text: /**
   * Copyright (c) 2000-2001 Aaron D. Gifford
   * Copyright (c) 2013 Pavol Rusnak
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the copyright holder nor the names of contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <string.h>
  #include <stdint.h>
  #include "sha2.h"
  
  /*
   * ASSERT NOTE:
   * Some sanity checking code is included using assert().  On my FreeBSD
   * system, this additional code can be removed by compiling with NDEBUG
   * defined.  Check your own systems manpage on assert() to see how to
   * compile WITHOUT the sanity checking code on your system.
   *
   * UNROLLED TRANSFORM LOOP NOTE:
   * You can define SHA2_UNROLL_TRANSFORM to use the unrolled transform
   * loop version for the hash transform rounds (defined using macros
   * later in this file).  Either define on the command line, for example:
   *
   *   cc -DSHA2_UNROLL_TRANSFORM -o sha2 sha2.c sha2prog.c
   *
   * or define below:
   *
   *   #define SHA2_UNROLL_TRANSFORM
   *
   */
  
  
  /*** SHA-256/384/512 Machine Architecture Definitions *****************/
  /*
   * BYTE_ORDER NOTE:
   *
   * Please make sure that your system defines BYTE_ORDER.  If your
   * architecture is little-endian, make sure it also defines
   * LITTLE_ENDIAN and that the two (BYTE_ORDER and LITTLE_ENDIAN) are
   * equivilent.
   *
   * If your system does not define the above, then you can do so by
   * hand like this:
   *
   *   #define LITTLE_ENDIAN 1234
   *   #define BIG_ENDIAN    4321
   *
   * And for little-endian machines, add:
   *
   *   #define BYTE_ORDER LITTLE_ENDIAN
   *
   * Or for big-endian machines:
   *
   *   #define BYTE_ORDER BIG_ENDIAN
   *
   * The FreeBSD machine this was written on defines BYTE_ORDER
   * appropriately by including <sys/types.h> (which in turn includes
   * <machine/endian.h> where the appropriate definitions are actually
   * made).
   */
  
  #ifndef LITTLE_ENDIAN
  #define LITTLE_ENDIAN 1234
  #define BIG_ENDIAN    4321
  #endif
  
  #ifndef BYTE_ORDER
  #define BYTE_ORDER LITTLE_ENDIAN
  #endif
  
  #if !defined(BYTE_ORDER) || (BYTE_ORDER != LITTLE_ENDIAN && BYTE_ORDER != BIG_ENDIAN)
  #error Define BYTE_ORDER to be equal to either LITTLE_ENDIAN or BIG_ENDIAN
  #endif
  
  typedef uint8_t  sha2_byte; /* Exactly 1 byte */
  typedef uint32_t sha2_word32;   /* Exactly 4 bytes */
  typedef uint64_t sha2_word64;   /* Exactly 8 bytes */
  
  /*** SHA-256/384/512 Various Length Definitions ***********************/
  /* NOTE: Most of these are in sha2.h */
  #define SHA256_SHORT_BLOCK_LENGTH   (SHA256_BLOCK_LENGTH - 8)
  #define SHA512_SHORT_BLOCK_LENGTH   (SHA512_BLOCK_LENGTH - 16)
  
  
  /*** ENDIAN REVERSAL MACROS *******************************************/
  #if BYTE_ORDER == LITTLE_ENDIAN
  #define REVERSE32(w,x)  { \
      sha2_word32 tmp = (w); \
      tmp = (tmp >> 16) | (tmp << 16); \
      (x) = ((tmp & 0xff00ff00UL) >> 8) | ((tmp & 0x00ff00ffUL) << 8); \
  }
  #define REVERSE64(w,x)  { \
      sha2_word64 tmp = (w); \
      tmp = (tmp >> 32) | (tmp << 32); \
      tmp = ((tmp & 0xff00ff00ff00ff00ULL) >> 8) | \
            ((tmp & 0x00ff00ff00ff00ffULL) << 8); \
      (x) = ((tmp & 0xffff0000ffff0000ULL) >> 16) | \
            ((tmp & 0x0000ffff0000ffffULL) << 16); \
  }
  #endif /* BYTE_ORDER == LITTLE_ENDIAN */
  
  /*
   * Macro for incrementally adding the unsigned 64-bit integer n to the
   * unsigned 128-bit integer (represented using a two-element array of
   * 64-bit words):
   */
  #define ADDINC128(w,n)  { \
      (w)[0] += (sha2_word64)(n); \
      if ((w)[0] < (n)) { \
          (w)[1]++; \
      } \
  }
  
