logarithm in OpenSSL

[Dr Paul Dale]

I’m wondering why you need the log function?
If you’re measuring performance, could the analysis tool perform the logarithm?

A first order approximation to log_2(n) where n is a BIGNUM would be BN_num_bits(n).


Pauli
-- 
Dr Paul Dale | Cryptographer | Network Security & Encryption 
Phone +61 7 3031 7217
Oracle Australia



> On 25 Jul 2019, at 2:22 am, Niklas Niere <nniklas at mail.uni-paderborn.de> wrote:
> 
> Hello,
> 
> we are implementing a TLS 1.3 feature into OpenSSL to get an idea of how well our feature performs in a concrete server library. In the feature, we want to use the log function.
> 
> When we try to use the log function from the math.h header, OpenSSL won't compile with the statement that 'log' is a reference to an undefined function. The BigNum library from OpenSSL does also not seem to offer a log function.
> 
> We suspect that the compile error comes from the fact that OpenSSL is C90 compatible but are unsure. Does anyone know how to compute the logarithm of a number in OpenSSL?
> 
> Thanks,
> Niklas
>