/* kyber-kdep.c - the Kyber key encapsulation mechanism (KYBER_K dependent part)
 * Copyright (C) 2024 g10 Code GmbH
 *
 * This file was modified for use by Libgcrypt.
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This file is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, see <https://www.gnu.org/licenses/>.
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * You can also use this file under the same licence of original code.
 * SPDX-License-Identifier: CC0 OR Apache-2.0
 *
 */
/*
  Original code from:

  Repository: https://github.com/pq-crystals/kyber.git
  Branch: standard
  Commit: 11d00ff1f20cfca1f72d819e5a45165c1e0a2816

  Licence:
  Public Domain (https://creativecommons.org/share-your-work/public-domain/cc0/);
  or Apache 2.0 License (https://www.apache.org/licenses/LICENSE-2.0.html).

  Authors:
        Joppe Bos
        Léo Ducas
        Eike Kiltz
        Tancrède Lepoint
        Vadim Lyubashevsky
        John Schanck
        Peter Schwabe
        Gregor Seiler
        Damien Stehlé

  Kyber Home: https://www.pq-crystals.org/kyber/
 */
/*
 * From original code, following modification was made.
 *
 * - C++ style comments are changed to C-style.
 *
 * - With the change of "verify" routine (now "verify1"), no negation
 *   for the cmov argument in crypto_kem_dec.
 *
 * - Call to xof_init and xof_close are added in gen_matrix.
 */

/*************** kyber/ref/polyvec.h */
typedef struct{
  poly vec[KYBER_K];
} polyvec;

static void polyvec_compress(uint8_t r[KYBER_POLYVECCOMPRESSEDBYTES], const polyvec *a);
static void polyvec_decompress(polyvec *r, const uint8_t a[KYBER_POLYVECCOMPRESSEDBYTES]);

static void polyvec_tobytes(uint8_t r[KYBER_POLYVECBYTES], const polyvec *a);
static void polyvec_frombytes(polyvec *r, const uint8_t a[KYBER_POLYVECBYTES]);

static void polyvec_ntt(polyvec *r);
static void polyvec_invntt_tomont(polyvec *r);

static void polyvec_basemul_acc_montgomery(poly *r, const polyvec *a, const polyvec *b);

static void polyvec_reduce(polyvec *r);

static void polyvec_add(polyvec *r, const polyvec *a, const polyvec *b);

/*************** kyber/ref/indcpa.h */
static void gen_matrix(polyvec *a, const uint8_t seed[KYBER_SYMBYTES], int transposed);

static void indcpa_keypair_derand(uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
                                  uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES],
                                  const uint8_t coins[KYBER_SYMBYTES]);

static void indcpa_enc(uint8_t c[KYBER_INDCPA_BYTES],
                       const uint8_t m[KYBER_INDCPA_MSGBYTES],
                       const uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
                       const uint8_t coins[KYBER_SYMBYTES]);

static void indcpa_dec(uint8_t m[KYBER_INDCPA_MSGBYTES],
                       const uint8_t c[KYBER_INDCPA_BYTES],
                       const uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES]);

/*************** kyber/ref/kem.h */

static int crypto_kem_keypair_derand(uint8_t *pk, uint8_t *sk, const uint8_t *coins);

static int crypto_kem_enc_derand(uint8_t *ct, uint8_t *ss, const uint8_t *pk, const uint8_t *coins);

/*************** kyber/ref/indcpa.c */

/*************************************************
* Name:        pack_pk
*
* Description: Serialize the public key as concatenation of the
*              serialized vector of polynomials pk
*              and the public seed used to generate the matrix A.
*
* Arguments:   uint8_t *r: pointer to the output serialized public key
*              polyvec *pk: pointer to the input public-key polyvec
*              const uint8_t *seed: pointer to the input public seed
**************************************************/
static void pack_pk(uint8_t r[KYBER_INDCPA_PUBLICKEYBYTES],
                    polyvec *pk,
                    const uint8_t seed[KYBER_SYMBYTES])
{
  polyvec_tobytes(r, pk);
  memcpy(r+KYBER_POLYVECBYTES, seed, KYBER_SYMBYTES);
}

