diff --git a/src/main/java/cz/trask/adfs/AdfsAuthMsConstants.java b/src/main/java/cz/trask/adfs/AdfsAuthMsConstants.java
new file mode 100644
index 0000000..da9591f
--- /dev/null
+++ b/src/main/java/cz/trask/adfs/AdfsAuthMsConstants.java
@@ -0,0 +1,39 @@
+package cz.trask.adfs;
+
+public final class AdfsAuthMsConstants {
+
+    public static final String AUTH_PREFIX_BEARER = "Bearer ";
+    public static final String HEADER_AUTHORIZATION = "Authorization";
+
+    // Error codes
+    public static final String ERR_SERVER_ERROR = "server_error";
+    public static final String ERR_TOO_MANY_REQUESTS = "too_many_requests";
+    public static final String ERR_INVALID_CONFIG = "invalid_configuration";
+    public static final String ERR_PROCESS_FAILED = "process_failed";
+
+    // AdfsTokenService constants
+    public static final String PARAM_RESOURCE = "resource";
+    public static final String PARAM_CLIENT_ID = "client_id";
+    public static final String PARAM_CLIENT_ASSERTION_TYPE = "client_assertion_type";
+    public static final String PARAM_CLIENT_ASSERTION = "client_assertion";
+    public static final String PARAM_GRANT_TYPE = "grant_type";
+
+    public static final String GRANT_TYPE_CLIENT_CREDENTIALS = "client_credentials";
+    public static final String CLIENT_ASSERTION_TYPE = "urn:ietf:params:oauth:client-assertion-type:jwt-bearer";
+
+    public static final String HEADER_CONTENT_TYPE = "Content-Type";
+    public static final String CONTENT_TYPE_FORM = "application/x-www-form-urlencoded";
+    public static final String METHOD_POST = "POST";
+
+    // Config validation names
+    public static final String CFG_TOKEN_URL = "tokenUrl";
+    public static final String CFG_AUDIENCE = "audience";
+    public static final String CFG_RESOURCE = "resource";
+    public static final String CFG_CLIENT_IDS = "clientIds";
+    public static final String CFG_CERTIFICATE = "certificate";
+    public static final String CFG_PRIVATE_KEY = "privateKey";
+
+    // SSL System properties
+    public static final String PROP_TRUST_STORE = "javax.net.ssl.trustStore";
+    public static final String PROP_TRUST_STORE_PASSWORD = "javax.net.ssl.trustStorePassword";
+}
diff --git a/src/main/java/cz/trask/adfs/AdfsAuthMsServer.java b/src/main/java/cz/trask/adfs/AdfsAuthMsServer.java
index da850c6..a91ca13 100644
--- a/src/main/java/cz/trask/adfs/AdfsAuthMsServer.java
+++ b/src/main/java/cz/trask/adfs/AdfsAuthMsServer.java
@@ -23,6 +23,7 @@ import cz.trask.adfs.config.AppConfig.ContextConfig;
 import cz.trask.adfs.config.ConfigurationManager;
 import cz.trask.adfs.context.BaseContextHandler;
 import cz.trask.adfs.service.AdfsTokenService;
+import static cz.trask.adfs.AdfsAuthMsConstants.*;
 
 public class AdfsAuthMsServer {
 
@@ -69,10 +70,10 @@ public class AdfsAuthMsServer {
 
     private void applySslTrustProperties(AppConfig config) {
         if (config.getTrustStore() != null && !config.getTrustStore().isBlank()) {
-            logger.info("Setting javax.net.ssl.trustStore to {}", config.getTrustStore());
-            System.setProperty("javax.net.ssl.trustStore", config.getTrustStore());
+            logger.info("Setting {} to {}", PROP_TRUST_STORE, config.getTrustStore());
+            System.setProperty(PROP_TRUST_STORE, config.getTrustStore());
             if (config.getTrustStorePassword() != null) {
-                System.setProperty("javax.net.ssl.trustStorePassword", config.getTrustStorePassword());
+                System.setProperty(PROP_TRUST_STORE_PASSWORD, config.getTrustStorePassword());
             }
         }
     }
diff --git a/src/main/java/cz/trask/adfs/context/ProcessHandler.java b/src/main/java/cz/trask/adfs/context/ProcessHandler.java
index 99708e6..72ced5f 100644
--- a/src/main/java/cz/trask/adfs/context/ProcessHandler.java
+++ b/src/main/java/cz/trask/adfs/context/ProcessHandler.java
@@ -13,16 +13,10 @@ import com.sun.net.httpserver.Headers;
 import com.sun.net.httpserver.HttpExchange;
 
