diff --git a/protocol.md b/protocol.md
index 0c51e1c..c7238fd 100644
--- a/protocol.md
+++ b/protocol.md
@@ -102,8 +102,8 @@ Communication between the master server and clients will be done over a WebSocke
  </thead>
  <tr>
   <td>1</td>
-  <td>Error Message</td>
-  <td>String</td>
+  <td>Error Code</td>
+  <td>Packed Unsigned Short</td>
  </tr>
 </table>
 
@@ -145,8 +145,8 @@ Communication between the master server and clients will be done over a WebSocke
  </tr>
  <tr>
   <td>2</td>
-  <td>Error Message</td>
-  <td>String</td>
+  <td>Error Code</td>
+  <td>Packed Unsigned Short</td>
  </tr>
 </table>
 
@@ -466,11 +466,16 @@ TODO: MAKE THIS SECTION NOT LOOK LIKE SHIT
 
 ### Master / Slave
 
-#### S -> M (ID 1)
+#### M -> S (ID 2)
 0x01: KEY SIZE WAS INCORRECT
 
 0x02: COULD NOT PARSE KEY
 
+#### M -> S (ID 4)
+0x01: LICENSE DATA INCORRECT
+
+0x02: LICENSE LIMIT REACHED
+
 ### Master / Client
 
 ### Slave / Client
\ No newline at end of file
diff --git a/server/src/db/_init_sql.hpp b/server/src/db/_init_sql.hpp
index 7fae755..be4a662 100644
--- a/server/src/db/_init_sql.hpp
+++ b/server/src/db/_init_sql.hpp
@@ -24,8 +24,8 @@ const std::vector<const char*> _hard_db_sql = {
     /** START MIGRATION 0 **/
     "CREATE TABLE `SERVER_LICENSES` ("
         "`KEY_ID` TEXT NOT NULL UNIQUE,"
-        "`SECRET` TEXT NOT NULL UNIQUE,"
-        "`ALLOWANCE` INTEGER NOT NULL"
+        "`SECRET` BLOB NOT NULL UNIQUE,"
+        "`ALLOWANCE` INTEGER NOT NULL DEFAULT 0"
     ");\n"
 
     "CREATE TABLE `USERS` ("
diff --git a/server/src/hosts/master.hpp b/server/src/hosts/master.hpp
index 5fe1f6c..1c75cdd 100644
--- a/server/src/hosts/master.hpp
+++ b/server/src/hosts/master.hpp
@@ -8,6 +8,8 @@
 #include "../crypto/keyex.hpp"
 #include "../crypto/cipher.hpp"
 
+#include "../db/database.hpp"
+
 namespace sosc {
 /** MASTER -> CLIENT **/
     
@@ -59,6 +61,11 @@ private:
     IntraClient sock;
     cgc::KeyExchange key;
     cgc::Cipher cipher;
+
+    bool authed;
+    int auth_attempts;
+    const int MAX_AUTH_ATTEMPTS = 3;
+    std::string license;
 };
 
 class MasterIntraPool : public Pool<MasterIntra> {
diff --git a/server/src/hosts/master_intra.cpp b/server/src/hosts/master_intra.cpp
index ab7d8a2..f128880 100644
--- a/server/src/hosts/master_intra.cpp
+++ b/server/src/hosts/master_intra.cpp
@@ -1,7 +1,10 @@
 #include "master.hpp"
+#include "../db/database.hpp"
 
 sosc::MasterIntra::MasterIntra(const IntraClient& client) {
     this->sock = client;
+    this->authed = false;
+    this->auth_attempts = 0;
 }
 
 bool sosc::MasterIntra::Process() {
@@ -36,7 +39,20 @@ bool sosc::MasterIntra::InitAttempt(sosc::Packet &pck) {
 }
 
 bool sosc::MasterIntra::Authentication(sosc::Packet &pck) {
+    if(this->authed)
+        return true;
 
+    if(!pck.Check(2, PCK_ANY, 512))
+        return this->Close(Packet(kNegativeAck, { "\x01" }));
+
+    db::Query  = db::Query::ScalarInt32(
+        "SELECT COUNT(*) FROM SERVER_LICENSES "
+        "WHERE KEY_ID = ? AND SECRET = ?"
+    );
+
+    if(isValid > 0) {
+
+    }
 }
 
 bool sosc::MasterIntra::StatusUpdate(sosc::Packet &pck) {