diff -r c7c34916027a -r 177826044cd9 wp/wp-includes/sodium_compat/src/File.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/sodium_compat/src/File.php	Mon Oct 14 18:28:13 2019 +0200
@@ -0,0 +1,1543 @@
+<?php
+
+if (class_exists('ParagonIE_Sodium_File', false)) {
+    return;
+}
+/**
+ * Class ParagonIE_Sodium_File
+ */
+class ParagonIE_Sodium_File extends ParagonIE_Sodium_Core_Util
+{
+    /* PHP's default buffer size is 8192 for fread()/fwrite(). */
+    const BUFFER_SIZE = 8192;
+
+    /**
+     * Box a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_box(), but produces
+     * the same result.
+     *
+     * @param string $inputFile  Absolute path to a file on the filesystem
+     * @param string $outputFile Absolute path to a file on the filesystem
+     * @param string $nonce      Number to be used only once
+     * @param string $keyPair    ECDH secret key and ECDH public key concatenated
+     *
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function box($inputFile, $outputFile, $nonce, $keyPair)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given.');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($nonce)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($nonce) . ' given.');
+        }
+
+        /* Input validation: */
+        if (!is_string($keyPair)) {
+            throw new TypeError('Argument 4 must be a string, ' . gettype($keyPair) . ' given.');
+        }
+        if (self::strlen($nonce) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_NONCEBYTES) {
+            throw new TypeError('Argument 3 must be CRYPTO_BOX_NONCEBYTES bytes');
+        }
+        if (self::strlen($keyPair) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_BOX_KEYPAIRBYTES bytes');
+        }
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        $res = self::box_encrypt($ifp, $ofp, $size, $nonce, $keyPair);
+        fclose($ifp);
+        fclose($ofp);
+        return $res;
+    }
+
+    /**
+     * Open a boxed file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_box_open(), but produces
+     * the same result.
+     *
+     * Warning: Does not protect against TOCTOU attacks. You should
+     * just load the file into memory and use crypto_box_open() if
+     * you are worried about those.
+     *
+     * @param string $inputFile
+     * @param string $outputFile
+     * @param string $nonce
+     * @param string $keypair
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function box_open($inputFile, $outputFile, $nonce, $keypair)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given.');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($nonce)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($nonce) . ' given.');
+        }
+        if (!is_string($keypair)) {
+            throw new TypeError('Argument 4 must be a string, ' . gettype($keypair) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($nonce) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_NONCEBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_BOX_NONCEBYTES bytes');
+        }
+        if (self::strlen($keypair) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_BOX_KEYPAIRBYTES bytes');
+        }
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        $res = self::box_decrypt($ifp, $ofp, $size, $nonce, $keypair);
+        fclose($ifp);
+        fclose($ofp);
+        try {
+            ParagonIE_Sodium_Compat::memzero($nonce);
+            ParagonIE_Sodium_Compat::memzero($ephKeypair);
+        } catch (SodiumException $ex) {
+            unset($ephKeypair);
+        }
+        return $res;
+    }
+
+    /**
+     * Seal a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_box_seal(), but produces
+     * the same result.
+     *
+     * @param string $inputFile  Absolute path to a file on the filesystem
+     * @param string $outputFile Absolute path to a file on the filesystem
+     * @param string $publicKey  ECDH public key
+     *
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function box_seal($inputFile, $outputFile, $publicKey)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given.');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($publicKey)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($publicKey) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($publicKey) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_PUBLICKEYBYTES) {
+            throw new TypeError('Argument 3 must be CRYPTO_BOX_PUBLICKEYBYTES bytes');
+        }
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        /** @var string $ephKeypair */
+        $ephKeypair = ParagonIE_Sodium_Compat::crypto_box_keypair();
+
+        /** @var string $msgKeypair */
+        $msgKeypair = ParagonIE_Sodium_Compat::crypto_box_keypair_from_secretkey_and_publickey(
+            ParagonIE_Sodium_Compat::crypto_box_secretkey($ephKeypair),
+            $publicKey
+        );
+
+        /** @var string $ephemeralPK */
+        $ephemeralPK = ParagonIE_Sodium_Compat::crypto_box_publickey($ephKeypair);
+
+        /** @var string $nonce */
+        $nonce = ParagonIE_Sodium_Compat::crypto_generichash(
+            $ephemeralPK . $publicKey,
+            '',
+            24
+        );
+
+        /** @var int $firstWrite */
+        $firstWrite = fwrite(
+            $ofp,
+            $ephemeralPK,
+            ParagonIE_Sodium_Compat::CRYPTO_BOX_PUBLICKEYBYTES
+        );
+        if (!is_int($firstWrite)) {
+            fclose($ifp);
+            fclose($ofp);
+            ParagonIE_Sodium_Compat::memzero($ephKeypair);
+            throw new SodiumException('Could not write to output file');
+        }
+        if ($firstWrite !== ParagonIE_Sodium_Compat::CRYPTO_BOX_PUBLICKEYBYTES) {
+            ParagonIE_Sodium_Compat::memzero($ephKeypair);
+            fclose($ifp);
+            fclose($ofp);
+            throw new SodiumException('Error writing public key to output file');
+        }
+
+        $res = self::box_encrypt($ifp, $ofp, $size, $nonce, $msgKeypair);
+        fclose($ifp);
+        fclose($ofp);
+        try {
+            ParagonIE_Sodium_Compat::memzero($nonce);
+            ParagonIE_Sodium_Compat::memzero($ephKeypair);
+        } catch (SodiumException $ex) {
+            unset($ephKeypair);
+        }
+        return $res;
+    }
+
+    /**
+     * Open a sealed file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_box_seal_open(), but produces
+     * the same result.