  #define MEMSET_BZERO(p,l)   memset((p), 0, (l))
  #define MEMCPY_BCOPY(d,s,l) memcpy((d), (s), (l))
  
  /*** THE SIX LOGICAL FUNCTIONS ****************************************/
  /*
   * Bit shifting and rotation (used by the six SHA-XYZ logical functions:
   *
   *   NOTE:  The naming of R and S appears backwards here (R is a SHIFT and
   *   S is a ROTATION) because the SHA-256/384/512 description document
   *   (see http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf) uses this
   *   same "backwards" definition.
   */
  /* Shift-right (used in SHA-256, SHA-384, and SHA-512): */
  #define R(b,x)      ((x) >> (b))
  /* 32-bit Rotate-right (used in SHA-256): */
  #define S32(b,x)    (((x) >> (b)) | ((x) << (32 - (b))))
  /* 64-bit Rotate-right (used in SHA-384 and SHA-512): */
  #define S64(b,x)    (((x) >> (b)) | ((x) << (64 - (b))))
  
  /* Two of six logical functions used in SHA-256, SHA-384, and SHA-512: */
  #define Ch(x,y,z)   (((x) & (y)) ^ ((~(x)) & (z)))
  #define Maj(x,y,z)  (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
  
  /* Four of six logical functions used in SHA-256: */
  #define Sigma0_256(x)   (S32(2,  (x)) ^ S32(13, (x)) ^ S32(22, (x)))
  #define Sigma1_256(x)   (S32(6,  (x)) ^ S32(11, (x)) ^ S32(25, (x)))
  #define sigma0_256(x)   (S32(7,  (x)) ^ S32(18, (x)) ^ R(3 ,   (x)))
  #define sigma1_256(x)   (S32(17, (x)) ^ S32(19, (x)) ^ R(10,   (x)))
  
  /* Four of six logical functions used in SHA-384 and SHA-512: */
  #define Sigma0_512(x)   (S64(28, (x)) ^ S64(34, (x)) ^ S64(39, (x)))
  #define Sigma1_512(x)   (S64(14, (x)) ^ S64(18, (x)) ^ S64(41, (x)))
  #define sigma0_512(x)   (S64( 1, (x)) ^ S64( 8, (x)) ^ R( 7,   (x)))
  #define sigma1_512(x)   (S64(19, (x)) ^ S64(61, (x)) ^ R( 6,   (x)))
  
  /*** INTERNAL FUNCTION PROTOTYPES *************************************/
  /* NOTE: These should not be accessed directly from outside this
   * library -- they are intended for private internal visibility/use
   * only.
   */
  void sha512_Last(SHA512_CTX *);
  void sha256_Transform(SHA256_CTX *, const sha2_word32 *);
  void sha512_Transform(SHA512_CTX *, const sha2_word64 *);
  
  
  /*** SHA-XYZ INITIAL HASH VALUES AND CONSTANTS ************************/
  /* Hash constant words K for SHA-256: */
  static const sha2_word32 K256[64] = {
      0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
      0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
      0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
      0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
      0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
      0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
      0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
      0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
      0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
      0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
      0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
      0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
      0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
      0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
      0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
      0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
  };
  
  /* Initial hash value H for SHA-256: */
  static const sha2_word32 sha256_initial_hash_value[8] = {
      0x6a09e667UL,
      0xbb67ae85UL,
      0x3c6ef372UL,
      0xa54ff53aUL,
      0x510e527fUL,
      0x9b05688cUL,
      0x1f83d9abUL,
      0x5be0cd19UL
  };
  
  /* Hash constant words K for SHA-384 and SHA-512: */
  static const sha2_word64 K512[80] = {
      0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL,
      0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL,
      0x3956c25bf348b538ULL, 0x59f111f1b605d019ULL,
      0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL,
      0xd807aa98a3030242ULL, 0x12835b0145706fbeULL,
      0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL,
      0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL,
      0x9bdc06a725c71235ULL, 0xc19bf174cf692694ULL,
      0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL,
      0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL,
      0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL,
      0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL,
      0x983e5152ee66dfabULL, 0xa831c66d2db43210ULL,
      0xb00327c898fb213fULL, 0xbf597fc7beef0ee4ULL,
      0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL,
      0x06ca6351e003826fULL, 0x142929670a0e6e70ULL,
      0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL,
      0x4d2c6dfc5ac42aedULL, 0x53380d139d95b3dfULL,
      0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL,
      0x81c2c92e47edaee6ULL, 0x92722c851482353bULL,
      0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL,
      0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL,
      0xd192e819d6ef5218ULL, 0xd69906245565a910ULL,
      0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL,
      0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL,
      0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL,
      0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL,
      0x5b9cca4f7763e373ULL, 0x682e6ff3d6b2b8a3ULL,
      0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL,
      0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL,
      0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL,
      0xbef9a3f7b2c67915ULL, 0xc67178f2e372532bULL,
      0xca273eceea26619cULL, 0xd186b8c721c0c207ULL,
      0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL,
      0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL,
      0x113f9804bef90daeULL, 0x1b710b35131c471bULL,
      0x28db77f523047d84ULL, 0x32caab7b40c72493ULL,
      0x3c9ebe0a15c9bebcULL, 0x431d67c49c100d4cULL,
      0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL,
      0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL
  };
  
