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home/digilove/public_html/110/libraries/php-encryption/Crypto.php000064400000060307152353132530021035 0ustar00<?php

/*
 * PHP Encryption Library
 * Copyright (c) 2014, Taylor Hornby
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, 
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation 
 * and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Web: https://defuse.ca/secure-php-encryption.htm
 * GitHub: https://github.com/defuse/php-encryption 
 *
 * WARNING: This encryption library is not a silver bullet. It only provides
 * symmetric encryption given a uniformly random key. This means you MUST NOT
 * use an ASCII string like a password as the key parameter, it MUST be
 * a uniformly random key generated by CreateNewRandomKey(). If you want to
 * encrypt something with a password, apply a password key derivation function
 * like PBKDF2 or scrypt with a random salt to generate a key.
 *
 * WARNING: Error handling is very important, especially for crypto code! 
 *
 * How to use this code:
 *
 *     Generating a Key
 *     ----------------
 *       try {
 *           $key = Crypto::CreateNewRandomKey();
 *           // WARNING: Do NOT encode $key with bin2hex() or base64_encode(),
 *           // they may leak the key to the attacker through side channels.
 *       } catch (CryptoTestFailedException $ex) {
 *           die('Cannot safely create a key');
 *       } catch (CannotPerformOperationException $ex) {
 *           die('Cannot safely create a key');
 *       }
 *
 *     Encrypting a Message
 *     --------------------
 *       $message = "ATTACK AT DAWN";
 *       try {
 *           $ciphertext = Crypto::Encrypt($message, $key);
 *       } catch (CryptoTestFailedException $ex) {
 *           die('Cannot safely perform encryption');
 *       } catch (CannotPerformOperationException $ex) {
 *           die('Cannot safely perform decryption');
 *       }
 *
 *     Decrypting a Message
 *     --------------------
 *       try {
 *           $decrypted = Crypto::Decrypt($ciphertext, $key);
 *       } catch (InvalidCiphertextException $ex) { // VERY IMPORTANT
 *           // Either:
 *           //   1. The ciphertext was modified by the attacker,
 *           //   2. The key is wrong, or
 *           //   3. $ciphertext is not a valid ciphertext or was corrupted.
 *           // Assume the worst.
 *           die('DANGER! DANGER! The ciphertext has been tampered with!');
 *       } catch (CryptoTestFailedException $ex) {
 *           die('Cannot safely perform encryption');
 *       } catch (CannotPerformOperationException $ex) {
 *           die('Cannot safely perform decryption');
 *       }
 */

/* 
 * Raised by Decrypt() when one of the following conditions are met:
 *  - The key is wrong.
 *  - The ciphertext is invalid or not in the correct format.
 *  - The attacker modified the ciphertext.
 */
class InvalidCiphertextException extends Exception {}
/* If you see these, it means it is NOT SAFE to do encryption on your system. */
class CannotPerformOperationException extends Exception {}
class CryptoTestFailedException extends Exception {}

class Crypto
{
    // Ciphertext format: [____HMAC____][____IV____][____CIPHERTEXT____].

    /* Do not change these constants! */
    const CIPHER = MCRYPT_RIJNDAEL_128;
    const KEY_BYTE_SIZE = 16;
    const CIPHER_MODE = 'cbc';
    const HASH_FUNCTION = 'sha256';
    const MAC_BYTE_SIZE = 32;
    const ENCRYPTION_INFO = 'DefusePHP|KeyForEncryption';
    const AUTHENTICATION_INFO = 'DefusePHP|KeyForAuthentication';

    /*
     * Use this to generate a random encryption key.
     */
    public static function CreateNewRandomKey()
    {
        Crypto::RuntimeTest();
        return self::SecureRandom(self::KEY_BYTE_SIZE);
    }

    /*
     * Encrypts a message.
     * $plaintext is the message to encrypt.
     * $key is the encryption key, a value generated by CreateNewRandomKey().
     * You MUST catch exceptions thrown by this function. See docs above.
     */
    public static function Encrypt($plaintext, $key)
    {
        Crypto::RuntimeTest();

        if (self::our_strlen($key) !== self::KEY_BYTE_SIZE)
        {
            throw new CannotPerformOperationException("Bad key.");
        }

        // Generate a sub-key for encryption.
        $keysize = self::KEY_BYTE_SIZE;
        $ekey = self::HKDF(self::HASH_FUNCTION, $key, $keysize, self::ENCRYPTION_INFO);

        // Generate a random initialization vector.
        self::EnsureFunctionExists("mcrypt_get_iv_size");
        $ivsize = mcrypt_get_iv_size(self::CIPHER, self::CIPHER_MODE);
        if ($ivsize === FALSE || $ivsize <= 0) {
            throw new CannotPerformOperationException();
        }
        $iv = self::SecureRandom($ivsize);

        $ciphertext = $iv . self::PlainEncrypt($plaintext, $ekey, $iv);

        // Generate a sub-key for authentication and apply the HMAC.
        $akey = self::HKDF(self::HASH_FUNCTION, $key, self::KEY_BYTE_SIZE, self::AUTHENTICATION_INFO);
        $auth = hash_hmac(self::HASH_FUNCTION, $ciphertext, $akey, true);
        $ciphertext = $auth . $ciphertext;

        return $ciphertext;
    }

    /*
     * Decrypts a ciphertext.
     * $ciphertext is the ciphertext to decrypt.
     * $key is the key that the ciphertext was encrypted with.
     * You MUST catch exceptions thrown by this function. See docs above.
     */
    public static function Decrypt($ciphertext, $key)
    {
        Crypto::RuntimeTest();

        // Extract the HMAC from the front of the ciphertext.
        if (self::our_strlen($ciphertext) <= self::MAC_BYTE_SIZE) {
            throw new InvalidCiphertextException();
        }
        $hmac = self::our_substr($ciphertext, 0, self::MAC_BYTE_SIZE);
        if ($hmac === FALSE) {
            throw new CannotPerformOperationException();
        }
        $ciphertext = self::our_substr($ciphertext, self::MAC_BYTE_SIZE);
        if ($ciphertext === FALSE) {
            throw new CannotPerformOperationException();
        }

        // Regenerate the same authentication sub-key.
        $akey = self::HKDF(self::HASH_FUNCTION, $key, self::KEY_BYTE_SIZE, self::AUTHENTICATION_INFO);

        if (self::VerifyHMAC($hmac, $ciphertext, $akey))
        {
            // Regenerate the same encryption sub-key.
            $keysize = self::KEY_BYTE_SIZE;
            $ekey = self::HKDF(self::HASH_FUNCTION, $key, $keysize, self::ENCRYPTION_INFO);

            // Extract the initialization vector from the ciphertext.
            self::EnsureFunctionExists("mcrypt_get_iv_size");
            $ivsize = mcrypt_get_iv_size(self::CIPHER, self::CIPHER_MODE);
            if ($ivsize === FALSE || $ivsize <= 0) {
                throw new CannotPerformOperationException();
            }
            if (self::our_strlen($ciphertext) <= $ivsize) {
                throw new InvalidCiphertextException();
            }
            $iv = self::our_substr($ciphertext, 0, $ivsize);
            if ($iv === FALSE) {
                throw new CannotPerformOperationException();
            }
            $ciphertext = self::our_substr($ciphertext, $ivsize);
            if ($ciphertext === FALSE) {
                throw new CannotPerformOperationException();
            }
            
            $plaintext = self::PlainDecrypt($ciphertext, $ekey, $iv);

            return $plaintext;
        }
        else
        {
            /*
             * We throw an exception instead of returning FALSE because we want
             * a script that doesn't handle this condition to CRASH, instead
             * of thinking the ciphertext decrypted to the value FALSE.
             */
             throw new InvalidCiphertextException();
        }
    }

    /*
     * Runs tests.
     * Raises CannotPerformOperationException or CryptoTestFailedException if
     * one of the tests fail. If any tests fails, your system is not capable of
     * performing encryption, so make sure you fail safe in that case.
     */
    public static function RuntimeTest()
    {
        // 0: Tests haven't been run yet.
        // 1: Tests have passed.
        // 2: Tests are running right now.
        // 3: Tests have failed.
        static $test_state = 0;

        if ($test_state === 1 || $test_state === 2) {
            return;
        }

        try {
            $test_state = 2;
            self::AESTestVector();
            self::HMACTestVector();
            self::HKDFTestVector();

            self::TestEncryptDecrypt();
            if (self::our_strlen(Crypto::CreateNewRandomKey()) != self::KEY_BYTE_SIZE) {
                throw new CryptoTestFailedException();
            }

            if (self::ENCRYPTION_INFO == self::AUTHENTICATION_INFO) {
                throw new CryptoTestFailedException();
            }
        } catch (CryptoTestFailedException $ex) {
            // Do this, otherwise it will stay in the "tests are running" state.
            $test_state = 3;
            throw $ex;
        }

