#include "rc4_encry.h"


quint8 RC4_Encry::BatteryKey[16] = {'8','A','D','2','1','1','0','E','0','0','1','B','3','6','9','C'};

RC4_Encry::RC4_Encry()
{
}


void RC4_Encry::battery_and_user_random_value_calc(quint8 *buff, const quint16 bufflen, quint16 *ret_value)
{
    quint8 key_status = 0;
    quint8 index = 0;
    quint16 sequence = 0;

    quint8 mb_rc4_buff[bufflen] = {0};

    for (key_status = 0; key_status < 2; key_status++)
    {
        for (int i = 0; i < bufflen; i++)
        {
            mb_rc4_buff[i] = buff[i];
        }

        rc4_encry(BatteryKey, 16, mb_rc4_buff, bufflen);
        index = (quint8)(mb_rc4_buff[0] & 0x0F);
        sequence = mb_rc4_buff[index];
        index = (quint8)(mb_rc4_buff[index] & 0x0F);
        sequence += (quint16)(mb_rc4_buff[index] << 8);
        ret_value[key_status] = sequence;
    }
}

void RC4_Encry::rc4_encry(quint8 *key, quint32 klen, quint8 *data, quint32 dlen)
{
    quint8 s[256] = {0};
    rc4_init(s,key,klen);
    rc4_crypt(s,data,dlen);
}

void RC4_Encry::rc4_init(quint8 *s, quint8 *key, quint32 len)
{
    int i=0;
    int j=0;
    quint8 tmp = 0;

    for(i=0;i<256;i++){
        s[i] = i;
    }

    for(i=0;i<256;i++){
        j = (j + s[i] + key[i%len]) % 256;
        tmp = s[i];
        s[i] = s[j];
        s[j] = tmp;
    }
}

void RC4_Encry::rc4_crypt(quint8 *s, quint8 *data, quint32 len)
{
    int i = 0, j = 0, t = 0;
    quint32 k = 0;
    quint8 tmp = 0;

    for (k = 0; k < len; k++)
    {
        i = (i + 1) % 256;
        j = (j + s[i]) % 256;

        tmp = s[i];
        s[i] = s[j];
        s[j] = tmp;

        t = (s[i] + s[j]) % 256;
        data[k] ^= s[t];
    }
}