331 lines
13 KiB
C
331 lines
13 KiB
C
#include "indcpa.h"
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#include "ntt.h"
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#include "params.h"
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#include "poly.h"
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#include "polyvec.h"
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#include "randombytes.h"
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#include "symmetric.h"
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#include <stddef.h>
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#include <stdint.h>
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/*************************************************
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* Name: pack_pk
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*
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* Description: Serialize the public key as concatenation of the
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* serialized vector of polynomials pk
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* and the public seed used to generate the matrix A.
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*
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* Arguments: uint8_t *r: pointer to the output serialized public key
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* polyvec *pk: pointer to the input public-key polyvec
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* const uint8_t *seed: pointer to the input public seed
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**************************************************/
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static void pack_pk(uint8_t r[KYBER_INDCPA_PUBLICKEYBYTES],
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polyvec *pk,
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const uint8_t seed[KYBER_SYMBYTES]) {
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size_t i;
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PQCLEAN_KYBER512_CLEAN_polyvec_tobytes(r, pk);
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for (i = 0; i < KYBER_SYMBYTES; i++) {
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r[i + KYBER_POLYVECBYTES] = seed[i];
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}
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}
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/*************************************************
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* Name: unpack_pk
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*
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* Description: De-serialize public key from a byte array;
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* approximate inverse of pack_pk
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*
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* Arguments: - polyvec *pk: pointer to output public-key polynomial vector
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* - uint8_t *seed: pointer to output seed to generate matrix A
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* - const uint8_t *packedpk: pointer to input serialized public key
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**************************************************/
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static void unpack_pk(polyvec *pk,
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uint8_t seed[KYBER_SYMBYTES],
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const uint8_t packedpk[KYBER_INDCPA_PUBLICKEYBYTES]) {
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size_t i;
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PQCLEAN_KYBER512_CLEAN_polyvec_frombytes(pk, packedpk);
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for (i = 0; i < KYBER_SYMBYTES; i++) {
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seed[i] = packedpk[i + KYBER_POLYVECBYTES];
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}
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}
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/*************************************************
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* Name: pack_sk
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*
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* Description: Serialize the secret key
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*
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* Arguments: - uint8_t *r: pointer to output serialized secret key
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* - polyvec *sk: pointer to input vector of polynomials (secret key)
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**************************************************/
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static void pack_sk(uint8_t r[KYBER_INDCPA_SECRETKEYBYTES], polyvec *sk) {
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PQCLEAN_KYBER512_CLEAN_polyvec_tobytes(r, sk);
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}
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/*************************************************
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* Name: unpack_sk
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*
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* Description: De-serialize the secret key; inverse of pack_sk
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*
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* Arguments: - polyvec *sk: pointer to output vector of polynomials (secret key)
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* - const uint8_t *packedsk: pointer to input serialized secret key
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**************************************************/
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static void unpack_sk(polyvec *sk, const uint8_t packedsk[KYBER_INDCPA_SECRETKEYBYTES]) {
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PQCLEAN_KYBER512_CLEAN_polyvec_frombytes(sk, packedsk);
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}
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/*************************************************
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* Name: pack_ciphertext
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*
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* Description: Serialize the ciphertext as concatenation of the
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* compressed and serialized vector of polynomials b
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* and the compressed and serialized polynomial v
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*
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* Arguments: uint8_t *r: pointer to the output serialized ciphertext
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* poly *pk: pointer to the input vector of polynomials b
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* poly *v: pointer to the input polynomial v
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**************************************************/
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static void pack_ciphertext(uint8_t r[KYBER_INDCPA_BYTES], polyvec *b, poly *v) {
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PQCLEAN_KYBER512_CLEAN_polyvec_compress(r, b);
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PQCLEAN_KYBER512_CLEAN_poly_compress(r + KYBER_POLYVECCOMPRESSEDBYTES, v);
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}
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/*************************************************
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* Name: unpack_ciphertext
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*
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* Description: De-serialize and decompress ciphertext from a byte array;
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* approximate inverse of pack_ciphertext
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*
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* Arguments: - polyvec *b: pointer to the output vector of polynomials b
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* - poly *v: pointer to the output polynomial v
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* - const uint8_t *c: pointer to the input serialized ciphertext
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**************************************************/
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static void unpack_ciphertext(polyvec *b, poly *v, const uint8_t c[KYBER_INDCPA_BYTES]) {
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PQCLEAN_KYBER512_CLEAN_polyvec_decompress(b, c);
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PQCLEAN_KYBER512_CLEAN_poly_decompress(v, c + KYBER_POLYVECCOMPRESSEDBYTES);
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}
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/*************************************************
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* Name: rej_uniform
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*
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* Description: Run rejection sampling on uniform random bytes to generate
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* uniform random integers mod q
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*
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* Arguments: - int16_t *r: pointer to output buffer
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* - unsigned int len: requested number of 16-bit integers (uniform mod q)