/*************************************************
* Name:        unpack_pk
*
* Description: De-serialize public key from a byte array;
*              approximate inverse of pack_pk
*
* Arguments:   - polyvec *pk: pointer to output public-key polynomial vector
*              - uint8_t *seed: pointer to output seed to generate matrix A
*              - const uint8_t *packedpk: pointer to input serialized public key
**************************************************/
static void unpack_pk(polyvec *pk,
                      uint8_t seed[KYBER_SYMBYTES],
                      const uint8_t packedpk[KYBER_INDCPA_PUBLICKEYBYTES])
{
  polyvec_frombytes(pk, packedpk);
  memcpy(seed, packedpk+KYBER_POLYVECBYTES, KYBER_SYMBYTES);
}

/*************************************************
* Name:        pack_sk
*
* Description: Serialize the secret key
*
* Arguments:   - uint8_t *r: pointer to output serialized secret key
*              - polyvec *sk: pointer to input vector of polynomials (secret key)
**************************************************/
static void pack_sk(uint8_t r[KYBER_INDCPA_SECRETKEYBYTES], polyvec *sk)
{
  polyvec_tobytes(r, sk);
}

/*************************************************
* Name:        unpack_sk
*
* Description: De-serialize the secret key; inverse of pack_sk
*
* Arguments:   - polyvec *sk: pointer to output vector of polynomials (secret key)
*              - const uint8_t *packedsk: pointer to input serialized secret key
**************************************************/
static void unpack_sk(polyvec *sk, const uint8_t packedsk[KYBER_INDCPA_SECRETKEYBYTES])
{
  polyvec_frombytes(sk, packedsk);
}

/*************************************************
* Name:        pack_ciphertext
*
* Description: Serialize the ciphertext as concatenation of the
*              compressed and serialized vector of polynomials b
*              and the compressed and serialized polynomial v
*
* Arguments:   uint8_t *r: pointer to the output serialized ciphertext
*              poly *pk: pointer to the input vector of polynomials b
*              poly *v: pointer to the input polynomial v
**************************************************/
static void pack_ciphertext(uint8_t r[KYBER_INDCPA_BYTES], polyvec *b, poly *v)
{
  polyvec_compress(r, b);
  poly_compress(r+KYBER_POLYVECCOMPRESSEDBYTES, v);
}

/*************************************************
* Name:        unpack_ciphertext
*
* Description: De-serialize and decompress ciphertext from a byte array;
*              approximate inverse of pack_ciphertext
*
* Arguments:   - polyvec *b: pointer to the output vector of polynomials b
*              - poly *v: pointer to the output polynomial v
*              - const uint8_t *c: pointer to the input serialized ciphertext
**************************************************/
static void unpack_ciphertext(polyvec *b, poly *v, const uint8_t c[KYBER_INDCPA_BYTES])
{
  polyvec_decompress(b, c);
  poly_decompress(v, c+KYBER_POLYVECCOMPRESSEDBYTES);
}

#define gen_a(A,B)  gen_matrix(A,B,0)
#define gen_at(A,B) gen_matrix(A,B,1)

/*************************************************
* Name:        gen_matrix
*
* Description: Deterministically generate matrix A (or the transpose of A)
*              from a seed. Entries of the matrix are polynomials that look
*              uniformly random. Performs rejection sampling on output of
*              a XOF
*
* Arguments:   - polyvec *a: pointer to ouptput matrix A
*              - const uint8_t *seed: pointer to input seed
*              - int transposed: boolean deciding whether A or A^T is generated
**************************************************/
#define GEN_MATRIX_NBLOCKS ((12*KYBER_N/8*(1 << 12)/KYBER_Q + XOF_BLOCKBYTES)/XOF_BLOCKBYTES)
void gen_matrix(polyvec *a, const uint8_t seed[KYBER_SYMBYTES], int transposed)
{
  unsigned int ctr, i, j, k;
  unsigned int buflen, off;
  uint8_t buf[GEN_MATRIX_NBLOCKS*XOF_BLOCKBYTES+2];
  xof_state state;

