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[分享]TEA、XTEA、XXTEA加解密
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发表于: 2021-9-16 17:28
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简介
TEA的分组长度为64位，密钥长度为128位，采用Feistel网络，建议32次循环加密即64轮
XTEA是TEA的扩展，同样是一个64位块的Feistel密码，使用128位密钥，建议64轮
XXTEA是一个非平衡Feistel网络分组密码，在可变长度块上运行，这些块是32位大小的任意倍数（最小64位），使用128位密钥
符号介绍
- 按位异或，⊕
- 模加，⊞
TEA加密
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | #include <stdio.h>void encrypt(unsigned int* v, unsigned int* key) { unsigned int l = v[0], r = v[1], sum = 0, delta = 0x9e3779b9; for (size_t i = 0; i < 32; i++) { sum += delta; l += ((r << 4) + key[0]) ^ (r + sum) ^ ((r >> 5) + key[1]); r += ((l << 4) + key[2]) ^ (l + sum) ^ ((l >> 5) + key[3]); } v[0] = l; v[1] = r;}void decrypt(unsigned int* v, unsigned int* key) { unsigned int l = v[0], r = v[1], sum = 0, delta = 0x9e3779b9; sum = delta *32; for (size_t i = 0; i < 32; i++) { r -= ((l << 4) + key[2]) ^ (l + sum) ^ ((l >> 5) + key[3]); l -= ((r << 4) + key[0]) ^ (r + sum) ^ ((r >> 5) + key[1]); sum -= delta; } v[0] = l; v[1] = r;}int main(int argc, char const *argv[]){ //test unsigned int v[2]={1,2},key[4]={1,2,3,4}; printf("%u,%u\n",v[0],v[1]); encrypt(v,key); printf("%u,%u\n",v[0],v[1]); decrypt(v,key); printf("%u,%u\n",v[0],v[1]); return 0;} |
XTEA加密
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | #include <stdio.h>void encrypt(unsigned int* v, unsigned int* key) { unsigned int l = v[0], r = v[1], sum = 0, delta = 0x9e3779b9; for (size_t i = 0; i < 32; i++) { l += (((r << 4) ^ (r >> 5)) + r) ^ (sum + key[sum & 3]); sum += delta; r += (((l << 4) ^ (l >> 5)) + l) ^ (sum + key[(sum >> 11) & 3]); } v[0] = l; v[1] = r;}void decrypt(unsigned int* v, unsigned int* key) { unsigned int l = v[0], r = v[1], sum = 0, delta = 0x9e3779b9; sum = delta * 32; for (size_t i = 0; i < 32; i++) { r -= (((l << 4) ^ (l >> 5)) + l) ^ (sum + key[(sum >> 11) & 3]); sum -= delta; l -= (((r << 4) ^ (r >> 5)) + r) ^ (sum + key[sum & 3]); } v[0] = l; v[1] = r;}int main(int argc, char const *argv[]){ //test unsigned int v[2]={1,2},key[4]={1,2,3,4}; printf("%u,%u\n",v[0],v[1]); encrypt(v,key); printf("%u,%u\n",v[0],v[1]); decrypt(v,key); printf("%u,%u\n",v[0],v[1]); return 0;} |
XXTEA加密
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | #include <stdio.h> #include <stdint.h> #define DELTA 0x9e3779b9 #define MX (((z>>5^y<<2) + (y>>3^z<<4)) ^ ((sum^y) + (key[(p&3)^e] ^ z))) void btea(uint32_t *v, int n, uint32_t const key[4]) { uint32_t y, z, sum; unsigned p, rounds, e; if (n > 1) /* Coding Part */ { rounds = 6 + 52/n; sum = 0; z = v[n-1]; do { sum += DELTA; e = (sum >> 2) & 3; for (p=0; p<n-1; p++) { y = v[p+1]; z = v[p] += MX; } y = v[0]; z = v[n-1] += MX; } while (--rounds); } else if (n < -1) /* Decoding Part */ { n = -n; rounds = 6 + 52/n; sum = rounds*DELTA; y = v[0]; do { e = (sum >> 2) & 3; for (p=n-1; p>0; p--) { z = v[p-1]; y = v[p] -= MX; } z = v[n-1]; y = v[0] -= MX; sum -= DELTA; } while (--rounds); } } int main() { uint32_t v[2]= {1,2}; uint32_t const k[4]= {2,2,3,4}; int n= 2; //n的绝对值表示v的长度，取正表示加密，取负表示解密 // v为要加密的数据是两个32位无符号整数 // k为加密解密密钥，为4个32位无符号整数，即密钥长度为128位 printf("加密前原始数据：%u %u\n",v[0],v[1]); btea(v, n, k); printf("加密后的数据：%u %u\n",v[0],v[1]); btea(v, -n, k); printf("解密后的数据：%u %u\n",v[0],v[1]); return 0; } |
逆向特征
TEA系列算法典型特征是采用密钥调度常数0x9e3779b9
参考
《加密与解密》
维基百科
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谢谢大佬补充 |
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