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Aloha!
Niels Möller wrote:
> There are lots of authentication functions which end by comparing
> two digests. The recent ccm_decrypt_message is typical, ending with
>
> return (memcmp(tag, src + mlength, tlength) == 0);
> int mem_equal (const void *ap, const void *bp, size_t n) { volatile
> const unsigned char *a = ap; volatile const unsigned char *b = bp
Missing semicolon for bp.
> volatile unsigned char d; size_t i; for (i = d = 0; i < n; i++) d |=
> a[i] ^ b[i]; return d == 0;
You should return d here if you want the behaviour to match memcmp.
FWIW I implemented the function above (minus changes to stdint types) in
my umactests. And for 100M messages, each 1024 Bytes I see something
like a few second total increase in performance in comparison to using
the memcmp provided in OSX. I can live with that.
- --
Med vänlig hälsning, Yours
Joachim Strömbergson - Alltid i harmonisk svängning.
========================================================================
Joachim Strömbergson Secworks AB [email protected]
========================================================================
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