+     *
+     * Warning: Does not protect against TOCTOU attacks. You should
+     * just load the file into memory and use crypto_box_seal_open() if
+     * you are worried about those.
+     *
+     * @param string $inputFile
+     * @param string $outputFile
+     * @param string $ecdhKeypair
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function box_seal_open($inputFile, $outputFile, $ecdhKeypair)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given.');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($ecdhKeypair)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($ecdhKeypair) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($ecdhKeypair) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_KEYPAIRBYTES) {
+            throw new TypeError('Argument 3 must be CRYPTO_BOX_KEYPAIRBYTES bytes');
+        }
+
+        $publicKey = ParagonIE_Sodium_Compat::crypto_box_publickey($ecdhKeypair);
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        $ephemeralPK = fread($ifp, ParagonIE_Sodium_Compat::CRYPTO_BOX_PUBLICKEYBYTES);
+        if (!is_string($ephemeralPK)) {
+            throw new SodiumException('Could not read input file');
+        }
+        if (self::strlen($ephemeralPK) !== ParagonIE_Sodium_Compat::CRYPTO_BOX_PUBLICKEYBYTES) {
+            fclose($ifp);
+            fclose($ofp);
+            throw new SodiumException('Could not read public key from sealed file');
+        }
+
+        $nonce = ParagonIE_Sodium_Compat::crypto_generichash(
+            $ephemeralPK . $publicKey,
+            '',
+            24
+        );
+        $msgKeypair = ParagonIE_Sodium_Compat::crypto_box_keypair_from_secretkey_and_publickey(
+            ParagonIE_Sodium_Compat::crypto_box_secretkey($ecdhKeypair),
+            $ephemeralPK
+        );
+
+        $res = self::box_decrypt($ifp, $ofp, $size, $nonce, $msgKeypair);
+        fclose($ifp);
+        fclose($ofp);
+        try {
+            ParagonIE_Sodium_Compat::memzero($nonce);
+            ParagonIE_Sodium_Compat::memzero($ephKeypair);
+        } catch (SodiumException $ex) {
+            unset($ephKeypair);
+        }
+        return $res;
+    }
+
+    /**
+     * Calculate the BLAKE2b hash of a file.
+     *
+     * @param string      $filePath     Absolute path to a file on the filesystem
+     * @param string|null $key          BLAKE2b key
+     * @param int         $outputLength Length of hash output
+     *
+     * @return string                   BLAKE2b hash
+     * @throws SodiumException
+     * @throws TypeError
+     * @psalm-suppress FailedTypeResolution
+     */
+    public static function generichash($filePath, $key = '', $outputLength = 32)
+    {
+        /* Type checks: */
+        if (!is_string($filePath)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($filePath) . ' given.');
+        }
+        if (!is_string($key)) {
+            if (is_null($key)) {
+                $key = '';
+            } else {
+                throw new TypeError('Argument 2 must be a string, ' . gettype($key) . ' given.');
+            }
+        }
+        if (!is_int($outputLength)) {
+            if (!is_numeric($outputLength)) {
+                throw new TypeError('Argument 3 must be an integer, ' . gettype($outputLength) . ' given.');
+            }
+            $outputLength = (int) $outputLength;
+        }
+
+        /* Input validation: */
+        if (!empty($key)) {
+            if (self::strlen($key) < ParagonIE_Sodium_Compat::CRYPTO_GENERICHASH_KEYBYTES_MIN) {
+                throw new TypeError('Argument 2 must be at least CRYPTO_GENERICHASH_KEYBYTES_MIN bytes');
+            }
+            if (self::strlen($key) > ParagonIE_Sodium_Compat::CRYPTO_GENERICHASH_KEYBYTES_MAX) {
+                throw new TypeError('Argument 2 must be at most CRYPTO_GENERICHASH_KEYBYTES_MAX bytes');
+            }
+        }
+        if ($outputLength < ParagonIE_Sodium_Compat::CRYPTO_GENERICHASH_BYTES_MIN) {
+            throw new SodiumException('Argument 3 must be at least CRYPTO_GENERICHASH_BYTES_MIN');
+        }
+        if ($outputLength > ParagonIE_Sodium_Compat::CRYPTO_GENERICHASH_BYTES_MAX) {
+            throw new SodiumException('Argument 3 must be at least CRYPTO_GENERICHASH_BYTES_MAX');
+        }
+
+        /** @var int $size */
+        $size = filesize($filePath);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $fp */
+        $fp = fopen($filePath, 'rb');
+        if (!is_resource($fp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+        $ctx = ParagonIE_Sodium_Compat::crypto_generichash_init($key, $outputLength);
+        while ($size > 0) {
+            $blockSize = $size > 64
+                ? 64
+                : $size;
+            $read = fread($fp, $blockSize);
+            if (!is_string($read)) {
+                throw new SodiumException('Could not read input file');
+            }
+            ParagonIE_Sodium_Compat::crypto_generichash_update($ctx, $read);
+            $size -= $blockSize;
+        }
+
+        fclose($fp);
+        return ParagonIE_Sodium_Compat::crypto_generichash_final($ctx, $outputLength);
+    }
+
+    /**
+     * Encrypt a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_secretbox(), but produces
+     * the same result.
