ROT13

For those of you too lazy to figure out what trak3r wrote, here is that writeup after going through ROT13:

ROT13 is a super lame encryption technique that consists of shifting each letter of the alphabet thirteen places. (uvag: guvf nccneragyl-tneoyrq fragrapr vf EBG13 rapbqrq)

For those people who don't have access to tr but have access to perl and the command line, here is a short little Perl program:

while(<>) {                   #for each line of data ...
    tr/a-zA-Z/n-za-mN-ZA-M/;  #... perform ROT-13 ...
    print;                    #... and display the translated line
}

dafydd, being a real Perl programmer, determined how to make the program a one-liner:

    tr/a-zA-Z/n-za-mN-ZA-M/ and print while <>

If you can't even do that, but have access to the site Everything 2 (probably a safe bet), JayBonci wrote E2 Rot13 Encoder, which lets E2 do all the work..

Plain    a b c d e f g h i j k l m n o p q r s t u v w x y z
ROT13    N O P Q R S T U V W X Y Z A B C D E F G H I J K L M

a b c d e f g h i j k l m
| | | | | | | | | | | | |
n o p q r s t u v w x y z

javascript:P9 = prompt( 'Text...', '' );

if ( P9 ) {
    S2b = '';

    for ( J7 = 0; J7 < P9.length; J7++ ) {
        C6 = P9.charCodeAt( J7 );

        if ( Math.abs( 16 - Math.abs( C6 - 93.5 ) ) <= 13 ) {
            W8b = ( C6 < 91 ) ? 65 : 97;
            S2b += String.fromCharCode(((C6 - W8b + 13) % 26 ) + W8b);
        } else {
            S2b += P9.charAt( J7 );
        }
    }

    alert( S2b );
} else {
    void ( null );
}

/*  Rot-13 encoder/decoder in C
 *
 *  This wretched little monstrosity is in the public domain.
 *  A much better solution is to use sed or tr. If you're on 
 *  Windows, go to the GNUish Project and download sed.
 *
 *  As with any simple character translation thing, a 
 *  lookup table would be more efficient, but... come on!
 *
 *  wharfinger  11/5/00
 */

#include <stdio.h>
#include <ctype.h>

int r13( int c );

int main()
{
    int c;

    while ( ( c = getchar() ) != EOF )
        putchar( r13( c ) );

    return 0;
}


int r13( int c )
{
    /*  Okay, it's a nested ternary. I know.
        This should probably be a macro, but macros this complex 
        get on my nerves.  
        'm' is the thirteenth letter of the alphabet.
        I mean, like, in case you didn't know or something.
    */
    return ( isalpha( c ) )
                ? ( ( tolower( c ) > 'm' ) ? ( c - 13 ) : ( c + 13 ) )
                : c;
}

rot13 /rot ther'teen/ n.,v.

[Usenet: from `rotate alphabet 13 places'] The simple Caesar-cypher encryption that replaces each English letter with the one 13 places forward or back along the alphabet, so that "The butler did it!" becomes "Gur ohgyre qvq vg!" Most Usenet news reading and posting programs include a rot13 feature. It is used to enclose the text in a sealed wrapper that the reader must choose to open -- e.g., for posting things that might offend some readers, or spoilers. A major advantage of rot13 over rot(N) for other N is that it is self-inverse, so the same code can be used for encoding and decoding. See also spoiler space, which has partly displaced rot13 since non-Unix-based newsreaders became common.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

javascript: if(document.all)sel=document.selection.createRange().text; else{sel=getSelection().toString(); }if(!sel)sel=prompt('Enter the text to ROT13',''); alpha="abcdefghijklmnopqrstuvwxyz"; alpha+=alpha+alpha.toUpperCase()+alpha.toUpperCase(); for(i=0,result=""; i<sel.length; result+=(alpha.indexOf(sel.charAt(i))<0)? sel.charAt(i++): alpha.charAt(alpha.indexOf(sel.charAt(i++))+13)); void(alert(result));

javascript:
if(document.all)
  sel=document.selection.createRange().text;
else {
  sel=getSelection().toString();
}
if(!sel)sel=prompt('Enter the text to ROT13','');
alpha="abcdefghijklmnopqrstuvwxyz";
alpha+=alpha+alpha.toUpperCase()+alpha.toUpperCase();
for(i=0,result=""; i < sel.length;
  result+=(alpha.indexOf(sel.charAt(i)) < 0)?
  sel.charAt(i++):
  alpha.charAt(alpha.indexOf(sel.charAt(i++))+13)
);
void(alert(result));

javascript:
p=document.getSelection();
if(!p)p=prompt('Text...','');
q='';
for(i=0; i<p.length; i++){
  c=p.charCodeAt(i);
  q+=String.fromCharCode(
    c+((c<65)^(c<91)^(c<97)^(c<123)? // *1
    (c-1)%32<13?13:-13:0)            // *2
  );
}
alert(q)

// *1 - true iff c represents an alphabet
// *2 - decide btwn move forward and loop around

Guvf znl abg pbzr va unaql...