XTEA加密算法

XTEA加密算法

#include <stdint.h>

/* take 64 bits of data in v[0] and v[1] and 128 bits of key[0] - key[3] */

void encipher(unsigned int num_rounds, uint32_t v[], uint32_t const key[]) {
    unsigned int i;
    uint32_t v0=v[], v1=v[], sum=, delta=0x9E3779B9;
    for (i=; i < num_rounds; i++) {
        v0 += (((v1 << ) ^ (v1 >> )) + v1) ^ (sum + key[sum & ]);
        sum += delta;
        v1 += (((v0 << ) ^ (v0 >> )) + v0) ^ (sum + key[(sum>>) & ]);
    }
    v[]=v0; v[]=v1;
}

void decipher(unsigned int num_rounds, uint32_t v[], uint32_t const key[]) {
    unsigned int i;
    uint32_t v0=v[], v1=v[], delta=0x9E3779B9, sum=delta*num_rounds;
    for (i=; i < num_rounds; i++) {
        v1 -= (((v0 << ) ^ (v0 >> )) + v0) ^ (sum + key[(sum>>) & ]);
        sum -= delta;
        v0 -= (((v1 << ) ^ (v1 >> )) + v1) ^ (sum + key[sum & ]);
    }
    v[]=v0; v[]=v1;
}