state[1], output, 4);
  PUT_UINT32_BE(ctx->state[2], output, 8);
  PUT_UINT32_BE(ctx->state[3], output, 12);
  PUT_UINT32_BE(ctx->state[4], output, 16);
}

/*
 * output = SHA-1( input buffer )
 */
void sha1(const uint8_t *input, size_t ilen,
          uint8_t output[SHA_DIGEST_LENGTH]) {
  sha1_context ctx;

  sha1_init(&ctx);
  sha1_starts(&ctx);
  sha1_update(&ctx, input, ilen);
  sha1_finish(&ctx, output);
  sha1_free(&ctx);
}