diff --git a/auth.cpp b/auth.cpp
new file mode 100644
index 0000000..797274e
--- /dev/null
+++ b/auth.cpp
@@ -0,0 +1,13 @@
+#include "auth.h"
+
+extern User users[];
+extern int nbUsers;
+
+int authentifier(std::string login, std::string password) {
+    for(int i = 0; i < nbUsers; i++) {
+        if(users[i].login == login && users[i].password == password) {
+            return i;
+        }
+    }
+    return -1;
+}
\ No newline at end of file