/* Based on the public domain implementation in crypto_hash/keccakc512/simple/ from
 * http://bench.cr.yp.to/supercop.html by Ronny Van Keer and the public domain "TweetFips202"
 * implementation from https://twitter.com/tweetfips202 by Gilles Van Assche, Daniel J. Bernstein,
 * and Peter Schwabe */

#include <stddef.h>
#include <stdint.h>
#include "fips202.h"

#define NROUNDS 24
#define ROL(a, offset) ((a << offset) ^ (a >> (64-offset)))

/*************************************************
* Name:        load64
*
* Description: Load 8 bytes into uint64_t in little-endian order
*
* Arguments:   - const uint8_t *x: pointer to input byte array
*
* Returns the loaded 64-bit unsigned integer
**************************************************/
static uint64_t load64(const uint8_t x[8]) {
  unsigned int i;
  uint64_t r = 0;

  for(i=0;i<8;i++)
    r |= (uint64_t)x[i] << 8*i;

  return r;
}

/*************************************************
* Name:        store64
*
* Description: Store a 64-bit integer to array of 8 bytes in little-endian order
*
* Arguments:   - uint8_t *x: pointer to the output byte array (allocated)
*              - uint64_t u: input 64-bit unsigned integer
**************************************************/
static void store64(uint8_t x[8], uint64_t u) {
  unsigned int i;

  for(i=0;i<8;i++)
    x[i] = u >> 8*i;
}

/* Keccak round constants */
const uint64_t KeccakF_RoundConstants[NROUNDS] = {
  (uint64_t)0x0000000000000001ULL,
  (uint64_t)0x0000000000008082ULL,
  (uint64_t)0x800000000000808aULL,
  (uint64_t)0x8000000080008000ULL,
  (uint64_t)0x000000000000808bULL,
  (uint64_t)0x0000000080000001ULL,
  (uint64_t)0x8000000080008081ULL,
  (uint64_t)0x8000000000008009ULL,
  (uint64_t)0x000000000000008aULL,
  (uint64_t)0x0000000000000088ULL,
  (uint64_t)0x0000000080008009ULL,
  (uint64_t)0x000000008000000aULL,
  (uint64_t)0x000000008000808bULL,
  (uint64_t)0x800000000000008bULL,
  (uint64_t)0x8000000000008089ULL,
  (uint64_t)0x8000000000008003ULL,
  (uint64_t)0x8000000000008002ULL,
  (uint64_t)0x8000000000000080ULL,
  (uint64_t)0x000000000000800aULL,
  (uint64_t)0x800000008000000aULL,
  (uint64_t)0x8000000080008081ULL,
  (uint64_t)0x8000000000008080ULL,
  (uint64_t)0x0000000080000001ULL,
  (uint64_t)0x8000000080008008ULL
};

/*************************************************
* Name:        KeccakF1600_StatePermute
*
* Description: The Keccak F1600 Permutation
*
* Arguments:   - uint64_t *state: pointer to input/output Keccak state
**************************************************/
static void KeccakF1600_StatePermute(uint64_t state[25])
{
        int round;

        uint64_t Aba, Abe, Abi, Abo, Abu;
        uint64_t Aga, Age, Agi, Ago, Agu;
        uint64_t Aka, Ake, Aki, Ako, Aku;
        uint64_t Ama, Ame, Ami, Amo, Amu;
        uint64_t Asa, Ase, Asi, Aso, Asu;
        uint64_t BCa, BCe, BCi, BCo, BCu;
        uint64_t Da, De, Di, Do, Du;
        uint64_t Eba, Ebe, Ebi, Ebo, Ebu;
        uint64_t Ega, Ege, Egi, Ego, Egu;
        uint64_t Eka, Eke, Eki, Eko, Eku;
        uint64_t Ema, Eme, Emi, Emo, Emu;
        uint64_t Esa, Ese, Esi, Eso, Esu;

