wallet: complete hot-cold implementation for Carrot/FCMP++ by jeffro256 · Pull Request #52 · seraphis-migration/monero

jeffro256 · 2025-06-01T04:03:14Z

Carrot/FCMP++ hot-cold wallets

Design goals

Protocol goals

Compact exported Carrot outputs format
Compact signed Carrot/FCMP++ transaction format (SA/L's and key image associations only)
Deferred FCMP / BP+ proving to hot wallets at time of submission
Allows for "state-less" transaction proposals and signing
Allows for state-less, cold-initiated transaction proposals
Allows for hot-cold setups for Carrot-key-hierarchy wallets
Allows hiding of sender-receiver secrets from hot wallet

Wallet implementation goals

New hot wallets backwards compatible with old cold wallets until FCMP++ hard fork activation
New cold wallets backwards compatible with old hot wallets until FCMP++ hard fork activation
User experience for hot-cold setups on CLI and RPC is unchanged before and after FCMP++ hard fork activation
Wallet RPC interface completely backwards compatible until FCMP++ hard fork activation
Wallet RPC interface only differs in fetching of transaction secret keys after FCMP++ hard fork activation

Testing

Importing/exporting outputs, subaddress and coinbase included
Carrot-key-hierarchy account signing
State-less transaction proposals and signing
Cold-initiated transaction proposals

New quirks

Sender-receiver secrets for Carrot/FCMP++ transactions now need to fetched by the signable transaction hash, not TXID, from the cold wallet. The hot wallet RPC returns the signable transaction hash in the submit_transfer method. This is a breaking change.
Because finalizing transaction proposals into pruned Carrot/FCMP++ transactions requires knowing the private view-incoming key, a hot wallet without a differing private view-incoming key will cryptographically not be able to submit a signed transaction set. This shouldn't be a breaking change since the signed transaction payloads are encrypted using the private view-incoming key anyways.

Depends: #74, #75, #76, #77, #97, #98, #214, #216, #296

Will break this PR up into smaller pieces once the above are merged.

jeffro256 · 2025-06-05T20:00:12Z

Legacy cold_signing tests pass now (hard-fork table not updated). Also, src/wallet2.* are about ~1500 lines smaller ;)

ComputeryPony · 2025-07-23T07:44:55Z

src/wallet/hot_cold.cpp

+    const std::size_t prefix_size = magic_size + 1;
+    THROW_WALLET_EXCEPTION_IF(payload.size() <= prefix_size,
+        error::wallet_internal_error, "outputs payload too short");
+    THROW_WALLET_EXCEPTION_IF(memcmp(payload.data(), KEY_IMAGE_EXPORT_FILE_MAGIC.data(), magic_size),


OUTPUT_EXPORT_FILE_MAGIC

ComputeryPony · 2025-07-24T07:44:48Z

Not sure if it's just not implemented yet or a bug but I can almost make and use an offline wallet with this PR but I get an error when running submit_transfer at the very end.

[wallet 55WeP6]: submit_transfer
Error: unexpected error: std::get: wrong index for variant

jeffro256 · 2025-07-24T17:20:21Z

@ComputeryPony thanks for bringing that up, it was a bug. Does the latest commit fix it? It seems to work for me now

ComputeryPony · 2025-07-24T23:41:19Z

@ComputeryPony thanks for bringing that up, it was a bug. Does the latest commit fix it? It seems to work for me now

Yup, that fixed it. Thanks!

jeffro256 · 2025-07-25T00:41:21Z

Rebased against fcmp++-stage and remove usage of tools::add_element().

jeffro256 · 2025-09-08T22:01:56Z

Rebased

jeffro256 · 2025-12-16T21:03:46Z

Rebased

jeffro256 · 2026-02-25T20:38:32Z

Reworked to incorporate unbiased hash-to-point changes.

jeffro256 · 2026-02-25T22:41:53Z

Unit test failure is unrelated

jeffro256 · 2026-02-26T20:33:13Z

Rebased due to #296

jeffro256 · 2026-03-10T14:38:01Z

Rebased due to fcmp++-stage rebase against master

jeffro256 marked this pull request as draft June 1, 2025 04:03

j-berman mentioned this pull request Jun 5, 2025

TODO list for launch #53

Open

75 tasks

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 7153239 to bad06a9 Compare June 6, 2025 21:45

jeffro256 force-pushed the fcmp++-stage-cold-hot branch 3 times, most recently from d86ae71 to 1e7fc6a Compare July 8, 2025 20:16

