xpubcache: allow choosing if xpub computation should be repeated #1536
+90
−58
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This comment was marked as spam.
This comment was marked as spam.
Sorry, something went wrong.
Beerosagos
approved these changes
Aug 19, 2025
|
|
||
| /// Derives an xpub from the root xpub using the provided keypath. | ||
| fn from_keypath(keypath: &[u32]) -> Result<Self, ()>; | ||
| fn from_keypath(keypath: &[u32], compute: Compute) -> Result<Self, ()>; | ||
| } | ||
|
|
||
| /// Implements a cache for xpubs. Cached intermediate xpubs are used to derive child xpubs. |
There was a problem hiding this comment.
Unrelated to the change, but I think that the cache_keypath() in the comment should be changed to add_keypath()
There was a problem hiding this comment.
Added separate commit.
| @@ -17,12 +17,18 @@ use super::keystore; | |||
| use crate::bip32; | |||
| use alloc::vec::Vec; | |||
|
|
|||
| #[derive(Copy, Clone)] | |||
| pub enum Compute { | |||
There was a problem hiding this comment.
nit: Maybe it could be useful to add a comment here (or somewhere else) explaining that this is used as an additional bitflips check for sensitive operations
End-goal: reduce the number of secure chip ops when signing a BTC transaction, to reduce the chance of going over the Optiga chip's "rate limit", which induces throttling. By default keystore::get_xpub computed the xpub twice, to mitigate potential bitflips, which could be bad when delivering the wrong xpub (or derivatives) to the host. When signing a transaction however, one does not need the extra protection - if there is a bit flip, the resulting signature will be invalid. This commit reduces the number of secure chip ops needed when the bitflip mitigation is not required. The existing method `get_xpub` was renamed so the compiler can tell us all the instances where we need to decide between one or the other.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
End-goal: reduce the number of secure chip ops when signing a BTC transaction, to reduce the chance of going over the Optiga chip's "rate limit", which induces throttling.
By default keystore::get_xpub computed the xpub twice, to mitigate potential bitflips, which could be bad when delivering the wrong xpub (or derivatives) to the host.
When signing a transaction however, one does not need the extra protection - if there is a bit flip, the resulting signature will be invalid.
This commit reduces the number of secure chip ops needed when the bitflip mitigation is not required.
The existing method
get_xpubwas renamed so the compiler can tell us all the instances where we need to decide between one or the other.