Messages in this thread |  | | Date | Tue, 28 Apr 2026 18:30:05 +0200 | | From | "Ard Biesheuvel" <> | | Subject | Re: [PATCH v2] crypto: atmel-sha204a - drop hwrng quality reduction for ATSHA204A |
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On Tue, 28 Apr 2026, at 15:24, Marek Behún wrote: > Hi Thorsten, > > Bill also wrote about ATSHA204A [1] > > My best guess as to what's going on here is that the device has a > ring-oscillator based entropy source, but that it generates only a few bits > of entropy for each use. It seems to be called before generating each > 32-byte "random" value, which is why the second set of 32-bit values have > more possible values, and the 3rd has even more. However, the number of > unique values in the final column of 32*N byte values is always equal to > the number of unique values of the entire string of bytes. > > If this is true that the device generates <256 true random bits and then > mixes in non-volatile pseudorandom number generator to produce 256 bits, > then the quality should not be set to full 1024. >
This post is about the Hashlet, which has a ATSHA204 not ATSHA204A.
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