pqc/crypto_kem/kyber768-90s/avx2/poly.c

#include "align.h"
#include "cbd.h"
#include "consts.h"
#include "ntt.h"
#include "params.h"
#include "poly.h"
#include "reduce.h"
#include "symmetric.h"
#include <immintrin.h>
#include <stdint.h>

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_compress
*
* Description: Compression and subsequent serialization of a polynomial
*
* Arguments:   - uint8_t *r: pointer to output byte array
*                            (of length KYBER_POLYCOMPRESSEDBYTES)
*              - poly *a:    pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_compress(uint8_t r[KYBER_POLYCOMPRESSEDBYTES], poly *restrict a) {
    unsigned int i, j;
    uint8_t t[8];

    PQCLEAN_KYBER76890S_AVX2_poly_csubq(a);

    for (i = 0; i < KYBER_N / 8; i++) {
        for (j = 0; j < 8; j++) {
            t[j] = ((((uint16_t)a->coeffs[8 * i + j] << 4) + KYBER_Q / 2) / KYBER_Q) & 15;
        }

        r[0] = t[0] | (t[1] << 4);
        r[1] = t[2] | (t[3] << 4);
        r[2] = t[4] | (t[5] << 4);
        r[3] = t[6] | (t[7] << 4);
        r += 4;
    }
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_decompress
*
* Description: De-serialization and subsequent decompression of a polynomial;
*              approximate inverse of PQCLEAN_KYBER76890S_AVX2_poly_compress
*
* Arguments:   - poly *r:          pointer to output polynomial
*              - const uint8_t *a: pointer to input byte array
*                                  (of length KYBER_POLYCOMPRESSEDBYTES bytes)
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_decompress(poly *restrict r,
        const uint8_t a[KYBER_POLYCOMPRESSEDBYTES]) {
    unsigned int i;

    for (i = 0; i < KYBER_N / 2; i++) {
        r->coeffs[2 * i + 0] = (((uint16_t)(a[0] & 15) * KYBER_Q) + 8) >> 4;
        r->coeffs[2 * i + 1] = (((uint16_t)(a[0] >> 4) * KYBER_Q) + 8) >> 4;
        a += 1;
    }
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_tobytes
*
* Description: Serialization of a polynomial
*
* Arguments:   - uint8_t *r: pointer to output byte array
*                            (needs space for KYBER_POLYBYTES bytes)
*              - poly *a:    pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_tobytes(uint8_t r[KYBER_POLYBYTES], poly *a) {
    PQCLEAN_KYBER76890S_AVX2_ntttobytes_avx(r, a->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_frombytes
*
* Description: De-serialization of a polynomial;
*              inverse of PQCLEAN_KYBER76890S_AVX2_poly_tobytes
*
* Arguments:   - poly *r:          pointer to output polynomial
*              - const uint8_t *a: pointer to input byte array
*                                  (of KYBER_POLYBYTES bytes)
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_frombytes(poly *r, const uint8_t a[KYBER_POLYBYTES]) {
    PQCLEAN_KYBER76890S_AVX2_nttfrombytes_avx(r->coeffs, a, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_frommsg
*
* Description: Convert 32-byte message to polynomial
*
* Arguments:   - poly *r:            pointer to output polynomial
*              - const uint8_t *msg: pointer to input message
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_frommsg(poly *restrict r,
        const uint8_t msg[KYBER_INDCPA_MSGBYTES]) {
    __m256i f, g0, g1, g2, g3, h0, h1, h2, h3;
    const __m256i shift = _mm256_broadcastsi128_si256(_mm_set_epi32(0, 1, 2, 3));
    const __m256i idx = _mm256_broadcastsi128_si256(_mm_set_epi8(15, 14, 11, 10, 7, 6, 3, 2, 13, 12, 9, 8, 5, 4, 1, 0));
    const __m256i hqs = _mm256_set1_epi16((KYBER_Q + 1) / 2);

