diff --git a/api/BusinessLogic/Attachments/AttachmentHandler.php b/api/BusinessLogic/Attachments/AttachmentHandler.php
index c61a109d..04a73e42 100644
--- a/api/BusinessLogic/Attachments/AttachmentHandler.php
+++ b/api/BusinessLogic/Attachments/AttachmentHandler.php
@@ -3,14 +3,48 @@
 namespace BusinessLogic\Attachments;
 
 
-class AttachmentHandler {
+use BusinessLogic\Exceptions\ValidationException;
+use BusinessLogic\ValidationModel;
 
+class AttachmentHandler {
 
+    /**
+     * @param $createAttachmentModel CreateAttachmentForTicketModel
+     */
     function createAttachmentForTicket($createAttachmentModel) {
-
+        $this->validate($createAttachmentModel);
     }
 
+    /**
+     * @param $createAttachmentModel CreateAttachmentForTicketModel
+     * @throws ValidationException
+     */
     private function validate($createAttachmentModel) {
-
+        $errorKeys = array();
+        if ($createAttachmentModel->attachmentContents === null ||
+            trim($createAttachmentModel->attachmentContents) === '') {
+            $errorKeys[] = 'CONTENTS_EMPTY';
+        }
+
+        if (base64_decode($createAttachmentModel->attachmentContents, true) === false) {
+            $errorKeys[] = 'CONTENTS_NOT_BASE_64';
+        }
+
+        if ($createAttachmentModel->displayName === null ||
+            trim($createAttachmentModel->displayName === '')) {
+            $errorKeys[] = 'DISPLAY_NAME_EMPTY';
+        }
+
+        if ($createAttachmentModel->ticketId === null ||
+            $createAttachmentModel->ticketId < 1) {
+            $errorKeys[] = 'TICKET_ID_MISSING';
+        }
+
+        if (count($errorKeys) > 0) {
+            $validationModel = new ValidationModel();
+            $validationModel->errorKeys = $errorKeys;
+            $validationModel->valid = false;
+            throw new ValidationException($validationModel);
+        }
     }
 }
\ No newline at end of file
diff --git a/api/BusinessLogic/Attachments/CreateAttachmentModel.php b/api/BusinessLogic/Attachments/CreateAttachmentModel.php
index 209450d2..9a5f5428 100644
--- a/api/BusinessLogic/Attachments/CreateAttachmentModel.php
+++ b/api/BusinessLogic/Attachments/CreateAttachmentModel.php
@@ -13,6 +13,6 @@ class CreateAttachmentModel {
     /* @var $id int */
     public $fileSize;
 
-    /* @var $attachmentContents string [base64-encoded] */
+    /* @var $attachmentContents string */
     public $attachmentContents;
 }
\ No newline at end of file
diff --git a/api/Tests/BusinessLogic/Attachments/AttachmentHandlerTest.php b/api/Tests/BusinessLogic/Attachments/AttachmentHandlerTest.php
index 335b3b88..e956e321 100644
--- a/api/Tests/BusinessLogic/Attachments/AttachmentHandlerTest.php
+++ b/api/Tests/BusinessLogic/Attachments/AttachmentHandlerTest.php
@@ -4,6 +4,7 @@
 namespace BusinessLogic\Attachments;
 
 
+use BusinessLogic\Exceptions\ValidationException;
 use PHPUnit\Framework\TestCase;
 
 class AttachmentHandlerTest extends TestCase {
@@ -11,7 +12,98 @@ class AttachmentHandlerTest extends TestCase {
     /* @var $attachmentHandler AttachmentHandler */
     private $attachmentHandler;
 
+    /* @var $createAttachmentModel CreateAttachmentForTicketModel */
+    private $createAttachmentForTicketModel;
+
     protected function setUp() {
         $this->attachmentHandler = new AttachmentHandler();
+        $this->createAttachmentForTicketModel = new CreateAttachmentForTicketModel();
+        $this->createAttachmentForTicketModel->attachmentContents = base64_encode('string');
+        $this->createAttachmentForTicketModel->displayName = 'Display Name';
+        $this->createAttachmentForTicketModel->ticketId = 1;
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheAttachmentBodyIsNull() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->attachmentContents = null;
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/CONTENTS_EMPTY/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheAttachmentBodyIsEmpty() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->attachmentContents = '';
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/CONTENTS_EMPTY/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheAttachmentBodyIsInvalidBase64() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->attachmentContents = 'invalid base 64';
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/CONTENTS_NOT_BASE_64/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheDisplayNameIsNull() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->displayName = null;
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/DISPLAY_NAME_EMPTY/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheDisplayNameIsEmpty() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->displayName = '';
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/DISPLAY_NAME_EMPTY/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheTicketIdIsNull() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->ticketId = null;
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/TICKET_ID_MISSING/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
+    }
+
+    function testThatValidateThrowsAnExceptionWhenTheTicketIdIsANonPositiveInteger() {
+        //-- Arrange
+        $this->createAttachmentForTicketModel->ticketId = 0;
+
+        //-- Assert
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessageRegExp('/TICKET_ID_MISSING/');
+
+        //-- Act
+        $this->attachmentHandler->createAttachmentForTicket($this->createAttachmentForTicketModel);
     }
 }