        // Change this to '0' make the tests always re-run (for benchmarking).
        $test_state = 1;
    }

    /*
     * Never call this method directly!
     */
    private static function PlainEncrypt($plaintext, $key, $iv)
    {
        self::EnsureFunctionExists("mcrypt_module_open");
        $crypt = mcrypt_module_open(self::CIPHER, "", self::CIPHER_MODE, "");
        if ($crypt === FALSE) {
            throw new CannotPerformOperationException();
        }

        // Pad the plaintext to a multiple of the block size.
        self::EnsureFunctionExists("mcrypt_enc_get_block_size");
        $block = mcrypt_enc_get_block_size($crypt);
        $pad = $block - (self::our_strlen($plaintext) % $block);
        $plaintext .= str_repeat(chr($pad), $pad);

        self::EnsureFunctionExists("mcrypt_generic_init");
        $ret = mcrypt_generic_init($crypt, $key, $iv);
        if ($ret !== 0) {
            throw new CannotPerformOperationException();
        }
        self::EnsureFunctionExists("mcrypt_generic");
        $ciphertext = mcrypt_generic($crypt, $plaintext);
        self::EnsureFunctionExists("mcrypt_generic_deinit");
        $ret = mcrypt_generic_deinit($crypt);
        if ($ret !== TRUE) {
            throw new CannotPerformOperationException();
        }
        self::EnsureFunctionExists("mcrypt_module_close");
        $ret = mcrypt_module_close($crypt);
        if ($ret !== TRUE) {
            throw new CannotPerformOperationException();
        }

        return $ciphertext;
    }

    /*
     * Never call this method directly!
     */
    private static function PlainDecrypt($ciphertext, $key, $iv)
    {
        self::EnsureFunctionExists("mcrypt_module_open");
        $crypt = mcrypt_module_open(self::CIPHER, "", self::CIPHER_MODE, "");
        if ($crypt === FALSE) {
            throw new CannotPerformOperationException();
        }

        self::EnsureFunctionExists("mcrypt_enc_get_block_size");
        $block = mcrypt_enc_get_block_size($crypt);
        self::EnsureFunctionExists("mcrypt_generic_init");
        $ret = mcrypt_generic_init($crypt, $key, $iv);
        if ($ret !== 0) {
            throw new CannotPerformOperationException();
        }
        self::EnsureFunctionExists("mdecrypt_generic");
        $plaintext = mdecrypt_generic($crypt, $ciphertext);
        self::EnsureFunctionExists("mcrypt_generic_deinit");
        $ret = mcrypt_generic_deinit($crypt);
        if ($ret !== TRUE) {
            throw new CannotPerformOperationException();
        }
        self::EnsureFunctionExists("mcrypt_module_close");
        $ret = mcrypt_module_close($crypt);
        if ($ret !== TRUE) {
            throw new CannotPerformOperationException();
        }

        // Remove the padding.
        $pad = ord($plaintext[self::our_strlen($plaintext) - 1]);
        if ($pad <= 0 || $pad > $block) {
            throw new CannotPerformOperationException();
        }
        $plaintext = self::our_substr($plaintext, 0, self::our_strlen($plaintext) - $pad);
        if ($plaintext === FALSE) {
            throw new CannotPerformOperationException();
        }

        return $plaintext;
    }

    /*
     * Returns a random binary string of length $octets bytes.
     */
    private static function SecureRandom($octets)
    {
        self::EnsureFunctionExists("mcrypt_create_iv");
        $random = mcrypt_create_iv($octets, MCRYPT_DEV_URANDOM);
        if ($random === FALSE) {
            throw new CannotPerformOperationException();
        } else {
            return $random;
        }
    }

    /*
     * Use HKDF to derive multiple keys from one.
     * http://tools.ietf.org/html/rfc5869
     */
    private static function HKDF($hash, $ikm, $length, $info = '', $salt = NULL)
    {
        // Find the correct digest length as quickly as we can.
        $digest_length = self::MAC_BYTE_SIZE;
        if ($hash != self::HASH_FUNCTION) {
            $digest_length = self::our_strlen(hash_hmac($hash, '', '', true));
        }

        // Sanity-check the desired output length.
        if (empty($length) || !is_int($length) ||
            $length < 0 || $length > 255 * $digest_length) {
            throw new CannotPerformOperationException();
        }

        // "if [salt] not provided, is set to a string of HashLen zeroes."
        if (is_null($salt)) {
            $salt = str_repeat("\x00", $digest_length);
        }

        // HKDF-Extract:
        // PRK = HMAC-Hash(salt, IKM)
        // The salt is the HMAC key.
        $prk = hash_hmac($hash, $ikm, $salt, true);

        // HKDF-Expand:

        // This check is useless, but it serves as a reminder to the spec.
        if (self::our_strlen($prk) < $digest_length) {
            throw new CannotPerformOperationException();
        }

        // T(0) = ''
        $t = '';
        $last_block = '';
        for ($block_index = 1; self::our_strlen($t) < $length; $block_index++) {
            // T(i) = HMAC-Hash(PRK, T(i-1) | info | 0x??)
            $last_block = hash_hmac(
                $hash,
                $last_block . $info . chr($block_index),
                $prk,
                true
            );
            // T = T(1) | T(2) | T(3) | ... | T(N)
            $t .= $last_block;
        }

        // ORM = first L octets of T
        $orm = self::our_substr($t, 0, $length);
        if ($orm === FALSE) {
            throw new CannotPerformOperationException();
        }
        return $orm;
    }

    private static function VerifyHMAC($correct_hmac, $message, $key)
    {
        $message_hmac = hash_hmac(self::HASH_FUNCTION, $message, $key, true);

        // We can't just compare the strings with '==', since it would make
        // timing attacks possible. We could use the XOR-OR constant-time
        // comparison algorithm, but I'm not sure if that's good enough way up
        // here in an interpreted language. So we use the method of HMACing the 
        // strings we want to compare with a random key, then comparing those.

        // NOTE: This leaks information when the strings are not the same
        // length, but they should always be the same length here. Enforce it:
        if (self::our_strlen($correct_hmac) !== self::our_strlen($message_hmac)) {
            throw new CannotPerformOperationException();
        }

        $blind = self::CreateNewRandomKey();
        $message_compare = hash_hmac(self::HASH_FUNCTION, $message_hmac, $blind);
        $correct_compare = hash_hmac(self::HASH_FUNCTION, $correct_hmac, $blind);
        return $correct_compare === $message_compare;
    }

    private static function TestEncryptDecrypt()
    {
        $key = Crypto::CreateNewRandomKey();
        $data = "EnCrYpT EvErYThInG\x00\x00";

        // Make sure encrypting then decrypting doesn't change the message.
        $ciphertext = Crypto::Encrypt($data, $key);
        try {
            $decrypted = Crypto::Decrypt($ciphertext, $key);
        } catch (InvalidCiphertextException $ex) {
            // It's important to catch this and change it into a 
            // CryptoTestFailedException, otherwise a test failure could trick
            // the user into thinking it's just an invalid ciphertext!
            throw new CryptoTestFailedException();
        }
        if($decrypted !== $data)
        {
            throw new CryptoTestFailedException();
        }

        // Modifying the ciphertext: Appending a string.
        try {
            Crypto::Decrypt($ciphertext . "a", $key);
            throw new CryptoTestFailedException();
        } catch (InvalidCiphertextException $e) { /* expected */ }

        // Modifying the ciphertext: Changing an IV byte.
        try {
            $ciphertext[0] = chr((ord($ciphertext[0]) + 1) % 256);
            Crypto::Decrypt($ciphertext, $key);
            throw new CryptoTestFailedException();
        } catch (InvalidCiphertextException $e) { /* expected */ }

        // Decrypting with the wrong key.
        $key = Crypto::CreateNewRandomKey();
        $data = "abcdef";
        $ciphertext = Crypto::Encrypt($data, $key);
        $wrong_key = Crypto::CreateNewRandomKey();
        try {
            Crypto::Decrypt($ciphertext, $wrong_key);
            throw new CryptoTestFailedException();
        } catch (InvalidCiphertextException $e) { /* expected */ }

        // Ciphertext too small (shorter than HMAC).
        $key = Crypto::CreateNewRandomKey();
        $ciphertext = str_repeat("A", self::MAC_BYTE_SIZE - 1);
        try {
            Crypto::Decrypt($ciphertext, $key);
            throw new CryptoTestFailedException();
        } catch (InvalidCiphertextException $e) { /* expected */ }
    }

    private static function HKDFTestVector()
    {
        // HKDF test vectors from RFC 5869

