public function gensalt_blowfish($input)
{
// This one needs to use a different order of characters and a
// different encoding scheme from the one in encode64() above.
// We care because the last character in our encoded string will
// only represent 2 bits. While two known implementations of
// bcrypt will happily accept and correct a salt string which
// has the 4 unused bits set to non-zero, we do not want to take
// chances and we also do not want to waste an additional byte
// of entropy.
$itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
$output = '$2a$';
$output .= chr(ord('0') + $this->iteration_count_log2 / 10);
$output .= chr(ord('0') + $this->iteration_count_log2 % 10);
$output .= '$';
$i = 0;
do {
$c1 = ord($input[$i++]);
$output .= $itoa64[$c1 >> 2];
$c1 = ($c1 & 0x3) << 4;
if ($i >= 16) {
$output .= $itoa64[$c1];
break;
}
$c2 = ord($input[$i++]);
$c1 |= $c2 >> 4;
$output .= $itoa64[$c1];
$c1 = ($c2 & 0xf) << 2;
$c2 = ord($input[$i++]);
$c1 |= $c2 >> 6;
$output .= $itoa64[$c1];
$output .= $itoa64[$c2 & 0x3f];
} while (1);
return $output;
}