Software for offline shielded transactions?

robustus · August 26, 2020, 5:33pm

Is there any tooling for signing shielded transactions offline? Also, what’s the best way to do offline transactions in general (either t or z)? Thanks!

Autotunafish · August 27, 2020, 3:16pm

github.com/zcash/zcash

Unable to send a transaction signed on an offline node; fix create raw transaction so we are able to send on offline node

opened 02:24PM - 07 Jun 18 UTC

closed 11:57PM - 19 Sep 18 UTC

eb08a167

A-rpc-interface NU0-overwinter usi

### Describe the issue There is an error when signing a transaction on an offli…ne node as described at https://bitcoin.org/en/developer-examples#offline-signing. ### Can you reliably reproduce the issue? #### If so, please list the steps to reproduce below: 1. Setup an online node with the following zcash.conf. Continue once it's fully synced. ``` testnet=1 disablewallet=0 server=1 rpcuser=foo rpcpassword=bar rpcallowip=0.0.0.0/0 rpcallowip=::/0 rpcport=8762 printtoconsole=1 ``` 2. Make sure there is at least one UTXO and run the following commands to build an unsigned transaction. I included my results. ```shell $ zcash-cli listunspent [ { "txid": "a4fca062739f85a98b56e985e930b1174a1eb52873b35d94ef754d779923dc3f", "vout": 1, "generated": false, "address": "tmRTaMngZ81K44GyGpPjqajmdkB9NLWirj4", "account": "", "scriptPubKey": "76a914acb6a5f2de3f6859daddccda56c9903c1623b56d88ac", "amount": 2.99900000, "confirmations": 1, "spendable": true } ] $ zcash-cli getaddressesbyaccount "" [ "tmQHbuXodHL8mZtUsw8dYXxbcgS6PFo8rSd", "tmRTaMngZ81K44GyGpPjqajmdkB9NLWirj4" ] $ zcash-cli dumpprivkey tmRTaMngZ81K44GyGpPjqajmdkB9NLWirj4 cSXVP4HVBkW4cSoV2kv9F5jWz9gfRTwxJAW5gVA8uPGENyjz9CXU $ zcash-cli createrawtransaction '[{"txid": "a4fca062739f85a98b56e985e930b1174a1eb52873b35d94ef754d779923dc3f", "vout": 1}]' '{"tmQHbuXodHL8mZtUsw8dYXxbcgS6PFo8rSd": "2.998"}' 030000807082c403013fdc2399774d75ef945db37328b51e4a17b130e985e9568ba9859f7362a0fca40100000000ffffffff01c095de11000000001976a9149fdba78a88de72be825a80fc6de4ad239a03851588ac0000000074ca030000 ``` 3. Switch to an offline node with the following zcash.conf. It doesn't have to be fully synced. ``` testnet=1 disablewallet=0 server=1 rpcuser=foo rpcpassword=bar rpcallowip=0.0.0.0/0 rpcallowip=::/0 rpcport=8762 printtoconsole=1 maxconnections=0 ``` 4. Sign the transaction from the 2nd step. ```shell $ zcash-cli signrawtransaction 030000807082c403013fdc2399774d75ef945db37328b51e4a17b130e985e9568ba9859f7362a0fca40100000000ffffffff01c095de11000000001976a9149fdba78a88de72be825a80fc6de4ad239a03851588ac0000000074ca030000 '[{"txid": "a4fca062739f85a98b56e985e930b1174a1eb52873b35d94ef754d779923dc3f", "vout": 1, "scriptPubKey": "76a914acb6a5f2de3f6859daddccda56c9903c1623b56d88ac"}]' '["cSXVP4HVBkW4cSoV2kv9F5jWz9gfRTwxJAW5gVA8uPGENyjz9CXU"]' { "hex": "030000807082c403013fdc2399774d75ef945db37328b51e4a17b130e985e9568ba9859f7362a0fca4010000006b483045022100ba4a8a53511842c41bc7883733bbb66e1cf51377ef6b72bf89c5424601b47e0702206586793dd0ad460f3632de6894eeb2be77cd007ba9bf017fc7d0ecc39befba19012102674cafc2d1afba93a76398e045e1cca26a822618f6201725e7f7941539a1c8cbffffffff01c095de11000000001976a9149fdba78a88de72be825a80fc6de4ad239a03851588ac0000000074ca030000", "complete": true } ``` 5. Switch back to the online node and send the transaction from the previous step. ```shell $ zcash-cli sendrawtransaction 030000807082c403013fdc2399774d75ef945db37328b51e4a17b130e985e9568ba9859f7362a0fca4010000006b483045022100ba4a8a53511842c41bc7883733bbb66e1cf51377ef6b72bf89c5424601b47e0702206586793dd0ad460f3632de6894eeb2be77cd007ba9bf017fc7d0ecc39befba19012102674cafc2d1afba93a76398e045e1cca26a822618f6201725e7f7941539a1c8cbffffffff01c095de11000000001976a9149fdba78a88de72be825a80fc6de4ad239a03851588ac0000000074ca030000 error code: -26 error message: 16: mandatory-script-verify-flag-failed (Script evaluated without error but finished with a false/empty top stack element) ``` ### Expected behaviour The transaction is successfully broadcasted. Its TXID is obtained. ### Actual behaviour + errors `sendrawtransaction` fails with `mandatory-script-verify-flag-failed (Script evaluated without error but finished with a false/empty top stack element)` error message. I performed the steps above with the latest Bitcoin Core (except it had addresstype=legacy in its conf file) and it worked. ### The version of Zcash you were using: Zcash Daemon version v1.1.0-42e302523-dirty ### Machine specs: - OS: Arch Linux, latest: - CPU: Intel® Core™ i7-7700HQ CPU @ 2.80GHz × 8 - RAM: 15.5 GiB - Disk size: 502.7 GB - Disk Type (HD/SDD): SSD - Linux kernel version (uname -a): Linux archlinux 4.16.13-1-ARCH #1 SMP PREEMPT Thu May 31 23:29:29 UTC 2018 x86_64 GNU/Linux - Compiler version (gcc -version): gcc version 8.1.0 (GCC)

This person used createrawtranasction on a synced online node, signrawtransaction on a synced offline node then sendrawtransaction on the online node, the problem they had looks like they weren’t fully synced and perhaps that Zcashd maybe wasn’t really designed for that idk

robustus · August 27, 2020, 4:49pm

Thanks for the link. Looks like it’s reasonably possible with zcashd, at least for t-addresses. Is this process any different for z-addr transactions though?

Also, that thread is over 2 years old. I’m a little surprised no offline-tx specific tooling exists yet.

Autotunafish · August 27, 2020, 4:59pm

The z address calls usually have a “z_” pre-appended

robustus · August 27, 2020, 5:12pm

Yeah, but is the signing process exactly the same?

Autotunafish · August 27, 2020, 5:30pm

Im not sure, it doesn’t specify permitted types (I’d try to help more but Im at work and not able at the moment)

daira · August 29, 2020, 10:32am

There is somewhat recent development on this: Add RPC methods for creating shielded transactions offline · Issue #2542 · zcash/zcash · GitHub and Understand demos for PCZTs (partially-created zcash transactions) · Issue #4544 · zcash/zcash · GitHub . I encourage anyone interested in moving this along to comment on ticket #2542.