API Authentication Best Practices: Securing Your Endpoints

API Authentication Dashboard

API authentication is the foundation of API security, controlling access and protecting sensitive resources. Implementing robust authentication requires understanding different methods, security considerations, and best practices for modern applications.

Authentication Fundamentals

API authentication verifies the identity of clients making requests to your API endpoints. Proper authentication prevents unauthorized access and ensures data security.

Core Authentication Principles

Identity Verification

Confirming the client's claimed identity
Validating credentials against trusted sources
Establishing trust relationships
Maintaining session integrity

Authorization vs Authentication

Authentication: "Who are you?"
Authorization: "What can you do?"
Clear separation of concerns
Layered security approach

Authentication vs Authorization

Common Authentication Challenges

Security Vulnerabilities

Credential theft and replay attacks
Session hijacking and fixation
Brute force and dictionary attacks
Token leakage and misuse

Scalability Issues

Session state management
Distributed system complexity
Performance impact of validation
Cross-service authentication

Authentication Methods

Different authentication methods serve various use cases and security requirements.

Basic Authentication

Implementation

Username and password in HTTP headers
Base64 encoding (not encryption)
Simple but limited security
Suitable for internal APIs only

// Express.js Basic Auth middleware
import express from 'express'
import { createHmac } from 'crypto'

const app = express()

// Basic Authentication middleware
function basicAuth(req: express.Request, res: express.Response, next: express.NextFunction) {
  const authHeader = req.headers.authorization

  if (!authHeader || !authHeader.startsWith('Basic ')) {
    res.setHeader('WWW-Authenticate', 'Basic realm="API"')
    return res.status(401).json({ error: 'Authentication required' })
  }

  const base64Credentials = authHeader.split(' ')[1]
  const credentials = Buffer.from(base64Credentials, 'base64').toString('ascii')
  const [username, password] = credentials.split(':')

  // Validate against database or service
  if (!validateUserCredentials(username, password)) {
    return res.status(401).json({ error: 'Invalid credentials' })
  }

  req.user = { username }
  next()
}

// Usage
app.get('/api/protected', basicAuth, (req, res) => {
  res.json({ message: 'Access granted', user: req.user })
})

async function validateUserCredentials(username: string, password: string): Promise<boolean> {
  // Hash password for comparison (never store plain text)
  const hashedPassword = createHmac('sha256', process.env.PASSWORD_SALT!)
    .update(password)
    .digest('hex')

  // Query database or external service
  return await checkCredentialsInDB(username, hashedPassword)
}

Security Considerations

Always use HTTPS
Implement rate limiting
Consider for development only
Not recommended for production

Bearer Token Authentication

Token-Based Approach

Stateless authentication mechanism
Tokens carry authentication information
No server-side session storage
Scalable for distributed systems

// Bearer Token middleware
interface AuthenticatedRequest extends express.Request {
  user?: { userId: string; scopes: string[] }
}

function bearerAuth(req: AuthenticatedRequest, res: express.Response, next: express.NextFunction) {
  const authHeader = req.headers.authorization

  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({ error: 'Bearer token required' })
  }

  const token = authHeader.split(' ')[1]

  try {
    // Validate and decode token
    const decoded = validateToken(token)
    req.user = decoded
    next()
  } catch (error) {
    return res.status(401).json({ error: 'Invalid token' })
  }
}

// Token validation function
function validateToken(token: string): { userId: string; scopes: string[] } {
  // Verify token signature and expiration
  const decoded = jwt.verify(token, process.env.JWT_SECRET!) as any

  // Check if token is revoked (optional)
  if (isTokenRevoked(token)) {
    throw new Error('Token revoked')
  }

  return {
    userId: decoded.userId,
    scopes: decoded.scopes || []
  }
}

Token Types

Opaque tokens (random strings)
Structured tokens (JWT)
Short-lived access tokens
Long-lived refresh tokens

Token Authentication Flow

OAuth 2.0 Implementation

OAuth 2.0 provides a robust framework for secure API authentication and authorization.

