pqc/crypto_kem/kyber768/clean/polyvec.c

#include "polyvec.h"
#include "cbd.h"
#include "fips202.h"
#include "reduce.h"
#include <stdio.h>

/*************************************************
 * Name:        polyvec_compress
 *
 * Description: Compress and serialize vector of polynomials
 *
 * Arguments:   - unsigned char *r: pointer to output byte array
 *              - const polyvec *a: pointer to input vector of polynomials
 **************************************************/
void polyvec_compress(unsigned char *r, const polyvec *a) {
    int i, j, k;
    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] = ((((uint32_t)freeze(a->vec[i].coeffs[8 * j + k]) << 11) +
                         KYBER_Q / 2) /
                        KYBER_Q) &
                       0x7ff;
            }

            r[11 * j + 0] = t[0] & 0xff;
            r[11 * j + 1] = (t[0] >> 8) | ((t[1] & 0x1f) << 3);
            r[11 * j + 2] = (t[1] >> 5) | ((t[2] & 0x03) << 6);
            r[11 * j + 3] = (t[2] >> 2) & 0xff;
            r[11 * j + 4] = (t[2] >> 10) | ((t[3] & 0x7f) << 1);
            r[11 * j + 5] = (t[3] >> 7) | ((t[4] & 0x0f) << 4);
            r[11 * j + 6] = (t[4] >> 4) | ((t[5] & 0x01) << 7);
            r[11 * j + 7] = (t[5] >> 1) & 0xff;
            r[11 * j + 8] = (t[5] >> 9) | ((t[6] & 0x3f) << 2);
            r[11 * j + 9] = (t[6] >> 6) | ((t[7] & 0x07) << 5);
            r[11 * j + 10] = (t[7] >> 3);
        }
        r += 352;
    }
}

/*************************************************
 * 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
 *              - unsigned char *a: pointer to input byte array
 **************************************************/
void polyvec_decompress(polyvec *r, const unsigned char *a) {
    int i, j;
    for (i = 0; i < KYBER_K; i++) {
        for (j = 0; j < KYBER_N / 8; j++) {
            r->vec[i].coeffs[8 * j + 0] =
                (((a[11 * j + 0] | (((uint32_t)a[11 * j + 1] & 0x07) << 8)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 1] =
                ((((a[11 * j + 1] >> 3) |
                   (((uint32_t)a[11 * j + 2] & 0x3f) << 5)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 2] =
                ((((a[11 * j + 2] >> 6) |
                   (((uint32_t)a[11 * j + 3] & 0xff) << 2) |
                   (((uint32_t)a[11 * j + 4] & 0x01) << 10)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 3] =
                ((((a[11 * j + 4] >> 1) |
                   (((uint32_t)a[11 * j + 5] & 0x0f) << 7)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 4] =
                ((((a[11 * j + 5] >> 4) |
                   (((uint32_t)a[11 * j + 6] & 0x7f) << 4)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 5] =
                ((((a[11 * j + 6] >> 7) |
                   (((uint32_t)a[11 * j + 7] & 0xff) << 1) |
                   (((uint32_t)a[11 * j + 8] & 0x03) << 9)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 6] =
                ((((a[11 * j + 8] >> 2) |
                   (((uint32_t)a[11 * j + 9] & 0x1f) << 6)) *
                  KYBER_Q) +
                 1024) >>
                11;
            r->vec[i].coeffs[8 * j + 7] =
                ((((a[11 * j + 9] >> 5) |
                   (((uint32_t)a[11 * j + 10] & 0xff) << 3)) *
                  KYBER_Q) +
                 1024) >>
                11;
        }
        a += 352;
    }
}

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

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

/*************************************************
 * Name:        polyvec_pointwise_acc
 *
 * Description: Pointwise multiply elements of a and b and accumulate into r
 *
 * 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_pointwise_acc(poly *r, const polyvec *a, const polyvec *b) {
    int i, j;
    uint16_t t;
    for (j = 0; j < KYBER_N; j++) {
        t = montgomery_reduce(
            4613 * (uint32_t)b->vec[0].coeffs[j]); // 4613 = 2^{2*18} % q
        r->coeffs[j] = montgomery_reduce(a->vec[0].coeffs[j] * t);
        for (i = 1; i < KYBER_K; i++) {
            t = montgomery_reduce(4613 * (uint32_t)b->vec[i].coeffs[j]);
            r->coeffs[j] += montgomery_reduce(a->vec[i].coeffs[j] * t);
        }
        r->coeffs[j] = barrett_reduce(r->coeffs[j]);
    }
}

/*************************************************
 * 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) {
    int i;
    for (i = 0; i < KYBER_K; i++) {
        poly_add(&r->vec[i], &a->vec[i], &b->vec[i]);
    }
}