        // Test Case 1
        $ikm = str_repeat("\x0b", 22);
        $salt = self::hexToBytes("000102030405060708090a0b0c");
        $info = self::hexToBytes("f0f1f2f3f4f5f6f7f8f9");
        $length = 42;
        $okm = self::hexToBytes(
            "3cb25f25faacd57a90434f64d0362f2a" .
            "2d2d0a90cf1a5a4c5db02d56ecc4c5bf" .
            "34007208d5b887185865"
        );
        $computed_okm = self::HKDF("sha256", $ikm, $length, $info, $salt);
        if ($computed_okm !== $okm) {
            throw new CryptoTestFailedException();
        }

        // Test Case 7
        $ikm = str_repeat("\x0c", 22);
        $length = 42;
        $okm = self::hexToBytes(
            "2c91117204d745f3500d636a62f64f0a" .
            "b3bae548aa53d423b0d1f27ebba6f5e5" .
            "673a081d70cce7acfc48"
        );
        $computed_okm = self::HKDF("sha1", $ikm, $length);
        if ($computed_okm !== $okm) {
            throw new CryptoTestFailedException();
        }

    }

    private static function HMACTestVector()
    {
        // HMAC test vector From RFC 4231 (Test Case 1)
        $key = str_repeat("\x0b", 20);
        $data = "Hi There";
        $correct = "b0344c61d8db38535ca8afceaf0bf12b881dc200c9833da726e9376c2e32cff7";
        if (hash_hmac(self::HASH_FUNCTION, $data, $key) != $correct) {
            throw new CryptoTestFailedException();
        }
    }

    private static function AESTestVector()
    {
        // AES CBC mode test vector from NIST SP 800-38A
        $key = self::hexToBytes("2b7e151628aed2a6abf7158809cf4f3c");
        $iv = self::hexToBytes("000102030405060708090a0b0c0d0e0f");
        $plaintext = self::hexToBytes(
            "6bc1bee22e409f96e93d7e117393172a" . 
            "ae2d8a571e03ac9c9eb76fac45af8e51" .
            "30c81c46a35ce411e5fbc1191a0a52ef" .
            "f69f2445df4f9b17ad2b417be66c3710"
        );
        $ciphertext = self::hexToBytes(
            "7649abac8119b246cee98e9b12e9197d" .
            "5086cb9b507219ee95db113a917678b2" .
            "73bed6b8e3c1743b7116e69e22229516" .
            "3ff1caa1681fac09120eca307586e1a7" .
            /* Block due to padding. Not from NIST test vector. 
                Padding Block: 10101010101010101010101010101010
                Ciphertext:    3ff1caa1681fac09120eca307586e1a7
                           (+) 2fe1dab1780fbc19021eda206596f1b7 
                           AES 8cb82807230e1321d3fae00d18cc2012
             
             */
            "8cb82807230e1321d3fae00d18cc2012"
        );

        $computed_ciphertext = self::PlainEncrypt($plaintext, $key, $iv);
        if ($computed_ciphertext !== $ciphertext) {
            throw new CryptoTestFailedException();
        }

        $computed_plaintext = self::PlainDecrypt($ciphertext, $key, $iv);
        if ($computed_plaintext !== $plaintext) {
            throw new CryptoTestFailedException();
        }
    }

    /* WARNING: Do not call this function on secrets. It creates side channels. */
    private static function hexToBytes($hex_string)
    {
        return pack("H*", $hex_string);
    }

    private static function EnsureFunctionExists($name)
    {
        if (!function_exists($name)) {
            throw new CannotPerformOperationException();
        }
    }

    /*
     * We need these strlen() and substr() functions because when
     * 'mbstring.func_overload' is set in php.ini, the standard strlen() and
     * substr() are replaced by mb_strlen() and mb_substr().
     */

    private static function our_strlen($str)
    {
        if (function_exists('mb_strlen')) {
            $length = mb_strlen($str, '8bit');
            if ($length === FALSE) {
                throw new CannotPerformOperationException();
            }
            return $length;
        } else {
            return strlen($str);
        }
    }

    private static function our_substr($str, $start, $length = NULL)
    {
        if (function_exists('mb_substr'))
        {
            // mb_substr($str, 0, NULL, '8bit') returns an empty string on PHP
            // 5.3, so we have to find the length ourselves.
            if (!isset($length)) {
                if ($start >= 0) {
                    $length = self::our_strlen($str) - $start;
                } else {
                    $length = -$start;
                }
            }

            return mb_substr($str, $start, $length, '8bit');
        }

        // Unlike mb_substr(), substr() doesn't accept NULL for length
        if (isset($length)) {
            return substr($str, $start, $length);
        } else {
            return substr($str, $start);
        }
    }

}

/*
 * We want to catch all uncaught exceptions that come from the Crypto class,
 * since by default, PHP will leak the key in the stack trace from an uncaught
 * exception. This is a really ugly hack, but I think it's justified.
 *
 * Everything up to handler() getting called should be reliable, so this should
 * reliably suppress the stack traces. The rest is just a bonus so that we don't
 * make it impossible to debug other exceptions.
 *
 * This bit of code was adapted from: http://stackoverflow.com/a/7939492
 */

class CryptoExceptionHandler
{
    private $rethrow = NULL;

    public function __construct()
    {
        set_exception_handler(array($this, "handler"));
    }

    public function handler($ex)
    {
        if (
            $ex instanceof InvalidCiphertextException ||
            $ex instanceof CannotPerformOperationException ||
            $ex instanceof CryptoTestFailedException
        ) {
            echo "FATAL ERROR: Uncaught crypto exception. Suppresssing output.\n";
        } else {
            /* Re-throw the exception in the destructor. */
            $this->rethrow = $ex;
        }
    }

    public function __destruct() {
        if ($this->rethrow) {
            throw $this->rethrow;
        }
    }
}

$crypto_exception_handler_object_dont_touch_me = new CryptoExceptionHandler();

home/digilove/public_html/libraries/vendor/paragonie/sodium_compat/src/Crypto.php000064400000153032152432004350024443 0ustar00<?php

if (class_exists('ParagonIE_Sodium_Crypto', false)) {
    return;
}

/**
 * Class ParagonIE_Sodium_Crypto
 *
 * ATTENTION!
 *
 * If you are using this library, you should be using
 * ParagonIE_Sodium_Compat in your code, not this class.
 */
abstract class ParagonIE_Sodium_Crypto
{
    const aead_chacha20poly1305_KEYBYTES = 32;
    const aead_chacha20poly1305_NSECBYTES = 0;
    const aead_chacha20poly1305_NPUBBYTES = 8;
    const aead_chacha20poly1305_ABYTES = 16;

    const aead_chacha20poly1305_IETF_KEYBYTES = 32;
    const aead_chacha20poly1305_IETF_NSECBYTES = 0;
    const aead_chacha20poly1305_IETF_NPUBBYTES = 12;
    const aead_chacha20poly1305_IETF_ABYTES = 16;

    const aead_xchacha20poly1305_IETF_KEYBYTES = 32;
    const aead_xchacha20poly1305_IETF_NSECBYTES = 0;
    const aead_xchacha20poly1305_IETF_NPUBBYTES = 24;
    const aead_xchacha20poly1305_IETF_ABYTES = 16;

    const box_curve25519xsalsa20poly1305_SEEDBYTES = 32;
    const box_curve25519xsalsa20poly1305_PUBLICKEYBYTES = 32;
    const box_curve25519xsalsa20poly1305_SECRETKEYBYTES = 32;
    const box_curve25519xsalsa20poly1305_BEFORENMBYTES = 32;
    const box_curve25519xsalsa20poly1305_NONCEBYTES = 24;
    const box_curve25519xsalsa20poly1305_MACBYTES = 16;
    const box_curve25519xsalsa20poly1305_BOXZEROBYTES = 16;
    const box_curve25519xsalsa20poly1305_ZEROBYTES = 32;

    const onetimeauth_poly1305_BYTES = 16;
    const onetimeauth_poly1305_KEYBYTES = 32;

    const secretbox_xsalsa20poly1305_KEYBYTES = 32;
    const secretbox_xsalsa20poly1305_NONCEBYTES = 24;
    const secretbox_xsalsa20poly1305_MACBYTES = 16;
    const secretbox_xsalsa20poly1305_BOXZEROBYTES = 16;
    const secretbox_xsalsa20poly1305_ZEROBYTES = 32;

    const secretbox_xchacha20poly1305_KEYBYTES = 32;
    const secretbox_xchacha20poly1305_NONCEBYTES = 24;
    const secretbox_xchacha20poly1305_MACBYTES = 16;
    const secretbox_xchacha20poly1305_BOXZEROBYTES = 16;
    const secretbox_xchacha20poly1305_ZEROBYTES = 32;

    const stream_salsa20_KEYBYTES = 32;

    /**
     * AEAD Decryption with ChaCha20-Poly1305
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_chacha20poly1305_decrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        /** @var int $len - Length of message (ciphertext + MAC) */
        $len = ParagonIE_Sodium_Core_Util::strlen($message);