#define FROMMSG64(i)                        \
    g3 = _mm256_shuffle_epi32(f,0x55*(i));                \
    g3 = _mm256_sllv_epi32(g3,shift);             \
    g3 = _mm256_shuffle_epi8(g3,idx);             \
    g0 = _mm256_slli_epi16(g3,12);                \
    g1 = _mm256_slli_epi16(g3,8);                 \
    g2 = _mm256_slli_epi16(g3,4);                 \
    g0 = _mm256_srai_epi16(g0,15);                \
    g1 = _mm256_srai_epi16(g1,15);                \
    g2 = _mm256_srai_epi16(g2,15);                \
    g3 = _mm256_srai_epi16(g3,15);                \
    g0 = _mm256_and_si256(g0,hqs);  /* 19 18 17 16  3  2  1  0 */ \
    g1 = _mm256_and_si256(g1,hqs);  /* 23 22 21 20  7  6  5  4 */ \
    g2 = _mm256_and_si256(g2,hqs);  /* 27 26 25 24 11 10  9  8 */ \
    g3 = _mm256_and_si256(g3,hqs);  /* 31 30 29 28 15 14 13 12 */ \
    h0 = _mm256_unpacklo_epi64(g0,g1);                \
    h2 = _mm256_unpackhi_epi64(g0,g1);                \
    h1 = _mm256_unpacklo_epi64(g2,g3);                \
    h3 = _mm256_unpackhi_epi64(g2,g3);                \
    g0 = _mm256_permute2x128_si256(h0,h1,0x20);           \
    g2 = _mm256_permute2x128_si256(h0,h1,0x31);           \
    g1 = _mm256_permute2x128_si256(h2,h3,0x20);           \
    g3 = _mm256_permute2x128_si256(h2,h3,0x31);           \
    _mm256_store_si256((__m256i *)&r->coeffs[  0+32*(i)+ 0],g0);  \
    _mm256_store_si256((__m256i *)&r->coeffs[  0+32*(i)+16],g1);  \
    _mm256_store_si256((__m256i *)&r->coeffs[128+32*(i)+ 0],g2);  \
    _mm256_store_si256((__m256i *)&r->coeffs[128+32*(i)+16],g3)

    f = _mm256_load_si256((__m256i *)msg);
    FROMMSG64(0);
    FROMMSG64(1);
    FROMMSG64(2);
    FROMMSG64(3);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_tomsg
*
* Description: Convert polynomial to 32-byte message
*
* Arguments:   - uint8_t *msg: pointer to output message
*              - poly *a:      pointer to input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_tomsg(uint8_t msg[KYBER_INDCPA_MSGBYTES], poly *restrict a) {
    unsigned int i;
    uint32_t small;
    __m256i f0, f1, g0, g1;
    const __m256i hqs = _mm256_set1_epi16((KYBER_Q - 1) / 2);
    const __m256i hhqs = _mm256_set1_epi16((KYBER_Q - 5) / 4);

    for (i = 0; i < KYBER_N / 32; i++) {
        f0 = _mm256_load_si256((__m256i *)&a->coeffs[32 * i]);
        f1 = _mm256_load_si256((__m256i *)&a->coeffs[32 * i + 16]);
        f0 = _mm256_sub_epi16(hqs, f0);
        f1 = _mm256_sub_epi16(hqs, f1);
        g0 = _mm256_srai_epi16(f0, 15);
        g1 = _mm256_srai_epi16(f1, 15);
        f0 = _mm256_xor_si256(f0, g0);
        f1 = _mm256_xor_si256(f1, g1);
        f0 = _mm256_sub_epi16(hhqs, f0);
        f1 = _mm256_sub_epi16(hhqs, f1);
        f0 = _mm256_packs_epi16(f0, f1);
        small = _mm256_movemask_epi8(f0);
        small = ~small;
        msg[4 * i + 0] = small;
        msg[4 * i + 1] = small >> 16;
        msg[4 * i + 2] = small >>  8;
        msg[4 * i + 3] = small >> 24;
    }
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_getnoise
*
* Description: Sample a polynomial deterministically from a seed and a nonce,
*              with output polynomial close to centered binomial distribution
*              with parameter KYBER_ETA
*
* Arguments:   - poly *r:             pointer to output polynomial
*              - const uint8_t *seed: pointer to input seed
*                                     (of length KYBER_SYMBYTES bytes)
*              - uint8_t nonce:       one-byte input nonce
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_getnoise(poly *r, const uint8_t seed[KYBER_SYMBYTES], uint8_t nonce) {
    ALIGN32_ARRAY(uint8_t, KYBER_ETA * KYBER_N / 4) buf;
    prf(buf.arr, sizeof(buf.arr), seed, nonce);
    PQCLEAN_KYBER76890S_AVX2_cbd(r, buf.arr);
}


