A hardware wallet can show a Bitcoin payment on its own screen while the computer beside it handles the internet connection. The device authorizes the transaction using private keys held inside it, and connected software sends the signed transaction to the Bitcoin network. Signing and sending are separate operations. The hardware wallet can therefore complete its part offline while the payment still reaches an online destination.
The process starts with a receiving address and an amount. Wallet software uses those details to prepare an outgoing transaction. Services that accept Bitcoin deposits can also record incoming payments against customer accounts. The sender’s hardware wallet presents the transaction for review and signs it after approval. It does not manage the receiving service’s accounts.
A deposit to an account for bitcoin gambling follows the same sender-side payment process. Wallet software prepares a Bitcoin transfer to the receiving address, while the casino records the deposit as account credit used for gaming. A hardware wallet signs the outgoing transfer rather than operating the casino account. The platform’s balance and the sender’s wallet balance describe different records, connected by the deposit. The signing step concerns authorization to spend from the sender’s wallet. Preparing and approving that transfer can remain separate from the software that publishes it to the network.
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The app prepares the payment
Wallet software assembles the information that the signer needs. Preparing a transaction establishes what is being authorized, including its destination and amount. That data can be passed to the signing device without giving the connected app access to the private keys that will authorize the payment.
One format for this exchange is a Partially Signed Bitcoin Transaction, or PSBT. It packages a proposed transaction with the supporting information needed to review and sign the payment. A PSBT can be passed to a signer before it contains a signature. Preparing it organizes the proposed payment; authorization remains a separate operation.
Blockstream’s documented Jade Plus workflow provides an example. A companion wallet, including the Blockstream app, prepares a PSBT and displays it as an animated QR sequence. The sequence carries the PSBT across multiple frames, allowing Jade Plus to read the package with its camera. Once scanned, the package is ready for review on the hardware device. After approval, Jade Plus signs the transaction and displays a new QR code for the companion wallet to read.
The device displays the payment and signs it
Before signing, the hardware wallet’s own display provides a place to review the proposed payment. The person approving it can examine the destination and transaction details on the device that holds the signing keys. The review concerns the data presented to the signer, rather than relying entirely on the companion app’s description.
BitBox’s explanation of an independent display identifies this review as a central hardware-wallet function. Its display lets users verify transaction details and receiving addresses independently of the connected computer or phone. The app prepares the request; the hardware device presents the information on which approval rests.
Approval then permits the signing operation. A private key is secret information used to create a digital signature. The hardware wallet stores and uses keys, while the Bitcoin itself is accounted for on the network. Moving transaction data through the device therefore does not move coins into or out of its physical storage. The signature provides authorization that can be checked without disclosing that key. It travels with the signed transaction, while the private key stays within the signing device during this workflow.
Those keys are only as strong as the randomness used to create them, as our report on the Coldcard entropy flaw shows.
A signature is distinct from a password sent to a website. The receiving service does not need the sender’s private key to receive Bitcoin. Nor does a signature conceal the payment details: signing establishes authorization for the transaction. Keeping the signing operation separate from the connected app is the device’s role.
That separation assumes the device itself is genuine. Our report on tampered Ledger devices sold through a reseller covers an implant that read the recovery phrase during setup.
The app broadcasts the signed transaction
After signing, the transaction data returns to the companion wallet. In the Jade Plus QR workflow, the app reads the code displayed by the hardware device and handles broadcasting. The signing device has produced the authorization; the connected software supplies the route to the Bitcoin network.
Broadcasting delivers the signed transaction to the Bitcoin network, where its authorization can be checked as part of transaction validation. The connected app passes the signature along with the transaction data. Network participants can check that authorization without receiving the private key used to create it.
This also separates wallet authorization from account credit. A receiving service records the payment through its own account process. Completing the signing step does not itself update the receiving account’s balance. The sender’s approval and the platform’s account update mark different stages.
USB and QR carry transaction data
The exchange between app and signer needs a way to move information in both directions. USB provides an electronic connection; QR scanning transfers information through images. Blockstream describes both as supported ways of using Jade while keeping private keys on the device. Offline signing means the device can authorize the transaction without an internet connection of its own. A QR-based air gap also removes the direct electronic connection between the app and signer.
An offline signer still receives data and returns a result. With QR, that exchange happens through the camera and screen. The app prepares information the device can read, then reads back the signed result. Internet access is needed by the component broadcasting the transaction, while authorization can remain on the separate hardware device.
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