feat: replace cosi with regular multisig #4
Merged
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
cepetr
approved these changes
Jul 18, 2025
matejcik
reviewed
Jul 21, 2025
| ed25519_public_key pub; | ||
| if (true != compute_pubkey(BOOTLOADER_KEY_M, BOOTLOADER_KEY_N, BOOTLOADER_KEYS, sigmask, pub)) | ||
| { | ||
| int sig0_idx = sigmask & (1 << 0) ? 0 : 1; |
There was a problem hiding this comment.
This sigmask handling is wrong: it assumes that there are exactly two out of the first three bits signed and nothing else.
sigmask is part of the signed data so we really have to honor what the signers are commiting to.
the code as written still works if we verify the assumptions, that is:
__builtin_popcount(sigmask) == BOOTLOADER_KEY_M- bits above
BOOTLOADER_KEY_Nare zero, so ...sigmask & ~((1 << BOOTLOADER_KEY_N) - 1) == 0? i think
There was a problem hiding this comment.
(of course we shouldn't use BOOTLOADER_KEY_M because we're hardcoding the data structures for exactly two signatures; we should still use BOOTLOADER_KEY_N and _Static_assert(BOOTLOADER_KEY_N >= 2))
Merged
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Outdated suggestions cannot be applied.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.
CoSi is removed, replaced by regular multisig.
Sigmask is moved to protected area, means it is signed, this signers commit to who the other signer is.
imgtool is modified to support sigmask TLV. Otherwise it crashes when imgtool dumpinfo is ran on the binary.