        //copyFromState(A, state)
        Aba = state[ 0];
        Abe = state[ 1];
        Abi = state[ 2];
        Abo = state[ 3];
        Abu = state[ 4];
        Aga = state[ 5];
        Age = state[ 6];
        Agi = state[ 7];
        Ago = state[ 8];
        Agu = state[ 9];
        Aka = state[10];
        Ake = state[11];
        Aki = state[12];
        Ako = state[13];
        Aku = state[14];
        Ama = state[15];
        Ame = state[16];
        Ami = state[17];
        Amo = state[18];
        Amu = state[19];
        Asa = state[20];
        Ase = state[21];
        Asi = state[22];
        Aso = state[23];
        Asu = state[24];

        for(round = 0; round < NROUNDS; round += 2) {
            //    prepareTheta
            BCa = Aba^Aga^Aka^Ama^Asa;
            BCe = Abe^Age^Ake^Ame^Ase;
            BCi = Abi^Agi^Aki^Ami^Asi;
            BCo = Abo^Ago^Ako^Amo^Aso;
            BCu = Abu^Agu^Aku^Amu^Asu;

            //thetaRhoPiChiIotaPrepareTheta(round, A, E)
            Da = BCu^ROL(BCe, 1);
            De = BCa^ROL(BCi, 1);
            Di = BCe^ROL(BCo, 1);
            Do = BCi^ROL(BCu, 1);
            Du = BCo^ROL(BCa, 1);

            Aba ^= Da;
            BCa = Aba;
            Age ^= De;
            BCe = ROL(Age, 44);
            Aki ^= Di;
            BCi = ROL(Aki, 43);
            Amo ^= Do;
            BCo = ROL(Amo, 21);
            Asu ^= Du;
            BCu = ROL(Asu, 14);
            Eba =   BCa ^((~BCe)&  BCi );
            Eba ^= (uint64_t)KeccakF_RoundConstants[round];
            Ebe =   BCe ^((~BCi)&  BCo );
            Ebi =   BCi ^((~BCo)&  BCu );
            Ebo =   BCo ^((~BCu)&  BCa );
            Ebu =   BCu ^((~BCa)&  BCe );

            Abo ^= Do;
            BCa = ROL(Abo, 28);
            Agu ^= Du;
            BCe = ROL(Agu, 20);
            Aka ^= Da;
            BCi = ROL(Aka,  3);
            Ame ^= De;
            BCo = ROL(Ame, 45);
            Asi ^= Di;
            BCu = ROL(Asi, 61);
            Ega =   BCa ^((~BCe)&  BCi );
            Ege =   BCe ^((~BCi)&  BCo );
            Egi =   BCi ^((~BCo)&  BCu );
            Ego =   BCo ^((~BCu)&  BCa );
            Egu =   BCu ^((~BCa)&  BCe );

            Abe ^= De;
            BCa = ROL(Abe,  1);
            Agi ^= Di;
            BCe = ROL(Agi,  6);
            Ako ^= Do;
            BCi = ROL(Ako, 25);
            Amu ^= Du;
            BCo = ROL(Amu,  8);
            Asa ^= Da;
            BCu = ROL(Asa, 18);
            Eka =   BCa ^((~BCe)&  BCi );
            Eke =   BCe ^((~BCi)&  BCo );
            Eki =   BCi ^((~BCo)&  BCu );
            Eko =   BCo ^((~BCu)&  BCa );
            Eku =   BCu ^((~BCa)&  BCe );

            Abu ^= Du;
            BCa = ROL(Abu, 27);
            Aga ^= Da;
            BCe = ROL(Aga, 36);
            Ake ^= De;
            BCi = ROL(Ake, 10);
            Ami ^= Di;
            BCo = ROL(Ami, 15);
            Aso ^= Do;
            BCu = ROL(Aso, 56);
            Ema =   BCa ^((~BCe)&  BCi );
            Eme =   BCe ^((~BCi)&  BCo );
            Emi =   BCi ^((~BCo)&  BCu );
            Emo =   BCo ^((~BCu)&  BCa );
            Emu =   BCu ^((~BCa)&  BCe );

