diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8874fea..947ad115 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # Changelog
 
+## 2.0.26 - 2020-03-22
+
+- SFTP: another attempt at speeding up uploads (#1455)
+- SSH2: try logging in with none as an auth method first (#1454)
+- ASN1: fix for malformed ASN1 strings (#1456)
+
+## 2.0.25 - 2020-02-25
+
+- SFTP: re-add buffering (#1455)
+
 ## 2.0.24 - 2020-02-22
 
 - X509: fix PHP 5.3 compatability issue
diff --git a/phpseclib/Common/Functions/Strings.php b/phpseclib/Common/Functions/Strings.php
index 166e1a17..0ed27c8c 100644
--- a/phpseclib/Common/Functions/Strings.php
+++ b/phpseclib/Common/Functions/Strings.php
@@ -175,7 +175,7 @@ abstract class Strings
                     $result.= pack('N', $element);
                     break;
                 case 's':
-                    if (!is_string($element)) {
+                    if (!self::is_stringable($element)) {
                         throw new \InvalidArgumentException('A string was expected.');
                     }
                     $result.= pack('Na*', strlen($element), $element);
@@ -372,4 +372,16 @@ abstract class Strings
 
         return $var;
     }
+
+    /**
+     * Find whether the type of a variable is string (or could be converted to one)
+     *
+     * @param string|object $var
+     * @return boolean
+     * @access public
+     */
+    public static function is_stringable($var)
+    {
+        return is_string($var) || (is_object($var) && method_exists($var, '__toString'));
+    }
 }
diff --git a/phpseclib/Crypt/Common/AsymmetricKey.php b/phpseclib/Crypt/Common/AsymmetricKey.php
index 60ca9bb4..f3efb733 100644
--- a/phpseclib/Crypt/Common/AsymmetricKey.php
+++ b/phpseclib/Crypt/Common/AsymmetricKey.php
@@ -24,7 +24,7 @@ use phpseclib3\Crypt\DSA;
 use phpseclib3\Crypt\ECDSA;
 
 /**
- * Base Class for all stream cipher classes
+ * Base Class for all asymmetric cipher classes
  *
  * @package AsymmetricKey
  * @author  Jim Wigginton <terrafrost@php.net>
@@ -173,8 +173,8 @@ abstract class AsymmetricKey
         }
 
         $components['format'] = $format;
-
         $new = static::onLoad($components);
+        $new->format = $format;
         return $new instanceof PrivateKey ?
             $new->withPassword($password) :
             $new;
@@ -206,6 +206,7 @@ abstract class AsymmetricKey
         $components['format'] = $format;
 
         $new = static::onLoad($components);
+        $new->format = $format;
         return $new instanceof PrivateKey ?
             $new->withPassword($password) :
             $new;
@@ -304,7 +305,7 @@ abstract class AsymmetricKey
      * Returns the format of the loaded key.
      *
      * If the key that was loaded wasn't in a valid or if the key was auto-generated
-     * with RSA::createKey() then this will return false.
+     * with RSA::createKey() then this will throw an exception.
      *
      * @see self::load()
      * @access public
@@ -312,8 +313,8 @@ abstract class AsymmetricKey
      */
     public function getLoadedFormat()
     {
-        if ($this->format === false) {
-            return false;
+        if (empty($this->format)) {
+            throw new NoKeyLoadedException('This key was created with createKey - it was not loaded with load. Therefore there is no "loaded format"');
         }
 
         $meta = new \ReflectionClass($this->format);
diff --git a/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php b/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
index fc4e2906..9291f32e 100644
--- a/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
+++ b/phpseclib/Crypt/Common/Formats/Keys/OpenSSH.php
@@ -70,7 +70,7 @@ abstract class OpenSSH
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/Common/Formats/Keys/PKCS1.php b/phpseclib/Crypt/Common/Formats/Keys/PKCS1.php
index adaeb6b6..a362d938 100644
--- a/phpseclib/Crypt/Common/Formats/Keys/PKCS1.php
+++ b/phpseclib/Crypt/Common/Formats/Keys/PKCS1.php
@@ -22,6 +22,7 @@ use phpseclib3\Crypt\AES;
 use phpseclib3\Crypt\DES;
 use phpseclib3\Crypt\TripleDES;
 use phpseclib3\File\ASN1;
+use phpseclib3\Common\Functions\Strings;
 use phpseclib3\Exception\UnsupportedAlgorithmException;
 
