<?php
//hex input must be in uppercase, with no leading 0x
//This Script will test for both BTC and LTC depending on Input. There is no error checking. 
//Included at the bottom is a short test of the code, feel free to reuse or eliminate.
//This Script has been Modified by CrazyRabbit with help from Pooler to Validate LTC address
//Original Version by theymos
//Works without being connected to Litecoin Server
//To ask questions follow in the litecoin Forums Thread: //http://forum.litecoin.net/index.php/topic,521.0.html

function decodeHex($hex)
{
	$hex=strtoupper($hex);
	$chars="0123456789ABCDEF";
	$return="0";
	for($i=0;$i<strlen($hex);$i++)
	{
		$current=(string)strpos($chars,$hex[$i]);
		$return=(string)bcmul($return,"16",0);
		$return=(string)bcadd($return,$current,0);
	}
	return $return;
}

function encodeHex($dec)
{
	$chars="0123456789ABCDEF";
	$return="";
	while (bccomp($dec,0)==1)
	{
		$dv=(string)bcdiv($dec,"16",0);
		$rem=(integer)bcmod($dec,"16");
		$dec=$dv;
		$return=$return.$chars[$rem];
	}
	return strrev($return);
}

function decodeBase58($base58)
{
	$origbase58=$base58;
	
	$chars="123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
	$return="0";
	for($i=0;$i<strlen($base58);$i++)
	{
		$current=(string)strpos($chars,$base58[$i]);
		$return=(string)bcmul($return,"58",0);
		$return=(string)bcadd($return,$current,0);
	}
	
	$return=encodeHex($return);
	
	//leading zeros
	for($i=0;$i<strlen($origbase58)&&$origbase58[$i]=="1";$i++)
	{
		$return="00".$return;
	}
	
	if(strlen($return)%2!=0)
	{
		$return="0".$return;
	}
	
	return $return;
}

function encodeBase58($hex)
{
	if(strlen($hex)%2!=0)
	{
		die("encodeBase58: uneven number of hex characters");
	}
	$orighex=$hex;
	
	$chars="123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
	$hex=decodeHex($hex);
	$return="";
	while (bccomp($hex,0)==1)
	{
		$dv=(string)bcdiv($hex,"58",0);
		$rem=(integer)bcmod($hex,"58");
		$hex=$dv;
		$return=$return.$chars[$rem];
	}
	$return=strrev($return);
	
	//leading zeros
	for($i=0;$i<strlen($orighex)&&substr($orighex,$i,2)=="00";$i+=2)
	{
		$return="1".$return;
	}
	
	return $return;
}

function hash160ToAddress($hash160,$addressversion=ADDRESSVERSION)
{
	$hash160=$addressversion.$hash160;
	$check=pack("H*" , $hash160);
	$check=hash("sha256",hash("sha256",$check,true));
	$check=substr($check,0,8);
	$hash160=strtoupper($hash160.$check);
	return encodeBase58($hash160);
}

function addressToHash160($addr)
{
	$addr=decodeBase58($addr);
	$addr=substr($addr,2,strlen($addr)-10);
	return $addr;
}

function checkAddressBTC($addr,$addressversion=ADDRESSVERSION)
{
	$addr=decodeBase58($addr);
	if(strlen($addr)!=50)
	{
		return false;
	}
	$version=substr($addr,0,2);
	if(hexdec($version)>hexdec($addressversion)) 
	{
		return false;
	}
	$check=substr($addr,0,strlen($addr)-8);
	$check=pack("H*" , $check);
	$check=strtoupper(hash("sha256",hash("sha256",$check,true)));
	$check=substr($check,0,8);
	return $check==substr($addr,strlen($addr)-8);
}

function checkAddressLTC($addr,$addressversion=ADDRESSVERSION)
{
	$addr=decodeBase58($addr);
	if(strlen($addr)!=50)
	{
		return false;
	}
	$version=substr($addr,0,2);
	if(hexdec($version)!=hexdec($addressversion)) //Changed from ">" to "!=" for LTC
	{
		return false;
	}
	$check=substr($addr,0,strlen($addr)-8);
	$check=pack("H*" , $check);
	$check=strtoupper(hash("sha256",hash("sha256",$check,true)));
	$check=substr($check,0,8);
	return $check==substr($addr,strlen($addr)-8);
}

function hash160($data)
{
	$data=pack("H*" , $data);
	return strtoupper(hash("ripemd160",hash("sha256",$data,true)));
}

function pubKeyToAddress($pubkey)
{
	return hash160ToAddress(hash160($pubkey));
}

function remove0x($string)
{
	if(substr($string,0,2)=="0x"||substr($string,0,2)=="0X")
	{
		$string=substr($string,2);
	}
	return $string;
}

//start of BTC LTC switch
function determineValidity($address, $addressType)
{
	// https://en.bitcoin.it/wiki/List_of_address_prefixes
	switch ($addressType) {
		case "BTC": return checkAddressBTC($address,"00");
		case "LTC": return checkAddressLTC($address,"30");
		case "NMC": return checkAddressLTC($address,"34"); // https://github.com/namecoin/namecoin/blob/master/src/namecoin.cpp#L2485
		case "BTCTEST": return checkAddressLTC($address,"6F");
		case "NVC": return checkAddressLTC($address,"08"); // https://github.com/CryptoManiac/novacoin/blob/master/src/base58.h#L279
		case "PPC": return checkAddressLTC($address,"37"); // https://github.com/ppcoin/ppcoin/blob/master/src/base58.h#L267
		case "DOGE": return checkAddressLTC($address,"1E"); // https://github.com/dogecoin/dogecoin/blob/master/src/base58.h#L281
		default:
			$error_Address_type = "Address type not correctly specified";
			return $error_Address_type;
	}
}