+     *
+     * @param string $inputFile  Absolute path to a file on the filesystem
+     * @param string $outputFile Absolute path to a file on the filesystem
+     * @param string $nonce      Number to be used only once
+     * @param string $key        Encryption key
+     *
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function secretbox($inputFile, $outputFile, $nonce, $key)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given..');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($nonce)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($nonce) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($nonce) !== ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_NONCEBYTES) {
+            throw new TypeError('Argument 3 must be CRYPTO_SECRETBOX_NONCEBYTES bytes');
+        }
+        if (!is_string($key)) {
+            throw new TypeError('Argument 4 must be a string, ' . gettype($key) . ' given.');
+        }
+        if (self::strlen($key) !== ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_KEYBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_SECRETBOX_KEYBYTES bytes');
+        }
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        $res = self::secretbox_encrypt($ifp, $ofp, $size, $nonce, $key);
+        fclose($ifp);
+        fclose($ofp);
+        return $res;
+    }
+    /**
+     * Seal a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_secretbox_open(), but produces
+     * the same result.
+     *
+     * Warning: Does not protect against TOCTOU attacks. You should
+     * just load the file into memory and use crypto_secretbox_open() if
+     * you are worried about those.
+     *
+     * @param string $inputFile
+     * @param string $outputFile
+     * @param string $nonce
+     * @param string $key
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function secretbox_open($inputFile, $outputFile, $nonce, $key)
+    {
+        /* Type checks: */
+        if (!is_string($inputFile)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($inputFile) . ' given.');
+        }
+        if (!is_string($outputFile)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($outputFile) . ' given.');
+        }
+        if (!is_string($nonce)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($nonce) . ' given.');
+        }
+        if (!is_string($key)) {
+            throw new TypeError('Argument 4 must be a string, ' . gettype($key) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($nonce) !== ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_NONCEBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_SECRETBOX_NONCEBYTES bytes');
+        }
+        if (self::strlen($key) !== ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_KEYBYTES) {
+            throw new TypeError('Argument 4 must be CRYPTO_SECRETBOXBOX_KEYBYTES bytes');
+        }
+
+        /** @var int $size */
+        $size = filesize($inputFile);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $ifp */
+        $ifp = fopen($inputFile, 'rb');
+        if (!is_resource($ifp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var resource $ofp */
+        $ofp = fopen($outputFile, 'wb');
+        if (!is_resource($ofp)) {
+            fclose($ifp);
+            throw new SodiumException('Could not open output file for writing');
+        }
+
+        $res = self::secretbox_decrypt($ifp, $ofp, $size, $nonce, $key);
+        fclose($ifp);
+        fclose($ofp);
+        try {
+            ParagonIE_Sodium_Compat::memzero($key);
+        } catch (SodiumException $ex) {
+            unset($key);
+        }
+        return $res;
+    }
+
+    /**
+     * Sign a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_sign_detached(), but produces
+     * the same result.
+     *
+     * @param string $filePath  Absolute path to a file on the filesystem
+     * @param string $secretKey Secret signing key
+     *
+     * @return string           Ed25519 signature
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    public static function sign($filePath, $secretKey)
+    {
+        /* Type checks: */
+        if (!is_string($filePath)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($filePath) . ' given.');
+        }
+        if (!is_string($secretKey)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($secretKey) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($secretKey) !== ParagonIE_Sodium_Compat::CRYPTO_SIGN_SECRETKEYBYTES) {
+            throw new TypeError('Argument 2 must be CRYPTO_SIGN_SECRETKEYBYTES bytes');
+        }
+        if (PHP_INT_SIZE === 4) {
+            return self::sign_core32($filePath, $secretKey);
+        }
+
+        /** @var int $size */
+        $size = filesize($filePath);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $fp */
+        $fp = fopen($filePath, 'rb');
+        if (!is_resource($fp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var string $az */
+        $az = hash('sha512', self::substr($secretKey, 0, 32), true);
+
+        $az[0] = self::intToChr(self::chrToInt($az[0]) & 248);
+        $az[31] = self::intToChr((self::chrToInt($az[31]) & 63) | 64);
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($az, 32, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+
+        /** @var string $nonceHash */
+        $nonceHash = hash_final($hs, true);
+
+        /** @var string $pk */
+        $pk = self::substr($secretKey, 32, 32);
+
+        /** @var string $nonce */
+        $nonce = ParagonIE_Sodium_Core_Ed25519::sc_reduce($nonceHash) . self::substr($nonceHash, 32);
+
+        /** @var string $sig */
+        $sig = ParagonIE_Sodium_Core_Ed25519::ge_p3_tobytes(
+            ParagonIE_Sodium_Core_Ed25519::ge_scalarmult_base($nonce)
+        );
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($sig, 0, 32));
+        hash_update($hs, self::substr($pk, 0, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+
+        /** @var string $hramHash */
+        $hramHash = hash_final($hs, true);
+
+        /** @var string $hram */
+        $hram = ParagonIE_Sodium_Core_Ed25519::sc_reduce($hramHash);
+
+        /** @var string $sigAfter */
+        $sigAfter = ParagonIE_Sodium_Core_Ed25519::sc_muladd($hram, $az, $nonce);
+
+        /** @var string $sig */
+        $sig = self::substr($sig, 0, 32) . self::substr($sigAfter, 0, 32);
+
+        try {
+            ParagonIE_Sodium_Compat::memzero($az);
+        } catch (SodiumException $ex) {
+            $az = null;
+        }
+        fclose($fp);
+        return $sig;
+    }
+
+    /**
+     * Verify a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_sign_verify_detached(), but
+     * produces the same result.