  for(i=0;i<KYBER_K;i++) {
    for(j=0;j<KYBER_K;j++) {
      xof_init(&state);
      if(transposed)
        xof_absorb(&state, seed, i, j);
      else
        xof_absorb(&state, seed, j, i);

      xof_squeezeblocks(buf, GEN_MATRIX_NBLOCKS, &state);
      buflen = GEN_MATRIX_NBLOCKS*XOF_BLOCKBYTES;
      ctr = rej_uniform(a[i].vec[j].coeffs, KYBER_N, buf, buflen);

      while(ctr < KYBER_N) {
        off = buflen % 3;
        for(k = 0; k < off; k++)
          buf[k] = buf[buflen - off + k];
        xof_squeezeblocks(buf + off, 1, &state);
        buflen = off + XOF_BLOCKBYTES;
        ctr += rej_uniform(a[i].vec[j].coeffs + ctr, KYBER_N - ctr, buf, buflen);
      }
      xof_close (&state);
    }
  }
}

/*************************************************
* Name:        indcpa_keypair_derand
*
* Description: Generates public and private key for the CPA-secure
*              public-key encryption scheme underlying Kyber
*
* Arguments:   - uint8_t *pk: pointer to output public key
*                             (of length KYBER_INDCPA_PUBLICKEYBYTES bytes)
*              - uint8_t *sk: pointer to output private key
*                             (of length KYBER_INDCPA_SECRETKEYBYTES bytes)
*              - const uint8_t *coins: pointer to input randomness
*                             (of length KYBER_SYMBYTES bytes)
**************************************************/
void indcpa_keypair_derand(uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
                           uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES],
                           const uint8_t coins[KYBER_SYMBYTES])
{
  unsigned int i;
  uint8_t buf[2*KYBER_SYMBYTES];
  const uint8_t *publicseed = buf;
  const uint8_t *noiseseed = buf+KYBER_SYMBYTES;
  uint8_t nonce = 0;
  polyvec a[KYBER_K], e, pkpv, skpv;

  hash_g(buf, coins, KYBER_SYMBYTES);

  gen_a(a, publicseed);

  for(i=0;i<KYBER_K;i++)
    poly_getnoise_eta1(&skpv.vec[i], noiseseed, nonce++);
  for(i=0;i<KYBER_K;i++)
    poly_getnoise_eta1(&e.vec[i], noiseseed, nonce++);

  polyvec_ntt(&skpv);
  polyvec_ntt(&e);

  /* matrix-vector multiplication */
  for(i=0;i<KYBER_K;i++) {
    polyvec_basemul_acc_montgomery(&pkpv.vec[i], &a[i], &skpv);
    poly_tomont(&pkpv.vec[i]);
  }

  polyvec_add(&pkpv, &pkpv, &e);
  polyvec_reduce(&pkpv);

  pack_sk(sk, &skpv);
  pack_pk(pk, &pkpv, publicseed);
}


/*************************************************
* Name:        indcpa_enc
*
* Description: Encryption function of the CPA-secure
*              public-key encryption scheme underlying Kyber.
*
* Arguments:   - uint8_t *c: pointer to output ciphertext
*                            (of length KYBER_INDCPA_BYTES bytes)
*              - const uint8_t *m: pointer to input message
*                                  (of length KYBER_INDCPA_MSGBYTES bytes)
*              - const uint8_t *pk: pointer to input public key
*                                   (of length KYBER_INDCPA_PUBLICKEYBYTES)
*              - const uint8_t *coins: pointer to input random coins used as seed
*                                      (of length KYBER_SYMBYTES) to deterministically
*                                      generate all randomness
**************************************************/
void indcpa_enc(uint8_t c[KYBER_INDCPA_BYTES],
                const uint8_t m[KYBER_INDCPA_MSGBYTES],
                const uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
                const uint8_t coins[KYBER_SYMBYTES])
{
  unsigned int i;
  uint8_t seed[KYBER_SYMBYTES];
  uint8_t nonce = 0;
  polyvec sp, pkpv, ep, at[KYBER_K], b;
  poly v, k, epp;

