Bitcoin: Why doesn’t my PSBT input script have a public key?

The Mystery of Your PSBT’s Missing Public Key

As a Bitcoin developer or user, you’re probably familiar with the concept of public and private keys. In this article, we’ll dive into why your PSBT (Public Script Broadcast) might not have a public key.

Understanding PSBT and Private Keys

A PSBT is a script that contains information on how to broadcast a Bitcoin transaction across the network. It’s essentially a coded message that describes what actions to take when broadcasting a transaction. Each line of a PSBT represents a specific operation, such as “set recipient” or “create signed output.”

On the other hand, private keys are used to verify and sign Bitcoin transactions. They are generated using the Elliptic Curve Digital Signature Algorithm (ECDSA) with a specific public key.

Why might your PSBT be missing a public key?

There are several reasons why your PSBT might be missing a public key:

  • Missing Private Key: If you don’t have a corresponding private key for one of the operations in your PSBT, Bitcoin will still attempt to use it. However, this can lead to problems when trying to broadcast transactions.
  • Incorrect Private Key Usage

    Bitcoin: Why does my PSBT's input script not have a pub key?

    : If you are using the wrong private key for an operation or you neglect to specify which private key is being used, Bitcoin may not be able to generate the necessary scripts to broadcast transactions.

  • Private Key Expiration or Invalidation: If your private key has expired, been compromised, or is no longer valid (e.g. due to a wallet update), you will not be able to use it to sign your PSBT.

How ​​to identify and resolve the issue

To resolve this issue, follow these steps:

  • Check your ECDSA private keys: Make sure you have the correct private key for each operation in your PSBT. If you don’t know where to find your private keys or how to generate new ones, refer to your wallet documentation or contact your support specialist.
  • Check your public key usage: Double-check that you have specified the correct private key for each operation and that it has not been omitted from your PSBT.

Example of what your PSBT might look like

Here is an example of what your PSBT might look like:

0101020304a12f34d5e6c7b8a9c
00|  All Rights Reserved.