+     *
+     * @param string $sig       Ed25519 signature
+     * @param string $filePath  Absolute path to a file on the filesystem
+     * @param string $publicKey Signing public key
+     *
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     * @throws Exception
+     */
+    public static function verify($sig, $filePath, $publicKey)
+    {
+        /* Type checks: */
+        if (!is_string($sig)) {
+            throw new TypeError('Argument 1 must be a string, ' . gettype($sig) . ' given.');
+        }
+        if (!is_string($filePath)) {
+            throw new TypeError('Argument 2 must be a string, ' . gettype($filePath) . ' given.');
+        }
+        if (!is_string($publicKey)) {
+            throw new TypeError('Argument 3 must be a string, ' . gettype($publicKey) . ' given.');
+        }
+
+        /* Input validation: */
+        if (self::strlen($sig) !== ParagonIE_Sodium_Compat::CRYPTO_SIGN_BYTES) {
+            throw new TypeError('Argument 1 must be CRYPTO_SIGN_BYTES bytes');
+        }
+        if (self::strlen($publicKey) !== ParagonIE_Sodium_Compat::CRYPTO_SIGN_PUBLICKEYBYTES) {
+            throw new TypeError('Argument 3 must be CRYPTO_SIGN_PUBLICKEYBYTES bytes');
+        }
+        if (self::strlen($sig) < 64) {
+            throw new SodiumException('Signature is too short');
+        }
+
+        if (PHP_INT_SIZE === 4) {
+            return self::verify_core32($sig, $filePath, $publicKey);
+        }
+
+        /* Security checks */
+        if (ParagonIE_Sodium_Core_Ed25519::check_S_lt_L(self::substr($sig, 32, 32))) {
+            throw new SodiumException('S < L - Invalid signature');
+        }
+        if (ParagonIE_Sodium_Core_Ed25519::small_order($sig)) {
+            throw new SodiumException('Signature is on too small of an order');
+        }
+        if ((self::chrToInt($sig[63]) & 224) !== 0) {
+            throw new SodiumException('Invalid signature');
+        }
+        $d = 0;
+        for ($i = 0; $i < 32; ++$i) {
+            $d |= self::chrToInt($publicKey[$i]);
+        }
+        if ($d === 0) {
+            throw new SodiumException('All zero public key');
+        }
+
+        /** @var int $size */
+        $size = filesize($filePath);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+
+        /** @var resource $fp */
+        $fp = fopen($filePath, 'rb');
+        if (!is_resource($fp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+
+        /** @var bool The original value of ParagonIE_Sodium_Compat::$fastMult */
+        $orig = ParagonIE_Sodium_Compat::$fastMult;
+
+        // Set ParagonIE_Sodium_Compat::$fastMult to true to speed up verification.
+        ParagonIE_Sodium_Compat::$fastMult = true;
+
+        /** @var ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A */
+        $A = ParagonIE_Sodium_Core_Ed25519::ge_frombytes_negate_vartime($publicKey);
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($sig, 0, 32));
+        hash_update($hs, self::substr($publicKey, 0, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+        /** @var string $hDigest */
+        $hDigest = hash_final($hs, true);
+
+        /** @var string $h */
+        $h = ParagonIE_Sodium_Core_Ed25519::sc_reduce($hDigest) . self::substr($hDigest, 32);
+
+        /** @var ParagonIE_Sodium_Core_Curve25519_Ge_P2 $R */
+        $R = ParagonIE_Sodium_Core_Ed25519::ge_double_scalarmult_vartime(
+            $h,
+            $A,
+            self::substr($sig, 32)
+        );
+
+        /** @var string $rcheck */
+        $rcheck = ParagonIE_Sodium_Core_Ed25519::ge_tobytes($R);
+
+        // Close the file handle
+        fclose($fp);
+
+        // Reset ParagonIE_Sodium_Compat::$fastMult to what it was before.