  unpack_pk(&pkpv, seed, pk);
  poly_frommsg(&k, m);
  gen_at(at, seed);

  for(i=0;i<KYBER_K;i++)
    poly_getnoise_eta1(sp.vec+i, coins, nonce++);
  for(i=0;i<KYBER_K;i++)
    poly_getnoise_eta2(ep.vec+i, coins, nonce++);
  poly_getnoise_eta2(&epp, coins, nonce++);

  polyvec_ntt(&sp);

  /* matrix-vector multiplication */
  for(i=0;i<KYBER_K;i++)
    polyvec_basemul_acc_montgomery(&b.vec[i], &at[i], &sp);

  polyvec_basemul_acc_montgomery(&v, &pkpv, &sp);

  polyvec_invntt_tomont(&b);
  poly_invntt_tomont(&v);

  polyvec_add(&b, &b, &ep);
  poly_add(&v, &v, &epp);
  poly_add(&v, &v, &k);
  polyvec_reduce(&b);
  poly_reduce(&v);

  pack_ciphertext(c, &b, &v);
}

/*************************************************
* Name:        indcpa_dec
*
* Description: Decryption function of the CPA-secure
*              public-key encryption scheme underlying Kyber.
*
* Arguments:   - uint8_t *m: pointer to output decrypted message
*                            (of length KYBER_INDCPA_MSGBYTES)
*              - const uint8_t *c: pointer to input ciphertext
*                                  (of length KYBER_INDCPA_BYTES)
*              - const uint8_t *sk: pointer to input secret key
*                                   (of length KYBER_INDCPA_SECRETKEYBYTES)
**************************************************/
void indcpa_dec(uint8_t m[KYBER_INDCPA_MSGBYTES],
                const uint8_t c[KYBER_INDCPA_BYTES],
                const uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES])
{
  polyvec b, skpv;
  poly v, mp;

  unpack_ciphertext(&b, &v, c);
  unpack_sk(&skpv, sk);

  polyvec_ntt(&b);
  polyvec_basemul_acc_montgomery(&mp, &skpv, &b);
  poly_invntt_tomont(&mp);

  poly_sub(&mp, &v, &mp);
  poly_reduce(&mp);

  poly_tomsg(m, &mp);
}

/*************** kyber/ref/kem.c */
/*************************************************
* Name:        crypto_kem_keypair_derand
*
* Description: Generates public and private key
*              for CCA-secure Kyber key encapsulation mechanism
*
* Arguments:   - uint8_t *pk: pointer to output public key
*                (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
*              - uint8_t *sk: pointer to output private key
*                (an already allocated array of KYBER_SECRETKEYBYTES bytes)
*              - uint8_t *coins: pointer to input randomness
*                (an already allocated array filled with 2*KYBER_SYMBYTES random bytes)
**
* Returns 0 (success)
**************************************************/
int crypto_kem_keypair_derand(uint8_t *pk,
                              uint8_t *sk,
                              const uint8_t *coins)
{
  indcpa_keypair_derand(pk, sk, coins);
  memcpy(sk+KYBER_INDCPA_SECRETKEYBYTES, pk, KYBER_PUBLICKEYBYTES);
  hash_h(sk+KYBER_SECRETKEYBYTES-2*KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
  /* Value z for pseudo-random output on reject */
  memcpy(sk+KYBER_SECRETKEYBYTES-KYBER_SYMBYTES, coins+KYBER_SYMBYTES, KYBER_SYMBYTES);
  return 0;
}

