以下是一个用 C 语言实现 SHA256 算法的示例代码，包含 `init`、`update` 和 `finish` 三个过程，输入输出都是 `uint8_t` 类型的数组： ```c #include <stdio.h> #include <stdint.h> // 常量定义 #define SHA256_BLOCK_SIZE 64 // 轮常量 uint32_t k[64] = { 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 }; // 初始化哈希值 void 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; } // 逻辑函数 uint32_t Ch(uint32_t x, uint32_t y, uint32_t z) { return (x & y) ^ ((~x) & z); } uint32_t Maj(uint32_t x, uint32_t y, uint32_t z) { return (x & y) ^ (x & z) ^ (y & z); } uint32_t Sigma0(uint32_t x) { return (x >> 2 | x << 30) ^ (x >> 13 | x << 19) ^ (x >> 22 | x << 10); } uint32_t Sigma1(uint32_t x) { return (x >> 6 | x << 26) ^ (x >> 11 | x << 21) ^ (x >> 25 | x << 7); } uint32_t sigma0(uint32_t x) { return (x >> 7 | x << 25) ^ (x >> 18 | x << 14) ^ (x >> 3); } uint32_t sigma1(uint32_t x) { return (x >> 17 | x << 15) ^ (x >> 19 | x << 13) ^ (x >> 10); } // 处理一个 512 位的块 void processBlock(uint32_t *state, const uint8_t *block) { uint32_t w[64]; uint32_t a, b, c, d, e, f, g, h; uint32_t t1, t2; // 准备消息扩展 for (int i = 0; i < 16; i++) { w[i] = (block[i * 4] << 24) | (block[i * 4 + 1] << 16) | (block[i * 4 + 2] << 8) | block[i * 4 + 3]; } for (int i = 16; i < 64; i++) { w[i] = sigma1(w[i - 2]) + w[i - 7] + sigma0(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 (int i = 0; i < 64; i++) { t1 = h + Sigma1(e) + Ch(e, f, g) + k[i] + w[i]; t2 = Sigma0(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; } // 更新状态 void update(uint32_t *state, const uint8_t *data, size_t length) { size_t offset; uint8_t block[SHA256_BLOCK_SIZE]; offset = 0; while (length >= SHA256_BLOCK_SIZE) { memcpy(block, data + offset, SHA256_BLOCK_SIZE); processBlock(state, block); offset += SHA256_BLOCK_SIZE; length -= SHA256_BLOCK_SIZE; } } // 完成计算并输出结果 void finish(uint32_t *state, uint8_t *digest) { uint32_t i; for (i = 0; i < 8; i++) { digest[i * 4] = (state[i] >> 24) & 0xff; digest[i * 4 + 1] = (state[i] >> 16) & 0xff; digest[i * 4 + 2] = (state[i] >> 8) & 0xff; digest[i * 4 + 3] = state[i] & 0xff; } } int main() { uint32_t state[8]; uint8_t data[] = "Hello, World!"; uint8_t digest[32]; init(state); update(state, data, sizeof(data) - 1); finish(state, digest); for (int i = 0; i < 32; i++) { printf("%02x", digest[i]); } printf("\n"); return 0; } ``` 需要注意的逻辑点： 1. 数据的字节序处理要准确，确保在不同平台上都能正确运行。 2. 注意边界情况，比如输入数据长度不是 512 位整数倍的处理。 3. 代码中的常量和函数定义要确保准确无误，因为 SHA256 算法的精度要求较高。 [2024-12-01 09:29:56 | AI写代码神器 | 2239点数解答]