+        ParagonIE_Sodium_Compat::$fastMult = $orig;
+        return self::verify_32($rcheck, self::substr($sig, 0, 32));
+    }
+
+    /**
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int      $mlen
+     * @param string   $nonce
+     * @param string   $boxKeypair
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function box_encrypt($ifp, $ofp, $mlen, $nonce, $boxKeypair)
+    {
+        if (PHP_INT_SIZE === 4) {
+            return self::secretbox_encrypt(
+                $ifp,
+                $ofp,
+                $mlen,
+                $nonce,
+                ParagonIE_Sodium_Crypto32::box_beforenm(
+                    ParagonIE_Sodium_Crypto32::box_secretkey($boxKeypair),
+                    ParagonIE_Sodium_Crypto32::box_publickey($boxKeypair)
+                )
+            );
+        }
+        return self::secretbox_encrypt(
+            $ifp,
+            $ofp,
+            $mlen,
+            $nonce,
+            ParagonIE_Sodium_Crypto::box_beforenm(
+                ParagonIE_Sodium_Crypto::box_secretkey($boxKeypair),
+                ParagonIE_Sodium_Crypto::box_publickey($boxKeypair)
+            )
+        );
+    }
+
+
+    /**
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int      $mlen
+     * @param string   $nonce
+     * @param string   $boxKeypair
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function box_decrypt($ifp, $ofp, $mlen, $nonce, $boxKeypair)
+    {
+        if (PHP_INT_SIZE === 4) {
+            return self::secretbox_decrypt(
+                $ifp,
+                $ofp,
+                $mlen,
+                $nonce,
+                ParagonIE_Sodium_Crypto32::box_beforenm(
+                    ParagonIE_Sodium_Crypto32::box_secretkey($boxKeypair),
+                    ParagonIE_Sodium_Crypto32::box_publickey($boxKeypair)
+                )
+            );
+        }
+        return self::secretbox_decrypt(
+            $ifp,
+            $ofp,
+            $mlen,
+            $nonce,
+            ParagonIE_Sodium_Crypto::box_beforenm(
+                ParagonIE_Sodium_Crypto::box_secretkey($boxKeypair),
+                ParagonIE_Sodium_Crypto::box_publickey($boxKeypair)
+            )
+        );
+    }
+
+    /**
+     * Encrypt a file
+     *
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int $mlen
+     * @param string $nonce
+     * @param string $key
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function secretbox_encrypt($ifp, $ofp, $mlen, $nonce, $key)
+    {
+        if (PHP_INT_SIZE === 4) {
+            return self::secretbox_encrypt_core32($ifp, $ofp, $mlen, $nonce, $key);
+        }
+
+        $plaintext = fread($ifp, 32);
+        if (!is_string($plaintext)) {
+            throw new SodiumException('Could not read input file');
+        }
+        $first32 = ftell($ifp);
+
+        /** @var string $subkey */
+        $subkey = ParagonIE_Sodium_Core_HSalsa20::hsalsa20($nonce, $key);
+
+        /** @var string $realNonce */
+        $realNonce = ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8);
+
+        /** @var string $block0 */
+        $block0 = str_repeat("\x00", 32);
+
+        /** @var int $mlen - Length of the plaintext message */
+        $mlen0 = $mlen;
+        if ($mlen0 > 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES) {
+            $mlen0 = 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES;
+        }
+        $block0 .= ParagonIE_Sodium_Core_Util::substr($plaintext, 0, $mlen0);
+
+        /** @var string $block0 */
+        $block0 = ParagonIE_Sodium_Core_Salsa20::salsa20_xor(
+            $block0,
+            $realNonce,
+            $subkey
+        );
+
+        $state = new ParagonIE_Sodium_Core_Poly1305_State(
+            ParagonIE_Sodium_Core_Util::substr(
+                $block0,
+                0,
+                ParagonIE_Sodium_Crypto::onetimeauth_poly1305_KEYBYTES
+            )
+        );
+
+        // Pre-write 16 blank bytes for the Poly1305 tag
+        $start = ftell($ofp);
+        fwrite($ofp, str_repeat("\x00", 16));
+
+        /** @var string $c */
+        $cBlock = ParagonIE_Sodium_Core_Util::substr(
+            $block0,
+            ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES
+        );
+        $state->update($cBlock);
+        fwrite($ofp, $cBlock);
+        $mlen -= 32;
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        /*
+         * Set the cursor to the end of the first half-block. All future bytes will
+         * generated from salsa20_xor_ic, starting from 1 (second block).
+         */
+        fseek($ifp, $first32, SEEK_SET);
+
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $plaintext = fread($ifp, $blockSize);
+            if (!is_string($plaintext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $cBlock = ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
+                $plaintext,
+                $realNonce,
+                $iter,
+                $subkey
+            );
+            fwrite($ofp, $cBlock, $blockSize);
+            $state->update($cBlock);
+
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        try {
+            ParagonIE_Sodium_Compat::memzero($block0);
+            ParagonIE_Sodium_Compat::memzero($subkey);
+        } catch (SodiumException $ex) {
+            $block0 = null;
+            $subkey = null;
+        }
+        $end = ftell($ofp);
+
+        /*
+         * Write the Poly1305 authentication tag that provides integrity
+         * over the ciphertext (encrypt-then-MAC)
+         */
+        fseek($ofp, $start, SEEK_SET);
+        fwrite($ofp, $state->finish(), ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_MACBYTES);
+        fseek($ofp, $end, SEEK_SET);
+        unset($state);
+
+        return true;
+    }
+
+    /**
+     * Decrypt a file
+     *
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int $mlen
+     * @param string $nonce
+     * @param string $key
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function secretbox_decrypt($ifp, $ofp, $mlen, $nonce, $key)
+    {
+        if (PHP_INT_SIZE === 4) {
+            return self::secretbox_decrypt_core32($ifp, $ofp, $mlen, $nonce, $key);
+        }
+        $tag = fread($ifp, 16);
+        if (!is_string($tag)) {
+            throw new SodiumException('Could not read input file');
+        }
+
+        /** @var string $subkey */
+        $subkey = ParagonIE_Sodium_Core_HSalsa20::hsalsa20($nonce, $key);
+
+        /** @var string $realNonce */
+        $realNonce = ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8);
+
+        /** @var string $block0 */
+        $block0 = ParagonIE_Sodium_Core_Salsa20::salsa20(
+            64,
+            ParagonIE_Sodium_Core_Util::substr($nonce, 16, 8),
+            $subkey
+        );
+
+        /* Verify the Poly1305 MAC -before- attempting to decrypt! */
+        $state = new ParagonIE_Sodium_Core_Poly1305_State(self::substr($block0, 0, 32));
+        if (!self::onetimeauth_verify($state, $ifp, $tag, $mlen)) {
+            throw new SodiumException('Invalid MAC');
+        }
+
+        /*
+         * Set the cursor to the end of the first half-block. All future bytes will
+         * generated from salsa20_xor_ic, starting from 1 (second block).