 /**
@@ -127,7 +128,7 @@ abstract class PKCS1 extends PKCS
      */
     protected static function load($key, $password)
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/Common/Formats/Keys/PKCS8.php b/phpseclib/Crypt/Common/Formats/Keys/PKCS8.php
index f8c199de..638a58bf 100644
--- a/phpseclib/Crypt/Common/Formats/Keys/PKCS8.php
+++ b/phpseclib/Crypt/Common/Formats/Keys/PKCS8.php
@@ -37,6 +37,7 @@ use phpseclib3\Crypt\Random;
 use phpseclib3\Math\BigInteger;
 use phpseclib3\File\ASN1;
 use phpseclib3\File\ASN1\Maps;
+use phpseclib3\Common\Functions\Strings;
 use phpseclib3\Exception\UnsupportedAlgorithmException;
 
 /**
@@ -331,25 +332,7 @@ abstract class PKCS8 extends PKCS
      */
     protected static function load($key, $password = '')
     {
-        self::initialize_static_variables();
-
-        if (!is_string($key)) {
-            throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
-        }
-
-        if (self::$format != self::MODE_DER) {
-            $decoded = ASN1::extractBER($key);
-            if ($decoded !== false) {
-                $key = $decoded;
-            } elseif (self::$format == self::MODE_PEM) {
-                throw new \UnexpectedValueException('Expected base64-encoded PEM format but was unable to decode base64 text');
-            }
-        }
-
-        $decoded = ASN1::decodeBER($key);
-        if (empty($decoded)) {
-            throw new \RuntimeException('Unable to decode BER');
-        }
+        $decoded = self::preParse($key);
 
         $meta = [];
 
@@ -442,7 +425,7 @@ abstract class PKCS8 extends PKCS
                             if (isset($keyLength)) {
                                 $params[] = (int) $keyLength->toString();
                             }
-                            call_user_func_array([$cipher, 'setPassword'], $params);
+                            $cipher->setPassword(...$params);
                             $key = $cipher->decrypt($decrypted['encryptedData']);
                             $decoded = ASN1::decodeBER($key);
                             if (empty($decoded)) {
@@ -654,4 +637,65 @@ abstract class PKCS8 extends PKCS
                chunk_split(Base64::encode($key), 64) .
                "-----END PUBLIC KEY-----";
     }
+
+    /**
+     * Perform some preliminary parsing of the key
+     *
+     * @param string $key
+     * @return array
+     */
+    private static function preParse(&$key)
+    {
+        self::initialize_static_variables();
+
+        if (!Strings::is_stringable($key)) {
+            throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
+        }
+
+        if (self::$format != self::MODE_DER) {
+            $decoded = ASN1::extractBER($key);
+            if ($decoded !== false) {
+                $key = $decoded;
+            } elseif (self::$format == self::MODE_PEM) {
+                throw new \UnexpectedValueException('Expected base64-encoded PEM format but was unable to decode base64 text');
+            }
+        }
+
+        $decoded = ASN1::decodeBER($key);
+        if (empty($decoded)) {
+            throw new \RuntimeException('Unable to decode BER');
+        }
+
+        return $decoded;
+    }
+
+    /**
+     * Returns the encryption parameters used by the key
+     *
+     * @param string $key
+     * @return array
+     */
+    public static function extractEncryptionAlgorithm($key)
+    {
+        $decoded = self::preParse($key);
+
+        $r = ASN1::asn1map($decoded[0], ASN1\Maps\EncryptedPrivateKeyInfo::MAP);
+        if (!is_array($r)) {
+            throw new \RuntimeException('Unable to parse using EncryptedPrivateKeyInfo map');
+        }
+
+        if ($r['encryptionAlgorithm']['algorithm'] == 'id-PBES2') {
+            $decoded = ASN1::decodeBER($r['encryptionAlgorithm']['parameters']->element);
+            $r['encryptionAlgorithm']['parameters'] = ASN1::asn1map($decoded[0], ASN1\Maps\PBES2params::MAP);
+
+            $kdf = &$r['encryptionAlgorithm']['parameters']['keyDerivationFunc'];
+            switch ($kdf['algorithm']) {
+                case 'id-PBKDF2':
+                    $decoded = ASN1::decodeBER($kdf['parameters']->element);
+                    $kdf['parameters'] = ASN1::asn1map($decoded[0], Maps\PBKDF2params::MAP);
+            }
+        }
+
+        return $r['encryptionAlgorithm'];
+    }
 }
diff --git a/phpseclib/Crypt/Common/Formats/Keys/PuTTY.php b/phpseclib/Crypt/Common/Formats/Keys/PuTTY.php
index fb2ffa77..ccd06f75 100644
--- a/phpseclib/Crypt/Common/Formats/Keys/PuTTY.php
+++ b/phpseclib/Crypt/Common/Formats/Keys/PuTTY.php
@@ -80,7 +80,7 @@ abstract class PuTTY
      */
     public static function load($key, $password)
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
@@ -200,14 +200,14 @@ abstract class PuTTY
      */
     protected static function wrapPrivateKey($public, $private, $type, $password, array $options = [])
     {
-        $key = "PuTTY-User-Key-File-2: " . $type . "\r\nEncryption: ";
         $encryption = (!empty($password) || is_string($password)) ? 'aes256-cbc' : 'none';
-        $key.= $encryption;
-        $key.= "\r\nComment: " . self::$comment . "\r\n";
+        $comment = isset($options['comment']) ? $options['comment'] : self::$comment;
+
+        $key = "PuTTY-User-Key-File-2: " . $type . "\r\nEncryption: ";        $key.= $encryption;
+        $key.= "\r\nComment: " . $comment . "\r\n";
 
