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pycoin -- Python Cryptocoin Utilities

This is an implementation of a bunch of utility routines that may be useful when dealing with bitcoin and some alt-coins. It has been tested with Python 2.7, 3.3, 3.4 and 3.5.

See also pycoinnet for a library that speaks the bitcoin protocol.

Documentation at readthedocs

High Level

Keys & BIP32

The class pycoin.key.Key contains a convenience Key class that will parse the base58 representation of a BIP 32 wallet [BIP0032] or a WIF or a bitcoin (or altcoin) address, and convert downwards.

WARNING: be extremely careful giving out public wallet keys. If someone has access to a private wallet key P, of course they have access to all descendent wallet keys of P. But if they also have access to a public wallet key K where P is a subkey of K, you can actually work your way up the tree to determine the private key that corresponds to the public wallet key K (unless private derivation was used at some point between the two keys)! Be sure you understand this warning before giving out public wallet keys!

pycoin.key.Key

Key(hierarchical_wallet=None, 
    secret_exponent=None,
    public_pair=None, 
    hash160=None, 
    prefer_uncompressed=None, 
    is_compressed=True, 
    netcode)

Specify one of "hierarchical_wallet, secret_exponent, public_pair or hash160" to create a Key.

Or

Key.from_text(b58_text) accepts an address (bitcoin or other), a WIF, or a BIP32 wallet string and yield a Key.

Key.from_sec(sec) creates a Key from the SEC bytestream encoding of a public pair.

pycoin.key.BIP32Node (formerly pycoin.wallet.Wallet) provides a BIP32 hierarchical wallet.

Much of this API is exposed in the ku command-line utility. See also COMMAND-LINE-TOOLS.md.

See BIP32.txt for more information.

Transactions

pycoin.tx.Tx is a class that wraps a bitcoin transaction. You can create, edit, sign, or validate a transaction using methods in this class.

You can also use pycoin.tx.tx_utils which has create_tx and create_signed_tx, which gives you a very easy way to create signed transactions.

The command-line utility tx is a Swiss Army knife of transaction utilities. See also COMMAND-LINE-TOOLS.md.

Services

When signing or verifying signatures on a transaction, the source transactions are generally needed. If you set two environment variables in your .profile like this:

PYCOIN_CACHE_DIR=~/.pycoin_cache
PYCOIN_BTC_PROVIDERS="blockchain.info blockexplorer.com chain.so"
export PYCOIN_CACHE_DIR PYCOIN_BTC_PROVIDERS

and then tx will automatically fetch transactions from the web sites listed and cache the results in PYCOIN_CACHE_DIR when they are needed.

(The old syntax with PYCOIN_SERVICE_PROVIDERS is deprecated.)

The module pycoin.services includes two functions spendables_for_address, get_tx_db that look at the environment variables set to determine which web sites to use to fetch the underlying information. The sites are polled in the order they are listed in the environment variable.

Blocks

The command-line utility block will dump a block in a human-readable format. For further information, look at pycoin.block, which includes the object Block which will parse and stream the binary format of a block.

Low Level

ECDSA Signing and Verification

The module pycoin.ecdsa 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 pycoin.encoding module 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

Users

Here's a partial list of users of pycoin:

Email me at him@richardkiss.com to be added to this list.

Too Slow?

As of v0.60, there is experimental code that will call into OpenSSL for two slow functions. To enable this, set (and export) environment variable PYCOIN_NATIVE=openssl. Example:

$ PYCOIN_NATIVE=openssl
$ export PYCOIN_NATIVE

Donate

Want to donate? Feel free. Send to 1KissFDVu2wAYWPRm4UGh5ZCDU9sE9an8T. I'm also available for bitcoin consulting... him@richardkiss.com.

BIP0032