OAuth 2.0 Flows

Authorization Code Flow

Most secure for web applications
Server-side token exchange
PKCE extension for security
Suitable for confidential clients

Client Credentials Flow

Machine-to-machine authentication
No user interaction required
Service account authentication
Backend API integration

Implicit Flow (Deprecated)

Previously used for SPAs
Security vulnerabilities identified
Replaced by Authorization Code + PKCE
Not recommended for new implementations

OAuth Implementation Best Practices

Security Measures

Use HTTPS for all communications
Implement PKCE for public clients
Validate redirect URIs strictly
Use short-lived access tokens

Token Management

Secure token storage
Automatic token refresh
Proper token revocation
Scope-based access control

Proof-of-Possession and mTLS

DPoP (Demonstration of Proof-of-Possession)

Bind tokens to a client-generated key pair
Prevent token replay across different clients
Use with Authorization Code + PKCE for SPAs

Mutual TLS (mTLS)

Mutual certificate verification between client and server
Strong assurance for service-to-service calls
Combine with OAuth client credentials for zero-trust networks

// OAuth 2.0 Server Implementation with Express
import express from 'express'
import crypto from 'crypto'
import jwt from 'jsonwebtoken'

const app = express()
app.use(express.json())

interface OAuthToken {
  access_token: string
  token_type: 'Bearer'
  expires_in: number
  refresh_token?: string
  scope?: string
}

// Authorization Code Flow
app.post('/oauth/authorize', (req, res) => {
  const { client_id, redirect_uri, state, response_type, scope } = req.query

  // Validate client_id and redirect_uri
  if (!isValidClient(client_id as string)) {
    return res.status(400).json({ error: 'invalid_client' })
  }

  // Generate authorization code
  const authCode = crypto.randomBytes(32).toString('hex')
  const codeChallenge = req.query.code_challenge

  // Store auth code with PKCE verification
  storeAuthCode(authCode, {
    client_id,
    redirect_uri,
    scope,
    code_challenge: codeChallenge,
    expires_at: Date.now() + 10 * 60 * 1000 // 10 minutes
  })

  // Redirect to client's redirect_uri with auth code
  const redirectUrl = new URL(redirect_uri as string)
  redirectUrl.searchParams.set('code', authCode)
  redirectUrl.searchParams.set('state', state as string)

  res.redirect(redirectUrl.toString())
})

// Token Exchange Endpoint
app.post('/oauth/token', async (req, res) => {
  const { grant_type, code, redirect_uri, client_id, code_verifier } = req.body

  if (grant_type !== 'authorization_code') {
    return res.status(400).json({ error: 'unsupported_grant_type' })
  }

  // Validate authorization code
  const authData = await getAuthCodeData(code)
  if (!authData || authData.expires_at < Date.now()) {
    return res.status(400).json({ error: 'invalid_grant' })
  }

  // Verify PKCE (if provided)
  if (authData.code_challenge) {
    const expectedChallenge = crypto
      .createHash('sha256')
      .update(code_verifier)
      .digest('base64url')

    if (expectedChallenge !== authData.code_challenge) {
      return res.status(400).json({ error: 'invalid_grant' })
    }
  }

  // Generate tokens
  const accessToken = jwt.sign(
    { user_id: authData.user_id, scope: authData.scope },
    process.env.JWT_SECRET!,
    { expiresIn: '1h' }
  )

  const refreshToken = crypto.randomBytes(32).toString('hex')

  // Store refresh token
  await storeRefreshToken(refreshToken, {
    user_id: authData.user_id,
    client_id: authData.client_id,
    scope: authData.scope
  })

  const tokenResponse: OAuthToken = {
    access_token: accessToken,
    token_type: 'Bearer',
    expires_in: 3600,
    refresh_token: refreshToken,
    scope: authData.scope
  }

  res.json(tokenResponse)
})

// Refresh Token Endpoint
app.post('/oauth/refresh', async (req, res) => {
  const { refresh_token, grant_type } = req.body

  if (grant_type !== 'refresh_token') {
    return res.status(400).json({ error: 'unsupported_grant_type' })
  }