        /** @var int  $clen - Length of ciphertext */
        $clen = $len - self::aead_chacha20poly1305_ABYTES;

        /** @var int $adlen - Length of associated data */
        $adlen = ParagonIE_Sodium_Core_Util::strlen($ad);

        /** @var string $mac - Message authentication code */
        $mac = ParagonIE_Sodium_Core_Util::substr(
            $message,
            $clen,
            self::aead_chacha20poly1305_ABYTES
        );

        /** @var string $ciphertext - The encrypted message (sans MAC) */
        $ciphertext = ParagonIE_Sodium_Core_Util::substr($message, 0, $clen);

        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::stream(
            32,
            $nonce,
            $key
        );

        /* Recalculate the Poly1305 authentication tag (MAC): */
        $state = new ParagonIE_Sodium_Core_Poly1305_State($block0);
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
        } catch (SodiumException $ex) {
            $block0 = null;
        }
        $state->update($ad);
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update($ciphertext);
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($clen));
        $computed_mac = $state->finish();

        /* Compare the given MAC with the recalculated MAC: */
        if (!ParagonIE_Sodium_Core_Util::verify_16($computed_mac, $mac)) {
            throw new SodiumException('Invalid MAC');
        }

        // Here, we know that the MAC is valid, so we decrypt and return the plaintext
        return ParagonIE_Sodium_Core_ChaCha20::streamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );
    }

    /**
     * AEAD Encryption with ChaCha20-Poly1305
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_chacha20poly1305_encrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        /** @var int $len - Length of the plaintext message */
        $len = ParagonIE_Sodium_Core_Util::strlen($message);

        /** @var int $adlen - Length of the associated data */
        $adlen = ParagonIE_Sodium_Core_Util::strlen($ad);

        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::stream(
            32,
            $nonce,
            $key
        );
        $state = new ParagonIE_Sodium_Core_Poly1305_State($block0);
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
        } catch (SodiumException $ex) {
            $block0 = null;
        }

        /** @var string $ciphertext - Raw encrypted data */
        $ciphertext = ParagonIE_Sodium_Core_ChaCha20::streamXorIc(
            $message,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );

        $state->update($ad);
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update($ciphertext);
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($len));
        return $ciphertext . $state->finish();
    }

    /**
     * AEAD Decryption with ChaCha20-Poly1305, IETF mode (96-bit nonce)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_chacha20poly1305_ietf_decrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        /** @var int $adlen - Length of associated data */
        $adlen = ParagonIE_Sodium_Core_Util::strlen($ad);

        /** @var int $len - Length of message (ciphertext + MAC) */
        $len = ParagonIE_Sodium_Core_Util::strlen($message);

        /** @var int  $clen - Length of ciphertext */
        $clen = $len - self::aead_chacha20poly1305_IETF_ABYTES;

        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::ietfStream(
            32,
            $nonce,
            $key
        );

        /** @var string $mac - Message authentication code */
        $mac = ParagonIE_Sodium_Core_Util::substr(
            $message,
            $len - self::aead_chacha20poly1305_IETF_ABYTES,
            self::aead_chacha20poly1305_IETF_ABYTES
        );

        /** @var string $ciphertext - The encrypted message (sans MAC) */
        $ciphertext = ParagonIE_Sodium_Core_Util::substr(
            $message,
            0,
            $len - self::aead_chacha20poly1305_IETF_ABYTES
        );

        /* Recalculate the Poly1305 authentication tag (MAC): */
        $state = new ParagonIE_Sodium_Core_Poly1305_State($block0);
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
        } catch (SodiumException $ex) {
            $block0 = null;
        }
        $state->update($ad);
        $state->update(str_repeat("\x00", ((0x10 - $adlen) & 0xf)));
        $state->update($ciphertext);
        $state->update(str_repeat("\x00", (0x10 - $clen) & 0xf));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($clen));
        $computed_mac = $state->finish();

        /* Compare the given MAC with the recalculated MAC: */
        if (!ParagonIE_Sodium_Core_Util::verify_16($computed_mac, $mac)) {
            throw new SodiumException('Invalid MAC');
        }

        // Here, we know that the MAC is valid, so we decrypt and return the plaintext
        return ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );
    }

    /**
     * AEAD Encryption with ChaCha20-Poly1305, IETF mode (96-bit nonce)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_chacha20poly1305_ietf_encrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        /** @var int $len - Length of the plaintext message */
        $len = ParagonIE_Sodium_Core_Util::strlen($message);

        /** @var int $adlen - Length of the associated data */
        $adlen = ParagonIE_Sodium_Core_Util::strlen($ad);

        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::ietfStream(
            32,
            $nonce,
            $key
        );
        $state = new ParagonIE_Sodium_Core_Poly1305_State($block0);
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
        } catch (SodiumException $ex) {
            $block0 = null;
        }

        /** @var string $ciphertext - Raw encrypted data */
        $ciphertext = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $message,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );

        $state->update($ad);
        $state->update(str_repeat("\x00", ((0x10 - $adlen) & 0xf)));
        $state->update($ciphertext);
        $state->update(str_repeat("\x00", ((0x10 - $len) & 0xf)));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($len));
        return $ciphertext . $state->finish();
    }

    /**
     * AEAD Decryption with ChaCha20-Poly1305, IETF mode (96-bit nonce)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_xchacha20poly1305_ietf_decrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hChaCha20(
            ParagonIE_Sodium_Core_Util::substr($nonce, 0, 16),
            $key
        );
        $nonceLast = "\x00\x00\x00\x00" .
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8);

        return self::aead_chacha20poly1305_ietf_decrypt($message, $ad, $nonceLast, $subkey);
    }

    /**
     * AEAD Encryption with ChaCha20-Poly1305, IETF mode (96-bit nonce)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $ad
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function aead_xchacha20poly1305_ietf_encrypt(
        $message = '',
        $ad = '',
        $nonce = '',
        $key = ''
    ) {
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hChaCha20(
            ParagonIE_Sodium_Core_Util::substr($nonce, 0, 16),
            $key
        );
        $nonceLast = "\x00\x00\x00\x00" .
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8);

        return self::aead_chacha20poly1305_ietf_encrypt($message, $ad, $nonceLast, $subkey);
    }

    /**
     * HMAC-SHA-512-256 (a.k.a. the leftmost 256 bits of HMAC-SHA-512)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $key
     * @return string
     * @throws TypeError
     */
    public static function auth($message, $key)
    {
        return ParagonIE_Sodium_Core_Util::substr(
            hash_hmac('sha512', $message, $key, true),
            0,
            32
        );
    }

    /**
     * HMAC-SHA-512-256 validation. Constant-time via hash_equals().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $mac
     * @param string $message
     * @param string $key
     * @return bool
     * @throws SodiumException
     * @throws TypeError
     */
    public static function auth_verify($mac, $message, $key)
    {
        return ParagonIE_Sodium_Core_Util::hashEquals(
            $mac,
            self::auth($message, $key)
        );
    }

    /**
     * X25519 key exchange followed by XSalsa20Poly1305 symmetric encryption
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $plaintext
     * @param string $nonce
     * @param string $keypair
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box($plaintext, $nonce, $keypair)
    {
        $c = self::secretbox(
            $plaintext,
            $nonce,
            self::box_beforenm(
                self::box_secretkey($keypair),
                self::box_publickey($keypair)
            )
        );
        return $c;
    }

    /**
     * X25519-XSalsa20-Poly1305 with one ephemeral X25519 keypair.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $publicKey
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_seal($message, $publicKey)
    {
        /** @var string $ephemeralKeypair */
        $ephemeralKeypair = self::box_keypair();

        /** @var string $ephemeralSK */
        $ephemeralSK = self::box_secretkey($ephemeralKeypair);

        /** @var string $ephemeralPK */
        $ephemeralPK = self::box_publickey($ephemeralKeypair);

        /** @var string $nonce */
        $nonce = self::generichash(
            $ephemeralPK . $publicKey,
            '',
            24
        );

        /** @var string $keypair - The combined keypair used in crypto_box() */
        $keypair = self::box_keypair_from_secretkey_and_publickey($ephemeralSK, $publicKey);

        /** @var string $ciphertext Ciphertext + MAC from crypto_box */
        $ciphertext = self::box($message, $nonce, $keypair);
        try {
            ParagonIE_Sodium_Compat::memzero($ephemeralKeypair);
            ParagonIE_Sodium_Compat::memzero($ephemeralSK);
            ParagonIE_Sodium_Compat::memzero($nonce);
        } catch (SodiumException $ex) {
            $ephemeralKeypair = null;
            $ephemeralSK = null;
            $nonce = null;
        }
        return $ephemeralPK . $ciphertext;
    }

