PKCS8: fix public private checks for human readable keys

phpseclib/Crypt/Common/Formats/Keys/PKCS8.php

@@ -315,11 +315,15 @@ abstract class PKCS8 extends PKCS
      */
     protected static function load($key, $password = '')
     {
-        $decoded = self::preParse($key);
+        if (!Strings::is_stringable($key)) {
+            throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
+        }
 
         $isPublic = strpos($key, 'PUBLIC') !== false;
         $isPrivate = strpos($key, 'PRIVATE') !== false;
 
+        $decoded = self::preParse($key);
+
         $meta = [];
 
         $decrypted = ASN1::asn1map($decoded[0], Maps\EncryptedPrivateKeyInfo::MAP);
@@ -661,10 +665,6 @@ abstract class PKCS8 extends PKCS
     {
         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 ($decoded !== false) {
@@ -690,6 +690,10 @@ abstract class PKCS8 extends PKCS
      */
     public static function extractEncryptionAlgorithm($key)
     {
+        if (!Strings::is_stringable($key)) {
+            throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
+        }
+
         $decoded = self::preParse($key);
 
         $r = ASN1::asn1map($decoded[0], ASN1\Maps\EncryptedPrivateKeyInfo::MAP);

tests/Unit/Crypt/EC/KeyTest.php

@@ -678,4 +678,16 @@ MIIEDwIBADATBgcqhkjOPQIBBggqhkjOPQMBBwSCA/MwggPvAgEBBIID6P//////
         $key = PublicKeyLoader::load($key);
         $this->assertInstanceOf(PublicKey::class, $key);
     }
+
+    public function testMislabledPKCS8PubKey()
+    {
+        $this->expectException('\phpseclib3\Exception\NoKeyLoadedException');
+
+        $key = '-----BEGIN PRIVATE KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAErPJyxEu2/oKCrJaaTVTrq39DKJ2X
+cN6W+k8UvGf+Y/lDWNbFitQocabsDUvSN0edHH3UKP5QPTz4cOlyIPMrXQ==
+-----END PUBLIC KEY-----';
+        $key = PublicKeyLoader::load($key);
+        $this->assertInstanceOf(PublicKey::class, $key);
+    }
 }