Changes to the crypto unit state machine: added register ensuring constant-time execution#33
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jovanbulck merged 4 commits intosancus-tee:masterfrom May 19, 2025
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Updated the pull request to also mitigate the enable timing leak. |
martonbognar
changed the title
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See write up for full explanation.
The cryptographic unit uses comparison in hardware to check the tag of sancus_unwrap. The state machine used for this verification process leaks information through a timing side-channel.
To addres this issue, I have made the comparison constant time by adding a register to keep track of the result of the comparison!
Other solution considered: adding dummy states.
pullrequest.pdf