    /**
     * Opens a message encrypted via box_seal().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $keypair
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_seal_open($message, $keypair)
    {
        /** @var string $ephemeralPK */
        $ephemeralPK = ParagonIE_Sodium_Core_Util::substr($message, 0, 32);

        /** @var string $ciphertext (ciphertext + MAC) */
        $ciphertext = ParagonIE_Sodium_Core_Util::substr($message, 32);

        /** @var string $secretKey */
        $secretKey = self::box_secretkey($keypair);

        /** @var string $publicKey */
        $publicKey = self::box_publickey($keypair);

        /** @var string $nonce */
        $nonce = self::generichash(
            $ephemeralPK . $publicKey,
            '',
            24
        );

        /** @var string $keypair */
        $keypair = self::box_keypair_from_secretkey_and_publickey($secretKey, $ephemeralPK);

        /** @var string $m */
        $m = self::box_open($ciphertext, $nonce, $keypair);
        try {
            ParagonIE_Sodium_Compat::memzero($secretKey);
            ParagonIE_Sodium_Compat::memzero($ephemeralPK);
            ParagonIE_Sodium_Compat::memzero($nonce);
        } catch (SodiumException $ex) {
            $secretKey = null;
            $ephemeralPK = null;
            $nonce = null;
        }
        return $m;
    }

    /**
     * Used by crypto_box() to get the crypto_secretbox() key.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $sk
     * @param string $pk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_beforenm($sk, $pk)
    {
        return ParagonIE_Sodium_Core_HSalsa20::hsalsa20(
            str_repeat("\x00", 16),
            self::scalarmult($sk, $pk)
        );
    }

    /**
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @return string
     * @throws Exception
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_keypair()
    {
        $sKey = random_bytes(32);
        $pKey = self::scalarmult_base($sKey);
        return $sKey . $pKey;
    }

    /**
     * @param string $seed
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_seed_keypair($seed)
    {
        $sKey = ParagonIE_Sodium_Core_Util::substr(
            hash('sha512', $seed, true),
            0,
            32
        );
        $pKey = self::scalarmult_base($sKey);
        return $sKey . $pKey;
    }

    /**
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $sKey
     * @param string $pKey
     * @return string
     * @throws TypeError
     */
    public static function box_keypair_from_secretkey_and_publickey($sKey, $pKey)
    {
        return ParagonIE_Sodium_Core_Util::substr($sKey, 0, 32) .
            ParagonIE_Sodium_Core_Util::substr($pKey, 0, 32);
    }

    /**
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $keypair
     * @return string
     * @throws RangeException
     * @throws TypeError
     */
    public static function box_secretkey($keypair)
    {
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== 64) {
            throw new RangeException(
                'Must be ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES bytes long.'
            );
        }
        return ParagonIE_Sodium_Core_Util::substr($keypair, 0, 32);
    }

    /**
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $keypair
     * @return string
     * @throws RangeException
     * @throws TypeError
     */
    public static function box_publickey($keypair)
    {
        if (ParagonIE_Sodium_Core_Util::strlen($keypair) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES) {
            throw new RangeException(
                'Must be ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES bytes long.'
            );
        }
        return ParagonIE_Sodium_Core_Util::substr($keypair, 32, 32);
    }

    /**
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $sKey
     * @return string
     * @throws RangeException
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_publickey_from_secretkey($sKey)
    {
        if (ParagonIE_Sodium_Core_Util::strlen($sKey) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_SECRETKEYBYTES) {
            throw new RangeException(
                'Must be ParagonIE_Sodium_Compat::CRYPTO_BOX_SECRETKEYBYTES bytes long.'
            );
        }
        return self::scalarmult_base($sKey);
    }

    /**
     * Decrypt a message encrypted with box().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $ciphertext
     * @param string $nonce
     * @param string $keypair
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function box_open($ciphertext, $nonce, $keypair)
    {
        return self::secretbox_open(
            $ciphertext,
            $nonce,
            self::box_beforenm(
                self::box_secretkey($keypair),
                self::box_publickey($keypair)
            )
        );
    }

    /**
     * Calculate a BLAKE2b hash.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string|null $key
     * @param int $outlen
     * @return string
     * @throws RangeException
     * @throws SodiumException
     * @throws TypeError
     */
    public static function generichash($message, $key = '', $outlen = 32)
    {
        // This ensures that ParagonIE_Sodium_Core_BLAKE2b::$iv is initialized
        ParagonIE_Sodium_Core_BLAKE2b::pseudoConstructor();

        $k = null;
        if (!empty($key)) {
            /** @var SplFixedArray $k */
            $k = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($key);
            if ($k->count() > ParagonIE_Sodium_Core_BLAKE2b::KEYBYTES) {
                throw new RangeException('Invalid key size');
            }
        }

        /** @var SplFixedArray $in */
        $in = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($message);

        /** @var SplFixedArray $ctx */
        $ctx = ParagonIE_Sodium_Core_BLAKE2b::init($k, $outlen);
        ParagonIE_Sodium_Core_BLAKE2b::update($ctx, $in, $in->count());

        /** @var SplFixedArray $out */
        $out = new SplFixedArray($outlen);
        $out = ParagonIE_Sodium_Core_BLAKE2b::finish($ctx, $out);

        /** @var array<int, int> */
        $outArray = $out->toArray();
        return ParagonIE_Sodium_Core_Util::intArrayToString($outArray);
    }

    /**
     * Finalize a BLAKE2b hashing context, returning the hash.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $ctx
     * @param int $outlen
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function generichash_final($ctx, $outlen = 32)
    {
        if (!is_string($ctx)) {
            throw new TypeError('Context must be a string');
        }
        $out = new SplFixedArray($outlen);

        /** @var SplFixedArray $context */
        $context = ParagonIE_Sodium_Core_BLAKE2b::stringToContext($ctx);

        /** @var SplFixedArray $out */
        $out = ParagonIE_Sodium_Core_BLAKE2b::finish($context, $out);

        /** @var array<int, int> */
        $outArray = $out->toArray();
        return ParagonIE_Sodium_Core_Util::intArrayToString($outArray);
    }

    /**
     * Initialize a hashing context for BLAKE2b.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $key
     * @param int $outputLength
     * @return string
     * @throws RangeException
     * @throws SodiumException
     * @throws TypeError
     */
    public static function generichash_init($key = '', $outputLength = 32)
    {
        // This ensures that ParagonIE_Sodium_Core_BLAKE2b::$iv is initialized
        ParagonIE_Sodium_Core_BLAKE2b::pseudoConstructor();

        $k = null;
        if (!empty($key)) {
            $k = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($key);
            if ($k->count() > ParagonIE_Sodium_Core_BLAKE2b::KEYBYTES) {
                throw new RangeException('Invalid key size');
            }
        }

        /** @var SplFixedArray $ctx */
        $ctx = ParagonIE_Sodium_Core_BLAKE2b::init($k, $outputLength);

        return ParagonIE_Sodium_Core_BLAKE2b::contextToString($ctx);
    }

    /**
     * Initialize a hashing context for BLAKE2b.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $key
     * @param int $outputLength
     * @param string $salt
     * @param string $personal
     * @return string
     * @throws RangeException
     * @throws SodiumException
     * @throws TypeError
     */
    public static function generichash_init_salt_personal(
        $key = '',
        $outputLength = 32,
        $salt = '',
        $personal = ''
    ) {
        // This ensures that ParagonIE_Sodium_Core_BLAKE2b::$iv is initialized
        ParagonIE_Sodium_Core_BLAKE2b::pseudoConstructor();

        $k = null;
        if (!empty($key)) {
            $k = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($key);
            if ($k->count() > ParagonIE_Sodium_Core_BLAKE2b::KEYBYTES) {
                throw new RangeException('Invalid key size');
            }
        }
        if (!empty($salt)) {
            $s = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($salt);
        } else {
            $s = null;
        }
        if (!empty($salt)) {
            $p = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($personal);
        } else {
            $p = null;
        }

        /** @var SplFixedArray $ctx */
        $ctx = ParagonIE_Sodium_Core_BLAKE2b::init($k, $outputLength, $s, $p);

        return ParagonIE_Sodium_Core_BLAKE2b::contextToString($ctx);
    }

    /**
     * Update a hashing context for BLAKE2b with $message
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $ctx
     * @param string $message
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function generichash_update($ctx, $message)
    {
        // This ensures that ParagonIE_Sodium_Core_BLAKE2b::$iv is initialized
        ParagonIE_Sodium_Core_BLAKE2b::pseudoConstructor();

        /** @var SplFixedArray $context */
        $context = ParagonIE_Sodium_Core_BLAKE2b::stringToContext($ctx);

        /** @var SplFixedArray $in */
        $in = ParagonIE_Sodium_Core_BLAKE2b::stringToSplFixedArray($message);