/*************************************************
* Name:        crypto_kem_keypair
*
* Description: Generates public and private key
*              for CCA-secure Kyber key encapsulation mechanism
*
* Arguments:   - uint8_t *pk: pointer to output public key
*                (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
*              - uint8_t *sk: pointer to output private key
*                (an already allocated array of KYBER_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int crypto_kem_keypair(uint8_t *pk,
                       uint8_t *sk)
{
  uint8_t coins[2*KYBER_SYMBYTES];
  randombytes(coins, 2*KYBER_SYMBYTES);
  crypto_kem_keypair_derand(pk, sk, coins);
  return 0;
}

/*************************************************
* Name:        crypto_kem_enc_derand
*
* Description: Generates cipher text and shared
*              secret for given public key
*
* Arguments:   - uint8_t *ct: pointer to output cipher text
*                (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
*              - uint8_t *ss: pointer to output shared secret
*                (an already allocated array of KYBER_SSBYTES bytes)
*              - const uint8_t *pk: pointer to input public key
*                (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
*              - const uint8_t *coins: pointer to input randomness
*                (an already allocated array filled with KYBER_SYMBYTES random bytes)
**
* Returns 0 (success)
**************************************************/
int crypto_kem_enc_derand(uint8_t *ct,
                          uint8_t *ss,
                          const uint8_t *pk,
                          const uint8_t *coins)
{
  uint8_t buf[2*KYBER_SYMBYTES];
  /* Will contain key, coins */
  uint8_t kr[2*KYBER_SYMBYTES];

  memcpy(buf, coins, KYBER_SYMBYTES);

  /* Multitarget countermeasure for coins + contributory KEM */
  hash_h(buf+KYBER_SYMBYTES, pk, KYBER_PUBLICKEYBYTES);
  hash_g(kr, buf, 2*KYBER_SYMBYTES);

  /* coins are in kr+KYBER_SYMBYTES */
  indcpa_enc(ct, buf, pk, kr+KYBER_SYMBYTES);

  memcpy(ss,kr,KYBER_SYMBYTES);
  return 0;
}

/*************************************************
* Name:        crypto_kem_enc
*
* Description: Generates cipher text and shared
*              secret for given public key
*
* Arguments:   - uint8_t *ct: pointer to output cipher text
*                (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
*              - uint8_t *ss: pointer to output shared secret
*                (an already allocated array of KYBER_SSBYTES bytes)
*              - const uint8_t *pk: pointer to input public key
*                (an already allocated array of KYBER_PUBLICKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int crypto_kem_enc(uint8_t *ct,
                   uint8_t *ss,
                   const uint8_t *pk)
{
  uint8_t coins[KYBER_SYMBYTES];
  randombytes(coins, KYBER_SYMBYTES);
  crypto_kem_enc_derand(ct, ss, pk, coins);
  return 0;
}

/*************************************************
* Name:        crypto_kem_dec
*
* Description: Generates shared secret for given
*              cipher text and private key
*
* Arguments:   - uint8_t *ss: pointer to output shared secret
*                (an already allocated array of KYBER_SSBYTES bytes)
*              - const uint8_t *ct: pointer to input cipher text
*                (an already allocated array of KYBER_CIPHERTEXTBYTES bytes)
*              - const uint8_t *sk: pointer to input private key
*                (an already allocated array of KYBER_SECRETKEYBYTES bytes)
*
* Returns 0.
*
* On failure, ss will contain a pseudo-random value.
**************************************************/
int crypto_kem_dec(uint8_t *ss,
                   const uint8_t *ct,
                   const uint8_t *sk)
{
  unsigned int success;
  uint8_t buf[2*KYBER_SYMBYTES];
  /* Will contain key, coins */
  uint8_t kr[2*KYBER_SYMBYTES];
  uint8_t cmp[KYBER_CIPHERTEXTBYTES+KYBER_SYMBYTES];
  const uint8_t *pk = sk+KYBER_INDCPA_SECRETKEYBYTES;

  indcpa_dec(buf, ct, sk);

