<?php
class SharedKeys{
function Create($secret, $people, $show = false){
$step = 1;
# Truncate/Pad $secret to 16 characters
$secret = sprintf( "%-' 16s", substr($secret, 0, 16) );
$keys = array();
# Generate an array of random keys
if( $show ){
echo "\nGenerating Random Keys\n";
}
for( $n = 1; $n < $people; ++$n ){
# Create the binary string from an md5 hash
# Use mt_rand() to seed the hash
$keys[] = pack("H*", md5(mt_rand()));
if( $show ){
echo "Generating Random Key: ", $keys[count($keys) - 1],"\n";
}
}
# Generate the final key by XORing the
# previous keys together with the secret
if( $show ){
echo "\nDeconstructing Original Key\n",
"Deconstructing Original Key (Step 1): ", $secret, "\n";
}
$out = $secret;
foreach( $keys as $key ){
$out ^= $key;
if( $show ){
echo "Deconstructing Original Key (Step ", ++$step, "): " , $out,"\n";
}
}
array_push($keys, $out);
# Don't always allow $out to come last in the array
sort($keys);
return $keys;
}
function Assemble($keys, $show = false){
$step = 0;
$out = array_pop($keys);
if( $show ){
echo "\nReconstructing Original Key\n",
"Reconstructing Original Key (Step ", ++$step, "): " , $out,"\n";
}
foreach($keys as $key){
$out ^= $key;
if( $show ){
echo "Reconstructing Original Key (Step ", ++$step, "): ", $out,"\n";
}
}
return $out;
}
}
?>
