john-dev - pow64of32

Message-ID: <AANLkTik=9dXoR3B+oJP=ctmb2=iKYWere2Ojp-GTCmyg@mail.gmail.com>
Date: Thu, 24 Mar 2011 18:01:59 +0100
From: Łukasz Odzioba <lukas.odzioba@...il.com>
To: john-dev@...ts.openwall.com
Subject: pow64of32

Hi,
i was looking into the JtR sources and found that powering function
implementation is not optimal. It is O(n), but we can do that in
logarithmic time.
It's not a big deal but mayby code listed below, would be better (for
the peace of mind).

void pow64of32(int64 *dst,unsigned int x,int n)
{//O(logn)
  int64 tmp={0,1};
  while(n--){
    if(n%2)
      mul64by32(&tmp,x);
    x*=x;
    n/=2;
  }
}

pow64of32 function is defined in math.c .

Lukas

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