use the crypto library native call pbkdf2_hmac if available

[fdie]

The crypto library since OTP 24.2 contains a pbkdf2_hmac/5 method.
The significant performance benefit of this nif (see the execution sample below) on server side may be used to increase the number of iterations as requested by @tmolitor-stud-tu for good reasons.

Sample parameters

Algo = sha512.
Pass = <<"c477272edab242bba3fec995fa68f2c1">>.
Salt = <<20,80,86,171,183,106,121,6,234,82,4,108,242,162,157,16>>.
Iterations = 10000.

scram:hi/5 legacy algorithm

Cost(fun() -> scram:hi_legacy(Algo, Pass, Salt, Iterations) end).
[{reductions,161906},
 {duration,{t,0.038362},{sec,0},{millisec,38},{microsec,362}},
 {result,<<26,229,188,159,43,102,5,255,38,178,137,9,180,
           164,53,121,58,187,17,145,101,101,161,109,214,
           67,158,16,148,102,230,4,240,12,183,6,66,107,
           175,157,6,156,21,221,170,11,137,67,35,36,211,
           53,214,202,144,204,93,16,30,230,7,152,72,238>>}]

scram:hi/5 algorithm based on the native call pbkdf2_hmac/5

Cost(fun() -> scram:hi(Algo, Pass, Salt, Iterations) end).
[{reductions,25753},
 {duration,{t,0.006241},{sec,0},{millisec,6},{microsec,241}},
 {result,<<26,229,188,159,43,102,5,255,38,178,137,9,180,
           164,53,121,58,187,17,145,101,101,161,109,214,
           67,158,16,148,102,230,4,240,12,183,6,66,107,
           175,157,6,156,21,221,170,11,137,67,35,36,211,
           53,214,202,144,204,93,16,30,230,7,152,72,238>>}]

Improvements

~5 times less reductions
~6 times faster

Given the cost measure function

Cost = fun(F) ->
    {reductions, Red0} = process_info(self(), reductions),
    {MS0, Res} = timer:tc(fun() -> F() end),
    {reductions, Red} = process_info(self(), reductions),
    Sec = MS0 div 1000000,
    MS = (MS0 - 1000000 * Sec),
    MilliSec = MS div 1000,
    [
        {reductions, Red - Red0}, 
        {duration, 
            {t, MS0 / 1000000.0}, 
            {sec, Sec}, 
            {millisec, MS div 1000}, 
            {microsec, MS - 1000 * MilliSec}
        }, 
        {result, Res}
     ]
end.

[prefiks]

Except that one thing, rest looks ok

[prefiks]

Can you change that to "^(R|1|2[0123]|24.[01])", looks like this was added in 24.2

[fdie]

You are right, OTP 24.0 and 24.1 should be discarded, thanks

[prefiks]

Merged, thank you for your contribution!