//$Header$
//-------------------------------------------------------------------------------------------------
//This file is part of "David T. Ashley's Shared Source Code", a set of shared components
//integrated into many of David T. Ashley's projects.
//-------------------------------------------------------------------------------------------------
//This source code and any program in which it is compiled/used is provided under the MIT License,
//reproduced below.
//-------------------------------------------------------------------------------------------------
//Permission is hereby granted, free of charge, to any person obtaining a copy of
//this software and associated documentation files(the "Software"), to deal in the
//Software without restriction, including without limitation the rights to use,
//copy, modify, merge, publish, distribute, sublicense, and / or sell copies of the
//Software, and to permit persons to whom the Software is furnished to do so,
//subject to the following conditions :
//
//The above copyright notice and this permission notice shall be included in all
//copies or substantial portions of the Software.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//SOFTWARE.
//-------------------------------------------------------------------------------------------------
#define MODULE_ESRG_SHA512

#include <assert.h>
#include <stddef.h>
#include <string.h>

#include "charfunc.h"
#include "esrg_sha512.h"

//This is a right rotation macro for efficiency.  This
//macro rotates a 64-bit quantity x right (cyclically) by 
//n bits.  Nomenclature from FIPS 180-3.
#define ESRG_SHA512_FUNC_ROTR(x, n) (((x) >> (n)) | ((x) << (64-(n))))

//This is a right shift macro for efficiency.  This
//macro shifts a 64-bit quantity x right by 
//n bits.  Nomenclature from FIPS 180-3.
#define ESRG_SHA512_FUNC_SHR(x, n) ((x) >> (n))

//These functions come directly from FIPS 180-3.
#define ESRG_SHA512_FUNC_CH(x, y, z)  (((x) & (y)) ^ (~(x) & (z)))
#define ESRG_SHA512_FUNC_MAJ(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define ESRG_SHA512_FUNC_SIGMABIG_0(x) (ESRG_SHA512_FUNC_ROTR(x, 28) ^ ESRG_SHA512_FUNC_ROTR(x, 34) ^ ESRG_SHA512_FUNC_ROTR(x, 39))
#define ESRG_SHA512_FUNC_SIGMABIG_1(x) (ESRG_SHA512_FUNC_ROTR(x, 14) ^ ESRG_SHA512_FUNC_ROTR(x, 18) ^ ESRG_SHA512_FUNC_ROTR(x, 41))
#define ESRG_SHA512_FUNC_SIGMASMALL_0(x) (ESRG_SHA512_FUNC_ROTR(x,  1) ^ ESRG_SHA512_FUNC_ROTR(x,  8) ^ ESRG_SHA512_FUNC_SHR(x,  7))
#define ESRG_SHA512_FUNC_SIGMASMALL_1(x) (ESRG_SHA512_FUNC_ROTR(x, 19) ^ ESRG_SHA512_FUNC_ROTR(x, 61) ^ ESRG_SHA512_FUNC_SHR(x,  6))

