/**
 * Implementation of the Lyra2 Password Hashing Scheme (PHS).
 *
 * Author: The Lyra PHC team (http://www.lyra-kdf.net/) -- 2014.
 *
 * This software is hereby placed in the public domain.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''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 AUTHORS OR CONTRIBUTORS 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "Lyra2.h"
#include "Sponge.h"

/**
 * Executes Lyra2 based on the G function from Blake2b. This version supports salts and passwords
 * whose combined length is smaller than the size of the memory matrix, (i.e., (nRows x nCols x b) bits,
 * where "b" is the underlying sponge's bitrate). In this implementation, the "basil" is composed by all
 * integer parameters (treated as type "unsigned int") in the order they are provided, plus the value
 * of nCols, (i.e., basil = kLen || pwdlen || saltlen || timeCost || nRows || nCols).
 *
 * @param K The derived key to be output by the algorithm
 * @param kLen Desired key length
 * @param pwd User password
 * @param pwdlen Password length
 * @param salt Salt
 * @param saltlen Salt length
 * @param timeCost Parameter to determine the processing time (T)
 * @param nRows Number or rows of the memory matrix (R)
 * @param nCols Number of columns of the memory matrix (C)
 *
 * @return 0 if the key is generated correctly; -1 if there is an error (usually due to lack of memory for allocation)
 */
int LYRA2(void *K, uint64_t kLen, const void *pwd, uint64_t pwdlen, const void *salt, uint64_t saltlen, uint64_t timeCost, uint64_t nRows, uint64_t nCols) {

    //============================= Basic variables ============================//
    int64_t row = 2; //index of row to be processed
    int64_t prev = 1; //index of prev (last row ever computed/modified)
    int64_t rowa = 0; //index of row* (a previous row, deterministically picked during Setup and randomly picked while Wandering)
    int64_t tau; //Time Loop iterator
    int64_t step = 1; //Visitation step (used during Setup and Wandering phases)
    int64_t window = 2; //Visitation window (used to define which rows can be revisited during Setup)
    int64_t gap = 1; //Modifier to the step, assuming the values 1 or -1
    int64_t i; //auxiliary iteration counter
    uint64_t *wholeMatrix;
    uint64_t **memMatrix = malloc(nRows * sizeof (uint64_t*));
    uint64_t *ptrWord;
    uint64_t nBlocksInput = ((saltlen + pwdlen + 6 * sizeof (uint64_t)) / BLOCK_LEN_BLAKE2_SAFE_BYTES) + 1;
    byte *ptrByte;
    uint64_t *state;
    //==========================================================================/

    //========== Initializing the Memory Matrix and pointers to it =============//
    //Tries to allocate enough space for the whole memory matrix
    i = (int64_t) ((int64_t) nRows * (int64_t) ROW_LEN_BYTES);
    wholeMatrix = malloc(i);
    if (wholeMatrix == NULL) {
      return -1;
    }
    memset(wholeMatrix, 0, i);

    //Allocates pointers to each row of the matrix
    if (memMatrix == NULL) {
      return -1;
    }
    //Places the pointers in the correct positions
    ptrWord = wholeMatrix;
    for (i = 0; i < nRows; i++) {
      memMatrix[i] = ptrWord;
      ptrWord += ROW_LEN_INT64;
    }
    //==========================================================================/

    //============= Getting the password + salt + basil padded with 10*1 ===============//
    //OBS.:The memory matrix will temporarily hold the password: not for saving memory,
    //but this ensures that the password copied locally will be overwritten as soon as possible

    //First, we clean enough blocks for the password, salt, basil and padding
    
    memset(ptrByte, 0, nBlocksInput * BLOCK_LEN_BLAKE2_SAFE_BYTES);

    //Prepends the password
    ptrByte = (byte*) wholeMatrix;
    memcpy(ptrByte, pwd, pwdlen);
    ptrByte += pwdlen;

    //Concatenates the salt
    memcpy(ptrByte, salt, saltlen);
    ptrByte += saltlen;

    //Concatenates the basil: every integer passed as parameter, in the order they are provided by the interface
    memcpy(ptrByte, &kLen, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);
    memcpy(ptrByte, &pwdlen, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);
    memcpy(ptrByte, &saltlen, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);
    memcpy(ptrByte, &timeCost, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);
    memcpy(ptrByte, &nRows, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);
    memcpy(ptrByte, &nCols, sizeof (uint64_t));
    ptrByte += sizeof (uint64_t);