        ParagonIE_Sodium_Core_BLAKE2b::update($context, $in, $in->count());

        return ParagonIE_Sodium_Core_BLAKE2b::contextToString($context);
    }

    /**
     * Libsodium's crypto_kx().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $my_sk
     * @param string $their_pk
     * @param string $client_pk
     * @param string $server_pk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function keyExchange($my_sk, $their_pk, $client_pk, $server_pk)
    {
        return ParagonIE_Sodium_Compat::crypto_generichash(
            ParagonIE_Sodium_Compat::crypto_scalarmult($my_sk, $their_pk) .
            $client_pk .
            $server_pk
        );
    }

    /**
     * ECDH over Curve25519
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $sKey
     * @param string $pKey
     * @return string
     *
     * @throws SodiumException
     * @throws TypeError
     */
    public static function scalarmult($sKey, $pKey)
    {
        $q = ParagonIE_Sodium_Core_X25519::crypto_scalarmult_curve25519_ref10($sKey, $pKey);
        self::scalarmult_throw_if_zero($q);
        return $q;
    }

    /**
     * ECDH over Curve25519, using the basepoint.
     * Used to get a secret key from a public key.
     *
     * @param string $secret
     * @return string
     *
     * @throws SodiumException
     * @throws TypeError
     */
    public static function scalarmult_base($secret)
    {
        $q = ParagonIE_Sodium_Core_X25519::crypto_scalarmult_curve25519_ref10_base($secret);
        self::scalarmult_throw_if_zero($q);
        return $q;
    }

    /**
     * This throws an Error if a zero public key was passed to the function.
     *
     * @param string $q
     * @return void
     * @throws SodiumException
     * @throws TypeError
     */
    protected static function scalarmult_throw_if_zero($q)
    {
        $d = 0;
        for ($i = 0; $i < self::box_curve25519xsalsa20poly1305_SECRETKEYBYTES; ++$i) {
            $d |= ParagonIE_Sodium_Core_Util::chrToInt($q[$i]);
        }

        /* branch-free variant of === 0 */
        if (-(1 & (($d - 1) >> 8))) {
            throw new SodiumException('Zero public key is not allowed');
        }
    }

    /**
     * XSalsa20-Poly1305 authenticated symmetric-key encryption.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $plaintext
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function secretbox($plaintext, $nonce, $key)
    {
        /** @var string $subkey */
        $subkey = ParagonIE_Sodium_Core_HSalsa20::hsalsa20($nonce, $key);

        /** @var string $block0 */
        $block0 = str_repeat("\x00", 32);

        /** @var int $mlen - Length of the plaintext message */
        $mlen = ParagonIE_Sodium_Core_Util::strlen($plaintext);
        $mlen0 = $mlen;
        if ($mlen0 > 64 - self::secretbox_xsalsa20poly1305_ZEROBYTES) {
            $mlen0 = 64 - self::secretbox_xsalsa20poly1305_ZEROBYTES;
        }
        $block0 .= ParagonIE_Sodium_Core_Util::substr($plaintext, 0, $mlen0);

        /** @var string $block0 */
        $block0 = ParagonIE_Sodium_Core_Salsa20::salsa20_xor(
            $block0,
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
            $subkey
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core_Util::substr(
            $block0,
            self::secretbox_xsalsa20poly1305_ZEROBYTES
        );
        if ($mlen > $mlen0) {
            $c .= ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
                ParagonIE_Sodium_Core_Util::substr(
                    $plaintext,
                    self::secretbox_xsalsa20poly1305_ZEROBYTES
                ),
                ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
                1,
                $subkey
            );
        }
        $state = new ParagonIE_Sodium_Core_Poly1305_State(
            ParagonIE_Sodium_Core_Util::substr(
                $block0,
                0,
                self::onetimeauth_poly1305_KEYBYTES
            )
        );
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
            ParagonIE_Sodium_Compat::memzero($subkey);
        } catch (SodiumException $ex) {
            $block0 = null;
            $subkey = null;
        }

        $state->update($c);

        /** @var string $c - MAC || ciphertext */
        $c = $state->finish() . $c;
        unset($state);

        return $c;
    }

    /**
     * Decrypt a ciphertext generated via secretbox().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $ciphertext
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function secretbox_open($ciphertext, $nonce, $key)
    {
        /** @var string $mac */
        $mac = ParagonIE_Sodium_Core_Util::substr(
            $ciphertext,
            0,
            self::secretbox_xsalsa20poly1305_MACBYTES
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core_Util::substr(
            $ciphertext,
            self::secretbox_xsalsa20poly1305_MACBYTES
        );

        /** @var int $clen */
        $clen = ParagonIE_Sodium_Core_Util::strlen($c);

        /** @var string $subkey */
        $subkey = ParagonIE_Sodium_Core_HSalsa20::hsalsa20($nonce, $key);

        /** @var string $block0 */
        $block0 = ParagonIE_Sodium_Core_Salsa20::salsa20(
            64,
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
            $subkey
        );
        $verified = ParagonIE_Sodium_Core_Poly1305::onetimeauth_verify(
            $mac,
            $c,
            ParagonIE_Sodium_Core_Util::substr($block0, 0, 32)
        );
        if (!$verified) {
            try {
                ParagonIE_Sodium_Compat::memzero($subkey);
            } catch (SodiumException $ex) {
                $subkey = null;
            }
            throw new SodiumException('Invalid MAC');
        }

        /** @var string $m - Decrypted message */
        $m = ParagonIE_Sodium_Core_Util::xorStrings(
            ParagonIE_Sodium_Core_Util::substr($block0, self::secretbox_xsalsa20poly1305_ZEROBYTES),
            ParagonIE_Sodium_Core_Util::substr($c, 0, self::secretbox_xsalsa20poly1305_ZEROBYTES)
        );
        if ($clen > self::secretbox_xsalsa20poly1305_ZEROBYTES) {
            // We had more than 1 block, so let's continue to decrypt the rest.
            $m .= ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
                ParagonIE_Sodium_Core_Util::substr(
                    $c,
                    self::secretbox_xsalsa20poly1305_ZEROBYTES
                ),
                ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
                1,
                (string) $subkey
            );
        }
        return $m;
    }

    /**
     * XChaCha20-Poly1305 authenticated symmetric-key encryption.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $plaintext
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function secretbox_xchacha20poly1305($plaintext, $nonce, $key)
    {
        /** @var string $subkey */
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hChaCha20(
            ParagonIE_Sodium_Core_Util::substr($nonce, 0, 16),
            $key
        );
        $nonceLast = ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8);

        /** @var string $block0 */
        $block0 = str_repeat("\x00", 32);

        /** @var int $mlen - Length of the plaintext message */
        $mlen = ParagonIE_Sodium_Core_Util::strlen($plaintext);
        $mlen0 = $mlen;
        if ($mlen0 > 64 - self::secretbox_xchacha20poly1305_ZEROBYTES) {
            $mlen0 = 64 - self::secretbox_xchacha20poly1305_ZEROBYTES;
        }
        $block0 .= ParagonIE_Sodium_Core_Util::substr($plaintext, 0, $mlen0);

        /** @var string $block0 */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::streamXorIc(
            $block0,
            $nonceLast,
            $subkey
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core_Util::substr(
            $block0,
            self::secretbox_xchacha20poly1305_ZEROBYTES
        );
        if ($mlen > $mlen0) {
            $c .= ParagonIE_Sodium_Core_ChaCha20::streamXorIc(
                ParagonIE_Sodium_Core_Util::substr(
                    $plaintext,
                    self::secretbox_xchacha20poly1305_ZEROBYTES
                ),
                $nonceLast,
                $subkey,
                ParagonIE_Sodium_Core_Util::store64_le(1)
            );
        }
        $state = new ParagonIE_Sodium_Core_Poly1305_State(
            ParagonIE_Sodium_Core_Util::substr(
                $block0,
                0,
                self::onetimeauth_poly1305_KEYBYTES
            )
        );
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
            ParagonIE_Sodium_Compat::memzero($subkey);
        } catch (SodiumException $ex) {
            $block0 = null;
            $subkey = null;
        }

        $state->update($c);

        /** @var string $c - MAC || ciphertext */
        $c = $state->finish() . $c;
        unset($state);

        return $c;
    }

    /**
     * Decrypt a ciphertext generated via secretbox_xchacha20poly1305().
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $ciphertext
     * @param string $nonce
     * @param string $key
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function secretbox_xchacha20poly1305_open($ciphertext, $nonce, $key)
    {
        /** @var string $mac */
        $mac = ParagonIE_Sodium_Core_Util::substr(
            $ciphertext,
            0,
            self::secretbox_xchacha20poly1305_MACBYTES
        );

        /** @var string $c */
        $c = ParagonIE_Sodium_Core_Util::substr(
            $ciphertext,
            self::secretbox_xchacha20poly1305_MACBYTES
        );

