Completed
Pull Request — master (#702)
by thomas
29:32 queued 10:39
created

Bech32::convertBits()   B

Complexity

Conditions 9
Paths 13

Size

Total Lines 33

Duplication

Lines 0
Ratio 0 %

Code Coverage

Tests 10
CRAP Score 20.6407

Importance

Changes 0
Metric Value
cc 9
nc 13
nop 5
dl 0
loc 33
ccs 10
cts 21
cp 0.4762
crap 20.6407
rs 8.0555
c 0
b 0
f 0
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<?php
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declare(strict_types=1);
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namespace BitWasp\Bitcoin;
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use \BitWasp\Bech32\Exception\Bech32Exception;
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class Bech32
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{
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    /**
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     * @var string
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     */
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    protected static $charset = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l';
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    /**
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     * @var array
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     */
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    protected static $charsetKey = [
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        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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        15, -1, 10, 17, 21, 20, 26, 30,  7,  5, -1, -1, -1, -1, -1, -1,
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        -1, 29, -1, 24, 13, 25,  9,  8, 23, -1, 18, 22, 31, 27, 19, -1,
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        1,  0,  3, 16, 11, 28, 12, 14,  6,  4,  2, -1, -1, -1, -1, -1,
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        -1, 29, -1, 24, 13, 25,  9,  8, 23, -1, 18, 22, 31, 27, 19, -1,
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        1,  0,  3, 16, 11, 28, 12, 14,  6,  4,  2, -1, -1, -1, -1, -1
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    ];
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    /**
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     * @var array
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     */
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    protected static $generator = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3];
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    /**
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     * @param int[] $values
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     * @param int $numValues
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     * @return int
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     */
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    public static function polyMod(array $values, int $numValues): int
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    {
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        $chk = 1;
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        for ($i = 0; $i < $numValues; $i++) {
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            $top = $chk >> 25;
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            $chk = ($chk & 0x1ffffff) << 5 ^ $values[$i];
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            for ($j = 0; $j < 5; $j++) {
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                $value = (($top >> $j) & 1) ? self::$generator[$j] : 0;
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                $chk ^= $value;
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            }
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        }
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        return $chk;
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    }
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    /**
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     * Expands the human readable part into a character array for checksumming.
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     * @param string $hrp
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     * @param int $hrpLen
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     * @return int[]
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     */
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    public static function hrpExpand(string $hrp, int $hrpLen): array
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    {
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        $expand1 = [];
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        $expand2 = [];
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        for ($i = 0; $i < $hrpLen; $i++) {
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            $o = ord($hrp[$i]);
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            $expand1[] = $o >> 5;
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            $expand2[] = $o & 31;
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        }
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        return array_merge($expand1, [0], $expand2);
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    }
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    /**
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     * Converts words of $fromBits bits to $toBits bits in size.
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     *
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     * @param int[] $data - character array of data to convert
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     * @param int $inLen - number of elements in array
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     * @param int $fromBits - word (bit count) size of provided data
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     * @param int $toBits - requested word size (bit count)
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     * @param bool $pad - whether to pad (only when encoding)
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     * @return int[]
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     * @throws Bech32Exception
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     */
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    public static function convertBits(array $data, int $inLen, int $fromBits, int $toBits, bool $pad = true): array
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    {
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        $acc = 0;
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        $bits = 0;
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        $ret = [];
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        $maxv = (1 << $toBits) - 1;
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        $maxacc = (1 << ($fromBits + $toBits - 1)) - 1;
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        for ($i = 0; $i < $inLen; $i++) {
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            $value = $data[$i];
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            if ($value < 0 || $value >> $fromBits) {
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                throw new Bech32Exception('Invalid value for convert bits');
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            }
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            $acc = (($acc << $fromBits) | $value) & $maxacc;
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            $bits += $fromBits;
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            while ($bits >= $toBits) {
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                $bits -= $toBits;
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                $ret[] = (($acc >> $bits) & $maxv);
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            }
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        }
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        if ($pad) {
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            if ($bits) {
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                $ret[] = ($acc << $toBits - $bits) & $maxv;
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            }
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        } else if ($bits >= $fromBits || ((($acc << ($toBits - $bits))) & $maxv)) {
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            throw new \BitWasp\Bech32\Exception\Bech32Exception('Invalid data');
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        }
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        return $ret;
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    }
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    /**
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     * @param string $hrp
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     * @param int[] $convertedDataChars
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     * @return int[]
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     */
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    public static function createChecksum(string $hrp, array $convertedDataChars): array
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    {
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        $values = array_merge(self::hrpExpand($hrp, strlen($hrp)), $convertedDataChars);
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        $polyMod = self::polyMod(array_merge($values, [0, 0, 0, 0, 0, 0]), count($values) + 6) ^ 1;
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        $results = [];
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        for ($i = 0; $i < 6; $i++) {
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            $results[$i] = ($polyMod >> 5 * (5 - $i)) & 31;
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        }
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        return $results;
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    }
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    /**
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     * Verifies the checksum given $hrp and $convertedDataChars.
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     *
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     * @param string $hrp
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     * @param int[] $convertedDataChars
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     * @return bool
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     */
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    public static function verifyChecksum(string $hrp, array $convertedDataChars): bool
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    {
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        $expandHrp = self::hrpExpand($hrp, strlen($hrp));
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        $r = array_merge($expandHrp, $convertedDataChars);
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        $poly = self::polyMod($r, count($r));
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        return $poly === 1;
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    }
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    /**
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     * @param string $hrp
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     * @param array $combinedDataChars
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     * @return string
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     */
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    public static function encode(string $hrp, array $combinedDataChars): string
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    {
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        $checksum = self::createChecksum($hrp, $combinedDataChars);
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        $characters = array_merge($combinedDataChars, $checksum);
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        $encoded = [];
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        for ($i = 0, $n = count($characters); $i < $n; $i++) {
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            $encoded[$i] = self::$charset[$characters[$i]];
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        }
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        return "{$hrp}1" . implode('', $encoded);
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    }
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    /**
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     * Validates a bech32 string and returns [$hrp, $dataChars] if
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     * the conversion was successful. An exception is thrown on invalid
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     * data.
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     *
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     * @param string $sBech - the bech32 encoded string
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     * @return array - returns [$hrp, $dataChars]
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     * @throws Bech32Exception
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     */
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    public static function decode(string $sBech): array
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    {
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        return \BitWasp\Bech32\decode($sBech);
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    }
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}
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