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Mathematical Proof that memory hardness is not reversible? (infosec.pub)
submitted 1 month ago by to c/crypto@infosec.pub
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Hello, i have a question. I understand that government institutions probably do not want to certify memoryhard KDFs like argon* (because government agencies cannot bruteforce for clandestine or forensic purporses) but sometimes i wonder, if there is actual mathematical proof, that memory hardness like done for argon, scrypt and co. cannot be reverse into more bruteforce with a timetradeoff.

Can anyone explain this to me, because i feel like i do not understand something?

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[–] 1 point 2 weeks ago

PBKDF2 is almost entirely "linear", you can build an efficient pipeline which runs entirely on-chip without needing to reach out to external memory (a very large RAM requirement needs many more state holding gates than the FPGA has available, so it needs to start using external memory). The FPGA can essentially compose a digital conveyor belt for PBKDF2. This isn't as effective for Argon2id which forces it to stop and start and stop and start, etc.

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