/* This file is for Niederreiter encryption */ #include "encrypt.h" #include "params.h" #include "randombytes.h" #include "util.h" #include <stdint.h> /* output: e, an error vector of weight t */ static void gen_e(unsigned char *e) { size_t i, j; int eq; uint16_t ind[ SYS_T ]; uint8_t *ind8 = (uint8_t *)ind; uint64_t e_int[ SYS_N / 64 ]; uint64_t one = 1; uint64_t mask; uint64_t val[ SYS_T ]; while (1) { randombytes(ind8, sizeof(ind)); for (i = 0; i < sizeof(ind); i += 2) { ind[i / 2] = (uint16_t)ind8[i + 1] << 8 | ind8[i]; } for (i = 0; i < SYS_T; i++) { ind[i] &= GFMASK; } // check for repetition eq = 0; for (i = 1; i < SYS_T; i++) { for (j = 0; j < i; j++) { if (ind[i] == ind[j]) { eq = 1; } } } if (eq == 0) { break; } } for (j = 0; j < SYS_T; j++) { val[j] = one << (ind[j] & 63); } for (i = 0; i < SYS_N / 64; i++) { e_int[i] = 0; for (j = 0; j < SYS_T; j++) { mask = i ^ (ind[j] >> 6); mask -= 1; mask >>= 63; mask = -mask; e_int[i] |= val[j] & mask; } } for (i = 0; i < SYS_N / 64; i++) { PQCLEAN_MCELIECE8192128_VEC_store8(e + i * 8, e_int[i]); } } /* input: public key pk, error vector e */ /* output: syndrome s */ static void syndrome(unsigned char *s, const unsigned char *pk, const unsigned char *e) { uint64_t b; const uint8_t *e_ptr8 = e + SYND_BYTES; const uint8_t *pk_ptr8; int i, j; // for (i = 0; i < SYND_BYTES; i++) { s[i] = e[i]; } for (i = 0; i < PK_NROWS; i++) { pk_ptr8 = pk + PK_ROW_BYTES * i; b = 0; for (j = 0; j < PK_NCOLS / 64; j++) { b ^= PQCLEAN_MCELIECE8192128_VEC_load8(pk_ptr8 + 8 * j) & PQCLEAN_MCELIECE8192128_VEC_load8(e_ptr8 + 8 * j); } b ^= b >> 32; b ^= b >> 16; b ^= b >> 8; b ^= b >> 4; b ^= b >> 2; b ^= b >> 1; b &= 1; s[ i / 8 ] ^= (b << (i % 8)); } } /* input: public key pk */ /* output: error vector e, syndrome s */ void PQCLEAN_MCELIECE8192128_VEC_encrypt(unsigned char *s, unsigned char *e, const unsigned char *pk) { gen_e(e); syndrome(s, pk, e); }