Encryptor\Decryptor

KEWL!! thanks to you guys i have made an encrypter/decrypter . It works well on .txt files! plz try it and tell me what u think. It doesnt work on programs yet because sometimes a character or 2 add on to the end of the file. If you could tell me how to take them off i'd really appreciate it! thx in advance

First of all, it doesn't work. Second of all, you overwrite the file you are encrypting. That is totally bad, especially when your decryptor doesn't work.

So you should save the encrypted text to a new file name like filename-ciphered.txt. Or you should prompt for the filename to save the ciphered text to.

Here.. I have included an XOR encrypting program that works (most of the time). The problem with XOR encryption is that the ciphered text is completley unpredictable and can sometimes put in characters that you don't want (like newlines and terminators). But you can look at it to get a picture of some good ideas for an encryption program. I hope that helps.

it DOES work - but it doesnt accept spaces, and it adds 1 or 2 characters after the word lol

Ahh, see I encrypted a text file that had many a space. It took a 25 character file and encrypted it to like 5 characters. Then, when I tried to decrypt it, it was still garbage.

yah :/ do you know how to make it encrypt and decrypt spaces?

It does encrypt but it doesn't decrypt for me.

I am running XP just in case that might be a reason why.

naw, im using xp and works 4 me. you need to may it 1 word :/ if you want to write a sentace try-writing-it-like-this. it works

When I wrote my first rot13 encrypting program, I just skipped over the spaces.. As a matter of fact, hold on...... Ok, I got the algorithm I made for it:

Code:

   /* 
    * Begin getting text from user and char-by-char encrypting
    */
   while ((c = getchar()) != '\n')
   {
      if (!isspace(c))  // If its a space, there is no need to shift 
      {  
         if (isalnum(c))  // Make sure it's an alpha-numeric
         {    
            if (   c == 'x' || c == 'X' || c == 'y' || c == 'Y' || c == 'z' || c = 'Z' )
               *cipher++ = (c - 23);
            else
               *cipher++ = (c + 3);
         }
      }
      else
         *cipher++ = c; // Leave it alone if it is a space
   }

The main idea is to use the ctype (or the cctype for ANSI C++) functions isspace(), isalnum(), etc.. to test the character and do certain things based on the returns of those functions. I'm sorry if you can't understand the code. I wrote it a long, long time ago and it's C. Plus you probably have to understand Caesarian encryption (which isn't that hard to understand).

So basically test for spaces and don't encrypt them, just leave them alone and let them be spaces in the encrypted text.

I hope that helps.

EDIT:: Please do not flame me for this piece of code. I realize how lame it is and how unstructured it is (with 3 thresholds of indentation), but it works and it helps express my point.

*ciphertext++ = c; // Leave it alone if it is a space


in this line of code i need to know what c is :/ and ++ needs an l-value

Look at the top of the program block..

Code:

while ( (c = getchar()) != '\n' )
{
   // etc. etc.
}

c is a character that has been read from the user's input.

I don't know why the compiler is whining about *ciphertext++. To change it around replace it with this:

Code:

*ciphertext = c;
ciphertext++;

I hope you aren't trying to incorporate this into anything. It is based on a completley different scheme than what you were using.

i tried :

for(int i = 1; i < strlngth; i++)
{
if (!isspace(ciphertext[i]))
{
ciphertext[i] = plaintext[i] - opener;
}
else
ciphertext[i] = '¥';
};

but it just prints 
everytime i type in a space in the file. ass int 
is the WHOLE file :/

Why do you subtract 'opener'?

Just leave it:

Code:

for(int i = 1; i < strlngth; i++) 
{ 
   if (!isspace(ciphertext[i]))  
      ciphertext[i] = plaintext[i];  
   else 
      ciphertext[i] = '¥'; 
};

opener is a random number. it sits at the beginning of the file and when it gets opened it reads the number and subtracts it. therefore ytou must add it in the other or it will come out random again ^_^

Did you even try NOT subtracting opener?