Multi-factor Authentication (MFA) in FastAPI

Multi-factor Authentication (MFA) in FastAPI#

Multi-factor Authentication (MFA) is a security mechanism that requires users to verify their identity using multiple factors. These factors are typically categorized into:

  1. Something you know: A password or PIN.

  2. Something you have: A smartphone or a hardware token.

  3. Something you are: Biometrics, such as a fingerprint or facial recognition.

By combining multiple factors, MFA significantly reduces the risk of unauthorized access, even if one factor (e.g., a password) is compromised.

Advantages of MFA: - Enhanced Security: Even if passwords are stolen, attackers cannot access the system without the additional authentication factor. - Reduced Risk of Identity Theft: MFA makes it harder for attackers to impersonate users. - Compliance with Regulations: Many industries require MFA to comply with standards like GDPR or HIPAA. - User Trust: Implementing MFA shows users that their security is a priority.

This document demonstrates how to implement MFA in a FastAPI application using PyOTP for OTP generation and verification.

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Overview#

This example uses the following: - FastAPI: For building the web application. - PyOTP: For generating and verifying one-time passwords (OTPs). - Pydantic: For data validation. - SQLite: As the database for simplicity (can be replaced with other DB systems).

Step 1: Install Dependencies#

Install the required Python libraries using pip:

pip install fastapi uvicorn sqlalchemy pyotp sqlite3 pydantic

Step 2: Create the Database#

Define a simple SQLite database to store user data.

from sqlalchemy import create_engine, Column, Integer, String, Boolean
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

Base = declarative_base()
engine = create_engine("sqlite:///mfa_demo.db")
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

class User(Base):
    __tablename__ = "users"
    id = Column(Integer, primary_key=True, index=True)
    username = Column(String, unique=True, index=True)
    password = Column(String)
    otp_secret = Column(String)  # Stores the OTP secret
    is_otp_verified = Column(Boolean, default=False)

Base.metadata.create_all(bind=engine)

Step 3: Implement MFA Logic#

  1. Register Users: Allow users to register and generate a unique OTP secret.

  2. Login: Validate username and password, and then request OTP.

  3. Verify OTP: Verify the OTP provided by the user.

from fastapi import FastAPI, Depends, HTTPException
from sqlalchemy.orm import Session
import pyotp

app = FastAPI()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

@app.post("/register")
def register_user(username: str, password: str, db: Session = Depends(get_db)):
    otp_secret = pyotp.random_base32()
    new_user = User(username=username, password=password, otp_secret=otp_secret)
    db.add(new_user)
    db.commit()
    db.refresh(new_user)
    return {"message": "User registered!", "otp_secret": otp_secret}

@app.post("/login")
def login_user(username: str, password: str, db: Session = Depends(get_db)):
    user = db.query(User).filter(User.username == username).first()
    if not user or user.password != password:
        raise HTTPException(status_code=400, detail="Invalid credentials")
    return {"message": "Login successful, provide OTP"}

@app.post("/verify-otp")
def verify_otp(username: str, otp: str, db: Session = Depends(get_db)):
    user = db.query(User).filter(User.username == username).first()
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    totp = pyotp.TOTP(user.otp_secret)
    if not totp.verify(otp):
        raise HTTPException(status_code=400, detail="Invalid OTP")
    user.is_otp_verified = True
    db.commit()
    return {"message": "OTP verified successfully"}

Step 4: Test the Application#

  1. Start the Application: Run the FastAPI application using Uvicorn:

    uvicorn main:app --reload

  2. Register a User: Use a tool like Postman or cURL to register a new user:

    POST /register
{
    "username": "testuser",
    "password": "securepassword"
}

    Response:

    {
    "message": "User registered!",
    "otp_secret": "JBSWY3DPEHPK3PXP"
}

    Use the otp_secret to set up an OTP generator, such as Google Authenticator.

  3. Login: Authenticate the user using their username and password:

    POST /login
{
    "username": "testuser",
    "password": "securepassword"
}

    Response:

    {
    "message": "Login successful, provide OTP"
}

  4. Verify OTP: Verify the OTP provided by the user:

    POST /verify-otp
{
    "username": "testuser",
    "otp": "123456"
}

    Response:

    {
    "message": "OTP verified successfully"
}

Conclusion#

This demonstrates a simple implementation of Multi-factor Authentication (MFA) in FastAPI. For production-grade applications, ensure to use encrypted passwords (e.g., bcrypt) and secure storage mechanisms for secrets and sensitive data.