/* sha512 implementation, taken (with minor modification) from sha512crypt.c,
   which states:
   Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>.
   Neglegible modifications by Bastian Germann which stem from reprepro's
   sha256.c by Bernhard R. Link, also in the public domain.
*/

#include <config.h>

#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/types.h>

#include "sha512.h"

#ifndef WORDS_BIGENDIAN
# define SWAP(n) \
  (((n) << 56)					\
   | (((n) & 0xff00) << 40)			\
   | (((n) & 0xff0000) << 24)			\
   | (((n) & 0xff000000) << 8)			\
   | (((n) >> 8) & 0xff000000)			\
   | (((n) >> 24) & 0xff0000)			\
   | (((n) >> 40) & 0xff00)			\
   | ((n) >> 56))
#else
# define SWAP(n) (n)
#endif


/* This array contains the bytes used to pad the buffer to the next
   64-byte boundary.  (FIPS 180-2:5.1.2)  */
static const unsigned char fillbuf[128] = { 0x80, 0 /* , 0, 0, ...  */ };


/* Constants for SHA512 from FIPS 180-2:4.2.3.  */
static const uint64_t K[80] =
  {
    UINT64_C (0x428a2f98d728ae22), UINT64_C (0x7137449123ef65cd),
    UINT64_C (0xb5c0fbcfec4d3b2f), UINT64_C (0xe9b5dba58189dbbc),
    UINT64_C (0x3956c25bf348b538), UINT64_C (0x59f111f1b605d019),
    UINT64_C (0x923f82a4af194f9b), UINT64_C (0xab1c5ed5da6d8118),
    UINT64_C (0xd807aa98a3030242), UINT64_C (0x12835b0145706fbe),
    UINT64_C (0x243185be4ee4b28c), UINT64_C (0x550c7dc3d5ffb4e2),
    UINT64_C (0x72be5d74f27b896f), UINT64_C (0x80deb1fe3b1696b1),
    UINT64_C (0x9bdc06a725c71235), UINT64_C (0xc19bf174cf692694),
    UINT64_C (0xe49b69c19ef14ad2), UINT64_C (0xefbe4786384f25e3),
    UINT64_C (0x0fc19dc68b8cd5b5), UINT64_C (0x240ca1cc77ac9c65),
    UINT64_C (0x2de92c6f592b0275), UINT64_C (0x4a7484aa6ea6e483),
    UINT64_C (0x5cb0a9dcbd41fbd4), UINT64_C (0x76f988da831153b5),
    UINT64_C (0x983e5152ee66dfab), UINT64_C (0xa831c66d2db43210),
    UINT64_C (0xb00327c898fb213f), UINT64_C (0xbf597fc7beef0ee4),
    UINT64_C (0xc6e00bf33da88fc2), UINT64_C (0xd5a79147930aa725),
    UINT64_C (0x06ca6351e003826f), UINT64_C (0x142929670a0e6e70),
    UINT64_C (0x27b70a8546d22ffc), UINT64_C (0x2e1b21385c26c926),
    UINT64_C (0x4d2c6dfc5ac42aed), UINT64_C (0x53380d139d95b3df),
    UINT64_C (0x650a73548baf63de), UINT64_C (0x766a0abb3c77b2a8),
    UINT64_C (0x81c2c92e47edaee6), UINT64_C (0x92722c851482353b),
    UINT64_C (0xa2bfe8a14cf10364), UINT64_C (0xa81a664bbc423001),
    UINT64_C (0xc24b8b70d0f89791), UINT64_C (0xc76c51a30654be30),
    UINT64_C (0xd192e819d6ef5218), UINT64_C (0xd69906245565a910),
    UINT64_C (0xf40e35855771202a), UINT64_C (0x106aa07032bbd1b8),
    UINT64_C (0x19a4c116b8d2d0c8), UINT64_C (0x1e376c085141ab53),
    UINT64_C (0x2748774cdf8eeb99), UINT64_C (0x34b0bcb5e19b48a8),
    UINT64_C (0x391c0cb3c5c95a63), UINT64_C (0x4ed8aa4ae3418acb),
    UINT64_C (0x5b9cca4f7763e373), UINT64_C (0x682e6ff3d6b2b8a3),
    UINT64_C (0x748f82ee5defb2fc), UINT64_C (0x78a5636f43172f60),
    UINT64_C (0x84c87814a1f0ab72), UINT64_C (0x8cc702081a6439ec),
    UINT64_C (0x90befffa23631e28), UINT64_C (0xa4506cebde82bde9),
    UINT64_C (0xbef9a3f7b2c67915), UINT64_C (0xc67178f2e372532b),
    UINT64_C (0xca273eceea26619c), UINT64_C (0xd186b8c721c0c207),
    UINT64_C (0xeada7dd6cde0eb1e), UINT64_C (0xf57d4f7fee6ed178),
    UINT64_C (0x06f067aa72176fba), UINT64_C (0x0a637dc5a2c898a6),
    UINT64_C (0x113f9804bef90dae), UINT64_C (0x1b710b35131c471b),
    UINT64_C (0x28db77f523047d84), UINT64_C (0x32caab7b40c72493),
    UINT64_C (0x3c9ebe0a15c9bebc), UINT64_C (0x431d67c49c100d4c),
    UINT64_C (0x4cc5d4becb3e42b6), UINT64_C (0x597f299cfc657e2a),
    UINT64_C (0x5fcb6fab3ad6faec), UINT64_C (0x6c44198c4a475817)
  };