+         */
+        $first32 = fread($ifp, 32);
+        if (!is_string($first32)) {
+            throw new SodiumException('Could not read input file');
+        }
+        $first32len = self::strlen($first32);
+        fwrite(
+            $ofp,
+            self::xorStrings(
+                self::substr($block0, 32, $first32len),
+                self::substr($first32, 0, $first32len)
+            )
+        );
+        $mlen -= 32;
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        /* Decrypts ciphertext, writes to output file. */
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $ciphertext = fread($ifp, $blockSize);
+            if (!is_string($ciphertext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $pBlock = ParagonIE_Sodium_Core_Salsa20::salsa20_xor_ic(
+                $ciphertext,
+                $realNonce,
+                $iter,
+                $subkey
+            );
+            fwrite($ofp, $pBlock, $blockSize);
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        return true;
+    }
+
+    /**
+     * @param ParagonIE_Sodium_Core_Poly1305_State $state
+     * @param resource $ifp
+     * @param string $tag
+     * @param int $mlen
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function onetimeauth_verify(
+        ParagonIE_Sodium_Core_Poly1305_State $state,
+        $ifp,
+        $tag = '',
+        $mlen = 0
+    ) {
+        /** @var int $pos */
+        $pos = ftell($ifp);
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $ciphertext = fread($ifp, $blockSize);
+            if (!is_string($ciphertext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $state->update($ciphertext);
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        $res = ParagonIE_Sodium_Core_Util::verify_16($tag, $state->finish());
+
+        fseek($ifp, $pos, SEEK_SET);
+        return $res;
+    }
+
+    /**
+     * Update a hash context with the contents of a file, without
+     * loading the entire file into memory.
+     *
+     * @param resource|object $hash
+     * @param resource $fp
+     * @param int $size
+     * @return resource|object Resource on PHP < 7.2, HashContext object on PHP >= 7.2
+     * @throws SodiumException
+     * @throws TypeError
+     * @psalm-suppress PossiblyInvalidArgument
+     *                 PHP 7.2 changes from a resource to an object,
+     *                 which causes Psalm to complain about an error.
+     * @psalm-suppress TypeCoercion
+     *                 Ditto.
+     */
+    public static function updateHashWithFile($hash, $fp, $size = 0)
+    {
+        /* Type checks: */
+        if (PHP_VERSION_ID < 70200) {
+            if (!is_resource($hash)) {
+                throw new TypeError('Argument 1 must be a resource, ' . gettype($hash) . ' given.');
+            }
+        } else {
+            if (!is_object($hash)) {
+                throw new TypeError('Argument 1 must be an object (PHP 7.2+), ' . gettype($hash) . ' given.');
+            }
+        }
+
+        if (!is_resource($fp)) {
+            throw new TypeError('Argument 2 must be a resource, ' . gettype($fp) . ' given.');
+        }
+        if (!is_int($size)) {
+            throw new TypeError('Argument 3 must be an integer, ' . gettype($size) . ' given.');
+        }
+
+        /** @var int $originalPosition */
+        $originalPosition = ftell($fp);
+
+        // Move file pointer to beginning of file
+        fseek($fp, 0, SEEK_SET);
+        for ($i = 0; $i < $size; $i += self::BUFFER_SIZE) {
+            /** @var string|bool $message */
+            $message = fread(
+                $fp,
+                ($size - $i) > self::BUFFER_SIZE
+                    ? $size - $i
+                    : self::BUFFER_SIZE
+            );
+            if (!is_string($message)) {
+                throw new SodiumException('Unexpected error reading from file.');
+            }
+            /** @var string $message */
+            /** @psalm-suppress InvalidArgument */
+            hash_update($hash, $message);
+        }
+        // Reset file pointer's position
+        fseek($fp, $originalPosition, SEEK_SET);
+        return $hash;
+    }
+
+    /**
+     * Sign a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_sign_detached(), but produces
+     * the same result. (32-bit)
+     *
+     * @param string $filePath  Absolute path to a file on the filesystem
+     * @param string $secretKey Secret signing key
+     *
+     * @return string           Ed25519 signature
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    private static function sign_core32($filePath, $secretKey)
+    {
+        /** @var int|bool $size */
+        $size = filesize($filePath);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+        /** @var int $size */
+
+        /** @var resource|bool $fp */
+        $fp = fopen($filePath, 'rb');
+        if (!is_resource($fp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+        /** @var resource $fp */
+
+        /** @var string $az */
+        $az = hash('sha512', self::substr($secretKey, 0, 32), true);
+
+        $az[0] = self::intToChr(self::chrToInt($az[0]) & 248);
+        $az[31] = self::intToChr((self::chrToInt($az[31]) & 63) | 64);
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($az, 32, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+
+        /** @var string $nonceHash */
+        $nonceHash = hash_final($hs, true);
+
+        /** @var string $pk */
+        $pk = self::substr($secretKey, 32, 32);
+
+        /** @var string $nonce */
+        $nonce = ParagonIE_Sodium_Core32_Ed25519::sc_reduce($nonceHash) . self::substr($nonceHash, 32);
+
+        /** @var string $sig */
+        $sig = ParagonIE_Sodium_Core32_Ed25519::ge_p3_tobytes(
+            ParagonIE_Sodium_Core32_Ed25519::ge_scalarmult_base($nonce)
+        );
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($sig, 0, 32));
+        hash_update($hs, self::substr($pk, 0, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+
+        /** @var string $hramHash */