        /** @var int $clen */
        $clen = ParagonIE_Sodium_Core_Util::strlen($c);

        /** @var string $subkey */
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hchacha20($nonce, $key);

        /** @var string $block0 */
        $block0 = ParagonIE_Sodium_Core_ChaCha20::stream(
            64,
            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
            $subkey
        );
        $verified = ParagonIE_Sodium_Core_Poly1305::onetimeauth_verify(
            $mac,
            $c,
            ParagonIE_Sodium_Core_Util::substr($block0, 0, 32)
        );

        if (!$verified) {
            try {
                ParagonIE_Sodium_Compat::memzero($subkey);
            } catch (SodiumException $ex) {
                $subkey = null;
            }
            throw new SodiumException('Invalid MAC');
        }

        /** @var string $m - Decrypted message */
        $m = ParagonIE_Sodium_Core_Util::xorStrings(
            ParagonIE_Sodium_Core_Util::substr($block0, self::secretbox_xchacha20poly1305_ZEROBYTES),
            ParagonIE_Sodium_Core_Util::substr($c, 0, self::secretbox_xchacha20poly1305_ZEROBYTES)
        );

        if ($clen > self::secretbox_xchacha20poly1305_ZEROBYTES) {
            // We had more than 1 block, so let's continue to decrypt the rest.
            $m .= ParagonIE_Sodium_Core_ChaCha20::streamXorIc(
                ParagonIE_Sodium_Core_Util::substr(
                    $c,
                    self::secretbox_xchacha20poly1305_ZEROBYTES
                ),
                ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
                (string) $subkey,
                ParagonIE_Sodium_Core_Util::store64_le(1)
            );
        }
        return $m;
    }

    /**
     * @param string $key
     * @return array<int, string> Returns a state and a header.
     * @throws Exception
     * @throws SodiumException
     */
    public static function secretstream_xchacha20poly1305_init_push($key)
    {
        # randombytes_buf(out, crypto_secretstream_xchacha20poly1305_HEADERBYTES);
        $out = random_bytes(24);

        # crypto_core_hchacha20(state->k, out, k, NULL);
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hChaCha20($out, $key);
        $state = new ParagonIE_Sodium_Core_SecretStream_State(
            $subkey,
            ParagonIE_Sodium_Core_Util::substr($out, 16, 8) . str_repeat("\0", 4)
        );

        # _crypto_secretstream_xchacha20poly1305_counter_reset(state);
        $state->counterReset();

        # memcpy(STATE_INONCE(state), out + crypto_core_hchacha20_INPUTBYTES,
        #        crypto_secretstream_xchacha20poly1305_INONCEBYTES);
        # memset(state->_pad, 0, sizeof state->_pad);
        return array(
            $state->toString(),
            $out
        );
    }

    /**
     * @param string $key
     * @param string $header
     * @return string Returns a state.
     * @throws Exception
     */
    public static function secretstream_xchacha20poly1305_init_pull($key, $header)
    {
        # crypto_core_hchacha20(state->k, in, k, NULL);
        $subkey = ParagonIE_Sodium_Core_HChaCha20::hChaCha20(
            ParagonIE_Sodium_Core_Util::substr($header, 0, 16),
            $key
        );
        $state = new ParagonIE_Sodium_Core_SecretStream_State(
            $subkey,
            ParagonIE_Sodium_Core_Util::substr($header, 16)
        );
        $state->counterReset();
        # memcpy(STATE_INONCE(state), in + crypto_core_hchacha20_INPUTBYTES,
        #     crypto_secretstream_xchacha20poly1305_INONCEBYTES);
        # memset(state->_pad, 0, sizeof state->_pad);
        # return 0;
        return $state->toString();
    }

    /**
     * @param string $state
     * @param string $msg
     * @param string $aad
     * @param int $tag
     * @return string
     * @throws SodiumException
     */
    public static function secretstream_xchacha20poly1305_push(&$state, $msg, $aad = '', $tag = 0)
    {
        $st = ParagonIE_Sodium_Core_SecretStream_State::fromString($state);
        # crypto_onetimeauth_poly1305_state poly1305_state;
        # unsigned char                     block[64U];
        # unsigned char                     slen[8U];
        # unsigned char                    *c;
        # unsigned char                    *mac;

        $msglen = ParagonIE_Sodium_Core_Util::strlen($msg);
        $aadlen = ParagonIE_Sodium_Core_Util::strlen($aad);

        if ((($msglen + 63) >> 6) > 0xfffffffe) {
            throw new SodiumException(
                'message cannot be larger than SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_MESSAGEBYTES_MAX bytes'
            );
        }

        # if (outlen_p != NULL) {
        #     *outlen_p = 0U;
        # }
        # if (mlen > crypto_secretstream_xchacha20poly1305_MESSAGEBYTES_MAX) {
        #     sodium_misuse();
        # }

        # crypto_stream_chacha20_ietf(block, sizeof block, state->nonce, state->k);
        # crypto_onetimeauth_poly1305_init(&poly1305_state, block);
        # sodium_memzero(block, sizeof block);
        $auth = new ParagonIE_Sodium_Core_Poly1305_State(
            ParagonIE_Sodium_Core_ChaCha20::ietfStream(32, $st->getCombinedNonce(), $st->getKey())
        );

        # crypto_onetimeauth_poly1305_update(&poly1305_state, ad, adlen);
        $auth->update($aad);

        # crypto_onetimeauth_poly1305_update(&poly1305_state, _pad0,
        #     (0x10 - adlen) & 0xf);
        $auth->update(str_repeat("\0", ((0x10 - $aadlen) & 0xf)));

        # memset(block, 0, sizeof block);
        # block[0] = tag;
        # crypto_stream_chacha20_ietf_xor_ic(block, block, sizeof block,
        #                                    state->nonce, 1U, state->k);
        $block = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            ParagonIE_Sodium_Core_Util::intToChr($tag) . str_repeat("\0", 63),
            $st->getCombinedNonce(),
            $st->getKey(),
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );

        # crypto_onetimeauth_poly1305_update(&poly1305_state, block, sizeof block);
        $auth->update($block);

        # out[0] = block[0];
        $out = $block[0];
        # c = out + (sizeof tag);
        # crypto_stream_chacha20_ietf_xor_ic(c, m, mlen, state->nonce, 2U, state->k);
        $cipher = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $msg,
            $st->getCombinedNonce(),
            $st->getKey(),
            ParagonIE_Sodium_Core_Util::store64_le(2)
        );

        # crypto_onetimeauth_poly1305_update(&poly1305_state, c, mlen);
        $auth->update($cipher);

        $out .= $cipher;
        unset($cipher);

        # crypto_onetimeauth_poly1305_update
        # (&poly1305_state, _pad0, (0x10 - (sizeof block) + mlen) & 0xf);
        $auth->update(str_repeat("\0", ((0x10 - 64 + $msglen) & 0xf)));

        # STORE64_LE(slen, (uint64_t) adlen);
        $slen = ParagonIE_Sodium_Core_Util::store64_le($aadlen);

        # crypto_onetimeauth_poly1305_update(&poly1305_state, slen, sizeof slen);
        $auth->update($slen);

        # STORE64_LE(slen, (sizeof block) + mlen);
        $slen = ParagonIE_Sodium_Core_Util::store64_le(64 + $msglen);

        # crypto_onetimeauth_poly1305_update(&poly1305_state, slen, sizeof slen);
        $auth->update($slen);

        # mac = c + mlen;
        # crypto_onetimeauth_poly1305_final(&poly1305_state, mac);
        $mac = $auth->finish();
        $out .= $mac;

        # sodium_memzero(&poly1305_state, sizeof poly1305_state);
        unset($auth);


        # XOR_BUF(STATE_INONCE(state), mac,
        #     crypto_secretstream_xchacha20poly1305_INONCEBYTES);
        $st->xorNonce($mac);

        # sodium_increment(STATE_COUNTER(state),
        #     crypto_secretstream_xchacha20poly1305_COUNTERBYTES);
        $st->incrementCounter();
        // Overwrite by reference:
        $state = $st->toString();

        /** @var bool $rekey */
        $rekey = ($tag & ParagonIE_Sodium_Compat::CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_REKEY) !== 0;
        # if ((tag & crypto_secretstream_xchacha20poly1305_TAG_REKEY) != 0 ||
        #     sodium_is_zero(STATE_COUNTER(state),
        #         crypto_secretstream_xchacha20poly1305_COUNTERBYTES)) {
        #     crypto_secretstream_xchacha20poly1305_rekey(state);
        # }
        if ($rekey || $st->needsRekey()) {
            // DO REKEY
            self::secretstream_xchacha20poly1305_rekey($state);
        }
        # if (outlen_p != NULL) {
        #     *outlen_p = crypto_secretstream_xchacha20poly1305_ABYTES + mlen;
        # }
        return $out;
    }