         $public = Strings::packSSH2('s', $type) . $public;
 
-        $comment = isset($options['comment']) ? $options['comment'] : self::$comment;
         $source = Strings::packSSH2('ssss', $type, $encryption, $comment, $public);
 
         $public = Base64::encode($public);
diff --git a/phpseclib/Crypt/DH/Formats/Keys/PKCS8.php b/phpseclib/Crypt/DH/Formats/Keys/PKCS8.php
index 59b42646..e69fcee6 100644
--- a/phpseclib/Crypt/DH/Formats/Keys/PKCS8.php
+++ b/phpseclib/Crypt/DH/Formats/Keys/PKCS8.php
@@ -25,6 +25,7 @@ use phpseclib3\Math\BigInteger;
 use phpseclib3\Crypt\Common\Formats\Keys\PKCS8 as Progenitor;
 use phpseclib3\File\ASN1;
 use phpseclib3\File\ASN1\Maps;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#8 Formatted DH Key Handler
@@ -69,7 +70,7 @@ abstract class PKCS8 extends Progenitor
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/DSA.php b/phpseclib/Crypt/DSA.php
index ff62a290..71f32aae 100644
--- a/phpseclib/Crypt/DSA.php
+++ b/phpseclib/Crypt/DSA.php
@@ -95,7 +95,7 @@ abstract class DSA extends AsymmetricKey
      * @var string
      * @access private
      */
-    protected $format;
+    protected $sigFormat;
 
     /**
      * Signature Format (Short)
@@ -263,7 +263,7 @@ abstract class DSA extends AsymmetricKey
      */
     protected function __construct()
     {
-        $this->format = self::validatePlugin('Signature', 'ASN1');
+        $this->sigFormat = self::validatePlugin('Signature', 'ASN1');
         $this->shortFormat = 'ASN1';
 
         parent::__construct();
@@ -329,7 +329,7 @@ abstract class DSA extends AsymmetricKey
     {
         $new = clone $this;
         $new->shortFormat = $format;
-        $new->format = self::validatePlugin('Signature', $format);
+        $new->sigFormat = self::validatePlugin('Signature', $format);
         return $new;
     }
 
diff --git a/phpseclib/Crypt/DSA/Formats/Keys/PKCS8.php b/phpseclib/Crypt/DSA/Formats/Keys/PKCS8.php
index 4c79c969..e56f455f 100644
--- a/phpseclib/Crypt/DSA/Formats/Keys/PKCS8.php
+++ b/phpseclib/Crypt/DSA/Formats/Keys/PKCS8.php
@@ -29,6 +29,7 @@ use phpseclib3\Math\BigInteger;
 use phpseclib3\Crypt\Common\Formats\Keys\PKCS8 as Progenitor;
 use phpseclib3\File\ASN1;
 use phpseclib3\File\ASN1\Maps;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#8 Formatted DSA Key Handler
@@ -73,7 +74,7 @@ abstract class PKCS8 extends Progenitor
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/DSA/Formats/Keys/XML.php b/phpseclib/Crypt/DSA/Formats/Keys/XML.php
index 4251b77d..42b3bbb9 100644
--- a/phpseclib/Crypt/DSA/Formats/Keys/XML.php
+++ b/phpseclib/Crypt/DSA/Formats/Keys/XML.php
@@ -23,6 +23,7 @@ namespace phpseclib3\Crypt\DSA\Formats\Keys;
 
