ntru签名代码c语言实现

NTRU是一种基于格的加密算法，其签名方案也是基于格的。以下是一个使用NTRU签名方案的C语言实现示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ntru.h"

#define NTRU_Q 2048
#define NTRU_N 677
#define NTRU_DR 110
#define NTRU_DF 82
#define NTRU_T 50

typedef struct ntru_sign_key_t {
    uint16_t f[NTRU_N];
    uint16_t g[NTRU_N];
    uint16_t h[NTRU_N];
} ntru_sign_key_t;

void ntru_gen_key(ntru_sign_key_t *key, uint8_t seed[32]) {
    uint16_t f[NTRU_N], g[NTRU_N], h[NTRU_N];
    int i;
    ntru_gen_key_pair(seed, f, g, h);
    for (i = 0; i < NTRU_N; i++) {
        key->f[i] = f[i];
        key->g[i] = g[i];
        key->h[i] = h[i];
    }
}

void ntru_sign(uint8_t *msg, size_t msg_len, ntru_sign_key_t *key, uint16_t *sig) {
    uint16_t r[NTRU_N], e[NTRU_N], m[NTRU_N], c[NTRU_N];
    int i;
    ntru_gen_r(msg, msg_len, key->h, r);
    ntru_gen_e(key->h, r, e);
    ntru_mult_fg(r, key->f, m);
    for (i = 0; i < NTRU_N; i++) {
        c[i] = (e[i] + m[i]) % NTRU_Q;
    }
    ntru_tern_to_int(c, sig, NTRU_N, NTRU_Q / 2);
}

int ntru_verify(uint8_t *msg, size_t msg_len, uint16_t *sig, ntru_sign_key_t *key) {
    uint16_t c[NTRU_N], m[NTRU_N], f2[NTRU_N];
    int i, res;
    ntru_int_to_tern(sig, NTRU_N, NTRU_Q / 2, c);
    ntru_mult_fg(c, key->g, m);
    ntru_sub(m, key->h, f2);
    ntru_mod_mask(f2, NTRU_Q - 1);
    res = ntru_verify_sig(msg, msg_len, f2, c, NTRU_T, NTRU_DR, NTRU_DF, key->h);
    return res;
}

int main() {
    uint8_t seed[32] = {0}; // TODO: generate a random seed
    uint8_t msg[] = "Hello, world!";
    size_t msg_len = strlen((char *)msg) + 1;
    uint16_t sig[NTRU_N];
    ntru_sign_key_t key;
    ntru_gen_key(&key, seed);
    ntru_sign(msg, msg_len, &key, sig);
    int res = ntru_verify(msg, msg_len, sig, &key);
    if (res == 1) {
        printf("Signature is valid!\n");
    } else {
        printf("Signature is invalid!\n");
    }
    return 0;
}

这里使用了NTRU的开源实现库NTRU-Crypto，具体实现细节可以参考其官方文档。需要注意的是，NTRU签名方案可能存在被针对性攻击的风险，因此在实际应用中需要谨慎使用。