/* Process LEN bytes of BUFFER, accumulating context into CTX.
   It is assumed that LEN % 128 == 0.  */
static void
sha512_process_block (const void *buffer, size_t len, struct SHA512_Context *ctx)
{
  const uint64_t *words = buffer;
  size_t nwords = len / sizeof (uint64_t);
  uint64_t a = ctx->H[0];
  uint64_t b = ctx->H[1];
  uint64_t c = ctx->H[2];
  uint64_t d = ctx->H[3];
  uint64_t e = ctx->H[4];
  uint64_t f = ctx->H[5];
  uint64_t g = ctx->H[6];
  uint64_t h = ctx->H[7];

  /* First increment the byte count.  FIPS 180-2 specifies the possible
     length of the file up to 2^128 bits.  Here we only compute the
     number of bytes.  Do a double word increment.  */
  ctx->total[0] += len;
  if (ctx->total[0] < len)
    ++ctx->total[1];

  /* Process all bytes in the buffer with 128 bytes in each round of
     the loop.  */
  while (nwords > 0)
    {
      uint64_t W[80];
      uint64_t a_save = a;
      uint64_t b_save = b;
      uint64_t c_save = c;
      uint64_t d_save = d;
      uint64_t e_save = e;
      uint64_t f_save = f;
      uint64_t g_save = g;
      uint64_t h_save = h;

      /* Operators defined in FIPS 180-2:4.1.2.  */
#define Ch(x, y, z) ((x & y) ^ (~x & z))
#define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
#define S0(x) (CYCLIC (x, 28) ^ CYCLIC (x, 34) ^ CYCLIC (x, 39))
#define S1(x) (CYCLIC (x, 14) ^ CYCLIC (x, 18) ^ CYCLIC (x, 41))
#define R0(x) (CYCLIC (x, 1) ^ CYCLIC (x, 8) ^ (x >> 7))
#define R1(x) (CYCLIC (x, 19) ^ CYCLIC (x, 61) ^ (x >> 6))

      /* It is unfortunate that C does not provide an operator for
	 cyclic rotation.  Hope the C compiler is smart enough.  */
#define CYCLIC(w, s) ((w >> s) | (w << (64 - s)))

      /* Compute the message schedule according to FIPS 180-2:6.3.2 step 2.  */
      for (unsigned int t = 0; t < 16; ++t)
	{
	  W[t] = SWAP (*words);
	  ++words;
	}
      for (unsigned int t = 16; t < 80; ++t)
	W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];

      /* The actual computation according to FIPS 180-2:6.3.2 step 3.  */
      for (unsigned int t = 0; t < 80; ++t)
	{
	  uint64_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
	  uint64_t T2 = S0 (a) + Maj (a, b, c);
	  h = g;
	  g = f;
	  f = e;
	  e = d + T1;
	  d = c;
	  c = b;
	  b = a;
	  a = T1 + T2;
	}

      /* Add the starting values of the context according to FIPS 180-2:6.3.2
	 step 4.  */
      a += a_save;
      b += b_save;
      c += c_save;
      d += d_save;
      e += e_save;
      f += f_save;
      g += g_save;
      h += h_save;

      /* Prepare for the next round.  */
      nwords -= 16;
    }

  /* Put checksum in context given as argument.  */
  ctx->H[0] = a;
  ctx->H[1] = b;
  ctx->H[2] = c;
  ctx->H[3] = d;
  ctx->H[4] = e;
  ctx->H[5] = f;
  ctx->H[6] = g;
  ctx->H[7] = h;
}


