[ot] hw/opentitan: ot_aes: preserve external state when a new message is started #102
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
… is started The AES block does not clear the CPU-visible registers when starting a new message. Only "the state registers inside the cipher core are cleared with PRD during the last round of every encryption/decryption." Fixing this allows the OpenTitan `aes_test.c` test to pass, as more recent versions of it check the IV register state at the end of the test. Signed-off-by: Luís Marques <luismarques@lowrisc.org>
jwnrt
approved these changes
Jan 16, 2025
|
I'm not sure how the PR title relates to its content. |
Although state internal to the AES block is reset when a new message is started, other state (state that is externally visible) is not reset / randomized. The IV and keyshare registers are part of the externally visible state. Does that make sense?
|
Yes thanks. |
luismarques
merged commit 878918f
into
lowRISC:dev/ot-earlgrey-1.0.0-updates
6 checks passed
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Outdated suggestions cannot be applied.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.
The AES block does not clear the CPU-visible registers when starting a new message. Only "the state registers inside the cipher core are cleared with PRD during the last round of every encryption/decryption."
Fixing this allows the OpenTitan
aes_test.ctest to pass, as more recent versions of it check the IV register state at the end of the test.