ParagonIE_Sodium_Core_Ristretto255::h2c_string_to_hash_sha256() –

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Description

Usage

$string = ParagonIE_Sodium_Core_Ristretto255::h2c_string_to_hash_sha256( $hLen, $ctx, $msg );

Parameters

$hLen
( int ) required
$ctx
( ?string ) required
$msg
( string ) required

Returns

string

Source

File name: wordpress/wp-includes/sodium_compat/src/Core/Ristretto255.php


Lines:

1 to 42 of 42
    protected static function h2c_string_to_hash_sha256($hLen, $ctx, $msg)
    {
        $h = array_fill(0, $hLen, 0);
        $ctx_len = !is_null($ctx) ? self::strlen($ctx) : 0;
        if ($hLen > 0xff) {
            throw new SodiumException('Hash must be less than 256 bytes');
        }

        if ($ctx_len > 0xff) {
            $st = hash_init('sha256');
            self::hash_update($st, "H2C-OVERSIZE-DST-");
            self::hash_update($st, $ctx);
            $ctx = hash_final($st, true);
            $ctx_len = 32;
        }
        $t = array(0, $hLen, 0);
        $ux = str_repeat("\0", 64);
        $st = hash_init('sha256');
        self::hash_update($st, $ux);
        self::hash_update($st, $msg);
        self::hash_update($st, self::intArrayToString($t));
        self::hash_update($st, $ctx);
        self::hash_update($st, self::intToChr($ctx_len));
        $u0 = hash_final($st, true);

        for ($i = 0; $i < $hLen; $i += 64) {
            $ux = self::xorStrings($ux, $u0);
            ++$t[2];
            $st = hash_init('sha256');
            self::hash_update($st, $ux);
            self::hash_update($st, self::intToChr($t[2]));
            self::hash_update($st, $ctx);
            self::hash_update($st, self::intToChr($ctx_len));
            $ux = hash_final($st, true);
            $amount = min($hLen - $i, 64);
            for ($j = 0; $j < $amount; ++$j) {
                $h[$i + $j] = self::chrToInt($ux[$i]);
            }
        }
        return self::intArrayToString(array_slice($h, 0, $hLen));
    }
 

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