    /**
     * @param string $state
     * @param string $cipher
     * @param string $aad
     * @return bool|array{0: string, 1: int}
     * @throws SodiumException
     */
    public static function secretstream_xchacha20poly1305_pull(&$state, $cipher, $aad = '')
    {
        $st = ParagonIE_Sodium_Core_SecretStream_State::fromString($state);

        $cipherlen = ParagonIE_Sodium_Core_Util::strlen($cipher);
        #     mlen = inlen - crypto_secretstream_xchacha20poly1305_ABYTES;
        $msglen = $cipherlen - ParagonIE_Sodium_Compat::CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_ABYTES;
        $aadlen = ParagonIE_Sodium_Core_Util::strlen($aad);

        #     if (mlen > crypto_secretstream_xchacha20poly1305_MESSAGEBYTES_MAX) {
        #         sodium_misuse();
        #     }
        if ((($msglen + 63) >> 6) > 0xfffffffe) {
            throw new SodiumException(
                'message cannot be larger than SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_MESSAGEBYTES_MAX bytes'
            );
        }

        #     crypto_stream_chacha20_ietf(block, sizeof block, state->nonce, state->k);
        #     crypto_onetimeauth_poly1305_init(&poly1305_state, block);
        #     sodium_memzero(block, sizeof block);
        $auth = new ParagonIE_Sodium_Core_Poly1305_State(
            ParagonIE_Sodium_Core_ChaCha20::ietfStream(32, $st->getCombinedNonce(), $st->getKey())
        );

        #     crypto_onetimeauth_poly1305_update(&poly1305_state, ad, adlen);
        $auth->update($aad);

        #     crypto_onetimeauth_poly1305_update(&poly1305_state, _pad0,
        #         (0x10 - adlen) & 0xf);
        $auth->update(str_repeat("\0", ((0x10 - $aadlen) & 0xf)));


        #     memset(block, 0, sizeof block);
        #     block[0] = in[0];
        #     crypto_stream_chacha20_ietf_xor_ic(block, block, sizeof block,
        #                                        state->nonce, 1U, state->k);
        $block = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $cipher[0] . str_repeat("\0", 63),
            $st->getCombinedNonce(),
            $st->getKey(),
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );
        #     tag = block[0];
        #     block[0] = in[0];
        #     crypto_onetimeauth_poly1305_update(&poly1305_state, block, sizeof block);
        $tag = ParagonIE_Sodium_Core_Util::chrToInt($block[0]);
        $block[0] = $cipher[0];
        $auth->update($block);


        #     c = in + (sizeof tag);
        #     crypto_onetimeauth_poly1305_update(&poly1305_state, c, mlen);
        $auth->update(ParagonIE_Sodium_Core_Util::substr($cipher, 1, $msglen));

        #     crypto_onetimeauth_poly1305_update
        #     (&poly1305_state, _pad0, (0x10 - (sizeof block) + mlen) & 0xf);
        $auth->update(str_repeat("\0", ((0x10 - 64 + $msglen) & 0xf)));

        #     STORE64_LE(slen, (uint64_t) adlen);
        #     crypto_onetimeauth_poly1305_update(&poly1305_state, slen, sizeof slen);
        $slen = ParagonIE_Sodium_Core_Util::store64_le($aadlen);
        $auth->update($slen);

        #     STORE64_LE(slen, (sizeof block) + mlen);
        #     crypto_onetimeauth_poly1305_update(&poly1305_state, slen, sizeof slen);
        $slen = ParagonIE_Sodium_Core_Util::store64_le(64 + $msglen);
        $auth->update($slen);

        #     crypto_onetimeauth_poly1305_final(&poly1305_state, mac);
        #     sodium_memzero(&poly1305_state, sizeof poly1305_state);
        $mac = $auth->finish();

        #     stored_mac = c + mlen;
        #     if (sodium_memcmp(mac, stored_mac, sizeof mac) != 0) {
        #     sodium_memzero(mac, sizeof mac);
        #         return -1;
        #     }

        $stored = ParagonIE_Sodium_Core_Util::substr($cipher, $msglen + 1, 16);
        if (!ParagonIE_Sodium_Core_Util::hashEquals($mac, $stored)) {
            return false;
        }

        #     crypto_stream_chacha20_ietf_xor_ic(m, c, mlen, state->nonce, 2U, state->k);
        $out = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            ParagonIE_Sodium_Core_Util::substr($cipher, 1, $msglen),
            $st->getCombinedNonce(),
            $st->getKey(),
            ParagonIE_Sodium_Core_Util::store64_le(2)
        );

        #     XOR_BUF(STATE_INONCE(state), mac,
        #         crypto_secretstream_xchacha20poly1305_INONCEBYTES);
        $st->xorNonce($mac);

        #     sodium_increment(STATE_COUNTER(state),
        #         crypto_secretstream_xchacha20poly1305_COUNTERBYTES);
        $st->incrementCounter();

        #     if ((tag & crypto_secretstream_xchacha20poly1305_TAG_REKEY) != 0 ||
        #         sodium_is_zero(STATE_COUNTER(state),
        #             crypto_secretstream_xchacha20poly1305_COUNTERBYTES)) {
        #         crypto_secretstream_xchacha20poly1305_rekey(state);
        #     }

        // Overwrite by reference:
        $state = $st->toString();

        /** @var bool $rekey */
        $rekey = ($tag & ParagonIE_Sodium_Compat::CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_REKEY) !== 0;
        if ($rekey || $st->needsRekey()) {
            // DO REKEY
            self::secretstream_xchacha20poly1305_rekey($state);
        }
        return array($out, $tag);
    }

    /**
     * @param string $state
     * @return void
     * @throws SodiumException
     */
    public static function secretstream_xchacha20poly1305_rekey(&$state)
    {
        $st = ParagonIE_Sodium_Core_SecretStream_State::fromString($state);
        # unsigned char new_key_and_inonce[crypto_stream_chacha20_ietf_KEYBYTES +
        # crypto_secretstream_xchacha20poly1305_INONCEBYTES];
        # size_t        i;
        # for (i = 0U; i < crypto_stream_chacha20_ietf_KEYBYTES; i++) {
        #     new_key_and_inonce[i] = state->k[i];
        # }
        $new_key_and_inonce = $st->getKey();

        # for (i = 0U; i < crypto_secretstream_xchacha20poly1305_INONCEBYTES; i++) {
        #     new_key_and_inonce[crypto_stream_chacha20_ietf_KEYBYTES + i] =
        #         STATE_INONCE(state)[i];
        # }
        $new_key_and_inonce .= ParagonIE_Sodium_Core_Util::substR($st->getNonce(), 0, 8);

        # crypto_stream_chacha20_ietf_xor(new_key_and_inonce, new_key_and_inonce,
        #                                 sizeof new_key_and_inonce,
        #                                 state->nonce, state->k);

        $st->rekey(ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $new_key_and_inonce,
            $st->getCombinedNonce(),
            $st->getKey(),
            ParagonIE_Sodium_Core_Util::store64_le(0)
        ));

        # for (i = 0U; i < crypto_stream_chacha20_ietf_KEYBYTES; i++) {
        #     state->k[i] = new_key_and_inonce[i];
        # }
        # for (i = 0U; i < crypto_secretstream_xchacha20poly1305_INONCEBYTES; i++) {
        #     STATE_INONCE(state)[i] =
        #          new_key_and_inonce[crypto_stream_chacha20_ietf_KEYBYTES + i];
        # }
        # _crypto_secretstream_xchacha20poly1305_counter_reset(state);
        $st->counterReset();

        $state = $st->toString();
    }

    /**
     * Detached Ed25519 signature.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $sk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function sign_detached($message, $sk)
    {
        return ParagonIE_Sodium_Core_Ed25519::sign_detached($message, $sk);
    }

    /**
     * Attached Ed25519 signature. (Returns a signed message.)
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $message
     * @param string $sk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function sign($message, $sk)
    {
        return ParagonIE_Sodium_Core_Ed25519::sign($message, $sk);
    }

    /**
     * Opens a signed message. If valid, returns the message.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $signedMessage
     * @param string $pk
     * @return string
     * @throws SodiumException
     * @throws TypeError
     */
    public static function sign_open($signedMessage, $pk)
    {
        return ParagonIE_Sodium_Core_Ed25519::sign_open($signedMessage, $pk);
    }

    /**
     * Verify a detached signature of a given message and public key.
     *
     * @internal Do not use this directly. Use ParagonIE_Sodium_Compat.
     *
     * @param string $signature
     * @param string $message
     * @param string $pk
     * @return bool
     * @throws SodiumException
     * @throws TypeError
     */
    public static function sign_verify_detached($signature, $message, $pk)
    {
        return ParagonIE_Sodium_Core_Ed25519::verify_detached($signature, $message, $pk);
    }
}