  /* Initial hash value H for SHA-384 */
  /*static const sha2_word64 sha384_initial_hash_value[8] = {
      0xcbbb9d5dc1059ed8ULL,
      0x629a292a367cd507ULL,
      0x9159015a3070dd17ULL,
      0x152fecd8f70e5939ULL,
      0x67332667ffc00b31ULL,
      0x8eb44a8768581511ULL,
      0xdb0c2e0d64f98fa7ULL,
      0x47b5481dbefa4fa4ULL
  };*/
  
  /* Initial hash value H for SHA-512 */
  static const sha2_word64 sha512_initial_hash_value[8] = {
      0x6a09e667f3bcc908ULL,
      0xbb67ae8584caa73bULL,
      0x3c6ef372fe94f82bULL,
      0xa54ff53a5f1d36f1ULL,
      0x510e527fade682d1ULL,
      0x9b05688c2b3e6c1fULL,
      0x1f83d9abfb41bd6bULL,
      0x5be0cd19137e2179ULL
  };
  
  /*
   * Constant used by SHA256/384/512_End() functions for converting the
   * digest to a readable hexadecimal character string:
   */
  static const char *sha2_hex_digits = "0123456789abcdef";
  
  
  /*** SHA-256: *********************************************************/
  void sha256_Init(SHA256_CTX *context)
  {
      if (context == (SHA256_CTX *)0) {
          return;
      }
      MEMCPY_BCOPY(context->state, sha256_initial_hash_value, SHA256_DIGEST_LENGTH);
      MEMSET_BZERO(context->buffer, SHA256_BLOCK_LENGTH);
      context->bitcount = 0;
  }
  
  #ifdef SHA2_UNROLL_TRANSFORM
  
  /* Unrolled SHA-256 round macros: */
  
  #if BYTE_ORDER == LITTLE_ENDIAN
  
  #define ROUND256_0_TO_15(a,b,c,d,e,f,g,h)   \
      REVERSE32(*data++, W256[j]); \
      T1 = (h) + Sigma1_256(e) + Ch((e), (f), (g)) + \
               K256[j] + W256[j]; \
      (d) += T1; \
      (h) = T1 + Sigma0_256(a) + Maj((a), (b), (c)); \
      j++
  
  
  #else /* BYTE_ORDER == LITTLE_ENDIAN */
  
  #define ROUND256_0_TO_15(a,b,c,d,e,f,g,h)   \
      T1 = (h) + Sigma1_256(e) + Ch((e), (f), (g)) + \
           K256[j] + (W256[j] = *data++); \
      (d) += T1; \
      (h) = T1 + Sigma0_256(a) + Maj((a), (b), (c)); \
      j++
  
  #endif /* BYTE_ORDER == LITTLE_ENDIAN */
  
  #define ROUND256(a,b,c,d,e,f,g,h)   \
      s0 = W256[(j+1)&0x0f]; \
      s0 = sigma0_256(s0); \
      s1 = W256[(j+14)&0x0f]; \
      s1 = sigma1_256(s1); \
      T1 = (h) + Sigma1_256(e) + Ch((e), (f), (g)) + K256[j] + \
           (W256[j&0x0f] += s1 + W256[(j+9)&0x0f] + s0); \
      (d) += T1; \
      (h) = T1 + Sigma0_256(a) + Maj((a), (b), (c)); \
      j++
  
  void sha256_Transform(SHA256_CTX *context, const sha2_word32 *data)
  {
      sha2_word32 a, b, c, d, e, f, g, h, s0, s1;
      sha2_word32 T1, *W256;
      int     j;
  
      W256 = (sha2_word32 *)context->buffer;
  