            Abi ^= Di;
            BCa = ROL(Abi, 62);
            Ago ^= Do;
            BCe = ROL(Ago, 55);
            Aku ^= Du;
            BCi = ROL(Aku, 39);
            Ama ^= Da;
            BCo = ROL(Ama, 41);
            Ase ^= De;
            BCu = ROL(Ase,  2);
            Esa =   BCa ^((~BCe)&  BCi );
            Ese =   BCe ^((~BCi)&  BCo );
            Esi =   BCi ^((~BCo)&  BCu );
            Eso =   BCo ^((~BCu)&  BCa );
            Esu =   BCu ^((~BCa)&  BCe );

            //    prepareTheta
            BCa = Eba^Ega^Eka^Ema^Esa;
            BCe = Ebe^Ege^Eke^Eme^Ese;
            BCi = Ebi^Egi^Eki^Emi^Esi;
            BCo = Ebo^Ego^Eko^Emo^Eso;
            BCu = Ebu^Egu^Eku^Emu^Esu;

            //thetaRhoPiChiIotaPrepareTheta(round+1, E, A)
            Da = BCu^ROL(BCe, 1);
            De = BCa^ROL(BCi, 1);
            Di = BCe^ROL(BCo, 1);
            Do = BCi^ROL(BCu, 1);
            Du = BCo^ROL(BCa, 1);

            Eba ^= Da;
            BCa = Eba;
            Ege ^= De;
            BCe = ROL(Ege, 44);
            Eki ^= Di;
            BCi = ROL(Eki, 43);
            Emo ^= Do;
            BCo = ROL(Emo, 21);
            Esu ^= Du;
            BCu = ROL(Esu, 14);
            Aba =   BCa ^((~BCe)&  BCi );
            Aba ^= (uint64_t)KeccakF_RoundConstants[round+1];
            Abe =   BCe ^((~BCi)&  BCo );
            Abi =   BCi ^((~BCo)&  BCu );
            Abo =   BCo ^((~BCu)&  BCa );
            Abu =   BCu ^((~BCa)&  BCe );

            Ebo ^= Do;
            BCa = ROL(Ebo, 28);
            Egu ^= Du;
            BCe = ROL(Egu, 20);
            Eka ^= Da;
            BCi = ROL(Eka, 3);
            Eme ^= De;
            BCo = ROL(Eme, 45);
            Esi ^= Di;
            BCu = ROL(Esi, 61);
            Aga =   BCa ^((~BCe)&  BCi );
            Age =   BCe ^((~BCi)&  BCo );
            Agi =   BCi ^((~BCo)&  BCu );
            Ago =   BCo ^((~BCu)&  BCa );
            Agu =   BCu ^((~BCa)&  BCe );

            Ebe ^= De;
            BCa = ROL(Ebe, 1);
            Egi ^= Di;
            BCe = ROL(Egi, 6);
            Eko ^= Do;
            BCi = ROL(Eko, 25);
            Emu ^= Du;
            BCo = ROL(Emu, 8);
            Esa ^= Da;
            BCu = ROL(Esa, 18);
            Aka =   BCa ^((~BCe)&  BCi );
            Ake =   BCe ^((~BCi)&  BCo );
            Aki =   BCi ^((~BCo)&  BCu );
            Ako =   BCo ^((~BCu)&  BCa );
            Aku =   BCu ^((~BCa)&  BCe );

            Ebu ^= Du;
            BCa = ROL(Ebu, 27);
            Ega ^= Da;
            BCe = ROL(Ega, 36);
            Eke ^= De;
            BCi = ROL(Eke, 10);
            Emi ^= Di;
            BCo = ROL(Emi, 15);
            Eso ^= Do;
            BCu = ROL(Eso, 56);
            Ama =   BCa ^((~BCe)&  BCi );
            Ame =   BCe ^((~BCi)&  BCo );
            Ami =   BCi ^((~BCo)&  BCu );
            Amo =   BCo ^((~BCu)&  BCa );
            Amu =   BCu ^((~BCa)&  BCe );