 import cz.trask.adfs.dto.TokenPayloadIdp;
+import static cz.trask.adfs.AdfsAuthMsConstants.*;
 
 public class ProcessHandler extends BaseContextHandler {
 
-    private static final String AUTH_PREFIX_BEARER = "Bearer ";
-    
-    private static final String ERR_SERVER_ERROR = "server_error";
-    private static final String ERR_TOO_MANY_REQUESTS = "too_many_requests";
-    private static final String ERR_INVALID_CONFIG = "invalid_configuration";
-    private static final String ERR_PROCESS_FAILED = "process_failed";
-
     private final AtomicInteger clientIdIndex = new AtomicInteger(0);
 
     @Override
diff --git a/src/main/java/cz/trask/adfs/service/AdfsTokenService.java b/src/main/java/cz/trask/adfs/service/AdfsTokenService.java
index d1e083a..53e744d 100644
--- a/src/main/java/cz/trask/adfs/service/AdfsTokenService.java
+++ b/src/main/java/cz/trask/adfs/service/AdfsTokenService.java
@@ -33,25 +33,12 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 
 import cz.trask.adfs.config.AdfsConfig;
 import cz.trask.adfs.dto.TokenPayloadIdp;
+import static cz.trask.adfs.AdfsAuthMsConstants.*;
 
 public class AdfsTokenService {
 
     private static final Logger logger = LogManager.getLogger(AdfsTokenService.class);
 
-    private static final String PARAM_RESOURCE = "resource";
-    private static final String PARAM_CLIENT_ID = "client_id";
-    private static final String PARAM_CLIENT_ASSERTION_TYPE = "client_assertion_type";
-    private static final String PARAM_CLIENT_ASSERTION = "client_assertion";
-    private static final String PARAM_GRANT_TYPE = "grant_type";
-
-    private static final String GRANT_TYPE_CLIENT_CREDENTIALS = "client_credentials";
-    private static final String CLIENT_ASSERTION_TYPE =
-            "urn:ietf:params:oauth:client-assertion-type:jwt-bearer";
-
-    private static final String HEADER_CONTENT_TYPE = "Content-Type";
-    private static final String CONTENT_TYPE_FORM = "application/x-www-form-urlencoded";
-    private static final String METHOD_POST = "POST";
-
     private final AdfsConfig config;
     private final ObjectMapper objectMapper;
 
@@ -258,14 +245,14 @@ public class AdfsTokenService {
     }
 
     private void validateConfig() {
-        requireValue(config.getTokenUrl(), "tokenUrl");
-        requireValue(config.getAudience(), "audience");
-        requireValue(config.getResource(), "resource");
+        requireValue(config.getTokenUrl(), CFG_TOKEN_URL);
+        requireValue(config.getAudience(), CFG_AUDIENCE);
+        requireValue(config.getResource(), CFG_RESOURCE);
         if (config.getClientIds() == null || config.getClientIds().isEmpty()) {
-            throw new IllegalArgumentException("Missing or empty config value: clientIds");
+            throw new IllegalArgumentException("Missing or empty config value: " + CFG_CLIENT_IDS);
         }
-        requireValue(config.getCertificate(), "certificate");
-        requireValue(config.getPrivateKey(), "privateKey");
+        requireValue(config.getCertificate(), CFG_CERTIFICATE);
+        requireValue(config.getPrivateKey(), CFG_PRIVATE_KEY);
     }
 
     private void requireValue(String value, String name) {