/* EMAIL ENCRYPTION SCRIPT */

// This script is (c) copyright 2008 by Dan Appleman under the
// GNU General Public License (http://www.gnu.org/licenses/gpl.html)
// This script is modified from an original script by Jim Tucek
// For more information, visit www.danappleman.com 
// Leave the above comments alone!
// see encryption_instructions.txt for explanation of usage

// thx to http://www.danappleman.com/?page_id=61

var decryption_cache = new Array();

function decrypt_string(crypted_string,n,decryption_key,just_email_address) {
    var cache_index = "'"+crypted_string+","+just_email_address+"'";

    if(decryption_cache[cache_index])                   // If this string has already been decrypted, just
        return decryption_cache[cache_index];               // return the cached version.

    if(addresses[crypted_string])                       // Is crypted_string an index into the addresses array
        var crypted_string = addresses[crypted_string];         // or an actual string of numbers?

    if(!crypted_string.length)                      // Make sure the string is actually a string
        return "Error, not a valid index.";

    if(n == 0 || decryption_key == 0) {                 // If the decryption key and n are not passed to the
        var numbers = crypted_string.split(' ');            // function, assume they are stored as the first two
        n = numbers[0]; decryption_key = numbers[1];            // numbers in crypted string.
        numbers[0] = ""; numbers[1] = "";               // Remove them from the crypted string and continue
        crypted_string = numbers.join(" ").substr(2);
    }

    var decrypted_string = '';
    var crypted_characters = crypted_string.split(' ');

    for(var i in crypted_characters) {
        var current_character = crypted_characters[i];
        var decrypted_character = exponentialModulo(current_character,n,decryption_key);
        if(just_email_address && i < 7)             // Skip 'mailto:' part
            continue;
        if(just_email_address && decrypted_character == 63) // Stop at '?subject=....'
            break;
        decrypted_string += String.fromCharCode(decrypted_character);
    }
        decryption_cache[cache_index] = decrypted_string;           // Cache this string for any future calls

    return decrypted_string;
}

function decrypt_and_email(crypted_string,n,decryption_key) {
    if(!n || !decryption_key) { n = 0; decryption_key = 0; }
    if(!crypted_string) crypted_string = 0;

    var decrypted_string = decrypt_string(crypted_string,n,decryption_key,false);
    parent.location = decrypted_string;
}

function decrypt_and_echo(crypted_string,n,decryption_key) {
    if(!n || !decryption_key) { n = 0; decryption_key = 0; }
    if(!crypted_string) crypted_string = 0;

    var decrypted_string = decrypt_string(crypted_string,n,decryption_key,true);
    document.write(decrypted_string);
    return true;
}

// Finds base^exponent % y for large values of (base^exponent)
function exponentialModulo(base,exponent,y) {
    if (y % 2 == 0) {
        answer = 1;
        for(var i = 1; i <= y/2; i++) {
            temp = (base*base) % exponent;
            answer = (temp*answer) % exponent;
        }
    } else {
        answer = base;
        for(var i = 1; i <= y/2; i++) {
            temp = (base*base) % exponent;
            answer = (temp*answer) % exponent;
        }
    }
    return answer;
}