/* Initialize structure containing state of computation.
   (FIPS 180-2:5.3.3)  */
void
SHA512Init (struct SHA512_Context *ctx)
{
  ctx->H[0] = UINT64_C (0x6a09e667f3bcc908);
  ctx->H[1] = UINT64_C (0xbb67ae8584caa73b);
  ctx->H[2] = UINT64_C (0x3c6ef372fe94f82b);
  ctx->H[3] = UINT64_C (0xa54ff53a5f1d36f1);
  ctx->H[4] = UINT64_C (0x510e527fade682d1);
  ctx->H[5] = UINT64_C (0x9b05688c2b3e6c1f);
  ctx->H[6] = UINT64_C (0x1f83d9abfb41bd6b);
  ctx->H[7] = UINT64_C (0x5be0cd19137e2179);

  ctx->total[0] = ctx->total[1] = 0;
  ctx->buflen = 0;
}


/* Process the remaining bytes in the internal buffer and the usual
   prolog according to the standard and write the result to digest.

   IMPORTANT: On some systems it is required that digest is correctly
   aligned for a 32 bits value.
*/
void
SHA512Final (struct SHA512_Context *ctx, uint8_t *digest)
{
  /* Take yet unprocessed bytes into account.  */
  uint64_t bytes = ctx->buflen;
  size_t pad;

  /* Now count remaining bytes.  */
  ctx->total[0] += bytes;
  if (ctx->total[0] < bytes)
    ++ctx->total[1];

  pad = bytes >= 112 ? 128 + 112 - bytes : 112 - bytes;
  memcpy (&ctx->buffer[bytes], fillbuf, pad);

  /* Put the 128-bit file length in *bits* at the end of the buffer.  */
  *(uint64_t *) &ctx->buffer[bytes + pad + 8] = SWAP (ctx->total[0] << 3);
  *(uint64_t *) &ctx->buffer[bytes + pad] = SWAP ((ctx->total[1] << 3) |
						  (ctx->total[0] >> 61));

  /* Process last bytes.  */
  sha512_process_block (ctx->buffer, bytes + pad + 16, ctx);

  for (unsigned int i = 0; i < 8; ++i)
    ((uint64_t *) digest)[i] = SWAP (ctx->H[i]);
}


void
SHA512Update (struct SHA512_Context *ctx, const uint8_t *buffer, size_t len)
{
  /* When we already have some bits in our internal buffer concatenate
     both inputs first.  */
  if (ctx->buflen != 0)
    {
      size_t left_over = ctx->buflen;
      size_t add = 256 - left_over > len ? len : 256 - left_over;

      memcpy (&ctx->buffer[left_over], buffer, add);
      ctx->buflen += add;

      if (ctx->buflen > 128)
	{
	  sha512_process_block (ctx->buffer, ctx->buflen & ~127, ctx);

	  ctx->buflen &= 127;
	  /* The regions in the following copy operation cannot overlap.  */
	  memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~127],
		  ctx->buflen);
	}

      buffer = buffer + add;
      len -= add;
    }

  /* Process available complete blocks.  */
  if (len >= 128)
    {
#if !_STRING_ARCH_unaligned
/* To check alignment gcc has an appropriate operator.  Other
   compilers don't.  */
# if __GNUC__ >= 2
#  define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint64_t) != 0)
# else
#  define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint64_t) != 0)
# endif
      if (UNALIGNED_P (buffer))
	while (len > 128)
	  {
	    sha512_process_block (memcpy (ctx->buffer, buffer, 128), 128,
				    ctx);
	    buffer = buffer + 128;
	    len -= 128;
	  }
      else
#endif
	{
	  sha512_process_block (buffer, len & ~127, ctx);
	  buffer = buffer + (len & ~127);
	  len &= 127;
	}
    }

  /* Move remaining bytes into internal buffer.  */
  if (len > 0)
    {
      size_t left_over = ctx->buflen;

      memcpy (&ctx->buffer[left_over], buffer, len);
      left_over += len;
      if (left_over >= 128)
	{
	  sha512_process_block (ctx->buffer, 128, ctx);
	  left_over -= 128;
	  memcpy (ctx->buffer, &ctx->buffer[128], left_over);
	}
      ctx->buflen = left_over;
    }
}
