Shrike Bitcoin Wallet

A full desktop Bitcoin wallet: hardware wallets, PSBT, multisig and airgapped signing, connecting to your own node. Shrike follows the BLAKE2b proof-of-work hardfork of Bitcoin.

It signs with SIGHASH_UNIFIED, so the transactions it builds cannot be replayed against nodes still running the pre-fork rules.

Download Replay protection

What it does

Shrike builds on Sparrow, so the wallet itself is a mature one.

Single signature and multisig wallets across the common script types
Hardware wallets over USB and in airgapped modes, with firmware available for Coldcard, SeedSigner and every current Trezor
Full PSBT import and export, and a transaction editor that shows the bytes before you broadcast
Replay protection marked per keystore, with the send screen reporting what each transaction actually got
Connects to your own node: Bitcoin Knots directly, or your own Electrum server indexing one
Tor built in, and fee rates, broadcast and explorer links pointed only at services that follow the fork
Installs alongside an existing Sparrow without sharing wallets, settings or state
Reproducible release binaries, with the proof of work and the signature hash checked against a live forked regtest node
mainnet, testnet, testnet4, regtest and signet

What Shrike changes

Everything not listed here is Sparrow: the same wallet model, the same hardware wallet support, the same PSBT workflow.

BLAKE2b proof of work

Validates the 164 byte v2 block header and takes the BLAKE2b hash as the block id past activation. The work itself lives in the drongo submodule.

Unified opt-in signature hash

Past activation, signs with SIGHASH_UNIFIED: the 0x20 flag set on the base hash type, 0x21 by default. The pre-fork rules reject that hash type, which is exactly what makes the signature unreplayable.

Per-keystore opt-in

Nothing a hardware device or watch-only keystore reports tells the wallet what firmware will sign for it, so you mark each one by hand. One marked signer in a quorum is enough.

Only adopting services

Fee rates, explorer links and broadcast go to mempool.guide. The preconfigured public Electrum servers are gone, because none of them follow the fork.

Separate application identity

Installs alongside an existing Sparrow without sharing state: its own ~/.shrike folder, packages, desktop entries, MIME types and macOS bundle identifier.

Verified end to end

The proof of work and the signature hash are both checked against a live forked regtest node, not just unit tested. The release binaries are reproducible.

Activation

Past these heights, Shrike validates BLAKE2b work and opts in when it signs.

Network	Height	Activated
mainnet	`961,640`	30 August 2026
testnet4	`150,308`	30 August 2026

Below these heights nothing changes: the same chain, the same coins, the same history. Past them, blocks carry BLAKE2b work and signatures opt in.

The compiled-in height is cross checked against the connected node wherever the node reports one. If the two disagree, Shrike declines to opt in rather than picking a side. Only Knots reports the height, through getdeploymentinfo; behind anything else the wallet still opts in and tells you the height went unchecked.

Check the send screen

A signature that does not opt in is valid under both rule sets, so it can be replayed. Shrike selects the opt-in by default and says plainly what each transaction got.

The send screen reporting a transaction as replay protected — Where the status reads otherwise, hovering it names what is refusing and what to do about it.

Anyone Can Pay is the exception. It commits only to its own input and the outputs, so that input can be lifted out and spent under the pre-fork rules even though the whole transaction cannot. Shrike names such signatures and never selects that mode on its own.

Read the full replay protection guide →