/* 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 */
static 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]);
    }
}