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* - const uint8_t *buf: pointer to input buffer (assumed to be uniformly random bytes)
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* - unsigned int buflen: length of input buffer in bytes
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*
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* Returns number of sampled 16-bit integers (at most len)
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**************************************************/
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static unsigned int rej_uniform(int16_t *r,
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unsigned int len,
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const uint8_t *buf,
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unsigned int buflen) {
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unsigned int ctr, pos;
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uint16_t val0, val1;
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ctr = pos = 0;
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while (ctr < len && pos + 3 <= buflen) {
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val0 = ((buf[pos + 0] >> 0) | ((uint16_t)buf[pos + 1] << 8)) & 0xFFF;
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val1 = ((buf[pos + 1] >> 4) | ((uint16_t)buf[pos + 2] << 4)) & 0xFFF;
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pos += 3;
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if (val0 < KYBER_Q) {
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r[ctr++] = val0;
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}
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if (ctr < len && val1 < KYBER_Q) {
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r[ctr++] = val1;
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}
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}
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return ctr;
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}
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#define gen_a(A,B) PQCLEAN_KYBER512_CLEAN_gen_matrix(A,B,0)
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#define gen_at(A,B) PQCLEAN_KYBER512_CLEAN_gen_matrix(A,B,1)
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/*************************************************
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* Name: PQCLEAN_KYBER512_CLEAN_gen_matrix
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*
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* Description: Deterministically generate matrix A (or the transpose of A)
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* from a seed. Entries of the matrix are polynomials that look
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* uniformly random. Performs rejection sampling on output of
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* a XOF
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*
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* Arguments: - polyvec *a: pointer to ouptput matrix A
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* - const uint8_t *seed: pointer to input seed
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* - int transposed: boolean deciding whether A or A^T is generated
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**************************************************/
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#define GEN_MATRIX_NBLOCKS ((12*KYBER_N/8*(1 << 12)/KYBER_Q + XOF_BLOCKBYTES)/XOF_BLOCKBYTES)
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// Not static for benchmarking
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void PQCLEAN_KYBER512_CLEAN_gen_matrix(polyvec *a, const uint8_t seed[KYBER_SYMBYTES], int transposed) {
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unsigned int ctr, i, j, k;
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unsigned int buflen, off;
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uint8_t buf[GEN_MATRIX_NBLOCKS * XOF_BLOCKBYTES + 2];
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xof_state state;
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for (i = 0; i < KYBER_K; i++) {
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for (j = 0; j < KYBER_K; j++) {
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if (transposed) {
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xof_absorb(&state, seed, (uint8_t)i, (uint8_t)j);
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} else {
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xof_absorb(&state, seed, (uint8_t)j, (uint8_t)i);
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}
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xof_squeezeblocks(buf, GEN_MATRIX_NBLOCKS, &state);
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buflen = GEN_MATRIX_NBLOCKS * XOF_BLOCKBYTES;
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ctr = rej_uniform(a[i].vec[j].coeffs, KYBER_N, buf, buflen);
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while (ctr < KYBER_N) {
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off = buflen % 3;
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for (k = 0; k < off; k++) {
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buf[k] = buf[buflen - off + k];
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}
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xof_squeezeblocks(buf + off, 1, &state);
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buflen = off + XOF_BLOCKBYTES;
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ctr += rej_uniform(a[i].vec[j].coeffs + ctr, KYBER_N - ctr, buf, buflen);
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}
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xof_ctx_release(&state);
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}
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}
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}
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/*************************************************
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* Name: PQCLEAN_KYBER512_CLEAN_indcpa_keypair
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*
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* Description: Generates public and private key for the CPA-secure
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* public-key encryption scheme underlying Kyber
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*
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* Arguments: - uint8_t *pk: pointer to output public key
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* (of length KYBER_INDCPA_PUBLICKEYBYTES bytes)
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* - uint8_t *sk: pointer to output private key
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(of length KYBER_INDCPA_SECRETKEYBYTES bytes)
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**************************************************/
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void PQCLEAN_KYBER512_CLEAN_indcpa_keypair(uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
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uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES]) {
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unsigned int i;
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uint8_t buf[2 * KYBER_SYMBYTES];
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const uint8_t *publicseed = buf;
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const uint8_t *noiseseed = buf + KYBER_SYMBYTES;
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uint8_t nonce = 0;
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polyvec a[KYBER_K], e, pkpv, skpv;
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randombytes(buf, KYBER_SYMBYTES);
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hash_g(buf, buf, KYBER_SYMBYTES);
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gen_a(a, publicseed);
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_poly_getnoise_eta1(&skpv.vec[i], noiseseed, nonce++);
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}
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_poly_getnoise_eta1(&e.vec[i], noiseseed, nonce++);
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}
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PQCLEAN_KYBER512_CLEAN_polyvec_ntt(&skpv);
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PQCLEAN_KYBER512_CLEAN_polyvec_ntt(&e);
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// matrix-vector multiplication
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_polyvec_basemul_acc_montgomery(&pkpv.vec[i], &a[i], &skpv);
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PQCLEAN_KYBER512_CLEAN_poly_tomont(&pkpv.vec[i]);
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}
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PQCLEAN_KYBER512_CLEAN_polyvec_add(&pkpv, &pkpv, &e);
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PQCLEAN_KYBER512_CLEAN_polyvec_reduce(&pkpv);
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pack_sk(sk, &skpv);
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pack_pk(pk, &pkpv, publicseed);
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}
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/*************************************************
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* Name: PQCLEAN_KYBER512_CLEAN_indcpa_enc
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*
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* Description: Encryption function of the CPA-secure
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* public-key encryption scheme underlying Kyber.