            Ebi ^= Di;
            BCa = ROL(Ebi, 62);
            Ego ^= Do;
            BCe = ROL(Ego, 55);
            Eku ^= Du;
            BCi = ROL(Eku, 39);
            Ema ^= Da;
            BCo = ROL(Ema, 41);
            Ese ^= De;
            BCu = ROL(Ese, 2);
            Asa =   BCa ^((~BCe)&  BCi );
            Ase =   BCe ^((~BCi)&  BCo );
            Asi =   BCi ^((~BCo)&  BCu );
            Aso =   BCo ^((~BCu)&  BCa );
            Asu =   BCu ^((~BCa)&  BCe );
        }

        //copyToState(state, A)
        state[ 0] = Aba;
        state[ 1] = Abe;
        state[ 2] = Abi;
        state[ 3] = Abo;
        state[ 4] = Abu;
        state[ 5] = Aga;
        state[ 6] = Age;
        state[ 7] = Agi;
        state[ 8] = Ago;
        state[ 9] = Agu;
        state[10] = Aka;
        state[11] = Ake;
        state[12] = Aki;
        state[13] = Ako;
        state[14] = Aku;
        state[15] = Ama;
        state[16] = Ame;
        state[17] = Ami;
        state[18] = Amo;
        state[19] = Amu;
        state[20] = Asa;
        state[21] = Ase;
        state[22] = Asi;
        state[23] = Aso;
        state[24] = Asu;
}

/*************************************************
* Name:        keccak_init
*
* Description: Initializes the Keccak state.
*
* Arguments:   - uint64_t *s: pointer to Keccak state
**************************************************/
static void keccak_init(uint64_t s[25])
{
  unsigned int i;
  for(i=0;i<25;i++)
    s[i] = 0;
}

/*************************************************
* Name:        keccak_absorb
*
* Description: Absorb step of Keccak; incremental.
*
* Arguments:   - uint64_t *s: pointer to Keccak state
*              - unsigned int pos: position in current block to be absorbed
*              - unsigned int r: rate in bytes (e.g., 168 for SHAKE128)
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
*
* Returns new position pos in current block
**************************************************/
static unsigned int keccak_absorb(uint64_t s[25],
                                  unsigned int pos,
                                  unsigned int r,
                                  const uint8_t *in,
                                  size_t inlen)
{
  unsigned int i;

  while(pos+inlen >= r) {
    for(i=pos;i<r;i++)
      s[i/8] ^= (uint64_t)*in++ << 8*(i%8);
    inlen -= r-pos;
    KeccakF1600_StatePermute(s);
    pos = 0;
  }

  for(i=pos;i<pos+inlen;i++)
    s[i/8] ^= (uint64_t)*in++ << 8*(i%8);

  return i;
}

/*************************************************
* Name:        keccak_finalize
*
* Description: Finalize absorb step.
*
* Arguments:   - uint64_t *s: pointer to Keccak state
*              - unsigned int pos: position in current block to be absorbed
*              - unsigned int r: rate in bytes (e.g., 168 for SHAKE128)
*              - uint8_t p: domain separation byte
**************************************************/
static void keccak_finalize(uint64_t s[25], unsigned int pos, unsigned int r, uint8_t p)
{
  s[pos/8] ^= (uint64_t)p << 8*(pos%8);
  s[r/8-1] ^= 1ULL << 63;
}