//Constants, from FIPS 180-3.
const unsigned __int64 ESRG_SHA512_K[80] =
            {0x428a2f98d728ae22UL, 0x7137449123ef65cdUL,
             0xb5c0fbcfec4d3b2fUL, 0xe9b5dba58189dbbcUL,
             0x3956c25bf348b538UL, 0x59f111f1b605d019UL,
             0x923f82a4af194f9bUL, 0xab1c5ed5da6d8118UL,
             0xd807aa98a3030242UL, 0x12835b0145706fbeUL,
             0x243185be4ee4b28cUL, 0x550c7dc3d5ffb4e2UL,
             0x72be5d74f27b896fUL, 0x80deb1fe3b1696b1UL,
             0x9bdc06a725c71235UL, 0xc19bf174cf692694UL,
             0xe49b69c19ef14ad2UL, 0xefbe4786384f25e3UL,
             0x0fc19dc68b8cd5b5UL, 0x240ca1cc77ac9c65UL,
             0x2de92c6f592b0275UL, 0x4a7484aa6ea6e483UL,
             0x5cb0a9dcbd41fbd4UL, 0x76f988da831153b5UL,
             0x983e5152ee66dfabUL, 0xa831c66d2db43210UL,
             0xb00327c898fb213fUL, 0xbf597fc7beef0ee4UL,
             0xc6e00bf33da88fc2UL, 0xd5a79147930aa725UL,
             0x06ca6351e003826fUL, 0x142929670a0e6e70UL,
             0x27b70a8546d22ffcUL, 0x2e1b21385c26c926UL,
             0x4d2c6dfc5ac42aedUL, 0x53380d139d95b3dfUL,
             0x650a73548baf63deUL, 0x766a0abb3c77b2a8UL,
             0x81c2c92e47edaee6UL, 0x92722c851482353bUL,
             0xa2bfe8a14cf10364UL, 0xa81a664bbc423001UL,
             0xc24b8b70d0f89791UL, 0xc76c51a30654be30UL,
             0xd192e819d6ef5218UL, 0xd69906245565a910UL,
             0xf40e35855771202aUL, 0x106aa07032bbd1b8UL,
             0x19a4c116b8d2d0c8UL, 0x1e376c085141ab53UL,
             0x2748774cdf8eeb99UL, 0x34b0bcb5e19b48a8UL,
             0x391c0cb3c5c95a63UL, 0x4ed8aa4ae3418acbUL,
             0x5b9cca4f7763e373UL, 0x682e6ff3d6b2b8a3UL,
             0x748f82ee5defb2fcUL, 0x78a5636f43172f60UL,
             0x84c87814a1f0ab72UL, 0x8cc702081a6439ecUL,
             0x90befffa23631e28UL, 0xa4506cebde82bde9UL,
             0xbef9a3f7b2c67915UL, 0xc67178f2e372532bUL,
             0xca273eceea26619cUL, 0xd186b8c721c0c207UL,
             0xeada7dd6cde0eb1eUL, 0xf57d4f7fee6ed178UL,
             0x06f067aa72176fbaUL, 0x0a637dc5a2c898a6UL,
             0x113f9804bef90daeUL, 0x1b710b35131c471bUL,
             0x28db77f523047d84UL, 0x32caab7b40c72493UL,
             0x3c9ebe0a15c9bebcUL, 0x431d67c49c100d4cUL,
             0x4cc5d4becb3e42b6UL, 0x597f299cfc657e2aUL,
             0x5fcb6fab3ad6faecUL, 0x6c44198c4a475817UL};


void ESRG_SHA512_Sha512StateStructOpen(struct ESRG_SHA512_Sha512StateStruct *arg)
   {
   assert(arg != NULL);

   memset(arg, 0, sizeof(struct ESRG_SHA512_Sha512StateStruct));
      //Everything to zero, processed bitcount automatically set to zero.

   //This assignment comes directly from FIPS 180-3.
   arg->H0 = 0x6a09e667f3bcc908UL;
   arg->H1 = 0xbb67ae8584caa73bUL;
   arg->H2 = 0x3c6ef372fe94f82bUL;
   arg->H3 = 0xa54ff53a5f1d36f1UL;
   arg->H4 = 0x510e527fade682d1UL;
   arg->H5 = 0x9b05688c2b3e6c1fUL;
   arg->H6 = 0x1f83d9abfb41bd6bUL;
   arg->H7 = 0x5be0cd19137e2179UL;
   }


//Copies the byte buffer to the word buffer within the state block.
//This is done in a way which hides big-endian/little-endian concerns.
//
static void ESRG_SHA512_CopyBytesToWords(struct ESRG_SHA512_Sha512StateStruct *arg)
   {
   unsigned int i;

   assert(arg != NULL);

