Support ZIP-244 TxIDs

[andrewkozlik]

The NU5 network upgrade in Zcash introduces a new TxID digest [1]. The legacy TxIDs will still be accepted by the network, but in order for Trezor to be able to spend UTXOs from transactions which use the new ZIP-244 digest, Trezor will apparently need to implement the new algorithm, so that it may verify previous transaction output amounts. The NU5 upgrade should activate on Zcash Mainnet on 18th April 2022 [2].

• In trezor-core the Zcashlike class will need to override get_prevtx_output() to compute the legacy TxID or ZIP-244 TxID depending on the transaction version. @jarys
• The same will be needed in trezor-legacy. @andrewkozlik
• Updates will also be needed in trezor-suite and blockbook in order to process the new transaction format [3]. See also discussion about backwards compatibility [4]. @martinboehm

[1] ZIP-244: https://zips.z.cash/zip-0244#txid-digest
[2] https://z.cash/support/schedule/
[3] ZIP-225: https://zips.z.cash/zip-0225
[4] Backwards compatibility discussion: zcash/zips#580

[krnak]

I'm working on ZIP-244 support for TT.

Also I proposed ZIP-244 changes to enable not checking prevouts (as in Taproot). zcash/zips#574

I will keep this thread updated.

[krnak]

ZIP-244 will be modified in order simplify the signing process on HWW. They will include sha_amounts and sha_scriptpubkeys fields introduced BIP-341. [source]

[prusnak]

@hynek-jina Why is this marked as blocked?

@martinboehm Are there any changes on the blockbook side of things? I don't remember exactly if we had to do any changes in blockbook related to previous network upgrades. Can you please deploy Zcash Testnet blockbook to see if it works as intended?

[hynek-jina]

@prusnak
I thought it was blocked by the activation on the Zcash Mainnet planned on April.

[prusnak]

I thought it was blocked by the activation on the Zcash Mainnet planned on April.

We need to implement this before the Zcash upgrade is in effect not after. Removing blocked status and bumping priority ...

[martinboehm]

@prusnak the testnet is running (behind firewall) here https://blockbook-dev.corp.sldev.cz:19132/ and there are version 5 transactions already, for example https://blockbook-dev.corp.sldev.cz:19132/tx/68ac26aebc57e1a0bfa89dc4f52c816d92c3606de7209e0bb4c6286e4739c1c3.

[ondracja]

Is this testable on our side or was the needs qa label added automatically?

[andrewkozlik]

Not testable until we have trezor/trezor-suite#5344.

[andrewkozlik]

@trezor/qa test cases when trezor/trezor-suite#5344 is finished:

• Sign a Zcash transaction which spends two UTXOs, one coming from a v4 transaction and the other from a v5 transaction.