btclib 2020.11.10

A library for 'bitcoin cryptography'

A Python library for 'bitcoin cryptography'

btclib is a Python3 type annotated library intended for teaching, learning, and using bitcoin, its blockchain, and the associated elliptic curve cryptography.

It is rigorously and extensively tested: the test suite covers 100% of the code base and reproduces results from both informal and major reference sources.

Originally developed for the Bitcoin and Blockchain Technology course at the University of Milano-Bicocca, btclib is not intended for production environments: it is often refactored for improved clarity, without care for backward compatibility; moreover, some of its algorithms could be broken using side-channel attacks.

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Included features are:

• modulo algebra functions (gcd, inverse, legendre symbol, square root)
• octets / integer / varint / point conversion functions
• elliptic curve class
  • fast algebra implemented using Jacobian coordinates
  • double scalar multiplication (Straus's algorithm, also known as Shamir's trick)
  • multi scalar multiplication (Bos-coster's algorithm)
  • point simmetry solution: odd/even, low/high, and quadratic residue
• elliptic curves: SEC 1 v1 and v2, NIST, Brainpool, and low cardinality test curves
• ECDSA signature with (transaction) DER encoding
• ECDSA signature with (message) compact encoding: standard p2pkh and BIP137/Electrum extensions to p2wpkh and p2wpkh-p2sh
• EC Schnorr signature (according to BIP340 bitcoin standardization)
  • batch validation
  • threshold signature (see test-suite)
  • MuSig multi-signature (see test-suite)
• Borromean ring signature
• RFC 6979 to make signature schemes deterministic
• Sign-to-contract commitment
• Diffie-Hellman
• Pedersen committment
• Base58 encoding/decoding
• p2pkh/p2sh addresses and WIFs
• Bech32 encoding/decoding
• p2wpkh/p2wsh native SegWit addresses and their legacy p2sh-wrapped versions
• BIP32 hierarchical deterministic key chains
• SLIP132 key versions (xprv, yprv, zprv, Yprv, Zprv, tprv, uprv, vprv, and Uprv) with corresponding mapping to p2pkh/p2sh, p2wpkh-p2sh, p2wpkh, p2wsh-p2sh, and p2wsh addresses
• BIP39 wordlists and mnemonic for generating deterministic keys
• Electrum standard for mnemonic
• Script encoding/decoding
• nulldata, p2pk, p2ms, p2pkh, p2sh, p2wpkh, and p2wsh ScriptPubKeys
• BlockHeader and Block data classes
• OutPoint, TxIn, TxOut, and TX data classes
• segwit_v0_sighash
• BIP174 partially signed bitcoin transactions (PSBT): PsbtIn, PbstOut, and Psbt data classes

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To install (and/or upgrade) btclib and its requirements:

python -m pip install --upgrade -r requirements.txt
python -m pip install --upgrade btclib

You might want to install btclib and its requirements into a python virtual environment; e.g. from the root folder:

Bash shell

python -m venv venv
source ./venv/bin/activate
pip install --upgrade -r requirements.txt
pip install --upgrade btclib

Windows CMD or PowerShell:

python -m venv venv
.\venv\Scripts\activate
pip install --upgrade -r requirements.txt
pip install --upgrade btclib

Windows Git bash shell:

python -m venv venv
cd ./venv/Scripts
. activate
cd ../..
pip install --upgrade -r requirements.txt
pip install --upgrade btclib

Some development tools are required to develop and test btclib; they can be installed with:

python -m pip install --upgrade -r requirements-dev.txt

Developers might also consider to install btclib in editable way:

python -m pip install --upgrade -e ./