/*************************************************
* Name:        keccak_squeeze
*
* Description: Squeeze step of Keccak. Squeezes arbitratrily many bytes.
*              Modifies the state. Can be called multiple times to keep
*              squeezing, i.e., is incremental.
*
* Arguments:   - uint8_t *out: pointer to output
*              - size_t outlen: number of bytes to be squeezed (written to out)
*              - uint64_t *s: pointer to input/output Keccak state
*              - unsigned int pos: number of bytes in current block already squeezed
*              - unsigned int r: rate in bytes (e.g., 168 for SHAKE128)
*
* Returns new position pos in current block
**************************************************/
static unsigned int keccak_squeeze(uint8_t *out,
                                   size_t outlen,
                                   uint64_t s[25],
                                   unsigned int pos,
                                   unsigned int r)
{
  unsigned int i;

  while(outlen) {
    if(pos == r) {
      KeccakF1600_StatePermute(s);
      pos = 0;
    }
    for(i=pos;i < r && i < pos+outlen; i++)
      *out++ = s[i/8] >> 8*(i%8);
    outlen -= i-pos;
    pos = i;
  }

  return pos;
}


/*************************************************
* Name:        keccak_absorb_once
*
* Description: Absorb step of Keccak;
*              non-incremental, starts by zeroeing the state.
*
* Arguments:   - uint64_t *s: pointer to (uninitialized) output Keccak state
*              - unsigned int r: rate in bytes (e.g., 168 for SHAKE128)
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
*              - uint8_t p: domain-separation byte for different Keccak-derived functions
**************************************************/
static void keccak_absorb_once(uint64_t s[25],
                               unsigned int r,
                               const uint8_t *in,
                               size_t inlen,
                               uint8_t p)
{
  unsigned int i;

  for(i=0;i<25;i++)
    s[i] = 0;

  while(inlen >= r) {
    for(i=0;i<r/8;i++)
      s[i] ^= load64(in+8*i);
    in += r;
    inlen -= r;
    KeccakF1600_StatePermute(s);
  }

  for(i=0;i<inlen;i++)
    s[i/8] ^= (uint64_t)in[i] << 8*(i%8);

  s[i/8] ^= (uint64_t)p << 8*(i%8);
  s[(r-1)/8] ^= 1ULL << 63;
}

/*************************************************
* Name:        keccak_squeezeblocks
*
* Description: Squeeze step of Keccak. Squeezes full blocks of r bytes each.
*              Modifies the state. Can be called multiple times to keep
*              squeezing, i.e., is incremental. Assumes zero bytes of current
*              block have already been squeezed.
*
* Arguments:   - uint8_t *out: pointer to output blocks
*              - size_t nblocks: number of blocks to be squeezed (written to out)
*              - uint64_t *s: pointer to input/output Keccak state
*              - unsigned int r: rate in bytes (e.g., 168 for SHAKE128)
**************************************************/
static void keccak_squeezeblocks(uint8_t *out,
                                 size_t nblocks,
                                 uint64_t s[25],
                                 unsigned int r)
{
  unsigned int i;

  while(nblocks) {
    KeccakF1600_StatePermute(s);
    for(i=0;i<r/8;i++)
      store64(out+8*i, s[i]);
    out += r;
    nblocks -= 1;
  }
}

/*************************************************
* Name:        shake128_init
*
* Description: Initilizes Keccak state for use as SHAKE128 XOF
*
* Arguments:   - keccak_state *state: pointer to (uninitialized) Keccak state
**************************************************/
void shake128_init(keccak_state *state)
{
  keccak_init(state->s);
  state->pos = 0;
}

/*************************************************
* Name:        shake128_absorb
*
* Description: Absorb step of the SHAKE128 XOF; incremental.
*
* Arguments:   - keccak_state *state: pointer to (initialized) output Keccak state
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
**************************************************/
void shake128_absorb(keccak_state *state, const uint8_t *in, size_t inlen)
{
  state->pos = keccak_absorb(state->s, state->pos, SHAKE128_RATE, in, inlen);
}

/*************************************************
* Name:        shake128_finalize
*
* Description: Finalize absorb step of the SHAKE128 XOF.
*
* Arguments:   - keccak_state *state: pointer to Keccak state
**************************************************/
void shake128_finalize(keccak_state *state)
{
  keccak_finalize(state->s, state->pos, SHAKE128_RATE, 0x1F);
  state->pos = SHAKE128_RATE;
}

