XOR encrypt

xor_encrypt.c

/**
 * $ gcc -o program xor_encrypt.c
 * $ ./program
 */

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

#define LOG printf

char *xor_encrypt(const char * message, const char * key) {
    size_t messagelen = strlen(message);
    size_t keylen     = strlen(key);
    char * encrypted  = malloc((messagelen + 1)* sizeof(char));

    int i;
    for(i = 0; i < messagelen; i++) {
        encrypted[i] = message[i] ^ key[i % keylen];
        while (encrypted[i] >90) encrypted[i]-=10;
        while (encrypted[i] <65) encrypted[i]+=10;
    }
    encrypted[messagelen] = '\0';
    return encrypted;
}

void test_case_01() {
    LOG("---Running: test_case_01\n");
    const char *message = "CFCUUSHISIFRIJF";
    const char *key     = "IJGJGJVGDIFTEESDGIHJBGDARTJIIHHGIQBJAHFDQGHYWUSWVCJETDEGHYHFHDDHYCGIEVCJCATXXSHEGHBAGDIETQGHYDFTHI";

    const char *expected = "FHJGDAFJIFFBHAG";
    char *actual = xor_encrypt(message, key);
    LOG("Expect: %s\n", expected);
    LOG("Actual: %s\n", actual);
    if(strcmp(expected, actual) == 0) {
        LOG("Passed\n"); // Passed actually
    } else {
        LOG("Failed\n");
    }
    free(actual);
}

int main(int argc, char **argv)
{
    test_case_01();
    return 0;
}

hello my friend and to decrypter ?