diff --git a/iam-login-service/src/main/java/it/infn/mw/iam/api/requests/exception/GroupRequestValidationError.java b/iam-login-service/src/main/java/it/infn/mw/iam/api/requests/exception/GroupRequestValidationError.java
index 7c0475d79..205959e3d 100644
--- a/iam-login-service/src/main/java/it/infn/mw/iam/api/requests/exception/GroupRequestValidationError.java
+++ b/iam-login-service/src/main/java/it/infn/mw/iam/api/requests/exception/GroupRequestValidationError.java
@@ -22,4 +22,4 @@ public class GroupRequestValidationError extends IllegalArgumentException {
   public GroupRequestValidationError(String message) {
     super(message);
   }
-}
\ No newline at end of file
+}
diff --git a/iam-login-service/src/test/java/it/infn/mw/iam/test/api/aup/AupIntegrationTests.java b/iam-login-service/src/test/java/it/infn/mw/iam/test/api/aup/AupIntegrationTests.java
index 960972666..281c8c230 100644
--- a/iam-login-service/src/test/java/it/infn/mw/iam/test/api/aup/AupIntegrationTests.java
+++ b/iam-login-service/src/test/java/it/infn/mw/iam/test/api/aup/AupIntegrationTests.java
@@ -65,9 +65,9 @@ public class AupIntegrationTests extends AupTestSupport {
   private final String INVALID_AUP_URL =
       "https://iam.local.io/\"</script><script>alert(8);</script>";
 
-  private final static String DEFAULT_AUP_TEXT = null;
-  private final static String DEFAULT_AUP_URL = "http://updated-aup-text.org/";
-  private final static String DEFAULT_AUP_DESC = "desc";
+  private static final String DEFAULT_AUP_TEXT = null;
+  private static final String DEFAULT_AUP_URL = "http://updated-aup-text.org/";
+  private static final String DEFAULT_AUP_DESC = "desc";
 
 
   @Autowired
diff --git a/iam-persistence/pom.xml b/iam-persistence/pom.xml
index ac8ddf060..cfac508e3 100644
--- a/iam-persistence/pom.xml
+++ b/iam-persistence/pom.xml
@@ -44,11 +44,6 @@
       <artifactId>spring-boot-starter-validation</artifactId>
     </dependency>
 
-    <dependency>
-      <groupId>org.springframework.boot</groupId>
-      <artifactId>spring-boot-starter-validation</artifactId>
-    </dependency>
-
     <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-jpa</artifactId>
diff --git a/iam-persistence/src/main/java/it/infn/mw/iam/persistence/repository/IamX509CertificateRepository.java b/iam-persistence/src/main/java/it/infn/mw/iam/persistence/repository/IamX509CertificateRepository.java
new file mode 100644
index 000000000..7ce6d4ed7
--- /dev/null
+++ b/iam-persistence/src/main/java/it/infn/mw/iam/persistence/repository/IamX509CertificateRepository.java
@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) Istituto Nazionale di Fisica Nucleare (INFN). 2016-2021
+ *
+ * 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.
+ */
+package it.infn.mw.iam.persistence.repository;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.repository.query.Param;
+
+import it.infn.mw.iam.persistence.model.IamAccount;
+import it.infn.mw.iam.persistence.model.IamX509Certificate;
+
+public interface IamX509CertificateRepository
+    extends PagingAndSortingRepository<IamX509Certificate, Long> {
+
+  @Query("select c.account from IamX509Certificate c where c.subjectDn = :subject")
+  List<IamAccount> findBySubjectDn(@Param("subject") String subject);
+
+  public Optional<IamX509Certificate> findBySubjectDnAndIssuerDn(String subjectDn, String issuerDn);
+
+}
\ No newline at end of file