Simple JavaScript encryption function

Question

I have a function which has to change characters from one array to the characters from another. It is kind of simple encryption. I have:

var plainArray = ['A','B','C',...,'Z'];
var cipherArray = ['a','b','c',...,'z'];
function rotateToPosition(signalCharacter, indexCharacter, plainAlphabet, cipherAlphabet)

already working. Now I have to write a function which will change given word into encrypted word.

function encrypt(plainText, signalCharacter, indexCharacter, plainAlphabet, cipherAlphabet)
{
   var encryptedString = signalCharacter;
   //i is what will hold the results of the encrpytion until it can be appended to encryptedString
   var i;
   // rotate array to signal character position
   var rotateArray = rotateToPosition(signalCharacter, indexCharacter, plainAlphabet, cipherAlphabet);
   for (var count = 0; count < plainText.length; count++)
   {
       plainAlphabet = plainText.charAt(count);
       i = cipherAlphabet[plainAlphabet];
       encryptedString = encryptedString + rotateArray[i];
   }

   return encryptedString;
}

This function returns signal character and then a string of errors. Do you know what is wrong?

What are you using this for? I ask this because having your encryption algorithm in JS for all to see, isn't very secure. You would be better off having the encryption take place on the server. — toneplex
– toneplex, Commented May 21, 2011 at 13:55

pimvdb · Accepted Answer · 2011-05-21 13:54:42Z

1

You are overwriting plainAlphabet with one character, thus discarding the alphabet. I guess that's not what you want.

However, you only posted the signature of rotateToPosition and not the actual code of it, so I cannot test my solution.

function encrypt(plainText, signalCharacter, indexCharacter, plainAlphabet, cipherAlphabet) {
   var encryptedString = signalCharacter;
   //i is what will hold the results of the encrpytion until it can be appended to encryptedString
   var i;
   // rotate array to signal character position
   var rotateArray = rotateToPosition(signalCharacter, indexCharacter, plainAlphabet, cipherAlphabet);
   for (var count = 0; count < plainText.length; count++)
   {
       var plainLetter = plainText.charAt(count);
       i = cipherAlphabet[plainLetter];
       encryptedString = encryptedString + rotateArray[i];
   }

   return encryptedString;
}

edited May 21, 2011 at 13:54

answered May 21, 2011 at 13:41

pimvdb

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1 Comment

gaRex Over a year ago

Yes, I also think so. In JS most non-simple vars are by reference.

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