前言你有没有想过你输入的密码、发送的消息、存储的文件——是怎么变成一堆乱码让黑客看不懂的加密是信息安全的基石。今天我们从零实现两种经典加密算法· AES对称加密同一个密钥加密和解密速度快· RSA非对称加密公钥加密、私钥解密安全分发密钥---一、AES加密原理1. AES核心操作AES是分组加密算法每次处理16字节128位┌─────────────────────────────────────────────────────────────┐│ AES加密流程 ││ 明文(16B) → AddRoundKey → SubBytes → ShiftRows → MixCols ││ ↓ ││ 重复9/11/13轮取决于密钥长度 ││ ↓ ││ 密文(16B) │└─────────────────────────────────────────────────────────────┘操作 说明SubBytes 字节替换S盒查表ShiftRows 行移位MixColumns 列混合GF(2⁸)乘法AddRoundKey 与轮密钥异或---二、完整代码实现1. AES核心操作c#include stdio.h#include stdlib.h#include string.h#include stdint.h#include time.h#include math.h// AES S盒static const uint8_t sbox[256] {0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};// 逆S盒static const uint8_t inv_sbox[256] {0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d};// 轮常数static const uint8_t rcon[10] {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};// SubBytesvoid sub_bytes(uint8_t *state) {for (int i 0; i 16; i) {state[i] sbox[state[i]];}}void inv_sub_bytes(uint8_t *state) {for (int i 0; i 16; i) {state[i] inv_sbox[state[i]];}}// ShiftRowsvoid shift_rows(uint8_t *state) {uint8_t tmp[16];for (int i 0; i 4; i) {for (int j 0; j 4; j) {tmp[i * 4 j] state[i * 4 ((j i) % 4)];}}memcpy(state, tmp, 16);}void inv_shift_rows(uint8_t *state) {uint8_t tmp[16];for (int i 0; i 4; i) {for (int j 0; j 4; j) {tmp[i * 4 j] state[i * 4 ((j - i 4) % 4)];}}memcpy(state, tmp, 16);}// GF(2^8)乘法uint8_t gf_mul(uint8_t a, uint8_t b) {uint8_t result 0;for (int i 0; i 8; i) {if (b 1) result ^ a;b 1;a 1;if (a 0x100) a ^ 0x1b;}return result;}// MixColumnsvoid mix_columns(uint8_t *state) {uint8_t tmp[16];for (int i 0; i 4; i) {int idx i * 4;tmp[idx] gf_mul(state[idx], 2) ^ gf_mul(state[idx1], 3) ^ state[idx2] ^ state[idx3];tmp[idx1] state[idx] ^ gf_mul(state[idx1], 2) ^ gf_mul(state[idx2], 3) ^ state[idx3];tmp[idx2] state[idx] ^ state[idx1] ^ gf_mul(state[idx2], 2) ^ gf_mul(state[idx3], 3);tmp[idx3] gf_mul(state[idx], 3) ^ state[idx1] ^ state[idx2] ^ gf_mul(state[idx3], 2);}memcpy(state, tmp, 16);}void inv_mix_columns(uint8_t *state) {uint8_t tmp[16];for (int i 0; i 4; i) {int idx i * 4;tmp[idx] gf_mul(state[idx], 0x0e) ^ gf_mul(state[idx1], 0x0b) ^ gf_mul(state[idx2], 0x0d) ^ gf_mul(state[idx3], 0x09);tmp[idx1] gf_mul(state[idx], 0x09) ^ gf_mul(state[idx1], 0x0e) ^ gf_mul(state[idx2], 0x0b) ^ gf_mul(state[idx3], 0x0d);tmp[idx2] gf_mul(state[idx], 0x0d) ^ gf_mul(state[idx1], 0x09) ^ gf_mul(state[idx2], 0x0e) ^ gf_mul(state[idx3], 0x0b);tmp[idx3] gf_mul(state[idx], 0x0b) ^ gf_mul(state[idx1], 0x0d) ^ gf_mul(state[idx2], 0x09) ^ gf_mul(state[idx3], 0x0e);}memcpy(state, tmp, 16);}// AddRoundKeyvoid add_round_key(uint8_t *state, uint8_t *key) {for (int i 0; i 16; i) {state[i] ^ key[i];}}2. AES密钥扩展c// 密钥扩展void key_expansion(uint8_t *key, uint8_t *round_keys, int rounds) {int key_len 16; // AES-128int total_words (rounds 1) * 4;uint32_t *w (uint32_t*)round_keys;// 前4个字是原始密钥for (int i 0; i 4; i) {w[i] (key[i*4] 24) | (key[i*41] 16) |(key[i*42] 8) | key[i*43];}for (int i 4; i total_words; i) {uint32_t temp w[i-1];if (i % 4 0) {// RotWord SubWord Rcontemp (temp 8) | (temp 24);temp (sbox[temp 24] 24) | (sbox[(temp 16) 0xff] 16) |(sbox[(temp 8) 0xff] 8) | sbox[temp 0xff];temp ^ (rcon[i/4 - 1] 24);}w[i] w[i-4] ^ temp;}}3. AES加密/解密c// AES加密AES-128void aes_encrypt(uint8_t *input, uint8_t *output, uint8_t *key) {uint8_t state[16];memcpy(state, input, 16);int rounds 10;uint8_t round_keys[176];key_expansion(key, round_keys, rounds);// 初始轮add_round_key(state, round_keys);// 9轮for (int r 1; r rounds; r) {sub_bytes(state);shift_rows(state);mix_columns(state);add_round_key(state, round_keys