   //Copy the buffer contents into the words.  We need to be careful
   //to do this correctly, because of big-endian/little-endian concerns.
   //From FIPS 180-3 (alluded to, not really stated), the message is
   //loaded in from M[0] down to M[15].  Additionally, per the other
   //conventions in the document, the first byte is uppermost in each
   //word.
   for (i=0; i<16; i++)
      {
      assert((i * 8 + 3) < 128);
      arg->M[i] = (((unsigned __int64)(arg->buf[i*8+0])) << 56)
                  +
                  (((unsigned __int64)(arg->buf[i*8+1])) << 48)
                  +
                  (((unsigned __int64)(arg->buf[i*8+2])) << 40)
                  +
                  (((unsigned __int64)(arg->buf[i*8+3])) << 32)
                  +
                  (((unsigned __int64)(arg->buf[i*8+4])) << 24)
                  +
                  (((unsigned __int64)(arg->buf[i*8+5])) << 16)
                  +
                  (((unsigned __int64)(arg->buf[i*8+6])) <<  8)
                  +
                  (((unsigned __int64)(arg->buf[i*8+7])));
      }
   }


//Copies the buffer of words into a string buffer of string length 128, and also places
//the zero terminator, which means that the string supplied by the caller must be of size
//129 or larger.
//
static void ESRG_SHA512_CopyWordsToStringBuffer(struct ESRG_SHA512_Sha512ResultStruct *arg)
   {
   unsigned int i, j;
   unsigned char *puc;
   unsigned __int64 woi;

   assert(arg != NULL);

   //Copy the buffer contents into the words.  We need to be careful
   //to do this correctly, because of big-endian/little-endian concerns.
   //From FIPS 180-3 (alluded to, not really stated), the message is
   //loaded in from M[0] down to M[15].  Additionally, per the other
   //conventions in the document, the first byte is uppermost in each
   //word.
   for (i=0; i<8; i++)
      {
      woi = arg->sha512_words[i];

	  //Form a pointer to the buffer location of interest.  We work
	  //backwards.
	  puc = (unsigned char *)(arg->sha512_chars) + (i * 16) + 15;

	  //Fill in the buffer.
      for (j=0; j<16; j++)
	    {
        *puc = (unsigned char)CHARFUNC_nibble_to_lc_hex_digit((int)(woi & 0xF));
		woi >>= 4;
		puc--;
	    }
      }

   //Place the zero string terminator.
   arg->sha512_chars[128] = 0;
   }


//Does the SHA-512 rounds as specified by FIPS 180-3.

static void ESRG_SHA512_DoSha512Rounds(struct ESRG_SHA512_Sha512StateStruct *arg)
   {
   int i;
      //Iteration variable.
   unsigned __int64 T1, T2;
      //Temporary variables.  Nomenclature is from FIPS 180-3.
   unsigned __int64 M[16];
      //Buffer of message block to avoid repeated dereferences.
   unsigned __int64 H[8];
      //Buffer of hash state to avoid repeated dereferences.
   unsigned __int64 W[80];
      //Working variable.  Nomenclature directly from FIPS 180-3.
   unsigned __int64 a, b, c, d, e, f, g, h;
      //Nomenclature above directly from FIPS 180-3.

   assert(arg != NULL);

   //Copy bytes into words.
   ESRG_SHA512_CopyBytesToWords(arg);

   //Copy out the message buffer for speed.  This should avoid repeated
   //dereferences.
   M[ 0] = arg->M[ 0];
   M[ 1] = arg->M[ 1];
   M[ 2] = arg->M[ 2];
   M[ 3] = arg->M[ 3];
   M[ 4] = arg->M[ 4];
   M[ 5] = arg->M[ 5];
   M[ 6] = arg->M[ 6];
   M[ 7] = arg->M[ 7];
   M[ 8] = arg->M[ 8];
   M[ 9] = arg->M[ 9];
   M[10] = arg->M[10];
   M[11] = arg->M[11];
   M[12] = arg->M[12];
   M[13] = arg->M[13];
   M[14] = arg->M[14];
   M[15] = arg->M[15];

