obulpathi / pycoin

Python-based Bitcoin utility library.

pycoin -- Python Bitcoin Utilities

This is an implementation of a bunch of utility routines that may be useful when dealing with Bitcoin stuff. It has been tested with Python 2.7, 3.2 and 3.3.

ECDSA Signing and Verification

Instead of hiding behind a bunch of opaque abstraction, the library deals with ECDSA keys directly. Important structures include:

• the secret_exponent (a large integer that represents a private key)
• the public_pair (a pair of large integers x and y that represent a public key)

There are a handful of functions: you can do things like create a signature, verify a signature, generate the public pair from the secret exponent, and flush out the public pair from just the x value (there are two possible values for y of opposite even/odd parity, so you include a flag indicating which value for y you want).

Encoding

The library declares some conversion utilities useful when dealing with Bitcoin. Important structures include:

• base58 (the encoding used for Bitcoin addresses)
• hashed base58 (with a standard checksum)
• Bitcoin hashes (double sha256, ripemd160/sha256, known as "hash160")
• Bitcoin addresses
• WIF (Wallet import format)
• SEC (the gross internal format of public keys used by OpenSSL, both compressed and uncompressed)

The command-line utility "bu" ("Bitcoin utility") exposes a lot of this API on the command-line.

Wallets

The library implements a deterministic wallet that will securly generate Bitcoin addresses compliant with BIP0032.

This includes creating and parsing standard wallet keys.

Using this method, you can create a wallet that generates as many public keys as you need while keeping the private keys offline. For example,

xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8

is the public wallet the corresponds to the the private wallet

xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi

First, you generate a Wallet object from either a master secret (so a pass phrase of some kind) or a wallet key, like one of the above.

A Wallet object can generate a subkey using the "subkey" method, which is a child key that can be derived from the parent easily if you know the value for i (which usually ranges from 1 to as high as you want).

A private Wallet object can yield a public Wallet object (which generates only the corresponding public keys), but not the other way around.

A private Wallet object can generate a subkey whose addresses CANNOT be derived from the corresponding public Wallet object (to generate change addresses, for example). Set is_prime=True.

The command-line utility "genwallet" exposes a lot of this API on the command-line.

Transaction Validation and Signing

The UnsignedTx transaction class makes it easy to generate and sign new transactions that reassign the incoming coins to new public keys. Look at the test code in build_tx_test.py or the spend.py script for examples.

You will need to create a "solver", and provide it with the private keys relevant to the transaction, then pass it into the "sign" method.

The command-line utility "spend" provides sample code for generating transactions. Note that it doesn't post the transactions to the network, so you can mess around with relative impunity.

Donate

Want to donate? Feel free. Send to 1KissFDVu2wAYWPRm4UGh5ZCDU9sE9an8T.