Changes

CHES2016 CTF

997 bytes added, 17:41, 23 June 2016

→‎Required AES-128 Format

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'''NOTE:''' If the key setup takes longer than 100mS, there is a chance the AES core will miss some of the plaintext sent. Commonly this results in incorrect encryption outputs even though your implementation seems to be correct. Please contact us if this happens, but it's preferable to keep your key setup call < 737000 cycles to avoid this issue. You can do a lot in 737000 cycles so it shouldn't be an issue in most systems.

<u>Encryption Function</u>

==== Timing your AES Implementation ====

~~TODO - Check if~~ One of the requirements is that leakage occurs before 10 000 cycles. How can you test this? Luckily it's possible with the Atmel Studio ~~allows cycle~~simulator (you can also try other simulators, but it's unknown their support for the XMEGA device). Details of running the simulator are on the page [[Simulating the XMEGA Target Code]]. Note what it means that "leakage" is occurring is somewhat vague. For example Stage-bygate #3B does NOT cover all the first-~~cycle timing?~~round S-Boxs in 10 000 cycles, but people were still able to break it. Generally your AES should have somehow touched all the secret material inside that window is the objective.

== White Box Cryptography ==