diff --git a/main.py b/main.py
index 443a027..5a6607c 100644
--- a/main.py
+++ b/main.py
@@ -1,11 +1,11 @@
 import sys
 import atexit
 import signal
-from typing import Union
+from typing import Union, Annotated
 
 from contextlib import asynccontextmanager
 
-from fastapi import FastAPI, Request
+from fastapi import FastAPI, Request, Header
 from fastapi.middleware.cors import CORSMiddleware
 
 from pydantic import BaseModel
@@ -110,16 +110,46 @@ def postlogin(body: loginBody, request: Request):
     try:
         if userHandler.checkUserExistence(dbConnection, body.username):
             userID = userHandler.getIDByUsername(dbConnection, body.username)
-            if securityHandler.handlePassword(dbConnection, body.password, userID):
+            if securityHandler.handlePasswordVerification(dbConnection, body.password, userID):
                 return {"success": True, "authToken": tokenHandler.createToken(dbConnection, userID, body.rememberMe, request.client.host), "message": "User login success!"}
             else:
-                return {"success": False, "authToken": "none", "message": "User login failed! Please check your password."}
+                return {"success": False, "authToken": None, "message": "User login failed! Please check your password."}
         else:
-            return {"success": False, "authToken": "none", "message": "User login failed! User does not exist."}
+            return {"success": False, "authToken": None, "message": "User login failed! User does not exist."}
     except Exception as error:
         msg = "User login failed! Unexpected server error. " + repr(error)
         print(msg)
-        return {"success": False, "authToken": "none", "message": msg}
+        return {"success": False, "authToken": None, "message": msg}
+
+@app.get("/api/userIDByAuthToken")
+def getuserIDByAuthToken(authToken: Annotated[str | None, Header()] = None):
+    try:
+        if tokenHandler.validateTokenExistence(dbConnection, authToken):
+            userID = userHandler.getIDByAuthToken(dbConnection, authToken)
+            return {"success": True, "userID": userID, "message": "Get userID by authToken succeeded!"}
+        else:
+            return {"success": False, "userID": None, "message": "Get userID by authToken failed! authToken provided is not valid."}
+    except Exception as error:
+        msg = "Get userID by authToken failed! Unexpected server error. " + repr(error)
+        print(msg)
+        return {"success": False, "authToken": None, "message": msg}
+
+
+# GET
+# /api/userByAuthToken
+# - userID
+# /api/publicInfo/{userID}
+# - username
+# - firstname
+# - lastname
+# - profile picture
+# - location
+# - public email (For contact)
+# /api/privateInfo/{userID}
+# - private email (For authentication/login)
+
+# POST
+# /api/changeInfo/{infotype}
 
 @app.get("/api")
 def getapi():
diff --git a/requirements.txt b/requirements.txt
index 62b7f2c..905416b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,10 +1,14 @@
 annotated-types==0.6.0
 anyio==4.3.0
+argon2-cffi==23.1.0
+argon2-cffi-bindings==21.2.0
+cffi==1.16.0
 click==8.1.7
 fastapi==0.110.1
 h11==0.14.0
 idna==3.7
 psycopg2-binary==2.9.9
+pycparser==2.22
 pydantic==2.7.0
 pydantic_core==2.18.1
 sniffio==1.3.1
diff --git a/securityHandler.py b/securityHandler.py
index 8ed9896..6b8513f 100644
--- a/securityHandler.py
+++ b/securityHandler.py
@@ -34,7 +34,7 @@ def verifyRehash(hash: str) -> bool:
     except:
         return False
 
-def handlePassword(dbConnection: psycopg2.extensions.connection, password: str, userID: int) -> bool:
+def handlePasswordVerification(dbConnection: psycopg2.extensions.connection, password: str, userID: int) -> bool:
     hash = userHandler.getHashValueByUserID(dbConnection, userID)
     userIDstr = str(userID)
     debugPrint("Now verifying password against hash for user ID " + userIDstr + "...")
diff --git a/tokenHandler.py b/tokenHandler.py
index 9a4beff..1594bf4 100644
--- a/tokenHandler.py
+++ b/tokenHandler.py
@@ -11,6 +11,9 @@ def debugPrint(msg: str) -> None:
     if debug:
         print("(TOKEN HANDLER) PRINT:  " + msg)
 
+def validateTokenExistence(dbConnection: psycopg2.extensions.connection, authToken: str) -> bool:
+    return dbHandler.checkFieldValueExistence(dbConnection, "authtokens", "token", authToken)
+
 def createToken(dbConnection: psycopg2.extensions.connection, userID: int, rememberMe: bool, locationIP: str) -> str:
     debugPrint("Now initialising new token with following attributes : userID = " + str(userID) + ", rememberMe = " + str(rememberMe) + ", locationIP = " + locationIP + "...")
     randToken = secrets.token_hex(1023)
diff --git a/userHandler.py b/userHandler.py
index a11083f..f0cf353 100644
--- a/userHandler.py
+++ b/userHandler.py
@@ -31,3 +31,12 @@ def getIDByUsername(dbConnection: psycopg2.extensions.connection, username: str)
         username=sql.Literal(username)
     )
     return int(dbHandler._execQuery(dbConnection, sanitisedQuery)[0][0])
+
+def getIDByAuthToken(dbConnection: psycopg2.extensions.connection, authToken: str) -> int:
+    debugPrint("Attempting to get ID from authToken...")
+    sanitisedQuery = sql.SQL("""
+    SELECT ownerid FROM authtokens WHERE "token" = {authToken}
+    """).format(
+        authToken=sql.Literal(authToken)
+    )
+    return int(dbHandler._execQuery(dbConnection, sanitisedQuery)[0][0])