 use ParagonIE\ConstantTime\Base64;
 use phpseclib3\Math\BigInteger;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * XML Formatted DSA Key Handler
@@ -43,7 +44,7 @@ abstract class XML
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/DSA/PrivateKey.php b/phpseclib/Crypt/DSA/PrivateKey.php
index a8e70346..17e9ada3 100644
--- a/phpseclib/Crypt/DSA/PrivateKey.php
+++ b/phpseclib/Crypt/DSA/PrivateKey.php
@@ -85,7 +85,7 @@ class PrivateKey extends DSA implements Common\PrivateKey
      */
     public function sign($message)
     {
-        $format = $this->format;
+        $format = $this->sigFormat;
 
         if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
             $signature = '';
diff --git a/phpseclib/Crypt/DSA/PublicKey.php b/phpseclib/Crypt/DSA/PublicKey.php
index e352e905..b9741aa5 100644
--- a/phpseclib/Crypt/DSA/PublicKey.php
+++ b/phpseclib/Crypt/DSA/PublicKey.php
@@ -40,7 +40,7 @@ class PublicKey extends DSA implements Common\PublicKey
      */
     public function verify($message, $signature)
     {
-        $format = $this->format;
+        $format = $this->sigFormat;
 
         $params = $format::load($signature);
         if ($params === false || count($params) != 2) {
diff --git a/phpseclib/Crypt/EC.php b/phpseclib/Crypt/EC.php
index 1576b4fe..af6b2a22 100644
--- a/phpseclib/Crypt/EC.php
+++ b/phpseclib/Crypt/EC.php
@@ -244,7 +244,7 @@ abstract class EC extends AsymmetricKey
      */
     protected function __construct()
     {
-        $this->format = self::validatePlugin('Signature', 'ASN1');
+        $this->sigFormat = self::validatePlugin('Signature', 'ASN1');
         $this->shortFormat = 'ASN1';
 
         parent::__construct();
@@ -383,7 +383,7 @@ abstract class EC extends AsymmetricKey
 
         $new = clone $this;
         $new->shortFormat = $format;
-        $new->format = self::validatePlugin('Signature', $format);
+        $new->sigFormat = self::validatePlugin('Signature', $format);
         return $new;
     }
 
diff --git a/phpseclib/Crypt/EC/Formats/Keys/PKCS8.php b/phpseclib/Crypt/EC/Formats/Keys/PKCS8.php
index 9132807f..171d4b45 100644
--- a/phpseclib/Crypt/EC/Formats/Keys/PKCS8.php
+++ b/phpseclib/Crypt/EC/Formats/Keys/PKCS8.php
@@ -36,6 +36,7 @@ use phpseclib3\Math\Common\FiniteField\Integer;
 use phpseclib3\Crypt\EC\Curves\Ed25519;
 use phpseclib3\Crypt\EC\Curves\Ed448;
 use phpseclib3\Exception\UnsupportedCurveException;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#8 Formatted EC Key Handler
@@ -81,7 +82,7 @@ abstract class PKCS8 extends Progenitor
         // one that's called
         self::initialize_static_variables();
 
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/EC/Formats/Keys/XML.php b/phpseclib/Crypt/EC/Formats/Keys/XML.php
index 0bfd81e1..d6d8018a 100644
--- a/phpseclib/Crypt/EC/Formats/Keys/XML.php
+++ b/phpseclib/Crypt/EC/Formats/Keys/XML.php
@@ -26,6 +26,7 @@ use phpseclib3\Crypt\EC\BaseCurves\Base as BaseCurve;
 use phpseclib3\Crypt\EC\BaseCurves\Prime as PrimeCurve;
 use phpseclib3\Crypt\EC\BaseCurves\TwistedEdwards as TwistedEdwardsCurve;
 use phpseclib3\Crypt\EC\BaseCurves\Montgomery as MontgomeryCurve;
+use phpseclib3\Common\Functions\Strings;
 use phpseclib3\Exception\UnsupportedCurveException;
 
 /**
@@ -65,7 +66,7 @@ abstract class XML
     {
         self::initialize_static_variables();
 
