tari-project / tari / 35758794166

72%

Build Type

push

github

Committed by web-flow

Commit Message

fix(wallet): use the wallet output's own commitment mask key id when signing a multisig withdrawal (#8010)

## Depends on

This PR depends on #8009 — `PrepareWithdrawMultisigTransaction` (and the
whole multisig-withdrawal lookup path) is broken without that fix, so
this bug could not previously be exercised end-to-end via the real RPC
surface. Branched from that fix's branch.

## Bug

`TransactionServiceRequest::SignOneSidedWithdrawMultisigTransaction`
fabricates a brand new `TariKeyId::DHCommitmentMask` key id from the
wallet's raw view key and the input's `sender_offset_public_key`,
instead of using the key id that is already attached to the
`WalletOutput` being spent:

```rust
for pair_output in &mut request.info.inputs.iter_mut() {
    let view_key = key_manager.get_view_key();
    let spend_key = key_manager.get_spend_key();

    let commitment_mask_key_id = TariKeyId::DHCommitmentMask {
        private_key: view_key.key_id.clone().into(),
        public_key: pair_output.sender_offset_public_key().clone(),
    };
    let script_pubkey = key_manager
        .stealth_address_script_spending_key(&commitment_mask_key_id, &spend_key.pub_key)?;
    ...
```

Real on-chain multisig deposit outputs (produced by
`create_deposit_multisig_transaction` via `RecipientSpec::stealth(...)`
with `RecipientKeys::DiffieHellman`) carry a `commitment_mask_key_id`
field that is a `TariKeyId::Encrypted{ encrypted, key }` variant — an
encrypted wrapper around the real commitment mask private key, **not** a
freshly re-derivable `DHCommitmentMask`.

Because the handler ignores `pair_output.commitment_mask_key_id()` (the
real key id already on the output) and instead fabricates a different
key id from scratch, `stealth_address_script_spending_key` computes a
**different** public key than the one baked into the deposit's script
`PushPubKey` opcode at creation time. This trips the handler's own
consistency check unconditionally:

```rust
if pushed_pk != &script_pubkey {
    r... (continued)

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