/**
* Encode Signature
*
* This function accepts a signature object, and information about
* the txout being spent, and the relevant key for signing, and
* encodes the signature in DER format.
*
* @param \Signature $signature
* @return string
*/
public static function encode_signature(\Signature $signature)
{
// Pad r and s to 64 characters.
$rh = str_pad(BitcoinLib::hex_encode($signature->getR()), 64, '0', STR_PAD_LEFT);
$sh = str_pad(BitcoinLib::hex_encode($signature->getS()), 64, '0', STR_PAD_LEFT);
// Check if the first byte of each has its highest bit set,
$t1 = unpack("H*", pack('H*', substr($rh, 0, 2)) & pack('H*', '80'));
$t2 = unpack("H*", pack('H*', substr($sh, 0, 2)) & pack('H*', '80'));
// if so, the result != 00, and must be padded.
$r = $t1[1] !== '00' ? '00' . $rh : $rh;
$s = $t2[1] !== '00' ? '00' . $sh : $sh;
// Create the signature.
$der_sig = '30' . self::_dec_to_bytes(4 + (strlen($r) + strlen($s)) / 2, 1) . '02' . self::_dec_to_bytes(strlen($r) / 2, 1) . $r . '02' . self::_dec_to_bytes(strlen($s) / 2, 1) . $s . '01';
return $der_sig;
}
/**
* Decode Mnemonic
*
* This function decodes a string of 12 words to convert to the electrum
* seed. This is an implementation of http://tools.ietf.org/html/rfc1751,
* which is how electrum generates a 128-bit key from 12 words.
*
* @param string $words
* @return string
*/
public static function decode_mnemonic($words)
{
$words = explode(" ", $words);
$out = '';
$n = 1626;
for ($i = 0; $i < count($words) / 3; $i++) {
$a = 3 * $i;
list($word1, $word2, $word3) = array($words[$a], $words[$a + 1], $words[$a + 2]);
$index_w1 = array_search($word1, self::$words);
$index_w2 = array_search($word2, self::$words) % $n;
$index_w3 = array_search($word3, self::$words) % $n;
$x = $index_w1 + $n * \gmp_Utils::gmp_mod2($index_w2 - $index_w1, $n) + $n * $n * \gmp_Utils::gmp_mod2($index_w3 - $index_w2, $n);
$out .= BitcoinLib::hex_encode($x);
}
return $out;
}