Add wallet Sign Message flow for CEX ownership verification

[j0ntz]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Requirements

If you have made any visual changes to the GUI. Make sure you have:

• Tested on iOS device
• Tested on Android device
• Tested on small-screen device (iPod Touch)
• Tested on large-screen device (tablet)

Description

Adds an in-app Sign Message flow so a user can prove ownership of a self-hosted wallet by signing an exchange-provided message. This addresses EU Travel Rule / TFR withdrawal checks where CEXs/CASPs (Kraken, Coinbase, Bitvavo, Bitpanda, OKX, Bringin, NiceHash, etc.) require a signed message from the destination wallet instead of a manual ID/selfie proof.

BTC-first, per the task scope.

What it does

• Adds a Sign Message option to the wallet list menu, restricted to Bitcoin-family (UTXO) wallets whose plugin implements message signing.
• Opens a new SignMessageScene that shows the wallet's receive address (copyable, so the user can hand it to the exchange), a multiline message input, and a Sign Message button.
• Signs with wallet.signMessage(message, { otherParams: { publicAddress } }) and displays the resulting base64 signature in a copyable card.
• Includes a short phishing-safety note ("only sign messages from a service you trust; a signature never reveals your private keys").

Implementation notes

• signMessage is used rather than signBytes because for Bitcoin signBytes base64-re-encodes the bytes before signing, which would produce a signature over the wrong data. signMessage signs the literal UTF-8 message the exchange verifies (same pattern already used by bityProvider and EdgeProviderServer).
• The signing address is one the wallet owns (from wallet.getAddresses), because the UTXO plugin requires the address to be in its data layer.

Files

• SignMessageScene.tsx (new scene)
• routerTypes.tsx, Main.tsx (route + scene registration)
• WalletListMenuActions.tsx, WalletListMenuModal.tsx (menu entry, UTXO-scoped)
• en_US.ts (strings)

Asana: https://app.asana.com/0/1215088146871429/1209296431612665

Testing

Verified end-to-end on the iOS simulator (edge-funds, My Bitcoin wallet): opened the wallet menu, tapped Sign Message, entered a message, and confirmed a valid base64 signature was produced and displayed. Proof screenshots attached below.

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Note

Medium Risk
Signing invokes wallet private-key operations and users may sign untrusted messages, though keys are not exposed and address ownership is validated by the plugin.

Overview
Adds a Sign Message entry to the wallet list menu for Bitcoin-family (UTXO) wallets, so users can prove self-custody when a CEX asks for a signed withdrawal message (e.g. Travel Rule checks).

Choosing it opens a new signMessage screen: an editable signing address (prefilled from the wallet’s receive address, with Use default address), a multiline field for the exchange’s exact message, and a copyable signature after wallet.signMessage runs with that address. Inputs lock while signing; changing address or message clears a stale signature. Copy includes a short trust/safety note and clearer errors when the wallet does not own the address.

Navigation, menu actions, router types, and English strings are wired to match existing wallet-menu patterns.

^{Reviewed by Cursor Bugbot for commit 2a248af. Bugbot is set up for automated code reviews on this repo. Configure here.}

[j0ntz]

📸 Test evidence (iOS sim)

agent proof 1209296431612665 01 wallet menu sign message

agent proof 1209296431612665 02 sign message scene

agent proof 1209296431612665 03 signature success

Captured by the agent's in-app test run (build-and-test).

[j0ntz]

📸 Test evidence (after bugbot fixes)

agent proof 1209296431612665 04 segwit signature success

agent proof 1209296431612665 05 signature cleared on edit

Captured by the agent's in-app test run (build-and-test).

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 7624da7. Configure here.}

[j0ntz]

📸 Test evidence (followup: user-selectable signing address, Ravencoin UTXO wallet on iOS sim)

agent proof 1209296431612665 01 signmsg default address

agent proof 1209296431612665 02 signature default address

agent proof 1209296431612665 03 address edited signature cleared

agent proof 1209296431612665 04 signature after reset

Captured by the agent's in-app test run (build-and-test).