diff --git a/maxkey-common/src/main/java/org/maxkey/crypto/jwt/encryption/service/impl/RecipientJwtEncryptionAndDecryptionServiceBuilder.java b/maxkey-common/src/main/java/org/maxkey/crypto/jwt/encryption/service/impl/RecipientJwtEncryptionAndDecryptionServiceBuilder.java
index 4fde14806807f2f74bce358c16f63ead8f9d43ec..45f1330239cf4b3cd7e34b5acd2930ac9722020d 100644
--- a/maxkey-common/src/main/java/org/maxkey/crypto/jwt/encryption/service/impl/RecipientJwtEncryptionAndDecryptionServiceBuilder.java
+++ b/maxkey-common/src/main/java/org/maxkey/crypto/jwt/encryption/service/impl/RecipientJwtEncryptionAndDecryptionServiceBuilder.java
@@ -23,9 +23,11 @@ package org.maxkey.crypto.jwt.encryption.service.impl;
 import java.security.NoSuchAlgorithmException;
 import java.security.spec.InvalidKeySpecException;
 import java.text.ParseException;
-import org.apache.log4j.Logger;
 import org.maxkey.crypto.jose.keystore.JWKSetKeyStore;
 import org.maxkey.crypto.jwt.encryption.service.JwtEncryptionAndDecryptionService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import com.nimbusds.jose.JOSEException;
 import com.nimbusds.jose.jwk.JWKSet;
 
@@ -34,7 +36,7 @@ import com.nimbusds.jose.jwk.JWKSet;
  *
  */
 public class RecipientJwtEncryptionAndDecryptionServiceBuilder {
-	final static Logger logger = Logger.getLogger(RecipientJwtEncryptionAndDecryptionServiceBuilder.class);
+	final static Logger _logger = LoggerFactory.getLogger(RecipientJwtEncryptionAndDecryptionServiceBuilder.class);
 	
 	//private HttpClient httpClient = HttpClientBuilder.create().useSystemProperties().build();
 	//private HttpComponentsClientHttpRequestFactory httpFactory = new HttpComponentsClientHttpRequestFactory(httpClient);
@@ -49,11 +51,11 @@ public class RecipientJwtEncryptionAndDecryptionServiceBuilder {
 	
 	public JwtEncryptionAndDecryptionService serviceBuilder(String jwksUri){
 		
-		logger.debug("jwksUri : "+jwksUri);
+		_logger.debug("jwksUri : {}" , jwksUri);
 		
 		String jsonString ="";//= restTemplate.getForObject(jwksUri, String.class);
 		
-		logger.debug("jwks json String : "+jsonString);
+		_logger.debug("jwks json String : {}" , jsonString);
 		JwtEncryptionAndDecryptionService recipientJwtEncryptionAndDecryptionService;
 		try {
 			JWKSet jwkSet = JWKSet.parse(jsonString);
diff --git a/maxkey-common/src/main/java/org/maxkey/crypto/jwt/signer/service/impl/SymmetricSigningAndValidationServiceBuilder.java b/maxkey-common/src/main/java/org/maxkey/crypto/jwt/signer/service/impl/SymmetricSigningAndValidationServiceBuilder.java
index db47ebb0f20beedaa51d0ec99a598e854552205d..8f161401744a6f71b0b9c3872a744cc2963b50a1 100644
--- a/maxkey-common/src/main/java/org/maxkey/crypto/jwt/signer/service/impl/SymmetricSigningAndValidationServiceBuilder.java
+++ b/maxkey-common/src/main/java/org/maxkey/crypto/jwt/signer/service/impl/SymmetricSigningAndValidationServiceBuilder.java
@@ -24,8 +24,9 @@ import java.security.NoSuchAlgorithmException;
 import java.security.spec.InvalidKeySpecException;
 import java.util.Map;
 
-import org.apache.log4j.Logger;
 import org.maxkey.crypto.jwt.signer.service.JwtSigningAndValidationService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.google.common.collect.ImmutableMap;
 import com.nimbusds.jose.JOSEException;
@@ -36,7 +37,7 @@ import com.nimbusds.jose.jwk.JWK;
  * Builder Symmetric Signing Service
  */
 public class SymmetricSigningAndValidationServiceBuilder {
-	final static Logger logger = Logger.getLogger(SymmetricSigningAndValidationServiceBuilder.class);
+	final static Logger _logger = LoggerFactory.getLogger(SymmetricSigningAndValidationServiceBuilder.class);
 	public static final String SYMMETRIC_KEY = "SYMMETRIC-KEY";
 	/**
 	 * 
@@ -46,10 +47,10 @@ public class SymmetricSigningAndValidationServiceBuilder {
 	}
 	
 	public JwtSigningAndValidationService serviceBuilder(String sharedSecret){
-		logger.debug("shared Secret : "+sharedSecret);
-		logger.debug("Symmetric Id : "+SYMMETRIC_KEY);
+		_logger.debug("shared Secret : {}" , sharedSecret);
+		_logger.debug("Symmetric Id : {}" , SYMMETRIC_KEY);
 		if (sharedSecret == null) {
-			logger.error("Couldn't create symmetric SigningAndValidation");
+			_logger.error("Couldn't create symmetric SigningAndValidation");
 			return null;
 		}