SHA256 C语言代码

以下是SHA256 C语言代码的基本实现：

#include <stdio.h>
#include <stdint.h>
#include <string.h>

#define ROTR(x,n) (((x) >> (n)) | ((x) << (32 - (n))))
#define ROTL(x,n) (((x) << (n)) | ((x) >> (32 - (n))))
#define SHR(x,n) ((x) >> (n))

#define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define EP0(x) (ROTR(x,2) ^ ROTR(x,13) ^ ROTR(x,22))
#define EP1(x) (ROTR(x,6) ^ ROTR(x,11) ^ ROTR(x,25))
#define SIG0(x) (ROTR(x,7) ^ ROTR(x,18) ^ SHR(x,3))
#define SIG1(x) (ROTR(x,17) ^ ROTR(x,19) ^ SHR(x,10))

#define SHA256_BLOCK_SIZE 64

const uint32_t K[] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
    0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
    0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
    0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
    0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
    0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};

void sha256_transform(uint32_t state[], const uint8_t data[]) {
    uint32_t W[64];
    uint32_t A, B, C, D, E, F, G, H, T1, T2;
    int i;

    for (i = 0; i < 16; i++) {
        W[i] = ((uint32_t)data[i * 4] << 24) |
               ((uint32_t)data[i * 4 + 1] << 16) |
               ((uint32_t)data[i * 4 + 2] << 8) |
               ((uint32_t)data[i * 4 + 3]);
    }

    for (i = 16; i < 64; i++) {
        W[i] = SIG1(W[i - 2]) + W[i - 7] + SIG0(W[i - 15]) + W[i - 16];
    }

    A = state[0];
    B = state[1];
    C = state[2];
    D = state[3];
    E = state[4];
    F = state[5];
    G = state[6];
    H = state[7];

    for (i = 0; i < 64; i++) {
        T1 = H + EP1(E) + CH(E,F,G) + K[i] + W[i];
        T2 = EP0(A) + MAJ(A,B,C);
        H = G;
        G = F;
        F = E;
        E = D + T1;
        D = C;
        C = B;
        B = A;
        A = T1 + T2;
    }

    state[0] += A;
    state[1] += B;
    state[2] += C;
    state[3] += D;
    state[4] += E;
    state[5] += F;
    state[6] += G;
    state[7] += H;
}

void sha256_init(uint32_t state[]) {
    state[0] = 0x6a09e667;
    state[1] = 0xbb67ae85;
    state[2] = 0x3c6ef372;
    state[3] = 0xa54ff53a;
    state[4] = 0x510e527f;
    state[5] = 0x9b05688c;
    state[6] = 0x1f83d9ab;
    state[7] = 0x5be0cd19;
}

void sha256_update(uint32_t state[], uint32_t *bitlen, const uint8_t data[], size_t len) {
    uint32_t i, j;

    for (i = 0; i < len; i++) {
        state[8] += data[i];
        state[8] &= 0xff;

        if (++(*bitlen) == 512) {
            sha256_transform(state, &data[i - 63]);
            *bitlen = 0;
        }
    }

    j = i;

    if (*bitlen > 447) {
        for (; i < 512 / 8; i++) {
            state[8] += 0;
            state[8] &= 0xff;
        }

        sha256_transform(state, &data[j - 63]);
        memset(state, 0, 8 * sizeof(uint32_t));
    }

    for (; i < (512 - 64) / 8; i++) {
        state[8] += 0;
        state[8] &= 0xff;
    }

    uint64_t bitlen_tmp = (*bitlen) << 3;
    uint8_t *p = (uint8_t *)&bitlen_tmp;

    for (; i < 512 / 8; i++) {
        state[8] += p[7 - i % 8];
        state[8] &= 0xff;
    }

    sha256_transform(state, &data[j - 63]);
}

void sha256_final(uint32_t state[], uint32_t *bitlen, uint8_t hash[]) {
    int i;

    sha256_update(state, bitlen, (uint8_t *)"\x80", 1);

    while (*bitlen != 448) {
        sha256_update(state, bitlen, (uint8_t *)"\x00", 1);
    }

    uint64_t bitlen_tmp = (*bitlen) << 3;
    uint8_t *p = (uint8_t *)&bitlen_tmp;

    for (i = 0; i < 8; i++) {
        sha256_update(state, bitlen, &p[7 - i], 1);
    }

    for (i = 0; i < 8; i++) {
        hash[4 * i] = (state[i] >> 24) & 0xff;
        hash[4 * i + 1] = (state[i] >> 16) & 0xff;
        hash[4 * i + 2] = (state[i] >> 8) & 0xff;
        hash[4 * i + 3] = state[i] & 0xff;
    }
}

void sha256(const uint8_t data[], size_t len, uint8_t hash[]) {
    uint32_t state[8];
    uint32_t bitlen = 0;

    sha256_init(state);
    sha256_update(state, &bitlen, data, len);
    sha256_final(state, &bitlen, hash);
}

int main() {
    uint8_t data[] = "hello world";
    uint8_t hash[32];

    sha256(data, strlen((char *)data), hash);

    for (int i = 0; i < 32; i++) {
        printf("%02x", hash[i]);
    }

    printf("\n");

    return 0;
}

这个代码可以对输入的数据计算出其SHA256哈希值，并输出到控制台上。但需要注意，该实现并不是最优的，仅供参考。在实际应用中，应该使用更加优化的实现。