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/EC/PrivateKey.php b/phpseclib/Crypt/EC/PrivateKey.php
index 4ab15688..4ffa5fdf 100644
--- a/phpseclib/Crypt/EC/PrivateKey.php
+++ b/phpseclib/Crypt/EC/PrivateKey.php
@@ -100,7 +100,7 @@ class PrivateKey extends EC implements Common\PrivateKey
         $order = $this->curve->getOrder();
 
         $shortFormat = $this->shortFormat;
-        $format = $this->format;
+        $format = $this->sigFormat;
         if ($format === false) {
             return false;
         }
diff --git a/phpseclib/Crypt/EC/PublicKey.php b/phpseclib/Crypt/EC/PublicKey.php
index ef749470..2cb92ab6 100644
--- a/phpseclib/Crypt/EC/PublicKey.php
+++ b/phpseclib/Crypt/EC/PublicKey.php
@@ -52,7 +52,7 @@ class PublicKey extends EC implements Common\PublicKey
         }
 
         $shortFormat = $this->shortFormat;
-        $format = $this->format;
+        $format = $this->sigFormat;
         if ($format === false) {
             return false;
         }
diff --git a/phpseclib/Crypt/Hash.php b/phpseclib/Crypt/Hash.php
index 6c91dcd1..e0b9e464 100644
--- a/phpseclib/Crypt/Hash.php
+++ b/phpseclib/Crypt/Hash.php
@@ -93,7 +93,7 @@ class Hash
      * @var string
      * @access private
      */
-    private $hash;
+    private $algo;
 
     /**
      * Key
@@ -268,9 +268,9 @@ class Hash
             return;
         }
 
-        $this->computedKey = is_array($this->hash) ?
-            call_user_func($this->hash, $this->key) :
-            hash($this->hash, $this->key, true);
+        $this->computedKey = is_array($this->algo) ?
+            call_user_func($this->algo, $this->key) :
+            hash($this->algo, $this->key, true);
     }
 
     /**
@@ -302,7 +302,7 @@ class Hash
             case 'umac-128':
                 $this->blockSize = 128;
                 $this->length = abs(substr($hash, -3)) >> 3;
-                $this->hash = 'umac';
+                $this->algo = 'umac';
                 return;
             case 'md2-96':
             case 'md5-96':
@@ -439,7 +439,7 @@ class Hash
             $this->opad = str_repeat(chr(0x5C), $b);
         }
 
-        $this->hash = $hash;
+        $this->algo = $hash;
 
         $this->computeKey();
     }
@@ -785,7 +785,8 @@ class Hash
      */
     public function hash($text)
     {
-        if ($this->hash == 'umac') {
+        $algo = $this->algo;
+        if ($algo == 'umac') {
             if ($this->recomputeAESKey) {
                 if (!is_string($this->nonce)) {
                     throw new InsufficientSetupException('No nonce has been set');
@@ -837,9 +838,9 @@ class Hash
             return $hashedmessage ^ $this->pad;
         }
 
-        if (is_array($this->hash)) {
+        if (is_array($algo)) {
             if (empty($this->key) || !is_string($this->key)) {
-                return substr(call_user_func($this->hash, $text, ...array_values($this->parameters)), 0, $this->length);
+                return substr($algo($text, ...array_values($this->parameters)), 0, $this->length);
             }
 
             // SHA3 HMACs are discussed at https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf#page=30
@@ -847,17 +848,17 @@ class Hash
             $key    = str_pad($this->computedKey, $b, chr(0));
             $temp   = $this->ipad ^ $key;
             $temp  .= $text;
-            $temp   = substr(call_user_func($this->hash, $temp, ...array_values($this->parameters)), 0, $this->length);
+            $temp   = substr($algo($temp, ...array_values($this->parameters)), 0, $this->length);
             $output = $this->opad ^ $key;
             $output.= $temp;
-            $output = call_user_func($this->hash, $output, ...array_values($this->parameters));
+            $output = $algo($output, ...array_values($this->parameters));
 
             return substr($output, 0, $this->length);
         }
 
         $output = !empty($this->key) || is_string($this->key) ?
-            hash_hmac($this->hash, $text, $this->computedKey, true) :
-            hash($this->hash, $text, true);
+            hash_hmac($algo, $text, $this->computedKey, true) :
+            hash($algo, $text, true);
 
         return strlen($output) > $this->length
             ? substr($output, 0, $this->length)
diff --git a/phpseclib/Crypt/RC2.php b/phpseclib/Crypt/RC2.php
index 43f76c40..0e8ec502 100644
--- a/phpseclib/Crypt/RC2.php
+++ b/phpseclib/Crypt/RC2.php
@@ -393,7 +393,7 @@ class RC2 extends BlockCipher
         $l[0] = self::$invpitable[$l[0]];
         array_unshift($l, 'C*');
 
