These types of transactions are widely used in hardware wallets.
The PSBT creates a half-signed transaction, protecting the private keys.
Programmers Alekos Filini and Daniela Brozzoni have launched the website bip174.org. This works as a graphical interface allowing users to create and view partially signed transactions (PSBT), along with all the values that operate within a transaction of this type.
PSBT transactions are based on creating a partial signature of a transaction in Bitcoin, allowing the creation and sending of a transaction to be separated. This, in a practical area, allows you to create the transaction on a secure device, not connected to the Internet, and send it through another device, which is connected to the Internet but will not have access to the private keys.
The announcement of the launch of this tool was published on the Bitcoin (Bitcoin-dev) developer mailing list on August 25.
Although the PSBT tool is nothing new, published in BIP 174, whose first information the proposed tool on the bip174.org portal was released in mid-2018It does represent a novelty in that users can see the operation of this type of transaction.
The portal separates into sections each of the parties that make up a PSBT transaction, highlighting the Inputs (inputs) and Outputs (Departures). Between the Inputs To be placed are the UTXOs and the outgoing signatures.
While the tool may be useful, it may be a bit counterproductive to use it online as the goal for which the PSBT is most used is to protect private signatures. This is because, with a PSBT transaction, you can sign the transaction from an offline computer, then export it to another that does have an Internet connection, and proceed to send it.
However, to avoid this scenario, users can download the source code from the repository on GitHub, which does not require any kind of Internet connection.
Profit from PSBT transactions
This type of transaction, as already commented throughout the text, offers a extra layer of security over private keys by allowing the signing and sending of the transaction to be separated between 2 different devices.
These types of transactions are used, to a large extent, by hardware wallets such as Coldcard. With these, it is possible to create partially signed transactions from Coldcard and propagate them over the network from the Electrum wallet.
Security is because, if for any reason, the wallet that is connected to the Internet is compromised, the attacker will not be able to change anything in the PSBT transaction that you have created from another device, since the signatures needed to create a new transaction are elsewhere.