c xor result is different than javascript xor

Question

I'm trying to do some sort of xor file encryption in c, and decryption in javascript (using this as a basis, and for now I'm stuck at the following issue:

Say for example i want to do 73^122 in C, the result is 57 , but the same operation in javascript yields 51 . Why is this happening, and what would be the proper way to fix it?

Here's some C code of the encrypt function

void encrypt_data(FILE* input_file, FILE* output_file, char* key)
{
  int key_count = 0; //Used to restart key if strlen(key) < strlen(encrypt)
  int encrypt_byte;

  while( (encrypt_byte = fgetc(input_file)) != EOF) //Loop through each byte of file until EOF
  {
    //XOR the data and write it to a file
    fputc(encrypt_byte ^ key[key_count], output_file);
    printf("original %d\n", encrypt_byte); //yields 73
    printf("xoring with %d\n", key[key_count]); // yields 122
    printf("xored %d\n", encrypt_byte ^ key[key_count]); // yields 57
    break; //breaking just for example purpose

    //Increment key_count and start over if necessary
    key_count++;
    if(key_count == strlen(key))
        key_count = 0;
  }
}

Answer 1

I really doubt the result for C that you're mentioning. You should show some code.

That your right-hand side has more than 8 bits is a bit strange, normally for XOR encryption in C you'd do it one char at a time, which in practice means with 8-bit bytes.

Any chance you confused hexadecimal ( 0x73 and 0x122 ) vs decimal ( 73 and 122 ) number literals? Again, very hard to help when you're not showing your code.

Answer 2

When I run:

#include <stdio.h>

int main() {
    printf("%d\n", 73^122);
}

I get:

51

can you please show us the C code in question and we can show you the bug.