/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_ntt
*
* Description: Computes negacyclic number-theoretic transform (NTT) of
*              a polynomial in place;
*              inputs assumed to be in normal order, output in bitreversed order
*
* Arguments:   - uint16_t *r: pointer to in/output polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_ntt(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_ntt_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_invntt_tomont
*
* Description: Computes inverse of negacyclic number-theoretic transform (NTT)
*              of a polynomial in place;
*              inputs assumed to be in bitreversed order, output in normal order
*
* Arguments:   - uint16_t *a: pointer to in/output polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_invntt_tomont(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_invntt_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

void PQCLEAN_KYBER76890S_AVX2_poly_nttunpack(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_nttunpack_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_basemul_montgomery
*
* Description: Multiplication of two polynomials in NTT domain
*
* Arguments:   - poly *r:       pointer to output polynomial
*              - const poly *a: pointer to first input polynomial
*              - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_basemul_montgomery(poly *r, const poly *a, const poly *b) {
    PQCLEAN_KYBER76890S_AVX2_basemul_avx(r->coeffs, a->coeffs, b->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_tomont
*
* Description: Inplace conversion of all coefficients of a polynomial
*              from normal domain to Montgomery domain
*
* Arguments:   - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_tomont(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_tomont_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_reduce
*
* Description: Applies Barrett reduction to all coefficients of a polynomial
*              for details of the Barrett reduction see comments in reduce.c
*
* Arguments:   - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_reduce(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_reduce_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_csubq
*
* Description: Applies conditional subtraction of q to each coefficient
*              of a polynomial. For details of conditional subtraction
*              of q see comments in reduce.c
*
* Arguments:   - poly *r: pointer to input/output polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_csubq(poly *r) {
    PQCLEAN_KYBER76890S_AVX2_csubq_avx(r->coeffs, &PQCLEAN_KYBER76890S_AVX2_qdata);
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_add
*
* Description: Add two polynomials
*
* Arguments: - poly *r:       pointer to output polynomial
*            - const poly *a: pointer to first input polynomial
*            - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_add(poly *r, const poly *a, const poly *b) {
    unsigned int i;
    __m256i f0, f1;

    for (i = 0; i < KYBER_N; i += 16) {
        f0 = _mm256_load_si256((__m256i *)&a->coeffs[i]);
        f1 = _mm256_load_si256((__m256i *)&b->coeffs[i]);
        f0 = _mm256_add_epi16(f0, f1);
        _mm256_store_si256((__m256i *)&r->coeffs[i], f0);
    }
}

/*************************************************
* Name:        PQCLEAN_KYBER76890S_AVX2_poly_sub
*
* Description: Subtract two polynomials
*
* Arguments: - poly *r:       pointer to output polynomial
*            - const poly *a: pointer to first input polynomial
*            - const poly *b: pointer to second input polynomial
**************************************************/
void PQCLEAN_KYBER76890S_AVX2_poly_sub(poly *r, const poly *a, const poly *b) {
    unsigned int i;
    __m256i f0, f1;

    for (i = 0; i < KYBER_N; i += 16) {
        f0 = _mm256_load_si256((__m256i *)&a->coeffs[i]);
        f1 = _mm256_load_si256((__m256i *)&b->coeffs[i]);
        f0 = _mm256_sub_epi16(f0, f1);
        _mm256_store_si256((__m256i *)&r->coeffs[i], f0);
    }
}