Fix CMS CTR-ACPKM decrypt after ASN.1 parameter reinit#528
Open
rostislaved wants to merge 2 commits into
Open
Conversation
Author
|
The issue looked like this. It is a file after decryption: bytes after 4096 were incorrect |
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
I ran into an issue with Kuznyechik where, after decrypting files, bytes after offset 4096 were corrupted.
I do not understand the C code or these algorithms well enough, so I asked Codex to investigate it. It produced this pull request.
Codex found that CMS
kuznyechik-ctr-acpkmparameters set the ACPKM section size from ASN.1, but a later cipher reinit overwrote that value with the default section size. As a result, decryption switched keys at the wrong boundary.This PR preserves the ACPKM section size when it was explicitly set from ASN.1 or via ctrl. It also adds a regression test that reproduces the ASN.1 parameter + reinit flow.
Please take a look if this makes sense.