   //Copy out the hash state for speed.  This should avoid repeated dereferences.
   H[0]  = arg->H0;
   H[1]  = arg->H1;
   H[2]  = arg->H2;
   H[3]  = arg->H3;
   H[4]  = arg->H4;
   H[5]  = arg->H5;
   H[6]  = arg->H6;
   H[7]  = arg->H7;

   //Prepare the message schedule.  The nomenclature comes directly from FIPS 180-3.
   W[ 0] = M[ 0];
   W[ 1] = M[ 1];
   W[ 2] = M[ 2];
   W[ 3] = M[ 3];
   W[ 4] = M[ 4];
   W[ 5] = M[ 5];
   W[ 6] = M[ 6];
   W[ 7] = M[ 7];
   W[ 8] = M[ 8];
   W[ 9] = M[ 9];
   W[10] = M[10];
   W[11] = M[11];
   W[12] = M[12];
   W[13] = M[13];
   W[14] = M[14];
   W[15] = M[15];

   for (i=16; i<80; i++)
      {
      W[i] =    ESRG_SHA512_FUNC_SIGMASMALL_1(W[i-2])
		     +  W[i-7]
	         +  ESRG_SHA512_FUNC_SIGMASMALL_0(W[i-15])
			 +  W[i-16];
      }

   //Initialize the 8 working variables as specified in FIPS 180-3.
   a = H[0];
   b = H[1];
   c = H[2];
   d = H[3];
   e = H[4];
   f = H[5];
   g = H[6];
   h = H[7];

   //Perform the rounds as specified in FIPS 180-3.  Nomenclature below comes from 
   //FIPS 180-3.
   for (i=0; i<80; i++)
      {
      T1 =    h 
		    + ESRG_SHA512_FUNC_SIGMABIG_1(e) 
			+ ESRG_SHA512_FUNC_CH(e, f, g)
			+ ESRG_SHA512_K[i]
	        + W[i];
	  //
      T2 =    ESRG_SHA512_FUNC_SIGMABIG_0(a)
            + ESRG_SHA512_FUNC_MAJ(a, b, c);
      //
	  h = g;
	  //
	  g = f;
	  //
	  f = e;
	  //
	  e = d + T1;
	  //
	  d = c;
	  //
	  c = b;
	  //
	  b = a;
	  //
	  a = T1 + T2;
      }

   //Compute the next hash value.  The nomenclature comes from FIPS 180-3.
   H[0] = a + H[0];
   H[1] = b + H[1];
   H[2] = c + H[2];
   H[3] = d + H[3];
   H[4] = e + H[4];
   H[5] = f + H[5];
   H[6] = g + H[6];
   H[7] = h + H[7];

   //Place the local variables back in the structure.  This the only state that
   //gets preserved between the operation of doing the rounds.
   arg->H0 = H[0];
   arg->H1 = H[1];
   arg->H2 = H[2];
   arg->H3 = H[3];
   arg->H4 = H[4];
   arg->H5 = H[5];
   arg->H6 = H[6];
   arg->H7 = H[7];
   }


void ESRG_SHA512_Sha512StateStructAddData(struct    ESRG_SHA512_Sha512StateStruct *arg,
                                          void      *pointer_in,
                                          unsigned  len)
   {
   unsigned int   low_32;
   unsigned int   byte_offset;
   unsigned char *data;

   assert(arg        != NULL);
   assert(pointer_in != NULL);

   data = (unsigned char *)pointer_in;
      //It is easier to do it this way, rather than cast all the time.

   low_32 = (unsigned int)arg->bit_count;
      //Copy off the least significant bits.  Easier to do once.  We only
      //need the 32 least significant because the block size is 0 modulo 1024.

   byte_offset = low_32 >> 3;
      //This gives our byte offset, up to 500+Mb or so.

