以下是一个简单的 C 语言实现 SHA256 算法的示例代码： ```c #include <stdio.h> #include <string.h> // 常量定义 #define SHA256_BLOCK_SIZE 64 #define SHA256_DIGEST_SIZE 32 // 轮常量 const 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 }; // 右旋转函数 uint32_t ROTR(uint32_t x, int n) { return (x >> n) | (x << (32 - n)); } // 压缩函数 void sha256_transform(uint32_t state[8], const uint8_t data[SHA256_BLOCK_SIZE]) { 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] = (data[i * 4 + 0] << 24) | (data[i * 4 + 1] << 16) | (data[i * 4 + 2] << 8) | (data[i * 4 + 3]); } for (int i = 16; i < 64; i++) { uint32_t s0 = ROTR(w[i - 15], 7) ^ ROTR(w[i - 15], 18) ^ (w[i - 15] >> 3); uint32_t s1 = ROTR(w[i - 2], 17) ^ ROTR(w[i - 2], 19) ^ (w[i - 2] >> 10); w[i] = w[i - 16] + s0 + w[i - 7] + s1; } 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 + ROTR(e, 6) ^ ROTR(e, 11) ^ ROTR(e, 25) + ((e & f) ^ (~e & g)) + k[i] + w[i]; t2 = ROTR(a, 2) ^ ROTR(a, 13) ^ ROTR(a, 22) + ((a & b) ^ (a & c) ^ (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; } // 初始化哈希值 void sha256_init(uint32_t state[8]) { state[0] = 0x6a09e667; state[1] = 0xbb67ae85; state[2] = 0x3c6ef372; state[3] = 0xa54ff53a; state[4] = 0x510e527f; state[5] = 0x9b05688c; state[6] = 0x1f83d9ab; state[7] = 0x5be0cd19; } // 处理输入数据 void sha256_update(uint32_t state[8], const uint8_t *data, size_t len) { size_t offset; for (offset = 0; offset < len; offset += SHA256_BLOCK_SIZE) { sha256_transform(state, (const uint8_t *)&data[offset]); } } // 计算最终哈希值 void sha256_final(uint32_t state[8], uint8_t digest[SHA256_DIGEST_SIZE]) { int i; for (i = 0; i < 8; i++) { digest[i * 4 + 0] = (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; } } // 计算输入字符串的 SHA256 哈希值 void sha256(const char *input, uint8_t digest[SHA256_DIGEST_SIZE]) { uint32_t state[8]; sha256_init(state); size_t len = strlen(input); sha256_update(state, (const uint8_t *)input, len); sha256_final(state, digest); } int main() { uint8_t digest[SHA256_DIGEST_SIZE]; const char *message = "Hello, World!"; sha256(message, digest); printf("SHA256 hash of '%s': ", message); for (int i = 0; i < SHA256_DIGEST_SIZE; i++) { printf("%02x", digest[i]); } printf("\n"); return 0; } ``` 注意： 1. 此示例代码仅为简单实现，可能在性能和安全性方面存在不足。 2. 实际应用中，需要更严格的错误处理和边界检查。 3. 对于关键的密码学应用，建议使用经过专业验证和优化的库。 [2025-05-20 19:08:35 | AI写代码神器 | 2161点数解答]