      /* Initialize registers with the prev. intermediate value */
      a = context->state[0];
      b = context->state[1];
      c = context->state[2];
      d = context->state[3];
      e = context->state[4];
      f = context->state[5];
      g = context->state[6];
      h = context->state[7];
  
      j = 0;
      do {
          /* Rounds 0 to 15 (unrolled): */
          ROUND256_0_TO_15(a, b, c, d, e, f, g, h);
          ROUND256_0_TO_15(h, a, b, c, d, e, f, g);
          ROUND256_0_TO_15(g, h, a, b, c, d, e, f);
          ROUND256_0_TO_15(f, g, h, a, b, c, d, e);
          ROUND256_0_TO_15(e, f, g, h, a, b, c, d);
          ROUND256_0_TO_15(d, e, f, g, h, a, b, c);
          ROUND256_0_TO_15(c, d, e, f, g, h, a, b);
          ROUND256_0_TO_15(b, c, d, e, f, g, h, a);
      } while (j < 16);
  
      /* Now for the remaining rounds to 64: */
      do {
          ROUND256(a, b, c, d, e, f, g, h);
          ROUND256(h, a, b, c, d, e, f, g);
          ROUND256(g, h, a, b, c, d, e, f);
          ROUND256(f, g, h, a, b, c, d, e);
          ROUND256(e, f, g, h, a, b, c, d);
          ROUND256(d, e, f, g, h, a, b, c);
          ROUND256(c, d, e, f, g, h, a, b);
          ROUND256(b, c, d, e, f, g, h, a);
      } while (j < 64);
  
      /* Compute the current intermediate hash value */
      context->state[0] += a;
      context->state[1] += b;
      context->state[2] += c;
      context->state[3] += d;
      context->state[4] += e;
      context->state[5] += f;
      context->state[6] += g;
      context->state[7] += h;
  
      /* Clean up */
      a = b = c = d = e = f = g = h = T1 = 0;
  }
  
  #else /* SHA2_UNROLL_TRANSFORM */
  
  void sha256_Transform(SHA256_CTX *context, const sha2_word32 *data)
  {
      sha2_word32 a, b, c, d, e, f, g, h, s0, s1;
      sha2_word32 T1, T2, *W256;
      int     j;
  
      W256 = (sha2_word32 *)context->buffer;
  
      /* Initialize registers with the prev. intermediate value */
      a = context->state[0];
      b = context->state[1];
      c = context->state[2];
      d = context->state[3];
      e = context->state[4];
      f = context->state[5];
      g = context->state[6];
      h = context->state[7];
  
      j = 0;
      do {
  #if BYTE_ORDER == LITTLE_ENDIAN
          /* Copy data while converting to host byte order */
          REVERSE32(*data++, W256[j]);
          /* Apply the SHA-256 compression function to update a..h */
          T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + W256[j];
  #else /* BYTE_ORDER == LITTLE_ENDIAN */
          /* Apply the SHA-256 compression function to update a..h with copy */
          T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + (W256[j] = *data++);
  #endif /* BYTE_ORDER == LITTLE_ENDIAN */
          T2 = Sigma0_256(a) + Maj(a, b, c);
          h = g;
          g = f;
          f = e;
          e = d + T1;
          d = c;
          c = b;
          b = a;
          a = T1 + T2;
  
          j++;
      } while (j < 16);
  
      do {
          /* Part of the message block expansion: */
          s0 = W256[(j + 1) & 0x0f];
          s0 = sigma0_256(s0);
          s1 = W256[(j + 14) & 0x0f];
          s1 = sigma1_256(s1);
  
          /* Apply the SHA-256 compression function to update a..h */
          T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] +
               (W256[j & 0x0f] += s1 + W256[(j + 9) & 0x0f] + s0);
          T2 = Sigma0_256(a) + Maj(a, b, c);
          h = g;
          g = f;
          f = e;
          e = d + T1;
          d = c;
          c = b;
          b = a;
          a = T1 + T2;
  
          j++;
      } while (j < 64);
  
      /* Compute the current intermediate hash value */
      context->state[0] += a;
      context->state[1] += b;
      context->state[2] += c;
      context->state[3] += d;
      context->state[4] += e;
      context->state[5] += f;
      context->state[6] += g;
      context->state[7] += h;
  
