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2015's Argon2 publication suggests that cryptocurrency hashing like password hashing on backend servers should not be subject to side-channel attack:

Argon2d is optimized for settings where the adversary does not get regular access to system memory or CPU, i.e. he can not run side-channel attacks based on the timing information, nor can he recover the password much faster using garbage collection [17]. These settings are more typical for backend servers and cryptocurrency minings.

Why ?

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  • $\begingroup$ It is not a far-fetch scenario that when a value which hash has the desired property is found, the miner pool briefly stops while moving to the next block, creating a voltage surge on the power feed, detectable at a large distance by SPA. Time elapsed since start of mining the block could be revealing of the number that (conventionally) has a value. If there's no mechanism against that, it could allow an attacker to find that number effortlessly. There are various ways to counter that, including randomizing the starting point of mining in a block. This attack is unrelated to the hash itself. $\endgroup$ – fgrieu♦ Oct 20 '20 at 19:16
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It is generally assumed that cryptocurrency mining is an "offline" process, that is you take one input from outside, and then after a long while you report back with a result. In particular, it is assumed that an adversary does not see when exactly one search starts and when it ends nor do they see how many tries it took you exactly. This makes timing-based side-channels extremely hard - most likely impossible - to execute, even if you leak "a lot" in terms of traditional timing side channels. Furthermore the input to the hash function - which is what you'd want to recover - is only secret right up until you make your outside communication announcing said input - at which point a more sophisticated recovery of it would be pointless...

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  • $\begingroup$ and one ever doesn't know to select Argon2i or Argon2d the can use Argondi $\endgroup$ – kelalaka Oct 20 '20 at 15:13

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