diff --git a/pom.xml b/pom.xml
index 5b2a220..7a1e4cd 100644
--- a/pom.xml
+++ b/pom.xml
@@ -185,11 +185,6 @@
   </dependencyManagement>
 
   <dependencies>
-    <dependency>
-      <groupId>eu.europa.ec.dgc</groupId>
-      <artifactId>ddcc-gateway-lib</artifactId>
-      <version>2.0.1</version>
-    </dependency>
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter</artifactId>
diff --git a/src/test/java/tng/trustnetwork/keydistribution/service/TrustedIssuerDownloadServiceImplTest.java b/src/test/java/tng/trustnetwork/keydistribution/service/TrustedIssuerDownloadServiceImplTest.java
index a42e064..23c8430 100644
--- a/src/test/java/tng/trustnetwork/keydistribution/service/TrustedIssuerDownloadServiceImplTest.java
+++ b/src/test/java/tng/trustnetwork/keydistribution/service/TrustedIssuerDownloadServiceImplTest.java
@@ -1,7 +1,6 @@
 package tng.trustnetwork.keydistribution.service;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
@@ -10,8 +9,6 @@
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.test.context.TestPropertySource;
-import eu.europa.ec.dgc.gateway.connector.DgcGatewayDownloadConnector;
-import eu.europa.ec.dgc.gateway.connector.DgcGatewayTrustedIssuerDownloadConnector;
 import tng.trustnetwork.keydistribution.entity.TrustedIssuerEntity;
 import tng.trustnetwork.keydistribution.model.TrustedIssuer;
 import tng.trustnetwork.keydistribution.repository.TrustedIssuerRepository;
@@ -21,12 +18,6 @@
 @TestPropertySource(properties = {"dgc.trustedIssuerDownloader.enabled=true"})
 class TrustedIssuerDownloadServiceImplTest {
 
-    @MockBean
-    DgcGatewayDownloadConnector dgcGatewayDownloadConnectorMock;
-
-    @MockBean
-    DgcGatewayTrustedIssuerDownloadConnector dgcGatewayDownloadConnector;
-
     @Autowired
     TrustedIssuerDownloadServiceImpl trustedIssuerDownloadService;
 
diff --git a/src/test/java/tng/trustnetwork/keydistribution/testdata/CertificateUtils.java b/src/test/java/tng/trustnetwork/keydistribution/testdata/CertificateUtils.java
new file mode 100644
index 0000000..c323c1c
--- /dev/null
+++ b/src/test/java/tng/trustnetwork/keydistribution/testdata/CertificateUtils.java
@@ -0,0 +1,108 @@
+/*-
+ * ---license-start
+ * WorldHealthOrganization / tng-key-distribution
+ * ---
+ * Copyright (C) 2021 T-Systems International GmbH and all other contributors
+ * ---
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ---license-end
+ */
+
+package tng.trustnetwork.keydistribution.testdata;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+import java.util.Arrays;
+import java.util.Base64;
+import org.bouncycastle.cert.X509CertificateHolder;
+import org.bouncycastle.jcajce.provider.asymmetric.x509.CertificateFactory;
+import org.bouncycastle.util.encoders.Hex;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+@Service
+public class CertificateUtils {
+    private static final Logger log = LoggerFactory.getLogger(CertificateUtils.class);
+    private static final byte KID_BYTE_COUNT = 8;
+    private final CertificateFactory certificateFactory = new CertificateFactory();
+
+    public CertificateUtils() {
+    }
+
+    public String getCertKid(X509Certificate x509Certificate) {
+        try {
+            byte[] hashBytes = this.calculateHashBytes(x509Certificate.getEncoded());
+            byte[] kidBytes = Arrays.copyOfRange(hashBytes, 0, 8);
+            return Base64.getEncoder().encodeToString(kidBytes);
+        } catch (NoSuchAlgorithmException | CertificateEncodingException var4) {
+            log.error("Could not calculate kid of certificate.");
+            return null;
+        }
+    }
+
+    public String getCertKid(X509CertificateHolder x509CertificateHolder) {
+        try {
+            byte[] hashBytes = this.calculateHashBytes(x509CertificateHolder.getEncoded());
+            byte[] kidBytes = Arrays.copyOfRange(hashBytes, 0, 8);
+            return Base64.getEncoder().encodeToString(kidBytes);
+        } catch (IOException | NoSuchAlgorithmException var4) {
+            log.error("Could not calculate kid of certificate.");
+            return null;
+        }
+    }
+
+    public String getCertThumbprint(X509Certificate x509Certificate) {
+        try {
+            return this.calculateHash(x509Certificate.getEncoded());
+        } catch (CertificateEncodingException | NoSuchAlgorithmException var3) {
+            log.error("Could not calculate thumbprint of certificate.");
+            return null;
+        }
+    }
+
+    public String getCertThumbprint(X509CertificateHolder x509CertificateHolder) {
+        try {
+            return this.calculateHash(x509CertificateHolder.getEncoded());
+        } catch (NoSuchAlgorithmException | IOException var3) {
+            log.error("Could not calculate thumbprint of certificate.");
+            return null;
+        }
+    }
+
+    public X509CertificateHolder convertCertificate(X509Certificate inputCertificate) throws CertificateEncodingException, IOException {
+        return new X509CertificateHolder(inputCertificate.getEncoded());
+    }
+
+    public X509Certificate convertCertificate(X509CertificateHolder inputCertificate) throws CertificateException {
+        try {
+            return (X509Certificate)this.certificateFactory.engineGenerateCertificate(new ByteArrayInputStream(inputCertificate.getEncoded()));
+        } catch (IOException var3) {
+            throw new CertificateException(var3.getMessage(), var3.getCause());
+        }
+    }
+
+    public String calculateHash(byte[] data) throws NoSuchAlgorithmException {
+        byte[] certHashBytes = MessageDigest.getInstance("SHA-256").digest(data);
+        return Hex.toHexString(certHashBytes);
+    }
+
+    private byte[] calculateHashBytes(byte[] data) throws NoSuchAlgorithmException {
+        return MessageDigest.getInstance("SHA-256").digest(data);
+    }
+}
diff --git a/src/test/java/tng/trustnetwork/keydistribution/testdata/SignerInformationTestHelper.java b/src/test/java/tng/trustnetwork/keydistribution/testdata/SignerInformationTestHelper.java
index bcdd6c9..05e38ff 100644
--- a/src/test/java/tng/trustnetwork/keydistribution/testdata/SignerInformationTestHelper.java
+++ b/src/test/java/tng/trustnetwork/keydistribution/testdata/SignerInformationTestHelper.java
@@ -20,7 +20,6 @@
 
 package tng.trustnetwork.keydistribution.testdata;
 
-import eu.europa.ec.dgc.utils.CertificateUtils;
 import tng.trustnetwork.keydistribution.entity.SignerInformationEntity;
 import tng.trustnetwork.keydistribution.model.TrustListItem;
 import tng.trustnetwork.keydistribution.repository.SignerInformationRepository;