      /* Clean up */
      a = b = c = d = e = f = g = h = T1 = T2 = 0;
  }
  
  #endif /* SHA2_UNROLL_TRANSFORM */
  
  void sha256_Update(SHA256_CTX *context, const sha2_byte *data, size_t len)
  {
      unsigned int    freespace, usedspace;
  
      if (len == 0) {
          /* Calling with no data is valid - we do nothing */
          return;
      }
  
      usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
      if (usedspace > 0) {
          /* Calculate how much free space is available in the buffer */
          freespace = SHA256_BLOCK_LENGTH - usedspace;
  
          if (len >= freespace) {
              /* Fill the buffer completely and process it */
              MEMCPY_BCOPY(&context->buffer[usedspace], data, freespace);
              context->bitcount += freespace << 3;
              len -= freespace;
              data += freespace;
              sha256_Transform(context, (sha2_word32 *)context->buffer);
          } else {
              /* The buffer is not yet full */
              MEMCPY_BCOPY(&context->buffer[usedspace], data, len);
              context->bitcount += len << 3;
              /* Clean up: */
              usedspace = freespace = 0;
              return;
          }
      }
      while (len >= SHA256_BLOCK_LENGTH) {
          /* Process as many complete blocks as we can */
          sha256_Transform(context, (sha2_word32 *)data);
          context->bitcount += SHA256_BLOCK_LENGTH << 3;
          len -= SHA256_BLOCK_LENGTH;
          data += SHA256_BLOCK_LENGTH;
      }
      if (len > 0) {
          /* There's left-overs, so save 'em */
          MEMCPY_BCOPY(context->buffer, data, len);
          context->bitcount += len << 3;
      }
      /* Clean up: */
      usedspace = freespace = 0;
  }
  
  void sha256_Final(sha2_byte digest[], SHA256_CTX *context)
  {
      sha2_word32 *d = (sha2_word32 *)digest;
      unsigned int    usedspace;
  
      /* If no digest buffer is passed, we don't bother doing this: */
      if (digest != (sha2_byte *)0) {
          usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
  #if BYTE_ORDER == LITTLE_ENDIAN
          /* Convert FROM host byte order */
          REVERSE64(context->bitcount, context->bitcount);
  #endif
          if (usedspace > 0) {
              /* Begin padding with a 1 bit: */
              context->buffer[usedspace++] = 0x80;
  
              if (usedspace <= SHA256_SHORT_BLOCK_LENGTH) {
                  /* Set-up for the last transform: */
                  MEMSET_BZERO(&context->buffer[usedspace], SHA256_SHORT_BLOCK_LENGTH - usedspace);
              } else {
                  if (usedspace < SHA256_BLOCK_LENGTH) {
                      MEMSET_BZERO(&context->buffer[usedspace], SHA256_BLOCK_LENGTH - usedspace);
                  }
                  /* Do second-to-last transform: */
                  sha256_Transform(context, (sha2_word32 *)context->buffer);
  
                  /* And set-up for the last transform: */
                  MEMSET_BZERO(context->buffer, SHA256_SHORT_BLOCK_LENGTH);
              }
          } else {
              /* Set-up for the last transform: */
              MEMSET_BZERO(context->buffer, SHA256_SHORT_BLOCK_LENGTH);
  
              /* Begin padding with a 1 bit: */
              *context->buffer = 0x80;
          }
          /* Set the bit count: */
          sha2_word64 *t = (sha2_word64 *)&context->buffer[SHA256_SHORT_BLOCK_LENGTH];
          *t = context->bitcount;
  
          /* Final transform: */
          sha256_Transform(context, (sha2_word32 *)context->buffer);
  
  #if BYTE_ORDER == LITTLE_ENDIAN
          {
              /* Convert TO host byte order */
              int j;
              for (j = 0; j < 8; j++) {
                  REVERSE32(context->state[j], context->state[j]);
                  *d++ = context->state[j];
              }
          }
  #else
          MEMCPY_BCOPY(d, context->state, SHA256_DIGEST_LENGTH);
  #endif
      }
  
      /* Clean up state data: */
      MEMSET_BZERO(context, sizeof(SHA256_CTX));
      usedspace = 0;
  }
  
  char *sha256_End(SHA256_CTX *context, char buffer[])
  {
      sha2_byte   digest[SHA256_DIGEST_LENGTH], *d = digest;
  
      if (buffer != (char *)0) {
          sha256_Final(digest, context);
  
          for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
              *buffer++ = sha2_hex_digits[(*d & 0xf0) >> 4];
              *buffer++ = sha2_hex_digits[*d & 0x0f];
              d++;
          }
          *buffer = (char)0;
      } else {
          MEMSET_BZERO(context, sizeof(SHA256_CTX));
      }
      MEMSET_BZERO(digest, SHA256_DIGEST_LENGTH);
      return buffer;
  }
  
  void sha256_Raw(const sha2_byte *data, size_t len, uint8_t digest[SHA256_DIGEST_LENGTH])
  {
      SHA256_CTX  context;
      sha256_Init(&context);
      sha256_Update(&context, data, len);
      sha256_Final(digest, &context);
  }
  
  char *sha256_Data(const sha2_byte *data, size_t len,
                    char digest[SHA256_DIGEST_STRING_LENGTH])
  {
      SHA256_CTX  context;
      sha256_Init(&context);
      sha256_Update(&context, data, len);
      return sha256_End(&context, digest);
  }
  
