Georgios Solidakis / IndiCorp

Embedded systems coursework 2.

Fork of Crypto_light by Edward Stott

cipher/RC4.cpp

Committer:
feb11
Date:
2013-09-14
Revision:
7:2dbbdfb08123
Parent:
RC4.cpp@ 0:7a1237bd2d13
Child:
8:a090264e9b2d

File content as of revision 7:2dbbdfb08123:

#include "RC4.h"

RC4::RC4(uint8_t *key, uint8_t keyLength):
Cipher(),
s(),
i(0),
j(0)
{
    for(int k = 0; k < 256; ++k)
        s[k] = k;
    int l = 0;
    for(int k = 0; k < 256; ++k)
    {
        l = (l + s[k] + key[k % keyLength]) % 256;
        uint8_t tmp = s[l];
        s[l] = s[k];
        s[k] = tmp;
    } 
}

uint8_t RC4::encyptByte(uint8_t in)
{
    ++i;
    j += s[i];
    uint8_t tmp = s[i];
    s[i] = s[j];
    s[j] = tmp;
    uint8_t c = s[(s[i]+s[j])%256];
    return in^c;
}

void RC4::encrypt(uint8_t *out, uint8_t *in, uint32_t length)
{
    for(uint32_t l = 0; l < length; ++l)
        out[l] = encyptByte(in[l]);
}

void RC4::decrypt(uint8_t *out, uint8_t *in, uint32_t length)    
{
    encrypt(out, in, length);
}

uint32_t RC4::getBlockSize() const
{
    return 1;
}