-        $this->key = call_user_func_array('pack', $l);
+        $this->key = pack(...$l);
         $this->key_length = strlen($this->key);
         $this->changed = $this->nonIVChanged = true;
         $this->setEngine();
diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index dd3c3e71..b1952028 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -407,7 +407,6 @@ abstract class RSA extends AsymmetricKey
             new PublicKey :
             new PrivateKey;
 
-        $key->format = $components['format'];
         $key->modulus = $components['modulus'];
         $key->publicExponent = $components['publicExponent'];
         $key->k = $key->modulus->getLengthInBytes();
diff --git a/phpseclib/Crypt/RSA/Formats/Keys/MSBLOB.php b/phpseclib/Crypt/RSA/Formats/Keys/MSBLOB.php
index 06469913..4d95080d 100644
--- a/phpseclib/Crypt/RSA/Formats/Keys/MSBLOB.php
+++ b/phpseclib/Crypt/RSA/Formats/Keys/MSBLOB.php
@@ -76,7 +76,7 @@ abstract class MSBLOB
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/RSA/Formats/Keys/PKCS1.php b/phpseclib/Crypt/RSA/Formats/Keys/PKCS1.php
index 6ca838d5..64e707e0 100644
--- a/phpseclib/Crypt/RSA/Formats/Keys/PKCS1.php
+++ b/phpseclib/Crypt/RSA/Formats/Keys/PKCS1.php
@@ -28,6 +28,7 @@ use phpseclib3\Math\BigInteger;
 use phpseclib3\Crypt\Common\Formats\Keys\PKCS1 as Progenitor;
 use phpseclib3\File\ASN1;
 use phpseclib3\File\ASN1\Maps;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#1 Formatted RSA Key Handler
@@ -48,7 +49,7 @@ abstract class PKCS1 extends Progenitor
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/RSA/Formats/Keys/PKCS8.php b/phpseclib/Crypt/RSA/Formats/Keys/PKCS8.php
index 45a25683..1fcfeae1 100644
--- a/phpseclib/Crypt/RSA/Formats/Keys/PKCS8.php
+++ b/phpseclib/Crypt/RSA/Formats/Keys/PKCS8.php
@@ -30,6 +30,7 @@ namespace phpseclib3\Crypt\RSA\Formats\Keys;
 use phpseclib3\Math\BigInteger;
 use phpseclib3\Crypt\Common\Formats\Keys\PKCS8 as Progenitor;
 use phpseclib3\File\ASN1;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#8 Formatted RSA Key Handler
@@ -74,7 +75,7 @@ abstract class PKCS8 extends Progenitor
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/RSA/Formats/Keys/PSS.php b/phpseclib/Crypt/RSA/Formats/Keys/PSS.php
index 4e2276a0..c1cc7f89 100644
--- a/phpseclib/Crypt/RSA/Formats/Keys/PSS.php
+++ b/phpseclib/Crypt/RSA/Formats/Keys/PSS.php
@@ -29,6 +29,7 @@ use phpseclib3\Math\BigInteger;
 use phpseclib3\Crypt\Common\Formats\Keys\PKCS8 as Progenitor;
 use phpseclib3\File\ASN1;
 use phpseclib3\File\ASN1\Maps;
+use phpseclib3\Common\Functions\Strings;
 
 /**
  * PKCS#8 Formatted RSA-PSS Key Handler
@@ -107,7 +108,7 @@ abstract class PSS extends Progenitor
     {
         self::initialize_static_variables();
 
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/Crypt/RSA/Formats/Keys/XML.php b/phpseclib/Crypt/RSA/Formats/Keys/XML.php
index ef51c783..389f93a8 100644
--- a/phpseclib/Crypt/RSA/Formats/Keys/XML.php
+++ b/phpseclib/Crypt/RSA/Formats/Keys/XML.php
@@ -24,6 +24,7 @@ namespace phpseclib3\Crypt\RSA\Formats\Keys;
 
 use ParagonIE\ConstantTime\Base64;
 use phpseclib3\Math\BigInteger;
+use phpseclib3\Common\Functions\Strings;
 use phpseclib3\Exception\UnsupportedFormatException;
 
