diff --git a/readme.md b/readme.md
index 53c24d2..5aa59d5 100644
--- a/readme.md
+++ b/readme.md
@@ -97,7 +97,7 @@ $documentRegistory->register($cXml);
 ### Process incoming cXML documents
 
 ```php
-$headerProcessor = new \CXml\Processor\HeaderProcessor($credentialRegistry);
+$headerProcessor = new \CXml\Processor\HeaderProcessor($credentialRegistry, $credentialRegistry, $credentialRegistry);
 
 $cXmlProcessor = new \CXml\Processor\Processor(
   $headerProcessor, 
@@ -119,7 +119,7 @@ $handlerRegistry = new \CXml\Handler\HandlerRegistry();
 
 $builder = \CXml\Builder::create();
 
-$headerProcessor = new \CXml\Processor\HeaderProcessor($credentialRegistry, $credentialRegistry);
+$headerProcessor = new \CXml\Processor\HeaderProcessor($credentialRegistry, $credentialRegistry, $credentialRegistry);
 $cXmlProcessor = new \CXml\Processor\Processor(
   $headerProcessor, 
   $handlerRegistry,
diff --git a/src/CXml/Credential/CredentialValidatorInterface.php b/src/CXml/Credential/CredentialValidatorInterface.php
new file mode 100644
index 0000000..224d3c1
--- /dev/null
+++ b/src/CXml/Credential/CredentialValidatorInterface.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace CXml\Credential;
+
+use CXml\Exception\CXmlCredentialInvalidException;
+use CXml\Model\Credential;
+
+interface CredentialValidatorInterface
+{
+    /**
+     * @throws CXmlCredentialInvalidException
+     */
+    public function validate(Credential $credential): void;
+}
diff --git a/src/CXml/Credential/Registry.php b/src/CXml/Credential/Registry.php
index 7b07141..243e321 100644
--- a/src/CXml/Credential/Registry.php
+++ b/src/CXml/Credential/Registry.php
@@ -9,7 +9,7 @@
 use CXml\Model\Credential;
 use CXml\Model\Header;
 
-class Registry implements CredentialRepositoryInterface, AuthenticatorInterface
+class Registry implements CredentialRepositoryInterface, AuthenticatorInterface, CredentialValidatorInterface
 {
     /**
      * @var Credential[]
@@ -52,4 +52,16 @@ public function authenticate(Header $header, Context $context): void
             throw new CXmlAuthenticationInvalidException($senderCredential);
         }
     }
+
+    /**
+     * @throws CXmlCredentialInvalidException
+     */
+    public function validate(Credential $credential): void
+    {
+        // provoke an exception if credential was not found
+        $this->getCredentialByDomainAndId(
+            $credential->getDomain(),
+            $credential->getIdentity()
+        );
+    }
 }
diff --git a/src/CXml/Processor/HeaderProcessor.php b/src/CXml/Processor/HeaderProcessor.php
index a72168f..1c69f78 100644
--- a/src/CXml/Processor/HeaderProcessor.php
+++ b/src/CXml/Processor/HeaderProcessor.php
@@ -5,19 +5,24 @@
 use CXml\Authentication\AuthenticatorInterface;
 use CXml\Context;
 use CXml\Credential\CredentialRepositoryInterface;
+use CXml\Credential\CredentialValidatorInterface;
 use CXml\Exception\CXmlAuthenticationInvalidException;
 use CXml\Exception\CXmlCredentialInvalidException;
-use CXml\Model\Credential;
 use CXml\Model\Header;
 
 class HeaderProcessor
 {
     private CredentialRepositoryInterface $credentialRepository;
+    private CredentialValidatorInterface $credentialValidator;
     private AuthenticatorInterface $authenticator;
 
-    public function __construct(CredentialRepositoryInterface $credentialRepository, AuthenticatorInterface $authenticator)
-    {
+    public function __construct(
+        CredentialRepositoryInterface $credentialRepository,
+        CredentialValidatorInterface $credentialValidator,
+        AuthenticatorInterface $authenticator
+    ) {
         $this->credentialRepository = $credentialRepository;
+        $this->credentialValidator = $credentialValidator;
         $this->authenticator = $authenticator;
     }
 
@@ -37,22 +42,10 @@ public function process(Header $header, Context $context): void
      */
     private function validatePartys(Header $header): void
     {
-        $this->checkCredentialIsValid($header->getFrom()->getCredential());
-
-        $this->checkCredentialIsValid($header->getTo()->getCredential());
+        $this->credentialValidator->validate($header->getFrom()->getCredential());
 
-        $this->checkCredentialIsValid($header->getSender()->getCredential());
-    }
+        $this->credentialValidator->validate($header->getTo()->getCredential());
 
-    /**
-     * @throws CXmlCredentialInvalidException
-     */
-    private function checkCredentialIsValid(Credential $testCredential): void
-    {
-        // provoke an exception if credential was not found
-        $this->credentialRepository->getCredentialByDomainAndId(
-            $testCredential->getDomain(),
-            $testCredential->getIdentity()
-        );
+        $this->credentialValidator->validate($header->getSender()->getCredential());
     }
 }