Skip to main content

What is PSKT?

PSKT stands for Partially Signed Kaspa Transactions.

When HardKAS builds a transaction, it normally attempts to authorize it instantly by resolving a local account (like alice) and signing the inputs with its private key. But what happens if HardKAS does not have the key?

PSKT solves the problem of distributed authority. It is a coordination protocol (and binary format) that allows a Kaspa transaction to be transported between different environments, accumulating signatures along the way, without requiring any participant to have full network access or full authority.

PSKT is NOT Multisig​

Do not conflate these two concepts:

  • PSKT is a transport mechanism. It is the envelope used to carry an unsigned (or partially signed) transaction around.
  • Multisig is a spending condition enforced by Kaspa consensus (e.g., "3 of 5 signatures required").

You can use a PSKT for a perfectly normal, single-signature transaction if you want to sign it on an offline computer. PSKT is simply the container.

Upstream Integration​

HardKAS does not invent its own PSKT format: a PSKT adapter would delegate to the upstream rusty-kaspa PSKT implementation.

No adapter does in this build: hardkas pskt merge and hardkas pskt finalize refuse with a typed error (there is no pskt combine command; merging is pskt merge). See PSKT.

The Problem PSKT Solves​

PSKT solves three fundamental challenges in Kaspa transaction construction:

  1. Hardware / External Wallets: You want to construct a transaction on your laptop (which has node access to query UTXOs), but sign it on a Ledger or external signer (which has no network access).
  2. Multi-Party Coordination: You want to spend from a 2-of-3 multisig address. Alice signs the transaction on her computer and sends it to Bob. Bob adds his signature.
  3. Air-Gapped Security: You want to construct a transaction on an online machine, transfer it via USB to a completely offline (air-gapped) machine for signing, and bring the signed result back online for broadcasting.

PSKT ensures that all the metadata required to sign the transaction (UTXO scripts, amounts, network details) travels inside the PSKT artifact itself, meaning the signer does not need to trust an RPC node.