r * 16);}// 最后一轮sub_bytes(state);shift_rows(state);add_round_key(state, round_keys rounds * 16);memcpy(output, state, 16);}void aes_decrypt(uint8_t *input, uint8_t *output, uint8_t *key) {uint8_t state[16];memcpy(state, input, 16);int rounds 10;uint8_t round_keys[176];key_expansion(key, round_keys, rounds);// 初始轮逆add_round_key(state, round_keys rounds * 16);// 9轮逆for (int r rounds - 1; r 0; r--) {inv_shift_rows(state);inv_sub_bytes(state);add_round_key(state, round_keys r * 16);inv_mix_columns(state);}// 最后一轮逆inv_shift_rows(state);inv_sub_bytes(state);add_round_key(state, round_keys);memcpy(output, state, 16);}4. RSA加密c// 大整数运算简化版仅演示原理typedef struct big_int {uint32_t parts[32];int size;} big_int_t;// 快速幂模运算uint64_t mod_pow(uint64_t base, uint64_t exp, uint64_t mod) {uint64_t result 1;base % mod;while (exp 0) {if (exp 1) result (result * base) % mod;base (base * base) % mod;exp 1;}return result;}// 判断素数简单试除int is_prime(uint64_t n) {if (n 2) return 0;if (n 2) return 1;if (n % 2 0) return 0;for (uint64_t i 3; i * i n; i 2) {if (n % i 0) return 0;}return 1;}// 生成随机素数uint64_t random_prime(int bits) {uint64_t start 1ULL (bits - 1);uint64_t end (1ULL bits) - 1;uint64_t n;do {n start rand() % (end - start);if (n % 2 0) n;} while (!is_prime(n));return n;}// 扩展欧几里得uint64_t mod_inverse(uint64_t a, uint64_t m) {uint64_t m0 m, a0 a;uint64_t y 0, x 1;if (m 1) return 0;while (a 1) {uint64_t q a / m;uint64_t t m;m a % m;a t;t y;y x - q * y;x t;}if (x 0) x m0;return x;}// RSA密钥对typedef struct rsa_key {uint64_t n; // 模数uint64_t e; // 公钥指数uint64_t d; // 私钥指数} rsa_key_t;// 生成RSA密钥对rsa_key_t rsa_generate_keys(int bits) {uint64_t p random_prime(bits);uint64_t q random_prime(bits);uint64_t n p * q;uint64_t phi (p - 1) * (q - 1);uint64_t e 65537;uint64_t d mod_inverse(e, phi);rsa_key_t keys;keys.n n;keys.e e;keys.d d;return keys;}// RSA加密公钥uint64_t rsa_encrypt(uint64_t msg, uint64_t e, uint64_t n) {if (msg n) {fprintf(stderr, 消息过大需要分段加密\n);return 0;}return mod_pow(msg, e, n);}// RSA解密私钥uint64_t rsa_decrypt(uint64_t cipher, uint64_t d, uint64_t n) {return mod_pow(cipher, d, n);}5. 测试代码cvoid test_aes() {printf( AES加密测试 \n\n);uint8_t key[16] {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c};uint8_t plaintext[16] {0x32, 0x43, 0xf6, 0xa8, 0x88, 0x5a, 0x30, 0x8d,0x31, 0x31, 0x98, 0xa2, 0xe0, 0x37, 0x07, 0x34};printf(明文: );for (int i 0; i 16; i) printf(%02x , plaintext[i]);printf(\n);uint8_t ciphertext[16];aes_encrypt(plaintext, ciphertext, key);printf(密文: );for (int i 0; i 16; i) printf(%02x , ciphertext[i]);printf(\n);uint8_t decrypted[16];aes_decrypt(ciphertext, decrypted, key);printf(解密: );for (int i 0; i 16; i) printf(%02x , decrypted[i]);printf(\n);printf(原始解密: %s\n,memcmp(plaintext, decrypted, 16) 0 ? ✅ 成功 : ❌ 失败);}void test_rsa() {printf(\n RSA加密测试 \n\n);rsa_key_t keys rsa_generate_keys(8);printf(公钥: (n%llu, e%llu)\n, keys.n, keys.e);printf(私钥: (n%llu, d%llu)\n, keys.n, keys.d);uint64_t msg 42;printf(\n原文: %llu\n, msg);uint64_t cipher rsa_encrypt(msg, keys.e, keys.n);printf(加密: %llu\n, cipher);uint64_t decrypted rsa_decrypt(cipher, keys.d, keys.n);printf(解密: %llu\n, decrypted);printf(原始解密: %s\n, msg decrypted ? ✅ 成功 : ❌ 失败);}int main() {srand(time(NULL));test_aes();test_rsa();return 0;}---三、编译和运行bashgcc -o encryption encryption.c -lm./encryption---四、AES vs RSA特性 AES RSA类型 对称加密 非对称加密密钥 同一密钥 公钥私钥速度 快 慢慢1000倍密钥长度 128/192/256位 1024/2048/4096位适用场景 数据加密 密钥分发、数字签名---五、总结通过这篇文章你学会了· AES加密核心操作S盒、行移位、列混合、密钥扩展· RSA密钥生成和加解密· 两种加密算法的完整实现· 对称加密 vs 非对称加密的区别加密是信息安全的基石。掌握它你就理解了HTTPS、SSH、数字签名的底层原理。下一篇预告《从零实现一个网络防火墙包过滤与状态检测》---评论区分享一下你对加密技术的理解