  /* Multitarget countermeasure for coins + contributory KEM */
  memcpy(buf+KYBER_SYMBYTES, sk+KYBER_SECRETKEYBYTES-2*KYBER_SYMBYTES, KYBER_SYMBYTES);
  hash_g(kr, buf, 2*KYBER_SYMBYTES);

  /* coins are in kr+KYBER_SYMBYTES */
  indcpa_enc(cmp, buf, pk, kr+KYBER_SYMBYTES);

  success = verify1(ct, cmp, KYBER_CIPHERTEXTBYTES);

  /* Compute rejection key */
  rkprf(ss,sk+KYBER_SECRETKEYBYTES-KYBER_SYMBYTES,ct);

  /* Copy true key to return buffer if fail is false */
  cmov(ss,kr,KYBER_SYMBYTES,success);

  return 0;
}

/*************** kyber/ref/polyvec.c */

/*************************************************
* Name:        polyvec_compress
*
* Description: Compress and serialize vector of polynomials
*
* Arguments:   - uint8_t *r: pointer to output byte array
*                            (needs space for KYBER_POLYVECCOMPRESSEDBYTES)
*              - const polyvec *a: pointer to input vector of polynomials
**************************************************/
void polyvec_compress(uint8_t r[KYBER_POLYVECCOMPRESSEDBYTES], const polyvec *a)
{
  unsigned int i,j,k;
  uint64_t d0;

#if (KYBER_POLYVECCOMPRESSEDBYTES == (KYBER_K * 352))
  uint16_t t[8];
  for(i=0;i<KYBER_K;i++) {
    for(j=0;j<KYBER_N/8;j++) {
      for(k=0;k<8;k++) {
        t[k]  = a->vec[i].coeffs[8*j+k];
        t[k] += ((int16_t)t[k] >> 15) & KYBER_Q;
/*      t[k]  = ((((uint32_t)t[k] << 11) + KYBER_Q/2)/KYBER_Q) & 0x7ff; */
        d0 = t[k];
        d0 <<= 11;
        d0 += 1664;
        d0 *= 645084;
        d0 >>= 31;
        t[k] = d0 & 0x7ff;

      }

      r[ 0] = (t[0] >>  0);
      r[ 1] = (t[0] >>  8) | (t[1] << 3);
      r[ 2] = (t[1] >>  5) | (t[2] << 6);
      r[ 3] = (t[2] >>  2);
      r[ 4] = (t[2] >> 10) | (t[3] << 1);
      r[ 5] = (t[3] >>  7) | (t[4] << 4);
      r[ 6] = (t[4] >>  4) | (t[5] << 7);
      r[ 7] = (t[5] >>  1);
      r[ 8] = (t[5] >>  9) | (t[6] << 2);
      r[ 9] = (t[6] >>  6) | (t[7] << 5);
      r[10] = (t[7] >>  3);
      r += 11;
    }
  }
#elif (KYBER_POLYVECCOMPRESSEDBYTES == (KYBER_K * 320))
  uint16_t t[4];
  for(i=0;i<KYBER_K;i++) {
    for(j=0;j<KYBER_N/4;j++) {
      for(k=0;k<4;k++) {
        t[k]  = a->vec[i].coeffs[4*j+k];
        t[k] += ((int16_t)t[k] >> 15) & KYBER_Q;
/*      t[k]  = ((((uint32_t)t[k] << 10) + KYBER_Q/2)/ KYBER_Q) & 0x3ff; */
        d0 = t[k];
        d0 <<= 10;
        d0 += 1665;
        d0 *= 1290167;
        d0 >>= 32;
        t[k] = d0 & 0x3ff;
      }

      r[0] = (t[0] >> 0);
      r[1] = (t[0] >> 8) | (t[1] << 2);
      r[2] = (t[1] >> 6) | (t[2] << 4);
      r[3] = (t[2] >> 4) | (t[3] << 6);
      r[4] = (t[3] >> 2);
      r += 5;
    }
  }
#else
#error "KYBER_POLYVECCOMPRESSEDBYTES needs to be in {320*KYBER_K, 352*KYBER_K}"
#endif
}