 /**
@@ -45,7 +46,7 @@ abstract class XML
      */
     public static function load($key, $password = '')
     {
-        if (!is_string($key)) {
+        if (!Strings::is_stringable($key)) {
             throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
         }
 
diff --git a/phpseclib/File/ASN1.php b/phpseclib/File/ASN1.php
index ac10661f..e566b41f 100644
--- a/phpseclib/File/ASN1.php
+++ b/phpseclib/File/ASN1.php
@@ -553,7 +553,7 @@ abstract class ASN1
                     }
                     if (isset($value)) {
                         if (isset($special[$key])) {
-                            $value = call_user_func($special[$key], $value);
+                            $value = $special[$key]($value);
                         }
                         return [$key => $value];
                     }
@@ -637,7 +637,7 @@ abstract class ASN1
                     if ($maymatch) {
                         // Got the match: use it.
                         if (isset($special[$key])) {
-                            $candidate = call_user_func($special[$key], $candidate);
+                            $candidate = $special[$key]($candidate);
                         }
                         $map[$key] = $candidate;
                         $i++;
@@ -722,7 +722,7 @@ abstract class ASN1
 
                         // Got the match: use it.
                         if (isset($special[$key])) {
-                            $candidate = call_user_func($special[$key], $candidate);
+                            $candidate = $special[$key]($candidate);
                         }
                         $map[$key] = $candidate;
                         break;
@@ -881,7 +881,7 @@ abstract class ASN1
 
         if (isset($idx)) {
             if (isset($special[$idx])) {
-                $source = call_user_func($special[$idx], $source);
+                $source = $special[$idx]($source);
             }
             self::$location[] = $idx;
         }
diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index cb648c04..75847962 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -1941,7 +1941,7 @@ class SFTP extends SSH2
         $i = $j = 0;
         while ($dataCallback || ($size === 0 || $sent < $size)) {
             if ($dataCallback) {
-                $temp = call_user_func($dataCallback, $sftp_packet_size);
+                $temp = $dataCallback($sftp_packet_size);
                 if (is_null($temp)) {
                     break;
                 }
@@ -1962,7 +1962,7 @@ class SFTP extends SSH2
             }
             $sent+= strlen($temp);
             if (is_callable($progressCallback)) {
-                call_user_func($progressCallback, $sent);
+                $progressCallback($sent);
             }
 
             $i++;
@@ -2137,7 +2137,7 @@ class SFTP extends SSH2
                 $packet = null;
                 $read+= $packet_size;
                 if (is_callable($progressCallback)) {
-                    call_user_func($progressCallback, $read);
+                    $progressCallback($read);
                 }
                 $i++;
             }
diff --git a/phpseclib/Net/SFTP/Stream.php b/phpseclib/Net/SFTP/Stream.php
index 0c08266b..dca9b975 100644
--- a/phpseclib/Net/SFTP/Stream.php
+++ b/phpseclib/Net/SFTP/Stream.php
@@ -789,6 +789,6 @@ class Stream
         if (!method_exists($this, $name)) {
             return false;
         }
-        return call_user_func_array([$this, $name], $arguments);
+        return $this->$name(...$arguments);
     }
 }
diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 5cc839ac..8c0fbce7 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -2675,7 +2675,7 @@ class SSH2
                     return false;
                 default:
                     if (is_callable($callback)) {
-                        if (call_user_func($callback, $temp) === true) {
+                        if ($callback($temp) === true) {
                             $this->close_channel(self::CHANNEL_EXEC);
                             return true;
                         }
@@ -4190,7 +4190,9 @@ class SSH2
                     $output.= str_pad(dechex($j), 7, '0', STR_PAD_LEFT) . '0  ';
                 }
                 $fragment = Strings::shift($current_log, $this->log_short_width);
-                $hex = substr(preg_replace_callback('#.#s', [$this, 'format_log_helper'], $fragment), strlen($this->log_boundary));
+                $hex = substr(preg_replace_callback('#.#s', function ($matches) {
+                    return $this->log_boundary . str_pad(dechex(ord($matches[0])), 2, '0', STR_PAD_LEFT);
+                }, $fragment), strlen($this->log_boundary));
                 // replace non ASCII printable characters with dots
                 // http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters
                 // also replace < with a . since < messes up the output on web browsers