  
  /*** SHA-512: *********************************************************/
  void sha512_Init(SHA512_CTX *context)
  {
      if (context == (SHA512_CTX *)0) {
          return;
      }
      MEMCPY_BCOPY(context->state, sha512_initial_hash_value, SHA512_DIGEST_LENGTH);
      MEMSET_BZERO(context->buffer, SHA512_BLOCK_LENGTH);
      context->bitcount[0] = context->bitcount[1] =  0;
  }
  
  #ifdef SHA2_UNROLL_TRANSFORM
  
  /* Unrolled SHA-512 round macros: */
  #if BYTE_ORDER == LITTLE_ENDIAN
  
  #define ROUND512_0_TO_15(a,b,c,d,e,f,g,h)   \
      REVERSE64(*data++, W512[j]); \
      T1 = (h) + Sigma1_512(e) + Ch((e), (f), (g)) + \
               K512[j] + W512[j]; \
      (d) += T1, \
      (h) = T1 + Sigma0_512(a) + Maj((a), (b), (c)), \
      j++
  
  
  #else /* BYTE_ORDER == LITTLE_ENDIAN */
  
  #define ROUND512_0_TO_15(a,b,c,d,e,f,g,h)   \
      T1 = (h) + Sigma1_512(e) + Ch((e), (f), (g)) + \
               K512[j] + (W512[j] = *data++); \
      (d) += T1; \
      (h) = T1 + Sigma0_512(a) + Maj((a), (b), (c)); \
      j++
  
  #endif /* BYTE_ORDER == LITTLE_ENDIAN */
  
  #define ROUND512(a,b,c,d,e,f,g,h)   \
      s0 = W512[(j+1)&0x0f]; \
      s0 = sigma0_512(s0); \
      s1 = W512[(j+14)&0x0f]; \
      s1 = sigma1_512(s1); \
      T1 = (h) + Sigma1_512(e) + Ch((e), (f), (g)) + K512[j] + \
               (W512[j&0x0f] += s1 + W512[(j+9)&0x0f] + s0); \
      (d) += T1; \
      (h) = T1 + Sigma0_512(a) + Maj((a), (b), (c)); \
      j++
  
  void sha512_Transform(SHA512_CTX *context, const sha2_word64 *data)
  {
      sha2_word64 a, b, c, d, e, f, g, h, s0, s1;
      sha2_word64 T1, *W512 = (sha2_word64 *)context->buffer;
      int     j;
  
      /* Initialize registers with the prev. intermediate value */
      a = context->state[0];
      b = context->state[1];
      c = context->state[2];
      d = context->state[3];
      e = context->state[4];
      f = context->state[5];
      g = context->state[6];
      h = context->state[7];
  
      j = 0;
      do {
          ROUND512_0_TO_15(a, b, c, d, e, f, g, h);
          ROUND512_0_TO_15(h, a, b, c, d, e, f, g);
          ROUND512_0_TO_15(g, h, a, b, c, d, e, f);
          ROUND512_0_TO_15(f, g, h, a, b, c, d, e);
          ROUND512_0_TO_15(e, f, g, h, a, b, c, d);
          ROUND512_0_TO_15(d, e, f, g, h, a, b, c);
          ROUND512_0_TO_15(c, d, e, f, g, h, a, b);
          ROUND512_0_TO_15(b, c, d, e, f, g, h, a);
      } while (j < 16);
  
      /* Now for the remaining rounds up to 79: */
      do {
          ROUND512(a, b, c, d, e, f, g, h);
          ROUND512(h, a, b, c, d, e, f, g);
          ROUND512(g, h, a, b, c, d, e, f);
          ROUND512(f, g, h, a, b, c, d, e);
          ROUND512(e, f, g, h, a, b, c, d);
          ROUND512(d, e, f, g, h, a, b, c);
          ROUND512(c, d, e, f, g, h, a, b);
          ROUND512(b, c, d, e, f, g, h, a);
      } while (j < 80);
  
