wrayal/LICENSE.txt

## README.md

      
    Raw
  

              README.md
            
          
    The Vigenère Cypher

In 138b, this will encrypt/decrypt anything using the Vigenère cypher. Input is entered as solely lower case letters (no numbers, spaces, special characters etc). Outputs may be verified against http://sharkysoft.com/misc/vigenere/
Background

As described on http://ub.ly/um (the parser chokes on the full URL), the essence of the Vigenère cypher is that it is a cyclic version of the Caesar shift cypher. It's not unbreakable but it's pretty good. Also, as a corollary we get rot13 (use "n" as an encoding parameter - yes, as originally defined there's a one byte offset from what you might expect...) and of course Caesar.
Entry History

My initial attempts were encryption only (138b):
function(j,s,h,g,i,n){for(g="",i=0;i-j.length;g+=String.fromCharCode(n?n+64:90))n=(j.charCodeAt(i)+s.charCodeAt(i++%s.length)+15)%26;h(g)}
and encryption + decryption (151b):
function(j,s,h,t,g,i,n){for(g="",i=0;i-j.length;g+=String.fromCharCode(n?n+64:90))n=(j.charCodeAt(i)+t*s.charCodeAt(i++%s.length)+(t>0?15:27))%26;h(g)}
with t=+/- 1 being encryption/decryption. Thanks to all the help in the comments (especially @subzey!) this is now down to 138b, with both encryption and decryption.
What I learnt

The phrases "fromCharCode", "charCodeAt" and "String" are FAR too long =(
Savings don't always come where you expect them to (see @jed's ultimately unused 'harCode' hack in the comments). In fact, from my experience so far in 140byt.es, they most often come from some slight (or indeed major!) reworking of the algorithm (c.f. the successive contributions to fibonacci, base64 enc/dec etc).
http://esparser.qfox.nl/ is amazing

  
## annotated.js
function(
	a	//input string
	,b	//key string
	,c	//callback function
	,d	//direction (1=encrypt, -1=decrypt)
	,e	//output string
	,f	//iterator
	){
		for(
			f=e="";		//initialize; f will be coerced to a numerical value
			f<a.length;	//loop for all character in string
			e+=String.fromCharCode(90-25*(a.charCodeAt(f)+d*b.charCodeAt(f++%b.length)+27+~d*6)%26)
					//very neat trick to make the fact that 26%26=0 work for you rather than against you - see @subzey's description =)
					//note ~d=-2 for d=1, 0 for d=-1; and 27-15=12 (these are the magic unicode offsets =)
		)
		;
	c(e)	//and we're done! send back...
}

## index.js
function(a,b,c,d,e,f){for(f=e="";f<a.length;e+=String.fromCharCode(90-25*(a.charCodeAt(f)+d*b.charCodeAt(f++%b.length)+27+~d*6)%26));c(e)}

## LICENSE.txt
            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                    Version 2, December 2004

 Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE>

 Everyone is permitted to copy and distribute verbatim or modified
 copies of this license document, and changing it is allowed as long
 as the name is changed.

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. You just DO WHAT THE FUCK YOU WANT TO.

## package.json
{
  "name": "vigenereCypher",

  "description": "This will cypher using the vigenere method",

  "keywords": [
    "viegnere",
    "cypher",
    "encryption"
  ]
}

## test.html
<!DOCTYPE html>
<title>Vigenère encryption</title>
<pre>
Expected value: <b>HUMZWBGVMVOAORMWILRNVQESBESOSEGHMRSCELNGHQA</b>
Actual value:   <b id="ret"></b>
</pre>
<script>
function b(text)
{
	document.getElementById( "ret" ).innerHTML=text
}

var myFunction=function(a,b,c,d,e,f){for(f=e="";f<a.length;e+=String.fromCharCode(90-25*(a.charCodeAt(f)+d*b.charCodeAt(f++%b.length)+27+~d*6)%26));c(e)}


myFunction("thiscodeisonlyforstandardlowercaseplaintext","onehundredandthirtyninebytes",b,1)

//to test decryption:
//myFunction("humzwbgvmvoaormwilrnvqesbesoseghmrscelnghqa","onehundredandthirtyninebytes",b,-1)

</script>
</html>
	function(
	a //input string
	,b //key string
	,c //callback function
	,d //direction (1=encrypt, -1=decrypt)
	,e //output string
	,f //iterator
	){
	for(
	f=e=""; //initialize; f will be coerced to a numerical value
	f<a.length; //loop for all character in string
	e+=String.fromCharCode(90-25(a.charCodeAt(f)+db.charCodeAt(f++%b.length)+27+~d*6)%26)
	//very neat trick to make the fact that 26%26=0 work for you rather than against you - see @subzey's description =)
	//note ~d=-2 for d=1, 0 for d=-1; and 27-15=12 (these are the magic unicode offsets =)
	)
	;
	c(e) //and we're done! send back...
	}
	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	Version 2, December 2004

	Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE>

	Everyone is permitted to copy and distribute verbatim or modified
	copies of this license document, and changing it is allowed as long
	as the name is changed.

	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

	0. You just DO WHAT THE FUCK YOU WANT TO.
	{
	"name": "vigenereCypher",

	"description": "This will cypher using the vigenere method",

	"keywords": [
	"viegnere",
	"cypher",
	"encryption"
	]
	}
	<!DOCTYPE html>
	<title>Vigenère encryption</title>
	<pre>
	Expected value: <b>HUMZWBGVMVOAORMWILRNVQESBESOSEGHMRSCELNGHQA</b>
	Actual value: <b id="ret"></b>
	</pre>
	<script>
	function b(text)
	{
	document.getElementById( "ret" ).innerHTML=text
	}

	var myFunction=function(a,b,c,d,e,f){for(f=e="";f<a.length;e+=String.fromCharCode(90-25(a.charCodeAt(f)+db.charCodeAt(f++%b.length)+27+~d*6)%26));c(e)}


	myFunction("thiscodeisonlyforstandardlowercaseplaintext","onehundredandthirtyninebytes",b,1)

	//to test decryption:
	//myFunction("humzwbgvmvoaormwilrnvqesbesoseghmrscelnghqa","onehundredandthirtyninebytes",b,-1)

	</script>
	</html>