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*
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* Arguments: - uint8_t *c: pointer to output ciphertext
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* (of length KYBER_INDCPA_BYTES bytes)
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* - const uint8_t *m: pointer to input message
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* (of length KYBER_INDCPA_MSGBYTES bytes)
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* - const uint8_t *pk: pointer to input public key
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* (of length KYBER_INDCPA_PUBLICKEYBYTES)
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* - const uint8_t *coins: pointer to input random coins used as seed
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* (of length KYBER_SYMBYTES) to deterministically
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* generate all randomness
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**************************************************/
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void PQCLEAN_KYBER512_CLEAN_indcpa_enc(uint8_t c[KYBER_INDCPA_BYTES],
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const uint8_t m[KYBER_INDCPA_MSGBYTES],
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const uint8_t pk[KYBER_INDCPA_PUBLICKEYBYTES],
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const uint8_t coins[KYBER_SYMBYTES]) {
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unsigned int i;
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uint8_t seed[KYBER_SYMBYTES];
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uint8_t nonce = 0;
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polyvec sp, pkpv, ep, at[KYBER_K], b;
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poly v, k, epp;
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unpack_pk(&pkpv, seed, pk);
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PQCLEAN_KYBER512_CLEAN_poly_frommsg(&k, m);
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gen_at(at, seed);
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_poly_getnoise_eta1(sp.vec + i, coins, nonce++);
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}
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_poly_getnoise_eta2(ep.vec + i, coins, nonce++);
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}
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PQCLEAN_KYBER512_CLEAN_poly_getnoise_eta2(&epp, coins, nonce++);
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PQCLEAN_KYBER512_CLEAN_polyvec_ntt(&sp);
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// matrix-vector multiplication
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for (i = 0; i < KYBER_K; i++) {
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PQCLEAN_KYBER512_CLEAN_polyvec_basemul_acc_montgomery(&b.vec[i], &at[i], &sp);
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}
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PQCLEAN_KYBER512_CLEAN_polyvec_basemul_acc_montgomery(&v, &pkpv, &sp);
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PQCLEAN_KYBER512_CLEAN_polyvec_invntt_tomont(&b);
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PQCLEAN_KYBER512_CLEAN_poly_invntt_tomont(&v);
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PQCLEAN_KYBER512_CLEAN_polyvec_add(&b, &b, &ep);
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PQCLEAN_KYBER512_CLEAN_poly_add(&v, &v, &epp);
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PQCLEAN_KYBER512_CLEAN_poly_add(&v, &v, &k);
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PQCLEAN_KYBER512_CLEAN_polyvec_reduce(&b);
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PQCLEAN_KYBER512_CLEAN_poly_reduce(&v);
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pack_ciphertext(c, &b, &v);
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}
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/*************************************************
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* Name: PQCLEAN_KYBER512_CLEAN_indcpa_dec
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*
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* Description: Decryption function of the CPA-secure
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* public-key encryption scheme underlying Kyber.
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*
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* Arguments: - uint8_t *m: pointer to output decrypted message
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* (of length KYBER_INDCPA_MSGBYTES)
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* - const uint8_t *c: pointer to input ciphertext
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* (of length KYBER_INDCPA_BYTES)
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* - const uint8_t *sk: pointer to input secret key
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* (of length KYBER_INDCPA_SECRETKEYBYTES)
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**************************************************/
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void PQCLEAN_KYBER512_CLEAN_indcpa_dec(uint8_t m[KYBER_INDCPA_MSGBYTES],
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const uint8_t c[KYBER_INDCPA_BYTES],
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const uint8_t sk[KYBER_INDCPA_SECRETKEYBYTES]) {
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polyvec b, skpv;
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poly v, mp;
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unpack_ciphertext(&b, &v, c);
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unpack_sk(&skpv, sk);
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PQCLEAN_KYBER512_CLEAN_polyvec_ntt(&b);
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PQCLEAN_KYBER512_CLEAN_polyvec_basemul_acc_montgomery(&mp, &skpv, &b);
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PQCLEAN_KYBER512_CLEAN_poly_invntt_tomont(&mp);
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PQCLEAN_KYBER512_CLEAN_poly_sub(&mp, &v, &mp);
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PQCLEAN_KYBER512_CLEAN_poly_reduce(&mp);
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PQCLEAN_KYBER512_CLEAN_poly_tomsg(m, &mp);
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}
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