    //Now comes the padding
    *ptrByte = 0x80; //first byte of padding: right after the password
    ptrByte = (byte*) wholeMatrix; //resets the pointer to the start of the memory matrix
    ptrByte += nBlocksInput * BLOCK_LEN_BLAKE2_SAFE_BYTES - 1; //sets the pointer to the correct position: end of incomplete block
    *ptrByte ^= 0x01; //last byte of padding: at the end of the last incomplete block
    //==========================================================================/

    //======================= Initializing the Sponge State ====================//
    //Sponge state: 16 uint64_t, BLOCK_LEN_INT64 words of them for the bitrate (b) and the remainder for the capacity (c)
    state = malloc(16 * sizeof (uint64_t));
    if (state == NULL) {
      return -1;
    }
    initState(state);
    //==========================================================================/

    //================================ Setup Phase =============================//
    //Absorbing salt, password and basil: this is the only place in which the block length is hard-coded to 512 bits
    ptrWord = wholeMatrix;
    for (i = 0; i < nBlocksInput; i++) {
      absorbBlockBlake2Safe(state, ptrWord); //absorbs each block of pad(pwd || salt || basil)
      ptrWord += BLOCK_LEN_BLAKE2_SAFE_BYTES; //goes to next block of pad(pwd || salt || basil)
    }

    //Initializes M[0] and M[1]
    reducedSqueezeRow0(state, memMatrix[0]); //The locally copied password is most likely overwritten here
    reducedDuplexRow1(state, memMatrix[0], memMatrix[1]);

    do {
      //M[row] = rand; //M[row*] = M[row*] XOR rotW(rand)
      reducedDuplexRowSetup(state, memMatrix[prev], memMatrix[rowa], memMatrix[row]);


      //updates the value of row* (deterministically picked during Setup))
      rowa = (rowa + step) & (window - 1);
      //update prev: it now points to the last row ever computed
      prev = row;
      //updates row: goes to the next row to be computed
      row++;

      //Checks if all rows in the window where visited.
      if (rowa == 0) {
      step = window + gap; //changes the step: approximately doubles its value
      window *= 2; //doubles the size of the re-visitation window
      gap = -gap; //inverts the modifier to the step
    }

    } while (row < nRows);
    //==========================================================================/

    //============================ Wandering Phase =============================//
    row = 0; //Resets the visitation to the first row of the memory matrix
    for (tau = 1; tau <= timeCost; tau++) {
    	//Step is approximately half the number of all rows of the memory matrix for an odd tau; otherwise, it is -1
    	step = (tau % 2 == 0) ? -1 : nRows / 2 - 1;
    	do {
  	    //Selects a pseudorandom index row*
  	    //------------------------------------------------------------------------------------------
  	    //rowa = ((unsigned int)state[0]) & (nRows-1);	//(USE THIS IF nRows IS A POWER OF 2)
  	    rowa = ((uint64_t) (state[0])) % nRows; //(USE THIS FOR THE "GENERIC" CASE)
  	    //------------------------------------------------------------------------------------------

  	    //Performs a reduced-round duplexing operation over M[row*] XOR M[prev], updating both M[row*] and M[row]
  	    reducedDuplexRow(state, memMatrix[prev], memMatrix[rowa], memMatrix[row]);

  	    //update prev: it now points to the last row ever computed
  	    prev = row;

  	    //updates row: goes to the next row to be computed
  	    //------------------------------------------------------------------------------------------
  	    //row = (row + step) & (nRows-1);	//(USE THIS IF nRows IS A POWER OF 2)
  	    row = (row + step) % nRows; //(USE THIS FOR THE "GENERIC" CASE)
  	    //------------------------------------------------------------------------------------------

      } while (row != 0);
    }
    //==========================================================================/

    //============================ Wrap-up Phase ===============================//
    //Absorbs the last block of the memory matrix
    absorbBlock(state, memMatrix[rowa]);

    //Squeezes the key
    squeeze(state, K, kLen);
    //==========================================================================/

    //========================= Freeing the memory =============================//
    free(memMatrix);
    free(wholeMatrix);

    //Wiping out the sponge's internal state before freeing it
    memset(state, 0, 16 * sizeof (uint64_t));
    free(state);
    //==========================================================================/

    return 0;
}
