/**
* Perform Bit-String-to-Octet-String Conversion.
*
* Defined in SEC 1 section 2.3.1.
*
* @param BitString $bs
* @throws \RuntimeException
* @return OctetString
*/
public static function bitStringToOctetString(BitString $bs)
{
$str = $bs->string();
if ($bs->unusedBits()) {
// @todo pad string
throw new \RuntimeException("Unaligned bitstrings to supported");
}
return new OctetString($str);
}
/**
* Initialize from BitString.
*
* @param BitString $bs
* @param int $width
* @return self
*/
public static function fromBitString(BitString $bs, $width)
{
$num_bits = $bs->numBits();
$num = gmp_import($bs->string(), 1, GMP_MSW_FIRST | GMP_BIG_ENDIAN);
$num >>= $bs->unusedBits();
if ($num_bits < $width) {
$num <<= $width - $num_bits;
}
return new self(gmp_strval($num, 10), $width);
}
protected static function _fromDER($data, $critical)
{
return new self($critical, Flags::fromBitString(BitString::fromDER($data), 9)->number());
}
/**
* Get unique identifier as a string.
*
* @return string
*/
public function string()
{
return $this->_uid->string();
}