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/*
SHA-1 in C
By Steve Reid <sreid@sea-to-sky.net>
100% Public Domain

-----------------
Modified 7/98
By James H. Brown <jbrown@burgoyne.com>
Still 100% Public Domain

-----------------
Adopted for s/qmail 2/2020
feh
Still 100% Public Domain; though requiring fehQlibs-14

*/

#include "sha1.h"

#include <string.h>

#include "byte.h"

// #define SHA1HANDSOFF

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

/* blk0() and blk() perform the initial expand. */
/* I got the idea of expanding during the round function from SSLeay */
/* FIXME: can we do this in an endian-proof way? */
#ifndef WORDS_BIGENDIAN
  #define blk0(i) \
    (block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) | (rol(block->l[i], 8) & 0x00FF00FF))
#else
  #define blk0(i) block->l[i]
#endif
#define blk(i)                                                                                       \
  (block->l[i & 15] = rol(                                                                           \
       block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15] ^ block->l[(i + 2) & 15] ^ block->l[i & 15], \
       1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v, w, x, y, z, i)                                   \
  z += ((w & (x ^ y)) ^ y) + blk0(i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R1(v, w, x, y, z, i)                                  \
  z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R2(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5); \
  w = rol(w, 30);
#define R3(v, w, x, y, z, i)                                        \
  z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5); \
  w = rol(w, 30);
#define R4(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5); \
  w = rol(w, 30);

/* Hash a single 512-bit block. This is the core of the algorithm. */

void sha1_transform(uint32_t state[5], const uint8_t buffer[SHA1_BLOCKSIZE])
{
  uint32_t a, b, c, d, e;
  typedef union {
    uint8_t c[SHA1_BLOCKSIZE];
    uint32_t l[16];
  } CHAR64LONG16;
  CHAR64LONG16 *block;

#ifdef SHA1HANDSOFF
  static uint8_t workspace[SHA1_BLOCKSIZE];

  block = (CHAR64LONG16 *)workspace;
  byte_copy(block, SHA1_BLOCKSIZE, buffer);
#else
  block = (CHAR64LONG16 *)buffer;
#endif

  /* Copy context->state[] to working vars */
  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];

  /* 4 rounds of 20 operations each. Loop unrolled. */
  // clang-format off
  R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
  R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
  R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
  R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
  R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
  R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
  R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
  R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
  R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
  R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
  R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
  R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
  R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
  R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
  R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
  R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
  R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
  R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
  R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
  R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
  // clang-format on

  /* Add the working vars back into context.state[] */
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;

  /* Wipe variables */
  a = b = c = d = e = 0;

#ifdef SHA1HANDSOFF
  byte_zero(block, 64);
#endif
}

/* SHA1Init - Initialize new context */

void sha1_init(sha1_ctx *context)
{
  /* SHA1 initialization constants */
  context->state[0] = 0x67452301;
  context->state[1] = 0xEFCDAB89;
  context->state[2] = 0x98BADCFE;
  context->state[3] = 0x10325476;
  context->state[4] = 0xC3D2E1F0;
  context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */

void sha1_update(sha1_ctx *context, const uint8_t *data, uint32_t len)
{
  uint32_t i, j;

  j = (context->count[0] >> 3) & 63;
  if ((context->count[0] += len << 3) < (len << 3)) context->count[1]++;
  context->count[1] += (len >> 29);
  if ((j + len) > 63) {
    byte_copy(&context->buffer[j], (i = 64 - j), data);
    sha1_transform(context->state, context->buffer);
    for (; i + 63 < len; i += 64) {
      sha1_transform(context->state, data + i);
    }
    j = 0;
  } else {
    i = 0;
  }
  byte_copy(&context->buffer[j], len - i, &data[i]);
}

/* Add padding and return the message digest. */

void sha1_final(uint8_t digest[SHA1_DIGESTSIZE], sha1_ctx *context)
{
  uint32_t i;
  uint8_t finalcount[8];

  for (i = 0; i < 8; i++) {
    /* Endian independent */
    finalcount[i] = (uint8_t)((context->count[(i >= 4 ? 0 : 1)] >> ((3 - (i & 3)) * 8)) & 255);
  }
  sha1_update(context, (uint8_t *)"\200", 1);

  while ((context->count[0] & 504) != 448) sha1_update(context, (uint8_t *)"\0", 1);

  sha1_update(context, finalcount, 8); /* Should cause a SHA1_Transform() */

  for (i = 0; i < SHA1_DIGESTSIZE; i++)
    digest[i] = (uint8_t)((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255);

  /* Wipe variables */
  i = 0;
  byte_zero(context->buffer, 64);
  byte_zero(context->state, 20);
  byte_zero(context->count, 8);
  byte_zero(finalcount, 8);

#ifdef SHA1HANDSOFF /* make SHA1Transform overwrite its own static vars */
  sha1_transform(context->state, context->buffer);
#endif
}

void sha1_hash(char *hash, const char *str, uint32_t len)
{
  sha1_ctx context;
  int i;

  sha1_init(&context);
  for (i = 0; i < len; i++) sha1_update(&context, (uint8_t *)str + i, 1);

  sha1_final((uint8_t *)hash, &context);
  hash[20] = '\0';
}