diff --git a/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/DiscussionDTO.java b/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/DiscussionDTO.java
index 7b4d4f8..cd7f3cf 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/DiscussionDTO.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/DiscussionDTO.java
@@ -1,5 +1,13 @@
 package ovh.herisson.Clyde.DTO.Msg;
 
+/******************************************************
+ * @file DiscussionDTO.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * File to format a discussion using messageDTO 
+ ******************************************************/
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;
diff --git a/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/MessagesDTO.java b/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/MessagesDTO.java
index d9dfd14..2ce0228 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/MessagesDTO.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/DTO/Msg/MessagesDTO.java
@@ -1,5 +1,13 @@
 package ovh.herisson.Clyde.DTO.Msg;
 
+/******************************************************
+ * @file MessagesDTO.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * File to Format the response adding the sender field
+ ******************************************************/
+
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import ovh.herisson.Clyde.Tables.User;
diff --git a/backend/src/main/java/ovh/herisson/Clyde/EndPoints/Msg/MessagesController.java b/backend/src/main/java/ovh/herisson/Clyde/EndPoints/Msg/MessagesController.java
index 591e172..9f1db44 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/EndPoints/Msg/MessagesController.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/EndPoints/Msg/MessagesController.java
@@ -1,5 +1,13 @@
 package ovh.herisson.Clyde.EndPoints.Msg;
 
+/******************************************************
+ * @file MessagesController.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * Entry point for the messages application
+ ******************************************************/
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -48,6 +56,10 @@ public class MessagesController {
 
 	@GetMapping("/discussion/{id}")
 	public ResponseEntity<DiscussionDTO> getDiscussion(@RequestHeader("Authorization") String token, @PathVariable long id){
+		User user = authServ.getUserFromToken(token);
+		if(user == null || !discServ.hasDiscussion(user, id) ){
+			return new UnauthorizedResponse<>(null);
+		}
 		return new ResponseEntity<>(DiscussionDTO.construct(discRepo.findById(id).orElse(null), authServ.getUserFromToken(token)), HttpStatus.OK);
 	} 
 
diff --git a/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/DiscussionRepository.java b/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/DiscussionRepository.java
index 3e74cb4..9b2675b 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/DiscussionRepository.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/DiscussionRepository.java
@@ -1,5 +1,14 @@
 package ovh.herisson.Clyde.Repositories.Msg;
 
+/******************************************************
+ * @file DiscussionRepository.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * Repository of Discussion allowing to fetch discussion by user 
+ ******************************************************/
+
+
 import java.util.List;
 
 import org.springframework.data.jpa.repository.Query;
diff --git a/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/MessageRepository.java b/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/MessageRepository.java
index 8c90e92..021ac79 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/MessageRepository.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/Repositories/Msg/MessageRepository.java
@@ -1,8 +1,14 @@
 package ovh.herisson.Clyde.Repositories.Msg;
 
+/******************************************************
+ * @file MessageRepository.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ ******************************************************/
+
+
 import org.springframework.data.repository.CrudRepository;
 
 import ovh.herisson.Clyde.Tables.Msg.Message;
 
-public interface MessageRepository extends CrudRepository<Message, Long> {
-}
+public interface MessageRepository extends CrudRepository<Message, Long> {}
diff --git a/backend/src/main/java/ovh/herisson/Clyde/Services/Msg/DiscussionService.java b/backend/src/main/java/ovh/herisson/Clyde/Services/Msg/DiscussionService.java
index c1aa534..9a471da 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/Services/Msg/DiscussionService.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/Services/Msg/DiscussionService.java
@@ -1,5 +1,16 @@
 package ovh.herisson.Clyde.Services.Msg;
 
+import java.util.List;
+
+/******************************************************
+ * @file DiscussionService.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * Various function utilised by the messages application
+ ******************************************************/
+
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
@@ -20,12 +31,27 @@ public class DiscussionService {
 		return discRepo.save(new Discussion(name, author));
 	}
 
+	/**
+	 * list discussions owned by a certain user
+	 */
 	public Iterable<Discussion> getOwned(User author){
 		return discRepo.findByMembership(author.getRegNo());
 	}
 
+	/**
+	 * Create a message and link it to it's discussion
+	 */
 	public Discussion CreateMessage(Discussion disc, Message msg){
 		disc.addMessage(msg);
 		return discRepo.save(disc);
 	}
+
+	/**
+	 * Check if a user is in a discussion
+	 */
+    public boolean hasDiscussion(User user, long id) {
+		Discussion disc = discRepo.findById(id).orElse(null);
+		List<User> members = disc.getMembers();
+		return members.contains(user);
+    }
 }
diff --git a/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Discussion.java b/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Discussion.java
index ee0912e..4d76d5f 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Discussion.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Discussion.java
@@ -1,5 +1,15 @@
 package ovh.herisson.Clyde.Tables.Msg;
 
+/******************************************************
+ * @file Discussion.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * Discussion allow to regroupe multiple user in and message together
+ * for the messages application to work
+ ******************************************************/
+
+
 import java.util.List;
 
 import jakarta.persistence.CascadeType;
diff --git a/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Message.java b/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Message.java
index 246d92c..2afa6ba 100644
--- a/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Message.java
+++ b/backend/src/main/java/ovh/herisson/Clyde/Tables/Msg/Message.java
@@ -1,5 +1,14 @@
 package ovh.herisson.Clyde.Tables.Msg;
 
+/******************************************************
+ * @file Message.java
+ * @author Anthony Debucquoy
+ * @scope Extension messagerie
+ *
+ * Represent a message sent to a discussion
+ ******************************************************/
+
+
 import org.hibernate.annotations.CreationTimestamp;
 import org.hibernate.annotations.UpdateTimestamp;