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Tiny Bitcoin Library written in C, with nSPV added
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Latest commit 0f3cdb1 Aug 15, 2019


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libnspv – a portable C library for creating and manipulating data structures and interacting with the p2p network on Komodo-compatible Smart Chains including the KMD main chain.

Based on Libbtc


Build Status Coverage Status

What is libbtc?

Libbtc is a very portable C library for creating and manipulating bitcoin data structures and interacting with the p2p network.

Current features

  • Generating and storing private and public keys
  • ECDSA secp256k1 signing and verification (through libsecp256k1 included as git subtree)
  • Generate recoverable signatures (and recover pubkey from signatures)
  • BIP32 hierarchical deterministic key derivation
  • Transaction generation, manipulation, signing and ser-/deserialization including P2PKH, P2SH, multisig
  • Address generation
  • Base58check encoding
  • Native implementation of SHA256, SHA512, SHA512_HMAC, RIPEMD-160 including NIST testvectors
  • Native constant time AES (+256CBC) cipher implementation including NIST testvectors
  • Keystore (wallet) databases (through logdb
  • Event based bitcoin P2P client capable of connecting to multiple nodes in a single thread (requires libevent)

Advantages of libbtc?

  • No dependencies in case no p2p network client is required (only dependency is libsecp256k1 added as git subtree)
  • The only dependency for the p2p network client is libevent (very portable)
  • optimized for MCU and low mem environments
  • ~full test coverage
  • mem leak free (valgrind check during CI)

The bitcointool CLI

Generate a new privatekey WIF and HEX encoded:
./bitcointool -command genkey
> privatekey WIF: KwmAqzEiP7nJbQi6ofQywSEad4j5b9BXDJvyypQDDLSvrV6wACG8
> privatekey HEX: 102f1d9d91fa1c8d816ef469e74c1153a6b453d2a991e77fe187e5514a7b18ac
Generate the public key and p2pkh address from a WIF encoded private key
/bitcointool -command pubfrompriv -p KwmAqzEiP7nJbQi6ofQywSEad4j5b9BXDJvyypQDDLSvrV6wACG8
> pubkey: 023d86ca58e2519cce1729b4d36dfe5a053ad5f4ae6f7ef9360bee4e657f7e41c9
> p2pkh address: 1N5ZkjyabcZLLHMweJrSkn3qedsPGzAx9m
Generate the P2PKH address from a hex encoded compact public key
./bitcointool -command addrfrompub -pubkey 023d86ca58e2519cce1729b4d36dfe5a053ad5f4ae6f7ef9360bee4e657f7e41c9
> p2pkh address: 1N5ZkjyabcZLLHMweJrSkn3qedsPGzAx9m
Generate new BIP32 master key
./bitcointool -command hdgenmaster
> masterkey: xprv9s21ZrQH143K3C5hLMq2Upsh8mf9Z1p5C4QuXJkiodSSihp324YnWpFfRjvP7gqocJKz4oakVwZn5cUgRYTHtNRvGqU5DU2Gn8MPM9jHvfC
Print HD node
./bitcointool -command hdprintkey -privkey xprv9s21ZrQH143K3C5hLMq2Upsh8mf9Z1p5C4QuXJkiodSSihp324YnWpFfRjvP7gqocJKz4oakVwZn5cUgRYTHtNRvGqU5DU2Gn8MPM9jHvfC
> ext key: xprv9s21ZrQH143K3C5hLMq2Upsh8mf9Z1p5C4QuXJkiodSSihp324YnWpFfRjvP7gqocJKz4oakVwZn5cUgRYTHtNRvGqU5DU2Gn8MPM9jHvfC
> depth: 0
> p2pkh address: 1Fh1zA8mD6S2LBbCqdViEGuV3oDhggX3k4
> pubkey hex: 0394a83fcfa131afc47a3fcd1d32db399a0ffa7e68844546b2df7ed9f5ebd07b09
> extended pubkey: xpub661MyMwAqRbcFgAASPN2qxpRgoVdxUXvZHLWKhALMxyRbW9BZbs34ca9H3LrdsKxdMD4o5Fc7eqDg19cRTj3V9dCCeM4R1DRn8DvUq3rMva
Derive child key (second child key at level 1 in this case)
./bitcointool -command hdderive -keypath m/1h -privkey xprv9s21ZrQH143K3C5hLMq2Upsh8mf9Z1p5C4QuXJkiodSSihp324YnWpFfRjvP7gqocJKz4oakVwZn5cUgRYTHtNRvGqU5DU2Gn8MPM9jHvfC
> ext key: xprv9v5qiRbzrbhUzAVBdtfqi1tQx5tiRJ2jpNtAw8bRec8sTivLw55H85SoRTizNdx2JSVL4sNxmjvseASZkwpUopby3iGiJWnVH3Wjg2GkjrD
> depth: 1
> p2pkh address: 1DFBGZdcADGTcWwDEgf15RGPqnjmW2gokC
> pubkey hex: 0203a85ec401e66a218bf1583112599ee2a1268ebc90d91b7f457c87a50f2b011b
> extended pubkey: xpub695C7w8tgyFnCeZejvCr59q9W7jCpkkbBbomjX13CwfrLXFVUcPXfsmHGiSfpYds2JuHrXAFEoikMX6725W8VgrVL5x4ojBw9QFAPgtdw1G

