diff --git a/src/SAML2/Assertion/Processor.php b/src/SAML2/Assertion/Processor.php
index 306567bab..e131bfa43 100644
--- a/src/SAML2/Assertion/Processor.php
+++ b/src/SAML2/Assertion/Processor.php
@@ -5,7 +5,6 @@
 namespace SAML2\Assertion;
 
 use Psr\Log\LoggerInterface;
-
 use SAML2\Assertion;
 use SAML2\Assertion\Exception\InvalidAssertionException;
 use SAML2\Assertion\Exception\InvalidSubjectConfirmationException;
@@ -15,7 +14,6 @@
 use SAML2\Configuration\IdentityProvider;
 use SAML2\EncryptedAssertion;
 use SAML2\Response\Exception\InvalidSignatureException;
-use SAML2\Response\Exception\UnencryptedAssertionFoundException;
 use SAML2\Signature\Validator;
 use SAML2\Utilities\ArrayCollection;
 
@@ -95,7 +93,13 @@ public function decryptAssertions(ArrayCollection $assertions)
     {
         $decrypted = new ArrayCollection();
         foreach ($assertions->getIterator() as $assertion) {
-            $decrypted->add($this->decryptAssertion($assertion));
+            if ($assertion instanceof EncryptedAssertion) {
+                $decrypted->add($this->decryptAssertion($assertion));
+            } elseif ($assertion instanceof Assertion) {
+                $decrypted->add($assertion);
+            } else {
+                throw new InvalidAssertionException('The assertion must be of type: EncryptedAssertion or Assertion');
+            }
         }
 
         return $decrypted;
diff --git a/tests/SAML2/Assertion/ProcessorTest.php b/tests/SAML2/Assertion/ProcessorTest.php
new file mode 100644
index 000000000..2a37a9567
--- /dev/null
+++ b/tests/SAML2/Assertion/ProcessorTest.php
@@ -0,0 +1,81 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SAML2\Assertion;
+
+use Mockery as m;
+use Mockery\Adapter\Phpunit\MockeryTestCase;
+
+/**
+ * @runTestsInSeparateProcesses
+ */
+class ProcessorTest extends MockeryTestCase
+{
+    /**
+     * @var Processor
+     */
+    private $processor;
+
+    /**
+     * @var m\MockInterface&Decrypter
+     */
+    private $decrypter;
+
+    protected function setUp(): void
+    {
+        $this->decrypter = m::mock(Decrypter::class);
+        $validator = m::mock(\SAML2\Signature\Validator::class);
+        $assertionValidator = m::mock(\SAML2\Assertion\Validation\AssertionValidator::class);
+        $subjectConfirmationValidator = m::mock(\SAML2\Assertion\Validation\SubjectConfirmationValidator::class);
+        $transformer = m::mock(\SAML2\Assertion\Transformer\Transformer::class);
+        $identityProvider = new \SAML2\Configuration\IdentityProvider([]);
+        $logger = m::mock(\Psr\Log\LoggerInterface::class);
+
+        $this->processor = new Processor(
+            $this->decrypter,
+            $validator,
+            $assertionValidator,
+            $subjectConfirmationValidator,
+            $transformer,
+            $identityProvider,
+            $logger
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function processor_correctly_encrypts_assertions(): void
+    {
+        $testData = [
+            [new \SAML2\Assertion()],
+            [new \SAML2\EncryptedAssertion()],
+            [new \SAML2\Assertion(), new \SAML2\EncryptedAssertion(), new \SAML2\Assertion()],
+            [new \SAML2\EncryptedAssertion(), new \SAML2\EncryptedAssertion(), new \SAML2\EncryptedAssertion()],
+        ];
+
+        foreach ($testData as $assertions) {
+            $this->decrypter
+                ->shouldReceive('decrypt')
+                ->andReturn(new \SAML2\Assertion());
+
+            $collection = new \SAML2\Utilities\ArrayCollection($assertions);
+            $result = $this->processor->decryptAssertions($collection);
+            self::assertInstanceOf(\SAML2\Utilities\ArrayCollection::class, $result);
+            foreach ($result as $assertion) {
+                self::assertInstanceOf(\SAML2\Assertion::class, $assertion);
+            }
+        }
+    }
+
+    /**
+     * @test
+     */
+    public function unsuported_assertions_are_rejected(): void
+    {
+        $this->expectException('\SAML2\Assertion\Exception\InvalidAssertionException');
+        $this->expectExceptionMessage('The assertion must be of type: EncryptedAssertion or Assertion');
+        $this->processor->decryptAssertions(new \SAML2\Utilities\ArrayCollection([new \stdClass()]));
+    }
+}