   while(len--)
      {
      //We process rounds AFTER a byte is added to the buffer.  So
      //it is always safe to add a byte first.
      arg->buf[byte_offset & 0x7F] = *data;

      //Nothing to do unless this was the final byte of the buffer.
      if ((byte_offset & 0x7F) == 127)
         {
         ESRG_SHA512_DoSha512Rounds(arg);
         }

      //Increment.
      data++;
      byte_offset++;
      arg->bit_count += 8;
      }
   }


void ESRG_SHA512_Sha512StateStructClose(struct ESRG_SHA512_Sha512StateStruct  *state,
                                        struct ESRG_SHA512_Sha512ResultStruct *result)
   {
   unsigned __int64 msglen;
      //Used to hold message length before we pad the message.
   unsigned char c80 = 0x80;
      //Used to append the "1" per FIPS 180-3.
   unsigned char c00 = 0x00;
      //Used to add 0's per FIPS 180-3.
   unsigned char  length_buf[16];
      //Buffer used to form the message length and append it to the message per FIPS 180-3.

   //Be sure the input pointers aren't obviously invalid.
   assert(state  != NULL);
   assert(result != NULL);

   //Snapshot the message length.  We'll be changing it when we pad the message.
   msglen = state->bit_count;

   //Add the required "1" to the end of the message, per FIPS 180-3.  Because
   //this software module only allows the addition of bytes (not bits), adding the
   //"1" will always involve adding the byte 0x80.
   ESRG_SHA512_Sha512StateStructAddData(state, &c80, 1);

   //Add enough 0's to the message so that we have exactly room for 16 bytes (128 bits)
   //of length information at the end of the message.
   while ((state->bit_count & 0x3FF) != 896)
      ESRG_SHA512_Sha512StateStructAddData(state, &c00, 1);

   //Calculate the length as a series of bytes.
   length_buf[ 0] = 0;
   length_buf[ 1] = 0;
   length_buf[ 2] = 0;
   length_buf[ 3] = 0;
   length_buf[ 4] = 0;
   length_buf[ 5] = 0;
   length_buf[ 6] = 0;
   length_buf[ 7] = 0;
   length_buf[ 8] = (unsigned char)((msglen >> 56) & 0xFF);
   length_buf[ 9] = (unsigned char)((msglen >> 48) & 0xFF);
   length_buf[10] = (unsigned char)((msglen >> 40) & 0xFF);
   length_buf[11] = (unsigned char)((msglen >> 32) & 0xFF);
   length_buf[12] = (unsigned char)((msglen >> 24) & 0xFF);
   length_buf[13] = (unsigned char)((msglen >> 16) & 0xFF);
   length_buf[14] = (unsigned char)((msglen >>  8) & 0xFF);
   length_buf[15] = (unsigned char)((msglen) & 0xFF);

   //Add the length to the message.  This should work out to generate the
   //final manipulation round.
   ESRG_SHA512_Sha512StateStructAddData(state, length_buf, 16);

   //Copy the words from the state vector to the result vector.
   result->sha512_words[0] = state->H0;
   result->sha512_words[1] = state->H1;
   result->sha512_words[2] = state->H2;
   result->sha512_words[3] = state->H3;
   result->sha512_words[4] = state->H4;
   result->sha512_words[5] = state->H5;
   result->sha512_words[6] = state->H6;
   result->sha512_words[7] = state->H7;

   //Form a string from the hash vector.
   ESRG_SHA512_CopyWordsToStringBuffer(result);

   //Destroy the state, which may contain sensitive information.
   //This idea came from Rivest's sample code.
   memset(state, 0, sizeof(struct ESRG_SHA512_Sha512StateStruct));
   }


//Returns version control string for file.
//
const char *ESRG_SHA512_cvcinfo(void)
   {   
   return ("$Header$");
   }


//Returns version control string for associated .H file.
//
const char *ESRG_SHA512_hvcinfo(void)
   {   
   return (ESRG_SHA512_H_VERSION);
   }

//End of esrg_sha512.c.