The bitcoin-send-tx CLI

This tools can be used to broadcast a raw transaction to peers retrived from a dns seed or specified by ip/port. The application will try to connect to max 6 peers, send the transaction two two of them and listens on the remaining ones if the transaction has been relayed back.

Send a raw transaction to random peers on mainnet
./bitcoin-send-tx <txhex>
Send a raw transaction to random peers on testnet and show debug infos
./bitcoin-send-tx -d -t <txhex>
Send a raw transaction to specific peers on mainnet and show debug infos use a timeout of 5s
./bitcoin-send-tx -d -s 5 -i, <txhex>

How to Build

You will need to have some dev tools prior to building libnspv for your system.

Prepare system before building


# Install brew
/usr/bin/ruby -e "$(curl -fsSL"
# Install Xcode, opens a pop-up window to install CLT without installing the entire Xcode package
xcode-select --install
# Update brew and install dependencies
brew update
brew upgrade
brew install libsodium libevent cmake git wget
Intall using brew
brew tap jl777/homebrew-libnspv
brew install libnspv


# Install Termux
# Open and run the following commands
pkg upgrade
pkg install build-essential git wget libsodium libevent


sudo apt-get -y install build-essential pkg-config libc6-dev m4 autoconf \
libtool unzip git wget automake

Clone repository using Git

Once prepared your system, get the source code:

git clone
cd libnspv

Now you can follow the next instructions to compile and update

Full library including CLI tool and wallet database

make check

Pure library without wallet support

./configure --disable-wallet --disable-tools
make check

Updating libnspv

cd libnspv
git pull

libnspv does all the above, it also can launch a superlite nSPV client ./nspv KMD launches a KMD superlite ./nspv BTC launches the normal libbtc headers only SPV mode

for superlite clients, it will daemonize the nspv executable and it is accessible via JSON requests sent into the localhost rpc port. you can specify any available rpc port with -p option at the end.

there is a coins JSON file that comes from the which will define the default behavior of the superlite if it is a komodo "asset" and also has the following fields:

"p2p": 12985, "magic":"feb4cb23", "nSPV":",,,,,,,,,"

the "p2p" field is the coins peer to peer port, the "magic" is the netmagic of that chain. the decimal value of this can be obtained from the getinfo call, convert to hex and serialize it into the 4 hexbytes. if you got the direction wrong, just flip it around. finally, the "nSPV" field is a list of one or more ip addresses of a nSPV fullnode

the JSON api is very simple and almost a direct mapping of the nSPV=1 rpc commands in the komodod, the testvectors file at ~/libnspv/src/tools/testvectors will show specifically how to call it using curl. any other method to post the JSON to the rpc port will suffice. has initial docs

How To build in Termux on Android:

Check if your device will use the new Termux repos:

Update and install required packages

pkg upgrade && pkg install build-essential git wget libsodium libevent

Other packages may be required.

Clone and enter the repo

git clone
cd libnspv

Update scripts so target environment determined (from

find . -name 'config.sub' -exec chmod u+w '{}' \; -exec cp -f "${PREFIX}/share/libtool/build-aux/config.sub" '{}' \;
find . -name 'config.guess' -exec chmod u+w '{}' \; -exec cp -f "${PREFIX}/share/libtool/build-aux/config.guess" '{}' \;

Then the usual:


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