/*************************************************
* Name:        shake128_squeeze
*
* Description: Squeeze step of SHAKE128 XOF. Squeezes arbitraily many
*              bytes. Can be called multiple times to keep squeezing.
*
* Arguments:   - uint8_t *out: pointer to output blocks
*              - size_t outlen : number of bytes to be squeezed (written to output)
*              - keccak_state *s: pointer to input/output Keccak state
**************************************************/
void shake128_squeeze(uint8_t *out, size_t outlen, keccak_state *state)
{
  state->pos = keccak_squeeze(out, outlen, state->s, state->pos, SHAKE128_RATE);
}

/*************************************************
* Name:        shake128_absorb_once
*
* Description: Initialize, absorb into and finalize SHAKE128 XOF; non-incremental.
*
* Arguments:   - keccak_state *state: pointer to (uninitialized) output Keccak state
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
**************************************************/
void shake128_absorb_once(keccak_state *state, const uint8_t *in, size_t inlen)
{
  keccak_absorb_once(state->s, SHAKE128_RATE, in, inlen, 0x1F);
  state->pos = SHAKE128_RATE;
}

/*************************************************
* Name:        shake128_squeezeblocks
*
* Description: Squeeze step of SHAKE128 XOF. Squeezes full blocks of
*              SHAKE128_RATE bytes each. Can be called multiple times
*              to keep squeezing. Assumes new block has not yet been
*              started (state->pos = SHAKE128_RATE).
*
* Arguments:   - uint8_t *out: pointer to output blocks
*              - size_t nblocks: number of blocks to be squeezed (written to output)
*              - keccak_state *s: pointer to input/output Keccak state
**************************************************/
void shake128_squeezeblocks(uint8_t *out, size_t nblocks, keccak_state *state)
{
  keccak_squeezeblocks(out, nblocks, state->s, SHAKE128_RATE);
}

/*************************************************
* Name:        shake256_init
*
* Description: Initilizes Keccak state for use as SHAKE256 XOF
*
* Arguments:   - keccak_state *state: pointer to (uninitialized) Keccak state
**************************************************/
void shake256_init(keccak_state *state)
{
  keccak_init(state->s);
  state->pos = 0;
}

/*************************************************
* Name:        shake256_absorb
*
* Description: Absorb step of the SHAKE256 XOF; incremental.
*
* Arguments:   - keccak_state *state: pointer to (initialized) output Keccak state
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
**************************************************/
void shake256_absorb(keccak_state *state, const uint8_t *in, size_t inlen)
{
  state->pos = keccak_absorb(state->s, state->pos, SHAKE256_RATE, in, inlen);
}

/*************************************************
* Name:        shake256_finalize
*
* Description: Finalize absorb step of the SHAKE256 XOF.
*
* Arguments:   - keccak_state *state: pointer to Keccak state
**************************************************/
void shake256_finalize(keccak_state *state)
{
  keccak_finalize(state->s, state->pos, SHAKE256_RATE, 0x1F);
  state->pos = SHAKE256_RATE;
}

/*************************************************
* Name:        shake256_squeeze
*
* Description: Squeeze step of SHAKE256 XOF. Squeezes arbitraily many
*              bytes. Can be called multiple times to keep squeezing.
*
* Arguments:   - uint8_t *out: pointer to output blocks
*              - size_t outlen : number of bytes to be squeezed (written to output)
*              - keccak_state *s: pointer to input/output Keccak state
**************************************************/
void shake256_squeeze(uint8_t *out, size_t outlen, keccak_state *state)
{
  state->pos = keccak_squeeze(out, outlen, state->s, state->pos, SHAKE256_RATE);
}

