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NAME

Bitcoin::Crypto::Key::ExtPublic - Bitcoin extended public keys

SYNOPSIS

        use Bitcoin::Crypto qw(btc_extprv);
        use Bitcoin::Crypto::Util qw(generate_mnemonic to_format)

        my $mnemonic = generate_mnemonic;
        my $key = btc_extprv->from_mnemonic($mnemonic);

        # derive child public key
        my $path = "M/0";
        my $child_key = $key->derive_key($path);
        my $ser_child_key = to_format [base58 => $child_key->to_serialized];
        print "Your exported $path child key is: $ser_child_key";

        # create basic public key
        my $basic_public = $child_key->get_basic_key;

DESCRIPTION

This class allows you to create an extended public key instance.

You can use an extended public key to:

  • derive extended keys using a path (only public keys)

  • restore keys from serialized base58 format

see Bitcoin::Crypto::Network if you want to work with other networks than Bitcoin Mainnet.

METHODS

new

Constructor is reserved for internal and advanced use only. Use "from_serialized" instead.

to_serialized

        $serialized_key = $object->to_serialized()

Returns the key serialized in format specified in BIP32 as byte string.

to_serialized_base58

Deprecated. Use to_format [base58 => $key->to_serialized] instead.

from_serialized

        $key_object = $class->from_serialized($serialized, $network = undef)

Tries to unserialize byte string $serialized with format specified in BIP32.

Dies on errors. If multiple networks match serialized data specify $network manually (id of the network) to avoid exception.

from_serialized_base58

Deprecated. Use $class->from_serialized([base58 => $base58]) instead.

set_network

        $key_object = $object->set_network($val)

Change key's network state to $val. It can be either network name present in Bitcoin::Crypto::Network package or an instance of this class.

Returns current key instance.

get_basic_key

        $basic_key_object = $object->get_basic_key()

Returns the key in basic format: Bitcoin::Crypto::Key::Public

derive_key

        $derived_key_object = $object->derive_key($path)

Performs extended key derivation as specified in BIP32 on the current key with $path. Dies on error.

See BIP32 document for details on derivation paths and methods.

Note that public keys cannot derive private keys and your derivation path must start with M (capital m).

Returns a new extended key instance - result of a derivation.

derive_key_bip44

        $derived_key_object = $object->derive_key_bip44(%data)

A helper that constructs a Bitcoin::Crypto::BIP44 path from %data and calls "derive_key" with it. In extended public keys, bip44 is always constructed with public setting - it will always derive starting from account, effectively only using change and index attributes.

get_fingerprint

        $fingerprint = $object->get_fingerprint($len = 4)

Returns a fingerprint of the extended key of $len length (byte string)

EXCEPTIONS

This module throws an instance of Bitcoin::Crypto::Exception if it encounters an error. It can produce the following error types from the Bitcoin::Crypto::Exception namespace:

  • KeyDerive - key couldn't be derived correctly

  • KeyCreate - key couldn't be created correctly

  • NetworkConfig - incomplete or corrupted network configuration

SEE ALSO

Bitcoin::Crypto::Key::ExtPrivate
Bitcoin::Crypto::Network