How to unlock p2pkh

[Kelbie]

I'm new to using this library and constructing Bitcoin transactions in general so sorry if this is obvious.

I have been sent Bitcoin from a testnet faucet as can be seen here: txid: d9c9213136854a53211f1c80d202b743dfe971867558fd2c5628fe781a7f7ba9

Everytime I try and broadcast the transaction on blockcypher I get this error

Error validating transaction: Error running script for input 0 referencing d9c9213136854a53211f1c80d202b743dfe971867558fd2c5628fe781a7f7ba9 at 0: Script was NOT verified successfully..

Generating the address:

function generateAddress(mnemonic) {
    var seed = bip39.mnemonicToSeed(mnemonic)
    var root = bitcoin.HDNode.fromSeedBuffer(seed, bitcoin.networks.testnet)
    var child = root.derivePath("m/44'/1'/0'/0/0")
    var address = child.getAddress() // mpxhLRAzfGc6tH55kzG9NfZ3b2VZdo3Gq9
    return address
}

Generate transaction:

function send(mnemonic) {
    var seed = bip39.mnemonicToSeed(mnemonic)
    var root = bitcoin.HDNode.fromSeedBuffer(seed, bitcoin.networks.testnet)
    var child = root.derivePath("m/44'/1'/0'/0/0")
    var change = root.derivePath("m/44'/1'/0'/1/0")

    var txb = new bitcoin.TransactionBuilder(bitcoin.networks.testnet)
    txb.addInput("d9c9213136854a53211f1c80d202b743dfe971867558fd2c5628fe781a7f7ba9", 0)
    txb.addOutput(change.getAddress(), 100)
    txb.sign(0, child.keyPair)
    console.log(txb.build().toHex())
}

Here is the transaction hex if you are interested:

0100000001a97b7f1a78fe28562cfd58758671e9df43b702d2801c1f21534a85363121c9d9000000006a47304402202c142f548c830a2d1176fc4b296f85258bade9236f813add6a379a65ea09641302201e3bf5b91ae5b7b917287b174459131738345195cd262988164c7eb33b169c0c012103ee17f1f4b65794c05a67612ead47173884d22062c8150e1863ba5709b12a9ed5ffffffff0164000000000000001976a914acfc0a57a25500052cb20026ae994565cd43927b88ac00000000

I don't see where I am going wrong but if I had to guess it has something to do with the script type (pay-to-pubkey-hash) hence the title of this issue.

[afk11]

public key from tx:
pubkey: 03ee17f1f4b65794c05a67612ead47173884d22062c8150e1863ba5709b12a9ed5
pubkeyhash: b14b7ce2356525db27768f05b2f5cc7d9b55613c
address: mwgQKzcarE896qnUrr1tZ9WqphnBJwi4rp

output 0 on blockcypher
address: mpxhLRAzfGc6tH55kzG9NfZ3b2VZdo3Gq9

Child must be the wrong private key? You're probably running into this line of code, which just initializes the input for that key.. https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/src/transaction_builder.js#L352

Print out the public key or address for a few of the keys once again to check if your bip32 path is correct.

[Kelbie]

The child in generateAddress is mpxhLRAzfGc6tH55kzG9NfZ3b2VZdo3Gq9 which is expected.
The child in send is mwgQKzcarE896qnUrr1tZ9WqphnBJwi4rp which was not expected.

It seems like the output for root.derivePath("m/44'/1'/0'/0/0") is different the second time I called it and I was expecting it to be the same. Is this normal behaviour? And if it is do you mind explaining why it does this?

I successfully broadcasted the transaction

[Kelbie]

The problem I had was that I forgot to pass the mnemonic to the function and that took me way longer to see than it ought to.

[afk11]

It happens, glad to gear you got it sorted!

[dcousens]

The problem I had was that I forgot to pass the mnemonic to the function and that took me way longer to see than it ought to.

Why didn't it throw?

edit: https://github.com/bitcoinjs/bip39/blob/bafbcd352a6a5275bbc640a79c3917d0baee5bc8/index.js#L50 ... oh, I'll change that.

bitcoinjs/bip39#77

[afk11]

hmm, oh yea, that stuff :/ I never think to check the input to the normalization.. extra whitespace between two of the words can lead to similar confusion, as it's directly input to a hash function.

[dcousens]

@afk11 maybe it should:

• enforce no duplicate whitespace
• enforce non-zero length
• enforce only printable characters

I have had each of those burn me in the past, and nearly experienced fund loss in a duplicate whitespace case.

[afk11]

Yea I totally agree. Pretty sure this is repeated across the ecosystem, so probably a worth while effort :P