      /* Compute the current intermediate hash value */
      context->state[0] += a;
      context->state[1] += b;
      context->state[2] += c;
      context->state[3] += d;
      context->state[4] += e;
      context->state[5] += f;
      context->state[6] += g;
      context->state[7] += h;
  
      /* Clean up */
      a = b = c = d = e = f = g = h = T1 = 0;
  }
  
  #else /* SHA2_UNROLL_TRANSFORM */
  
  void sha512_Transform(SHA512_CTX *context, const sha2_word64 *data)
  {
      sha2_word64 a, b, c, d, e, f, g, h, s0, s1;
      sha2_word64 T1, T2, *W512 = (sha2_word64 *)context->buffer;
      int     j;
  
      /* Initialize registers with the prev. intermediate value */
      a = context->state[0];
      b = context->state[1];
      c = context->state[2];
      d = context->state[3];
      e = context->state[4];
      f = context->state[5];
      g = context->state[6];
      h = context->state[7];
  
      j = 0;
      do {
  #if BYTE_ORDER == LITTLE_ENDIAN
          /* Convert TO host byte order */
          REVERSE64(*data++, W512[j]);
          /* Apply the SHA-512 compression function to update a..h */
          T1 = h + Sigma1_512(e) + Ch(e, f, g) + K512[j] + W512[j];
  #else /* BYTE_ORDER == LITTLE_ENDIAN */
          /* Apply the SHA-512 compression function to update a..h with copy */
          T1 = h + Sigma1_512(e) + Ch(e, f, g) + K512[j] + (W512[j] = *data++);
  #endif /* BYTE_ORDER == LITTLE_ENDIAN */
          T2 = Sigma0_512(a) + Maj(a, b, c);
          h = g;
          g = f;
          f = e;
          e = d + T1;
          d = c;
          c = b;
          b = a;
          a = T1 + T2;
  
          j++;
      } while (j < 16);
  
      do {
          /* Part of the message block expansion: */
          s0 = W512[(j + 1) & 0x0f];
          s0 = sigma0_512(s0);
          s1 = W512[(j + 14) & 0x0f];
          s1 =  sigma1_512(s1);
  
          /* Apply the SHA-512 compression function to update a..h */
          T1 = h + Sigma1_512(e) + Ch(e, f, g) + K512[j] +
               (W512[j & 0x0f] += s1 + W512[(j + 9) & 0x0f] + s0);
          T2 = Sigma0_512(a) + Maj(a, b, c);
          h = g;
          g = f;
          f = e;
          e = d + T1;
          d = c;
          c = b;
          b = a;
          a = T1 + T2;
  
          j++;
      } while (j < 80);
  
      /* Compute the current intermediate hash value */
      context->state[0] += a;
      context->state[1] += b;
      context->state[2] += c;
      context->state[3] += d;
      context->state[4] += e;
      context->state[5] += f;
      context->state[6] += g;
      context->state[7] += h;
  
      /* Clean up */
      a = b = c = d = e = f = g = h = T1 = T2 = 0;
  }
  
  #endif /* SHA2_UNROLL_TRANSFORM */
  
  void sha512_Update(SHA512_CTX *context, const sha2_byte *data, size_t len)
  {
      unsigned int    freespace, usedspace;
  
      if (len == 0) {
          /* Calling with no data is valid - we do nothing */
          return;
      }
  
      usedspace = (context->bitcount[0] >> 3) % SHA512_BLOCK_LENGTH;
      if (usedspace > 0) {
          /* Calculate how much free space is available in the buffer */
          freespace = SHA512_BLOCK_LENGTH - usedspace;
  
          if (len >= freespace) {
              /* Fill the buffer completely and process it */
              MEMCPY_BCOPY(&context->buffer[usedspace], data, freespace);
              ADDINC128(context->bitcount, freespace << 3);
              len -= freespace;
              data += freespace;
              sha512_Transform(context, (sha2_word64 *)context->buffer);
          } else {
              /* The buffer is not yet full */
              MEMCPY_BCOPY(&context->buffer[usedspace], data, len);
              ADDINC128(context->bitcount, len << 3);
              /* Clean up: */
              usedspace = freespace = 0;
              return;
          }
      }
      while (len >= SHA512_BLOCK_LENGTH) {
          /* Process as many complete blocks as we can */
          sha512_Transform(context, (sha2_word64 *)data);
          ADDINC128(context->bitcount, SHA512_BLOCK_LENGTH << 3);
          len -= SHA512_BLOCK_LENGTH;
          data += SHA512_BLOCK_LENGTH;
      }
      if (len > 0) {
          /* There's left-overs, so save 'em */
          MEMCPY_BCOPY(context->buffer, data, len);
          ADDINC128(context->bitcount, len << 3);
      }
      /* Clean up: */
      usedspace = freespace = 0;
  }
  
