Bitcoin Forum

I have a database of bitcoin addresses and i need to validate them. Please explain the process , i don't care if its an api or a script as long as its efficient.

What do you mean by 'validate' exactly?

to see if its a real address

Not sure what you understand by “real”. This thread provides validation functions if various languages (https://bitcointalk.org/index.php?topic=1026.0). You can only check if the address is valid. If by real you mean that someone is actually using this address (someone has a private key), then you can't know that.

In PHP JSON-RPC you can use this code:

how can that be used in on a website that dosnt have access to the bitcoin client


https://blockchain.info/api/json_rpc_api
i guess i can use this right?

You can do it without a bitcoind node.

Look up the base58check routines.  There are several PHP implementations available.  Basically, that is all a bitcoind node would do.  (If the address belonged to a known key, it would provide other info too, but that doesn't matter.)

someone explain to me how to use the json rpc, with blockchains api. There is little to no documentation i want to stop wasting my time with this. Just help me.

<?php

function checkAddress($address)
{
    $origbase58 = $address;
    $dec = "0";

    for ($i = 0; $i < strlen($address); $i++)
    {
        $dec = bcadd(bcmul($dec,"58",0),strpos("123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz",substr($address,$i,1)),0);
    }

    $address = "";

    while (bccomp($dec,0) == 1)
    {
        $dv = bcdiv($dec,"16",0);
        $rem = (integer)bcmod($dec,"16");
        $dec = $dv;
        $address = $address.substr("0123456789ABCDEF",$rem,1);
    }

    $address = strrev($address);

    for ($i = 0; $i < strlen($origbase58) && substr($origbase58,$i,1) == "1"; $i++)
    {
        $address = "00".$address;
    }

    if (strlen($address)%2 != 0)
    {
        $address = "0".$address;
    }

    if (strlen($address) != 50)
    {
        return false;
    }

    if (hexdec(substr($address,0,2)) > 0)
    {
        return false;
    }

    return substr(strtoupper(hash("sha256",hash("sha256",pack("H*",substr($address,0,strlen($address)-8)),true))),0,8) == substr($address,strlen($address)-8);
}

?>
Here is a PHP function to validate a bitcoin address. ;)

thanks, i figured it out myself using the blockchain json rpc api. Ill try that code you took the time to post also thanks.

The code I posted is much faster than this, and does not need to connect to any other server (such as blockchain.info). ;)

Sometimes speed is not an issue.

The code you posted does not work with multisig addresses

Minor correction.  There actually is no "multisig addresses" just Pay2PubKeyHash addresses and Pay2ScriptHash addresses.  The code provided only properly handles the former.