BitWasp\Bitcoin\Bech32

Complexity

Total Complexity

46

Size/Duplication

Total Lines	265
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	3

Test Coverage

Coverage

96.52%

Importance

Changes

0

9 Methods

Rating	Name	Duplication	Size	Complexity
A	polyMod()	0	16	4
A	hrpExpand()	0	12	2
A	verifyChecksum()	0	7	1
C	decodeCheck()	0	59	18
D	convertBits()	0	33	9
A	createChecksum()	0	11	2
A	encode()	0	11	2
A	encodeSegwit()	0	16	1
C	decodeSegwit()	0	29	7

<?php

namespace BitWasp\Bitcoin;

use BitWasp\Bitcoin\Script\WitnessProgram;
use BitWasp\Buffertools\Buffer;

class Bech32
{
    protected static $CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";

    protected static $CHARSET_REV = [
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        15, -1, 10, 17, 21, 20, 26, 30,  7,  5, -1, -1, -1, -1, -1, -1,
        -1, 29, -1, 24, 13, 25,  9,  8, 23, -1, 18, 22, 31, 27, 19, -1,
        1,  0,  3, 16, 11, 28, 12, 14,  6,  4,  2, -1, -1, -1, -1, -1,
        -1, 29, -1, 24, 13, 25,  9,  8, 23, -1, 18, 22, 31, 27, 19, -1,
        1,  0,  3, 16, 11, 28, 12, 14,  6,  4,  2, -1, -1, -1, -1, -1
    ];

    /**
     * @param int[] $values
     * @param int $numValues
     * @return int
     */
    public static function polyMod(array $values, $numValues)
    {
        $generator = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3];
        $chk = 1;
        for ($i = 0; $i < $numValues; $i++) {
            $top = $chk >> 25;
            $chk = ($chk & 0x1ffffff) << 5 ^ $values[$i];

            for ($j = 0; $j < 5; $j++) {
                $value = (($top >> $j) & 1) ? $generator[$j] : 0;
                $chk ^= $value;
            }
        }

        return $chk;
    }

    /**
     * @param string $hrp
     * @param int $hrpLen
     * @return array
     */
    public static function hrpExpand($hrp, $hrpLen)
    {
        $expand1 = [];
        $expand2 = [];
        for ($i = 0; $i < $hrpLen; $i++) {
            $o = ord($hrp[$i]);
            $expand1[] = $o >> 5;
            $expand2[] = $o & 31;
        }

        return array_merge($expand1, [0], $expand2);
    }

    /**
     * @param string $hrp
     * @param int[] $convertedDataChars
     * @return bool
     */
    public static function verifyChecksum($hrp, array $convertedDataChars)
    {
        $expandHrp = self::hrpExpand($hrp, strlen($hrp));
        $r = array_merge($expandHrp, $convertedDataChars);
        $poly = self::polyMod($r, count($r));
        return $poly === 1;
    }

    /**
     * @param string $sBech
     * @return array
     */
    public static function decodeCheck($sBech)
    {
        $length = strlen($sBech);
        if ($length > 90) {
            throw new \RuntimeException("Bech32 string cannot exceed 90 characters in length");
        }

        $chars = array_values(unpack("C*", $sBech));

        $haveUpper = false;
        $haveLower = false;
        $positionOne = -1;

        for ($i = 0; $i < $length; $i++) {
            $x = $chars[$i];
            if ($x < 33 || $x > 126) {
                throw new \RuntimeException("Out of range value for bech");
            }

            if ($x >= 0x61 && $x <= 0x7a) {
                $haveLower = true;
            }

            if ($x >= 0x41 && $x <= 0x5a) {
                $haveUpper = true;
                $x = $chars[$i] = $x + 0x20;
            }

            // find location of last '1' character
            if ($x === 0x31) {
                $positionOne = $i;
            }
        }

        if ($haveUpper && $haveLower) {
            throw new \RuntimeException("Data contains mixture of higher/lower case characters");
        }

        if ($positionOne < 1 || ($positionOne + 7) > $length) {
            throw new \RuntimeException("Invalid location for '1' character");
        }

        $hrp = [];
        for ($i = 0; $i < $positionOne; $i++) {
            $hrp[$i] = chr($chars[$i]);
        }