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 1e7fc6a to 805a504 Compare July 22, 2025 05:28

ComputeryPony reviewed Jul 23, 2025

View reviewed changes

jeffro256 changed the title ~~wallet: finsih implementing and testing hot/cold wallet cryptography~~ wallet: complete hot-cold implementation for Carrot/FCMP++ Jul 23, 2025

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from ae24a60 to bb915d9 Compare July 25, 2025 00:34

jeffro256 marked this pull request as ready for review July 25, 2025 17:41

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 53ca25a to 024fc9c Compare July 29, 2025 01:33

Rucknium mentioned this pull request Jul 31, 2025

Monero Research Lab Meeting - Wed 30 July 2025, 17:00 UTC monero-project/meta#1247

Closed

j-berman force-pushed the fcmp++-stage branch from 8fb0f56 to 354062d Compare August 8, 2025 18:05

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 024fc9c to 0323828 Compare August 10, 2025 15:02

jeffro256 force-pushed the fcmp++-stage-cold-hot branch 3 times, most recently from 5357be6 to 0d16773 Compare August 19, 2025 17:30

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 0d16773 to 7909eca Compare September 2, 2025 21:15

jeffro256 mentioned this pull request Sep 2, 2025

carrot+fcmp: misc refactors of tx_builder b4 hot/cold support #98

Merged

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 7909eca to 98d00ef Compare September 2, 2025 23:27

jeffro256 force-pushed the fcmp++-stage-cold-hot branch 3 times, most recently from 59da132 to 03f9632 Compare September 8, 2025 22:01

jeffro256 force-pushed the fcmp++-stage branch from c20ec30 to a579b72 Compare September 9, 2025 01:59

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 03f9632 to ee32130 Compare September 9, 2025 03:55

j-berman force-pushed the fcmp++-stage branch from a579b72 to 64190fe Compare September 9, 2025 04:25

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from ee32130 to 8937e37 Compare September 13, 2025 15:18

jeffro256 mentioned this pull request Oct 29, 2025

TODO's for beta stressnet #166

Open

33 tasks

jeffro256 force-pushed the fcmp++-stage branch from 29f12ff to 7bfffa9 Compare October 30, 2025 03:37

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 8937e37 to ffcbaf1 Compare November 4, 2025 19:51

plowsof mentioned this pull request Nov 5, 2025

Monero Community Workgroup Meeting: Aug 23rd 16:00 UTC monero-project/meta#1257

Closed

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from ffcbaf1 to 56e9f7c Compare November 19, 2025 21:14

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 56e9f7c to 9600030 Compare December 16, 2025 21:03

jeffro256 force-pushed the fcmp++-stage-cold-hot branch 2 times, most recently from d976f5f to 0359592 Compare February 25, 2026 20:32

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from 0359592 to 0772894 Compare February 26, 2026 20:32

jeffro256 force-pushed the fcmp++-stage branch from 549b051 to 7dbeb59 Compare March 10, 2026 14:05

carrot+fcmp: complete hot/cold wallet implementation

ec68a53

jeffro256 force-pushed the fcmp++-stage-cold-hot branch from c8da52d to ec68a53 Compare March 10, 2026 14:31

Conversation

jeffro256 commented Jun 1, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Carrot/FCMP++ hot-cold wallets

Design goals

Protocol goals

Wallet implementation goals

Testing

New quirks

Uh oh!

jeffro256 commented Jun 5, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ComputeryPony Jul 23, 2025

Choose a reason for hiding this comment

Uh oh!

jeffro256 Jul 23, 2025

Choose a reason for hiding this comment

Uh oh!

ComputeryPony commented Jul 24, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

jeffro256 commented Jul 24, 2025

Uh oh!

ComputeryPony commented Jul 24, 2025

Uh oh!

jeffro256 commented Jul 25, 2025

Uh oh!

jeffro256 commented Sep 8, 2025

Uh oh!

jeffro256 commented Dec 16, 2025

Uh oh!

jeffro256 commented Feb 25, 2026

Uh oh!

jeffro256 commented Feb 25, 2026

Uh oh!

jeffro256 commented Feb 26, 2026

Uh oh!

jeffro256 commented Mar 10, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

jeffro256 commented Jun 1, 2025 •

edited

Loading

jeffro256 commented Jun 5, 2025 •

edited

Loading

ComputeryPony commented Jul 24, 2025 •

edited

Loading