public GF2Vector(int length,SecureRandom sr){
  this.length=length;
  int size=(length + 31) >> 5;
  v=new int[size];
  for (int i=size - 1; i >= 0; i--) {
    v[i]=sr.nextInt();
  }
  int r=length & 0x1f;
  if (r != 0) {
    v[size - 1]&=(1 << r) - 1;
  }
}

public GF2Vector ( int length , SecureRandom sr ) { this . length = length ; int size = ( length + 31 ) > > 5 ; v = new int [ size ] ; for ( int i = size - 1 ; i >= 0 ; i -- ) { v [ i ] = sr . nextInt ( ) ; } int r = length & 0x1f ; if ( r != 0 ) { v [ size - 1 ] &= ( 1 << r ) - 1 ; } }
construct a random gf2vector of the given length .
