#include <stdio.h>

void rc4(unsigned char *key, unsigned long keylen, unsigned char *data, unsigned long datalen) {

    unsigned char s[256];

    unsigned int i, j = 0, x,keylenl=0;

    // 初始化 S 盒

    for (i = 0; i < 256; i++) {

        s[i] = i;

    }

    for (i = 0; i < 256; i++) {

		 x = s[i];

        j = (2*j+ x  + key[ keylenl]) % 256;

        // 交换 S [i] 和 S [j]

        s[i] = s[j];

        s[j] = x;

		if(++keylenl >= 10) 

		keylenl = 0;

    }

    i = j = 0;

    for (unsigned long n = 0; n < datalen; n++) {

        i = (i + j) % 256;

        j = (j + s[i]) % 256;

        // 交换 S [i] 和 S [j]

        x = s[i];

        s[i] = s[j];

        s[j] = x;

		data[n] -=n%13;

        data[n] ^= s[(s[i]+j + s[j]) % 256];

    }

}

int main() {

    unsigned char key[] = {93,66,98,41,3,54,71,65,21,54};

    unsigned long keylen = sizeof(key) ; // 减去末尾的 '\0'

    unsigned char data[44] ;

	data[0] = -9;

  data[1] = 46;

  data[2] = 52;

  data[3] = -16;

  data[4] = 114;

  data[5] = -49;

  data[6] = 94;

  data[7] = 10;

  data[8] = -69;

  data[9] = -20;

  data[10] = -79;

  data[11] = 43;

  data[12] = 112;

  data[13] = -120;

  data[14] = -120;

  data[15] = -19;

  data[16] = 70;

  data[17] = 56;

  data[18] = -37;

  data[19] = -38;

  data[20] = 108;

  data[21] = -67;

  data[22] = -44;

  data[23] = 6;

  data[24] = 119;

  data[25] = -14;

  data[26] = -49;

  data[27] = 86;

  data[28] = -120;

  data[29] = -58;

  data[30] = 49;

  data[31] = -46;

  data[32] = -73;

  data[33] = 90;

  data[34] = -63;

  data[35] = 66;

  data[36] = -80;

  data[37] = -12;

  data[38] = 72;

  data[39] = 55;

  data[40] = -11;

  data[41] = 44;

  data[42] = -11;

  data[43] = 88;

    unsigned long datalen = sizeof(data) ; // 减去末尾的 '\0'

    rc4(key, keylen, data, datalen);

    printf("加密后：");

    for (unsigned long i = 0; i < datalen; i++) {

        printf("%02X ", data[i]);

    }

    //rc4(key, keylen, data, datalen);

    printf("\n解密后：%s", data);

    return 0;

}