Hmm....help me take a look at this: File Encryptor
I am trying to write an simple program to encrypt/decrypt the contents of a text file.
This is the function that I am using:
/*
* Encrypt/Decrypt a file by conducting an XOR operation on the contents
* of the file and the key provide.
* Returns 0 if successful and -1 if fail
*
* char *filename: The file to be encrypted/decrypted
* char *key: The key to encrypt/decrypt the file with
*/
int encrypt (char *filename, char *key)
{
FILE *fptR; /* File pointer to read from the file to be encrypted/decrypted */
FILE *fptW; /* File pointer to write to the file to be encryted/decrypted */
char reader; /* To store each char read from the file */
int keysize; /* Size of the key used to encrypt/decrypt */
int i; /* A counter to iterate the key */
char out[MAX_STRING]; /* Name of the output file */
/* Open the file for reading/writing */
if( ( fptR = fopen(filename, "r+") ) == NULL) {
printf("ERROR: file reader cannot be open\n");
return -1;
}
if( ( fptW = fopen(filename, "r+") ) == NULL) {
printf("ERROR: file writer cannot be open\n");
return -1;
}
/* Start Encrypting/decrypting file */
i = 0;
keysize = strlen(key);
reader = fgetc(fptR);
while(reader != EOF) {
/* Encrypt with key */
reader = reader ^ key[i];
/* Write Encrypted data back to file */
fputc(reader, fptW);
/* Update key & file pointers */
i = (i+1)%keysize;
reader = (char)fgetc(fptR);
}
/* Close files */
fclose(fptW);
fclose(fptR);
return 0;
}
It seems to works with a simple "hello world" text file. But when I try to decrypt a C source file, only the first few characters and the last few characters got decypted. The rest inbetween is still rubbish :(
Could it be fgetc?
Thanks in advance
