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How do I get to the value in the 'scriptPubKey' part of the transaction ?
The sender knows only the address (1A3XjcuZmcszX2tGoVn1TrMNchuHwdAxZV) so how did he get into 63339ebf4914d964fbc729b0dc4c1a44c4fb8f80 ? I've tried ripemd160(sha256(address)) didn't work . I've tried sha256(sha256(address)) didn't work.
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Addresses are kept in Base58Check format. Here's how you decode it.
Check that the last 4 bytes are a correct checksum of the rest. This is done (in Python) by:
sha256(sha256(data[0:21]))[:4] == data[-4:]
(Or, "take the first 4 bytes of a double-SHA256 of the first 21 bytes of the decoded data, then compare to the last 4 bytes of the decoded data.")
Take the middle 20 bytes (data[1:21]) and insert it into the following scriptPubKey.
OP_DUP OP_HASH160 <x> OP_EQUALVERIFY OP_CHECKSIG
Here are some libraries that will do steps 1-3:
bitcoinj (Java)
byte[] hash160 = new Address(NetworkParameters.prodNet(),
<addr>).getHash160();
coinstring.js (node.js)
require('coinstring').decode(<addr>)
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If you are using C# with NBitcoin
var address = new Script("OP_DUP OP_HASH160 ... OP_EQUALVERIFY OP_CHECKSIG").GetDestinationAddress(Network.Main);
It has the nice effect to work with P2SH addresses too.
Worked well accept "Check that the last four bytes are a correct checksum" , of what ? – Haddar Macdasi – 2015-03-28T21:02:18.663
@HaddarMacdasi Does the edit make it more clear? – Nick ODell – 2015-03-28T21:13:12.110
I'm trying with an online tool. can't seem to work it out. The checksum part. – Haddar Macdasi – 2015-03-28T21:18:44.763