/*************************************************
* Name:        shake256_absorb_once
*
* Description: Initialize, absorb into and finalize SHAKE256 XOF; non-incremental.
*
* Arguments:   - keccak_state *state: pointer to (uninitialized) output Keccak state
*              - const uint8_t *in: pointer to input to be absorbed into s
*              - size_t inlen: length of input in bytes
**************************************************/
void shake256_absorb_once(keccak_state *state, const uint8_t *in, size_t inlen)
{
  keccak_absorb_once(state->s, SHAKE256_RATE, in, inlen, 0x1F);
  state->pos = SHAKE256_RATE;
}

/*************************************************
* Name:        shake256_squeezeblocks
*
* Description: Squeeze step of SHAKE256 XOF. Squeezes full blocks of
*              SHAKE256_RATE bytes each. Can be called multiple times
*              to keep squeezing. Assumes next block has not yet been
*              started (state->pos = SHAKE256_RATE).
*
* Arguments:   - uint8_t *out: pointer to output blocks
*              - size_t nblocks: number of blocks to be squeezed (written to output)
*              - keccak_state *s: pointer to input/output Keccak state
**************************************************/
void shake256_squeezeblocks(uint8_t *out, size_t nblocks, keccak_state *state)
{
  keccak_squeezeblocks(out, nblocks, state->s, SHAKE256_RATE);
}

/*************************************************
* Name:        shake128
*
* Description: SHAKE128 XOF with non-incremental API
*
* Arguments:   - uint8_t *out: pointer to output
*              - size_t outlen: requested output length in bytes
*              - const uint8_t *in: pointer to input
*              - size_t inlen: length of input in bytes
**************************************************/
void shake128(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen)
{
  size_t nblocks;
  keccak_state state;

  shake128_absorb_once(&state, in, inlen);
  nblocks = outlen/SHAKE128_RATE;
  shake128_squeezeblocks(out, nblocks, &state);
  outlen -= nblocks*SHAKE128_RATE;
  out += nblocks*SHAKE128_RATE;
  shake128_squeeze(out, outlen, &state);
}

/*************************************************
* Name:        shake256
*
* Description: SHAKE256 XOF with non-incremental API
*
* Arguments:   - uint8_t *out: pointer to output
*              - size_t outlen: requested output length in bytes
*              - const uint8_t *in: pointer to input
*              - size_t inlen: length of input in bytes
**************************************************/
void shake256(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen)
{
  size_t nblocks;
  keccak_state state;

  shake256_absorb_once(&state, in, inlen);
  nblocks = outlen/SHAKE256_RATE;
  shake256_squeezeblocks(out, nblocks, &state);
  outlen -= nblocks*SHAKE256_RATE;
  out += nblocks*SHAKE256_RATE;
  shake256_squeeze(out, outlen, &state);
}

/*************************************************
* Name:        sha3_256
*
* Description: SHA3-256 with non-incremental API
*
* Arguments:   - uint8_t *h: pointer to output (32 bytes)
*              - const uint8_t *in: pointer to input
*              - size_t inlen: length of input in bytes
**************************************************/
void sha3_256(uint8_t h[32], const uint8_t *in, size_t inlen)
{
  unsigned int i;
  uint64_t s[25];

  keccak_absorb_once(s, SHA3_256_RATE, in, inlen, 0x06);
  KeccakF1600_StatePermute(s);
  for(i=0;i<4;i++)
    store64(h+8*i,s[i]);
}

/*************************************************
* Name:        sha3_512
*
* Description: SHA3-512 with non-incremental API
*
* Arguments:   - uint8_t *h: pointer to output (64 bytes)
*              - const uint8_t *in: pointer to input
*              - size_t inlen: length of input in bytes
**************************************************/
void sha3_512(uint8_t h[64], const uint8_t *in, size_t inlen)
{
  unsigned int i;
  uint64_t s[25];

  keccak_absorb_once(s, SHA3_512_RATE, in, inlen, 0x06);
  KeccakF1600_StatePermute(s);
  for(i=0;i<8;i++)
    store64(h+8*i,s[i]);
}