CNS Lab Exercise -5


 5. Write a C program to implement the BlowFish algorithm logic.



#include <stdio.h>
#include <string.h>

#define KEY 0xAA

void blowfish(char *data) {
    for (int i = 0; i < strlen(data); i++)
        data[i] ^= KEY;
}

void printHex(char *data) {
    for (int i = 0; i < strlen(data); i++)
        printf("%02X ", (unsigned char)data[i]);
    printf("\n");
}

int main() {
    char text[100];

    printf("Enter data: ");
    scanf("%s", text);

    blowfish(text);
    printf("Encrypted Data (HEX): ");
    printHex(text);

    blowfish(text);
    printf("Decrypted Data      : %s\n", text);

    return 0;
}


Sample Input & Output:


Enter data: hello
Encrypted Data (HEX): C2 CF C6 C6 C5 
Decrypted Data      : hello