        $hrp = implode("", $hrp);
        $data = [];
        for ($i = $positionOne + 1; $i < $length; $i++) {
            $data[] = ($chars[$i] & 0x80) ? -1 : self::$CHARSET_REV[$chars[$i]];
        }

        if (!self::verifyChecksum($hrp, $data)) {
            throw new \RuntimeException("Invalid bech32 checksum");
        }

        return [$hrp, array_slice($data, 0, -6)];
    }

    /**
     * @param array $data
     * @param int $inLen
     * @param int $fromBits
     * @param int $toBits
     * @param bool $pad
     * @return array
     */
    public static function convertBits(array $data, $inLen, $fromBits, $toBits, $pad = true)
    {
        $acc = 0;
        $bits = 0;
        $ret = [];
        $maxv = (1 << $toBits) - 1;
        $maxacc = (1 << ($fromBits + $toBits - 1)) - 1;

        for ($i = 0; $i < $inLen; $i++) {
            $value = $data[$i];
            if ($value < 0 || $value >> $fromBits) {
                throw new \InvalidArgumentException("Invalid value for convert bits");
            }

            $acc = (($acc << $fromBits) | $value) & $maxacc;
            $bits += $fromBits;

            while ($bits >= $toBits) {
                $bits -= $toBits;
                $ret[] = (($acc >> $bits) & $maxv);
            }
        }

        if ($pad) {
            if ($bits) {
                $ret[] = ($acc << $toBits - $bits) & $maxv;
            }
        } else if ($bits >= $fromBits || ((($acc << ($toBits - $bits))) & $maxv)) {
            throw new \RuntimeException("Invalid data");
        }

        return $ret;
    }

    /**
     * @param string $hrp
     * @param int[] $convertedDataChars
     * @return array
     */
    public static function createChecksum($hrp, array $convertedDataChars)
    {
        $values = array_merge(self::hrpExpand($hrp, strlen($hrp)), $convertedDataChars);
        $polyMod = self::polyMod(array_merge($values, [0, 0, 0, 0, 0, 0]), count($values) + 6) ^ 1;
        $results = [];
        for ($i = 0; $i < 6; $i++) {
            $results[$i] = ($polyMod >> 5 * (5 - $i)) & 31;
        }

        return $results;
    }

    /**
     * @param string $hrp
     * @param array $combinedDataChars
     * @return string
     */
    public static function encode($hrp, array $combinedDataChars)
    {
        $cs = self::createChecksum($hrp, $combinedDataChars);
        $combined = array_merge($combinedDataChars, $cs);
        $return = "{$hrp}1";
        for ($i = 0, $n = count($combined); $i < $n; $i++) {
            $return .= self::$CHARSET[$combined[$i]];
        }

        return $return;
    }

    /**
     * @param string $hrp
     * @param WitnessProgram $witnessProgram
     * @return string
     */
    public static function encodeSegwit($hrp, WitnessProgram $witnessProgram)
    {
        $prog = $witnessProgram->getProgram();
        $d = array_values(unpack("C*", $prog->getBinary()));
        $bits = self::convertBits($d, count($d), 8, 5);

        $data = array_merge(
            [$witnessProgram->getVersion()],
            $bits
        );

        return self::encode(
            $hrp,
            $data
        );
    }

    /**
     * @param string $hrp
     * @param string $bech32
     * @return WitnessProgram
     */
    public static function decodeSegwit($hrp, $bech32)
    {
        list ($hrpGot, $data) = self::decodeCheck($bech32);
        if ($hrpGot !== $hrp) {
            throw new \RuntimeException("Invalid prefix for address");
        }

        $decoded = self::convertBits(array_slice($data, 1), count($data) - 1, 5, 8, false);
        $decodeLen = count($decoded);
        if ($decodeLen < 2 || $decodeLen > 40) {
            throw new \RuntimeException("Invalid segwit address");
        }

        if ($data[0] > 16) {
            throw new \RuntimeException("Invalid witness program version");
        }

        $bytes = '';
        foreach ($decoded as $char) {
            $bytes .= chr($char);
        }
        $decoded = new Buffer($bytes);

        if (0 === $data[0]) {
            return WitnessProgram::v0($decoded);
        }

        return new WitnessProgram($data[0], $decoded);
    }
}