PCBC Private-encrypted Signing Code

gistfile1.php

<?php
// You can generate keys with:
// key=$(openssl genrsa 128);echo "$key" | sed '{:q;N;s/\n/\\n/g;t q}';echo "$key" | openssl rsa -pubout | sed '{:q;N;s/\n/\\n/g;t q}' 2>/dev/null

/**
 * Signs text with your private key, using PCBC.
 * @author Tyler Menezes tylermenezes@gmail.com
 */
function Sign($toEncrypt){
	$priv = openssl_pkey_get_private ("-----BEGIN RSA PRIVATE KEY-----\nMGQCAQACEQDEb/R70eBav9AmgH1GBvgZAgMBAAECEQCbMBNGyszjA2eKArxL3shN\nAgkA/O8v+KfoBc8CCQDG0XeJzSmFlwIJAIejmT0mheW/AghMu9+VEdfqtQIJAI16\nVWlE29KX\n-----END RSA PRIVATE KEY-----");

	$toEncrypt = unpack('H*', $toEncrypt);
	$toEncrypt = $toEncrypt[1];

	$result = "";

	while(strlen($toEncrypt)%16 != 0){
		$toEncrypt .= "00";
	}

	$iv = "1234567812345678";
	for($i = 0; $i < strlen($toEncrypt); $i+=16){
		$p = substr($toEncrypt, $i, 16);
		$x = $p ^ $iv;

		if(!openssl_private_encrypt($x, $e, $priv, OPENSSL_NO_PADDING)){
			throw new Exception(openssl_error_string());
		}

		$iv = $e ^ $p;

		$result .= $e;
	}

	$result = unpack('H*', $result);
	return $result[1];
}

/**
 * Decrypts text with the UReddit public key, using PCBC.
 * @author Tyler Menezes tylermenezes@gmail.com
 */
function Decrypt($toDecrypt){
	$pub = openssl_pkey_get_public ("-----BEGIN PUBLIC KEY-----\nMCwwDQYJKoZIhvcNAQEBBQADGwAwGAIRAMRv9HvR4Fq/0CaAfUYG+BkCAwEAAQ==\n-----END PUBLIC KEY-----");

	$toDecrypt = pack('H*', $toDecrypt);

	$result = "";
	$iv = "1234567812345678";

	for($i = 0; $i < strlen($toDecrypt); $i+=16){
		$e = substr($toDecrypt, $i, 16);

		if(!openssl_public_decrypt($e, $x, $pub, OPENSSL_NO_PADDING)){
			throw new Exception(openssl_error_string());
		}

		$p = $x ^ $iv;
		$result .= $p;

		$iv = $e ^ $p;
	}

	return pack('H*', $result);
}