xor.c

#include <stdio.h>

unsigned int Hash(const char * str)
{

    unsigned int hash = 0;

    for(; *str; str++)
    {
        hash += (unsigned char)(str);
        hash -= (hash << 13) | (hash >> 19);
    }

    return hash;

}






int main(void)
{
    char KeyWord[255], Plain[255], Enc[255], DecTemp[255];
    int i=0, ii=0, KeyLength=0, PlainLength=0, EncLength=0, DecLength=0;

    printf("Enter key: ");
    gets(KeyWord);

    while(KeyWord[KeyLength])
        KeyLength++;

    unsigned int HashedKey[KeyLength];
    for (i = 0; i<KeyLength; i++)
        HashedKey[i] = Hash(&KeyWord[i]);

    printf("Enter message: ");
    gets(Plain);

    while(Plain[PlainLength])
        PlainLength++;

    for (i=0; i<PlainLength; i++)
    {
        Enc[i] = Plain[i]^HashedKey[ii];
        EncLength++;
        if (ii<KeyLength)
            ii++;
        else
            ii=0;
    }
    printf("!!! ii = %d\n", ii);
    ii=0;
    for (i=0; i<EncLength; i++)
    {
        DecTemp[i] = Enc[i]^HashedKey[ii];
        DecLength++;
        if (ii<KeyLength)
            ii++;
        else
            ii=0;
    }
    printf("!!! ii = %d\n", ii);

    //char Decrypted[DecLength];
    //for(i=0; i<DecLength; i++)
    //    Decrypted[i] = DecTemp[i];

    printf("KEY: %s\n\nPLAINTEXT: %s\n\nKEYHASH: ", KeyWord, Plain);
    for (i=0; i<KeyLength; i++)
        printf("%X ", HashedKey[i]);

    printf("\n\nENCRYPTEDTEXT: %s\n\nDECRYPTEDTEXT: %s", Enc, DecTemp);

    printf("\n\nKEYLENGTH: %d\n\nPLAINLENGTH: %d\n\nENCLENGTH: %d\n\nDECLENGTH: %d\n\n", KeyLength, PlainLength, EncLength, DecLength);
    system("pause");
    return 0;
}