+        $hramHash = hash_final($hs, true);
+
+        /** @var string $hram */
+        $hram = ParagonIE_Sodium_Core32_Ed25519::sc_reduce($hramHash);
+
+        /** @var string $sigAfter */
+        $sigAfter = ParagonIE_Sodium_Core32_Ed25519::sc_muladd($hram, $az, $nonce);
+
+        /** @var string $sig */
+        $sig = self::substr($sig, 0, 32) . self::substr($sigAfter, 0, 32);
+
+        try {
+            ParagonIE_Sodium_Compat::memzero($az);
+        } catch (SodiumException $ex) {
+            $az = null;
+        }
+        fclose($fp);
+        return $sig;
+    }
+
+    /**
+     *
+     * Verify a file (rather than a string). Uses less memory than
+     * ParagonIE_Sodium_Compat::crypto_sign_verify_detached(), but
+     * produces the same result. (32-bit)
+     *
+     * @param string $sig       Ed25519 signature
+     * @param string $filePath  Absolute path to a file on the filesystem
+     * @param string $publicKey Signing public key
+     *
+     * @return bool
+     * @throws SodiumException
+     * @throws Exception
+     */
+    public static function verify_core32($sig, $filePath, $publicKey)
+    {
+        /* Security checks */
+        if (ParagonIE_Sodium_Core32_Ed25519::check_S_lt_L(self::substr($sig, 32, 32))) {
+            throw new SodiumException('S < L - Invalid signature');
+        }
+        if (ParagonIE_Sodium_Core32_Ed25519::small_order($sig)) {
+            throw new SodiumException('Signature is on too small of an order');
+        }
+        if ((self::chrToInt($sig[63]) & 224) !== 0) {
+            throw new SodiumException('Invalid signature');
+        }
+        $d = 0;
+        for ($i = 0; $i < 32; ++$i) {
+            $d |= self::chrToInt($publicKey[$i]);
+        }
+        if ($d === 0) {
+            throw new SodiumException('All zero public key');
+        }
+
+        /** @var int|bool $size */
+        $size = filesize($filePath);
+        if (!is_int($size)) {
+            throw new SodiumException('Could not obtain the file size');
+        }
+        /** @var int $size */
+
+        /** @var resource|bool $fp */
+        $fp = fopen($filePath, 'rb');
+        if (!is_resource($fp)) {
+            throw new SodiumException('Could not open input file for reading');
+        }
+        /** @var resource $fp */
+
+        /** @var bool The original value of ParagonIE_Sodium_Compat::$fastMult */
+        $orig = ParagonIE_Sodium_Compat::$fastMult;
+
+        // Set ParagonIE_Sodium_Compat::$fastMult to true to speed up verification.
+        ParagonIE_Sodium_Compat::$fastMult = true;
+
+        /** @var ParagonIE_Sodium_Core32_Curve25519_Ge_P3 $A */
+        $A = ParagonIE_Sodium_Core32_Ed25519::ge_frombytes_negate_vartime($publicKey);
+
+        $hs = hash_init('sha512');
+        hash_update($hs, self::substr($sig, 0, 32));
+        hash_update($hs, self::substr($publicKey, 0, 32));
+        /** @var resource $hs */
+        $hs = self::updateHashWithFile($hs, $fp, $size);
+        /** @var string $hDigest */
+        $hDigest = hash_final($hs, true);
+
+        /** @var string $h */
+        $h = ParagonIE_Sodium_Core32_Ed25519::sc_reduce($hDigest) . self::substr($hDigest, 32);
+
+        /** @var ParagonIE_Sodium_Core32_Curve25519_Ge_P2 $R */
+        $R = ParagonIE_Sodium_Core32_Ed25519::ge_double_scalarmult_vartime(
+            $h,
+            $A,
+            self::substr($sig, 32)
+        );
+
+        /** @var string $rcheck */
+        $rcheck = ParagonIE_Sodium_Core32_Ed25519::ge_tobytes($R);
+
+        // Close the file handle
+        fclose($fp);
+
+        // Reset ParagonIE_Sodium_Compat::$fastMult to what it was before.
+        ParagonIE_Sodium_Compat::$fastMult = $orig;
+        return self::verify_32($rcheck, self::substr($sig, 0, 32));
+    }
+
+    /**
+     * Encrypt a file (32-bit)
+     *
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int $mlen
+     * @param string $nonce
+     * @param string $key
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function secretbox_encrypt_core32($ifp, $ofp, $mlen, $nonce, $key)
+    {
+        $plaintext = fread($ifp, 32);
+        if (!is_string($plaintext)) {
+            throw new SodiumException('Could not read input file');
+        }
+        $first32 = ftell($ifp);
+
+        /** @var string $subkey */
+        $subkey = ParagonIE_Sodium_Core32_HSalsa20::hsalsa20($nonce, $key);
+
+        /** @var string $realNonce */
+        $realNonce = ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8);
+
+        /** @var string $block0 */
+        $block0 = str_repeat("\x00", 32);
+
+        /** @var int $mlen - Length of the plaintext message */
+        $mlen0 = $mlen;
+        if ($mlen0 > 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES) {
+            $mlen0 = 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES;
+        }
+        $block0 .= ParagonIE_Sodium_Core32_Util::substr($plaintext, 0, $mlen0);
+
+        /** @var string $block0 */
+        $block0 = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor(
+            $block0,
+            $realNonce,
+            $subkey
+        );
+
+        $state = new ParagonIE_Sodium_Core32_Poly1305_State(
+            ParagonIE_Sodium_Core32_Util::substr(
+                $block0,
+                0,
+                ParagonIE_Sodium_Crypto::onetimeauth_poly1305_KEYBYTES
+            )
+        );
+
+        // Pre-write 16 blank bytes for the Poly1305 tag
+        $start = ftell($ofp);
+        fwrite($ofp, str_repeat("\x00", 16));
+
+        /** @var string $c */
+        $cBlock = ParagonIE_Sodium_Core32_Util::substr(
+            $block0,
+            ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES
+        );
+        $state->update($cBlock);
+        fwrite($ofp, $cBlock);
+        $mlen -= 32;
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        /*
+         * Set the cursor to the end of the first half-block. All future bytes will
+         * generated from salsa20_xor_ic, starting from 1 (second block).