/*************************************************
* Name:        polyvec_decompress
*
* Description: De-serialize and decompress vector of polynomials;
*              approximate inverse of polyvec_compress
*
* Arguments:   - polyvec *r:       pointer to output vector of polynomials
*              - const uint8_t *a: pointer to input byte array
*                                  (of length KYBER_POLYVECCOMPRESSEDBYTES)
**************************************************/
void polyvec_decompress(polyvec *r, const uint8_t a[KYBER_POLYVECCOMPRESSEDBYTES])
{
  unsigned int i,j,k;

#if (KYBER_POLYVECCOMPRESSEDBYTES == (KYBER_K * 352))
  uint16_t t[8];
  for(i=0;i<KYBER_K;i++) {
    for(j=0;j<KYBER_N/8;j++) {
      t[0] = (a[0] >> 0) | ((uint16_t)a[ 1] << 8);
      t[1] = (a[1] >> 3) | ((uint16_t)a[ 2] << 5);
      t[2] = (a[2] >> 6) | ((uint16_t)a[ 3] << 2) | ((uint16_t)a[4] << 10);
      t[3] = (a[4] >> 1) | ((uint16_t)a[ 5] << 7);
      t[4] = (a[5] >> 4) | ((uint16_t)a[ 6] << 4);
      t[5] = (a[6] >> 7) | ((uint16_t)a[ 7] << 1) | ((uint16_t)a[8] << 9);
      t[6] = (a[8] >> 2) | ((uint16_t)a[ 9] << 6);
      t[7] = (a[9] >> 5) | ((uint16_t)a[10] << 3);
      a += 11;

      for(k=0;k<8;k++)
        r->vec[i].coeffs[8*j+k] = ((uint32_t)(t[k] & 0x7FF)*KYBER_Q + 1024) >> 11;
    }
  }
#elif (KYBER_POLYVECCOMPRESSEDBYTES == (KYBER_K * 320))
  uint16_t t[4];
  for(i=0;i<KYBER_K;i++) {
    for(j=0;j<KYBER_N/4;j++) {
      t[0] = (a[0] >> 0) | ((uint16_t)a[1] << 8);
      t[1] = (a[1] >> 2) | ((uint16_t)a[2] << 6);
      t[2] = (a[2] >> 4) | ((uint16_t)a[3] << 4);
      t[3] = (a[3] >> 6) | ((uint16_t)a[4] << 2);
      a += 5;

      for(k=0;k<4;k++)
        r->vec[i].coeffs[4*j+k] = ((uint32_t)(t[k] & 0x3FF)*KYBER_Q + 512) >> 10;
    }
  }
#else
#error "KYBER_POLYVECCOMPRESSEDBYTES needs to be in {320*KYBER_K, 352*KYBER_K}"
#endif
}

/*************************************************
* Name:        polyvec_tobytes
*
* Description: Serialize vector of polynomials
*
* Arguments:   - uint8_t *r: pointer to output byte array
*                            (needs space for KYBER_POLYVECBYTES)
*              - const polyvec *a: pointer to input vector of polynomials
**************************************************/
void polyvec_tobytes(uint8_t r[KYBER_POLYVECBYTES], const polyvec *a)
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_tobytes(r+i*KYBER_POLYBYTES, &a->vec[i]);
}