  void sha512_Last(SHA512_CTX *context)
  {
      unsigned int    usedspace;
  
      usedspace = (context->bitcount[0] >> 3) % SHA512_BLOCK_LENGTH;
  #if BYTE_ORDER == LITTLE_ENDIAN
      /* Convert FROM host byte order */
      REVERSE64(context->bitcount[0], context->bitcount[0]);
      REVERSE64(context->bitcount[1], context->bitcount[1]);
  #endif
      if (usedspace > 0) {
          /* Begin padding with a 1 bit: */
          context->buffer[usedspace++] = 0x80;
  
          if (usedspace <= SHA512_SHORT_BLOCK_LENGTH) {
              /* Set-up for the last transform: */
              MEMSET_BZERO(&context->buffer[usedspace], SHA512_SHORT_BLOCK_LENGTH - usedspace);
          } else {
              if (usedspace < SHA512_BLOCK_LENGTH) {
                  MEMSET_BZERO(&context->buffer[usedspace], SHA512_BLOCK_LENGTH - usedspace);
              }
              /* Do second-to-last transform: */
              sha512_Transform(context, (sha2_word64 *)context->buffer);
  
              /* And set-up for the last transform: */
              MEMSET_BZERO(context->buffer, SHA512_BLOCK_LENGTH - 2);
          }
      } else {
          /* Prepare for final transform: */
          MEMSET_BZERO(context->buffer, SHA512_SHORT_BLOCK_LENGTH);
  
          /* Begin padding with a 1 bit: */
          *context->buffer = 0x80;
      }
      /* Store the length of input data (in bits): */
      sha2_word64 *t;
      t = (sha2_word64 *)&context->buffer[SHA512_SHORT_BLOCK_LENGTH];
      *t = context->bitcount[1];
      t = (sha2_word64 *)&context->buffer[SHA512_SHORT_BLOCK_LENGTH + 8];
      *t = context->bitcount[0];
  
      /* Final transform: */
      sha512_Transform(context, (sha2_word64 *)context->buffer);
  }
  
  void sha512_Final(sha2_byte digest[], SHA512_CTX *context)
  {
      sha2_word64 *d = (sha2_word64 *)digest;
  
      /* If no digest buffer is passed, we don't bother doing this: */
      if (digest != (sha2_byte *)0) {
          sha512_Last(context);
  
          /* Save the hash data for output: */
  #if BYTE_ORDER == LITTLE_ENDIAN
          {
              /* Convert TO host byte order */
              int j;
              for (j = 0; j < 8; j++) {
                  REVERSE64(context->state[j], context->state[j]);
                  *d++ = context->state[j];
              }
          }
  #else
          MEMCPY_BCOPY(d, context->state, SHA512_DIGEST_LENGTH);
  #endif
      }
  
      /* Zero out state data */
      MEMSET_BZERO(context, sizeof(SHA512_CTX));
  }
  
  char *sha512_End(SHA512_CTX *context, char buffer[])
  {
      sha2_byte   digest[SHA512_DIGEST_LENGTH], *d = digest;
  
      if (buffer != (char *)0) {
          sha512_Final(digest, context);
  
          for (int i = 0; i < SHA512_DIGEST_LENGTH; i++) {
              *buffer++ = sha2_hex_digits[(*d & 0xf0) >> 4];
              *buffer++ = sha2_hex_digits[*d & 0x0f];
              d++;
          }
          *buffer = (char)0;
      } else {
          MEMSET_BZERO(context, sizeof(SHA512_CTX));
      }
      MEMSET_BZERO(digest, SHA512_DIGEST_LENGTH);
      return buffer;
  }
  
  void sha512_Raw(const sha2_byte *data, size_t len, uint8_t digest[SHA512_DIGEST_LENGTH])
  {
      SHA512_CTX  context;
      sha512_Init(&context);
      sha512_Update(&context, data, len);
      sha512_Final(digest, &context);
  }
  
  char *sha512_Data(const sha2_byte *data, size_t len,
                    char digest[SHA512_DIGEST_STRING_LENGTH])
  {
      SHA512_CTX  context;
  
      sha512_Init(&context);
      sha512_Update(&context, data, len);
      return sha512_End(&context, digest);
  }
  