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SubjectRe: [PATCH v2 1/6] SP800-90A Deterministic Random Bit Generator
Stephan Mueller wrote:
> This is a clean-room implementation of the DRBG defined in SP800-90A.

Why? I guess it's for certification?

> +static bool drbg_fips_continuous_test(struct drbg_state *drbg,
> + unsigned char *buf)
> ...
> + ret = memcmp(drbg->prev, buf, drbg_blocklen(drbg));
> + ...
> + /* invert the memcmp result, because the test shall pass when the
> + * two compared values do not match */
> + if (ret)
> + return true;
> + else
> + return false;

This looks strange. The return value of memcmp() is not really
a boolean, and the code appears not to match the comment because the
numeric value of ret is not actually inverted. How about this:

ret = memcmp(...);
...
/* the test shall pass when the compared values are not equal */
return ret != 0;


Regards,
Clemens


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