/*************************************************
* Name:        polyvec_frombytes
*
* Description: De-serialize vector of polynomials;
*              inverse of polyvec_tobytes
*
* Arguments:   - uint8_t *r:       pointer to output byte array
*              - const polyvec *a: pointer to input vector of polynomials
*                                  (of length KYBER_POLYVECBYTES)
**************************************************/
void polyvec_frombytes(polyvec *r, const uint8_t a[KYBER_POLYVECBYTES])
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_frombytes(&r->vec[i], a+i*KYBER_POLYBYTES);
}

/*************************************************
* Name:        polyvec_ntt
*
* Description: Apply forward NTT to all elements of a vector of polynomials
*
* Arguments:   - polyvec *r: pointer to in/output vector of polynomials
**************************************************/
void polyvec_ntt(polyvec *r)
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_ntt(&r->vec[i]);
}

/*************************************************
* Name:        polyvec_invntt_tomont
*
* Description: Apply inverse NTT to all elements of a vector of polynomials
*              and multiply by Montgomery factor 2^16
*
* Arguments:   - polyvec *r: pointer to in/output vector of polynomials
**************************************************/
void polyvec_invntt_tomont(polyvec *r)
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_invntt_tomont(&r->vec[i]);
}

/*************************************************
* Name:        polyvec_basemul_acc_montgomery
*
* Description: Multiply elements of a and b in NTT domain, accumulate into r,
*              and multiply by 2^-16.
*
* Arguments: - poly *r: pointer to output polynomial
*            - const polyvec *a: pointer to first input vector of polynomials
*            - const polyvec *b: pointer to second input vector of polynomials
**************************************************/
void polyvec_basemul_acc_montgomery(poly *r, const polyvec *a, const polyvec *b)
{
  unsigned int i;
  poly t;

  poly_basemul_montgomery(r, &a->vec[0], &b->vec[0]);
  for(i=1;i<KYBER_K;i++) {
    poly_basemul_montgomery(&t, &a->vec[i], &b->vec[i]);
    poly_add(r, r, &t);
  }

  poly_reduce(r);
}

/*************************************************
* Name:        polyvec_reduce
*
* Description: Applies Barrett reduction to each coefficient
*              of each element of a vector of polynomials;
*              for details of the Barrett reduction see comments in reduce.c
*
* Arguments:   - polyvec *r: pointer to input/output polynomial
**************************************************/
void polyvec_reduce(polyvec *r)
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_reduce(&r->vec[i]);
}

/*************************************************
* Name:        polyvec_add
*
* Description: Add vectors of polynomials
*
* Arguments: - polyvec *r: pointer to output vector of polynomials
*            - const polyvec *a: pointer to first input vector of polynomials
*            - const polyvec *b: pointer to second input vector of polynomials
**************************************************/
void polyvec_add(polyvec *r, const polyvec *a, const polyvec *b)
{
  unsigned int i;
  for(i=0;i<KYBER_K;i++)
    poly_add(&r->vec[i], &a->vec[i], &b->vec[i]);
}

/*****************/
#undef KYBER_K
#undef KYBER_POLYCOMPRESSEDBYTES
#undef KYBER_POLYVECCOMPRESSEDBYTES
#undef poly_compress
#undef poly_decompress
#undef poly_getnoise_eta1
#undef crypto_kem_keypair_derand
#undef crypto_kem_enc_derand
#undef crypto_kem_keypair
#undef crypto_kem_enc
#undef crypto_kem_dec
#undef polyvec
#undef polyvec_compress
#undef polyvec_decompress
#undef polyvec_tobytes
#undef polyvec_frombytes
#undef polyvec_ntt
#undef polyvec_invntt_tomont
#undef polyvec_basemul_acc_montgomery
#undef polyvec_reduce
#undef polyvec_add
#undef pack_pk
#undef unpack_pk
#undef pack_sk
#undef unpack_sk
#undef pack_ciphertext
#undef unpack_ciphertext
#undef gen_matrix
#undef indcpa_keypair_derand
#undef indcpa_enc
#undef indcpa_dec