+         */
+        fseek($ifp, $first32, SEEK_SET);
+
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $plaintext = fread($ifp, $blockSize);
+            if (!is_string($plaintext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $cBlock = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor_ic(
+                $plaintext,
+                $realNonce,
+                $iter,
+                $subkey
+            );
+            fwrite($ofp, $cBlock, $blockSize);
+            $state->update($cBlock);
+
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        try {
+            ParagonIE_Sodium_Compat::memzero($block0);
+            ParagonIE_Sodium_Compat::memzero($subkey);
+        } catch (SodiumException $ex) {
+            $block0 = null;
+            $subkey = null;
+        }
+        $end = ftell($ofp);
+
+        /*
+         * Write the Poly1305 authentication tag that provides integrity
+         * over the ciphertext (encrypt-then-MAC)
+         */
+        fseek($ofp, $start, SEEK_SET);
+        fwrite($ofp, $state->finish(), ParagonIE_Sodium_Compat::CRYPTO_SECRETBOX_MACBYTES);
+        fseek($ofp, $end, SEEK_SET);
+        unset($state);
+
+        return true;
+    }
+
+    /**
+     * Decrypt a file (32-bit)
+     *
+     * @param resource $ifp
+     * @param resource $ofp
+     * @param int $mlen
+     * @param string $nonce
+     * @param string $key
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function secretbox_decrypt_core32($ifp, $ofp, $mlen, $nonce, $key)
+    {
+        $tag = fread($ifp, 16);
+        if (!is_string($tag)) {
+            throw new SodiumException('Could not read input file');
+        }
+
+        /** @var string $subkey */
+        $subkey = ParagonIE_Sodium_Core32_HSalsa20::hsalsa20($nonce, $key);
+
+        /** @var string $realNonce */
+        $realNonce = ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8);
+
+        /** @var string $block0 */
+        $block0 = ParagonIE_Sodium_Core32_Salsa20::salsa20(
+            64,
+            ParagonIE_Sodium_Core32_Util::substr($nonce, 16, 8),
+            $subkey
+        );
+
+        /* Verify the Poly1305 MAC -before- attempting to decrypt! */
+        $state = new ParagonIE_Sodium_Core32_Poly1305_State(self::substr($block0, 0, 32));
+        if (!self::onetimeauth_verify_core32($state, $ifp, $tag, $mlen)) {
+            throw new SodiumException('Invalid MAC');
+        }
+
+        /*
+         * Set the cursor to the end of the first half-block. All future bytes will
+         * generated from salsa20_xor_ic, starting from 1 (second block).
+         */
+        $first32 = fread($ifp, 32);
+        if (!is_string($first32)) {
+            throw new SodiumException('Could not read input file');
+        }
+        $first32len = self::strlen($first32);
+        fwrite(
+            $ofp,
+            self::xorStrings(
+                self::substr($block0, 32, $first32len),
+                self::substr($first32, 0, $first32len)
+            )
+        );
+        $mlen -= 32;
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        /* Decrypts ciphertext, writes to output file. */
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $ciphertext = fread($ifp, $blockSize);
+            if (!is_string($ciphertext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $pBlock = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor_ic(
+                $ciphertext,
+                $realNonce,
+                $iter,
+                $subkey
+            );
+            fwrite($ofp, $pBlock, $blockSize);
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        return true;
+    }
+
+    /**
+     * One-time message authentication for 32-bit systems
+     *
+     * @param ParagonIE_Sodium_Core32_Poly1305_State $state
+     * @param resource $ifp
+     * @param string $tag
+     * @param int $mlen
+     * @return bool
+     * @throws SodiumException
+     * @throws TypeError
+     */
+    protected static function onetimeauth_verify_core32(
+        ParagonIE_Sodium_Core32_Poly1305_State $state,
+        $ifp,
+        $tag = '',
+        $mlen = 0
+    ) {
+        /** @var int $pos */
+        $pos = ftell($ifp);
+
+        /** @var int $iter */
+        $iter = 1;
+
+        /** @var int $incr */
+        $incr = self::BUFFER_SIZE >> 6;
+
+        while ($mlen > 0) {
+            $blockSize = $mlen > self::BUFFER_SIZE
+                ? self::BUFFER_SIZE
+                : $mlen;
+            $ciphertext = fread($ifp, $blockSize);
+            if (!is_string($ciphertext)) {
+                throw new SodiumException('Could not read input file');
+            }
+            $state->update($ciphertext);
+            $mlen -= $blockSize;
+            $iter += $incr;
+        }
+        $res = ParagonIE_Sodium_Core32_Util::verify_16($tag, $state->finish());
+
+        fseek($ifp, $pos, SEEK_SET);
+        return $res;
+    }
+}