ML-KEM: Move FIPS-abort upon PCT failure to top-level ML-KEM API #2195
+72
−12
Conversation
This file contains 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
hanno-becker
changed the title
If AWSLC_FIPS is set, ML-KEM includes a PCT check after key generation, in compliance with the FIPS-203 IG https://csrc.nist.gov/csrc/media/Projects/cryptographic-module-validation-program/documents/fips%20140-3/FIPS%20140-3%20IG.pdf If the PCT fails, AWS_LC_FIPS_failure is called to abort operation. This commit hoists the call to AWS_LC_FIPS_failure one level up, into the toplevel ML-KEM API of crypto/fipsmodule/ml_kem/ml_kem.h: When the PCT fails, the lower-level key generation API that invokes the PCT returns -1, which is caught by the top-level ML-KEM API and converted into a call to AWS_LC_FIPS_failure. There is no other failure condition during key generation. When the PCT fails in the randomized key generation API, the coins are still cleansed before propagating the PCT error. It could be considered whether the PK and SK should be cleansed in this case, too, but this commit does not change behvaiour in this regard. The change facilitates replacing the ML-KEM reference implementation, since only the return-value behaviour needs to be maintained, but an alternative implementation need not be aware of the abort macro AWS_LC_FIPS_failure. Signed-off-by: Hanno Becker <[email protected]>
hanno-becker
force-pushed
the
mlkem_fips_move
branch
from
625ae84 to
5ddb00b
Compare
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #2195 +/- ##
==========================================
- Coverage 79.04% 79.03% -0.02%
==========================================
Files 612 612
Lines 106067 106078 +11
Branches 14985 14984 -1
==========================================
- Hits 83842 83840 -2
- Misses 21571 21586 +15
+ Partials 654 652 -2 ☔ View full report in Codecov by Sentry. |
andrewhop
approved these changes
Feb 13, 2025
| ml_kem_512_params_init(¶ms); | ||
| return ml_kem_keypair_derand_ref(¶ms, public_key, secret_key, seed); | ||
| res = ml_kem_keypair_derand_ref(¶ms, public_key, secret_key, seed); | ||
| #if defined(AWSLC_FIPS) |
There was a problem hiding this comment.
Can this be implemented in AWS_LC_FIPS_failure?
Maybe can avoid littering the code-base with if defined(AWS_FIPS).
There was a problem hiding this comment.
I stuck with the precedent here. If one wants to change this, it should be a separate PR, as there are other calls to AWS_LC_FIPS_failure.
| AWS_LC_FIPS_failure("ML-KEM keygen PCT failed"); | ||
| } | ||
| #else | ||
| assert(res == 0); |
There was a problem hiding this comment.
Why capture here? All other code-paths normally throw it up the stack.
There was a problem hiding this comment.
This keeps the previous behavior from https://github.com/aws/aws-lc/pull/2195/files#diff-af6c334a9ca9f10f18987e623c41f74351fd662f0e01019d54a0716cdb710904L86. I'm OK either way.
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.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.
Discussed with: @andrewhop
If AWSLC_FIPS is set, ML-KEM includes a PCT check after key generation, in compliance with the FIPS-203 IG
https://csrc.nist.gov/csrc/media/Projects/cryptographic-module-validation-program/documents/fips%20140-3/FIPS%20140-3%20IG.pdf If the PCT fails, AWS_LC_FIPS_failure is called to abort operation.
This PR hoists the call to AWS_LC_FIPS_failure one level up, into the toplevel ML-KEM API of crypto/fipsmodule/ml_kem/ml_kem.h: When the PCT fails, the lower-level key generation API that invokes the PCT returns -1, which is caught by the top-level ML-KEM API and converted into a call to AWS_LC_FIPS_failure. There is no other failure condition during key generation.
When the PCT fails in the randomized key generation API, the coins are still cleansed before propagating the PCT error. It could be considered whether the PK and SK should be cleansed in this case, too, but this commit does not change behvaiour in this regard.
The change facilitates replacing the ML-KEM reference implementation, specifically mlkem-native (see #2176), since only the return-value behaviour needs to be maintained, but an alternative implementation need not be aware of the abort macro AWS_LC_FIPS_failure.