  // Validate refresh token
  const tokenData = await getRefreshTokenData(refresh_token)
  if (!tokenData) {
    return res.status(400).json({ error: 'invalid_grant' })
  }

  // Generate new access token
  const newAccessToken = jwt.sign(
    { user_id: tokenData.user_id, scope: tokenData.scope },
    process.env.JWT_SECRET!,
    { expiresIn: '1h' }
  )

  res.json({
    access_token: newAccessToken,
    token_type: 'Bearer',
    expires_in: 3600,
    scope: tokenData.scope
  })
})

OAuth 2.0 Flow Diagram

JWT Best Practices

JSON Web Tokens (JWT) provide a compact, self-contained way to securely transmit information.

JWT Structure and Security

Token Components

Header: Algorithm and token type
Payload: Claims and user data
Signature: Cryptographic verification
Base64URL encoding for transport

Security Best Practices

Use strong signing algorithms (RS256, ES256)
Avoid sensitive data in payload
Implement proper key rotation
Validate all claims thoroughly

Key Management and JWKS

Operational Guidance

Publish a JWKS endpoint for public keys (kid-based selection)
Rotate signing keys at least every 90 days; overlap during rollout
Pin issuers/audiences; enforce alg whitelist (reject none/HS when using RS)
Cache JWKS respecting Cache-Control; retry with backoff on fetch errors

Rotation and Revocation

Patterns

Use short-lived access tokens (5–15 min) and rotating refresh tokens
Maintain a token revocation list (TRL) or derive invalidation from a session version
Include jti and revoke on logout, credential change, or anomaly

JWT Implementation Guidelines

Token Validation

Verify signature cryptographically
Check expiration times (exp claim)
Validate issuer (iss claim)
Confirm audience (aud claim)

Claim Management

Use standard claims appropriately
Implement custom claims carefully
Minimize payload size
Consider token encryption for sensitive data

// JWT Implementation Example
interface JWTPayload {
  userId: string
  email: string
  role: string
  permissions: string[]
  iat: number
  exp: number
  iss: string
  aud: string
}

// Generate JWT token
function generateJWT(payload: Omit<JWTPayload, 'iat' | 'exp' | 'iss' | 'aud'>): string {
  const now = Math.floor(Date.now() / 1000)

  const tokenPayload: JWTPayload = {
    ...payload,
    iat: now,
    exp: now + (15 * 60), // 15 minutes
    iss: process.env.JWT_ISSUER!,
    aud: process.env.JWT_AUDIENCE!
  }

  // In production, sign with RS256/ES256 and expose public keys via JWKS
  // return jwt.sign(tokenPayload, PRIVATE_KEY, { algorithm: 'RS256', keyid: 'kid-2025-01' })
  return JSON.stringify(tokenPayload) // Simplified for article example
}

// Verify JWT token
function verifyJWT(token: string): JWTPayload {
  try {
    const decoded = JSON.parse(token) as JWTPayload

    // Validate expiration
    if (decoded.exp < Math.floor(Date.now() / 1000)) {
      throw new Error('Token expired')
    }

    // Validate issuer and audience
    if (decoded.iss !== process.env.JWT_ISSUER) {
      throw new Error('Invalid issuer')
    }

    return decoded
  } catch (error) {
    throw new Error('Invalid token')
  }
}

// Usage in middleware
function jwtAuth(req: any, res: any, next: any) {
  const authHeader = req.headers.authorization

  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({ error: 'JWT token required' })
  }

  const token = authHeader.split(' ')[1]

  try {
    const decoded = verifyJWT(token)
    req.user = decoded
    next()
  } catch (error) {
    return res.status(401).json({ error: 'Invalid token' })
  }
}

JWT Structure Diagram

API Key Management

API keys provide a simple authentication mechanism for many API integrations.

API Key Best Practices

Key Generation

Use cryptographically secure random generation
Sufficient entropy (minimum 128 bits)
Unique keys per client/application
Avoid predictable patterns

Key Distribution

Secure delivery channels
Environment-specific keys
Documentation and onboarding
Key activation workflows

Key Lifecycle Management

Rotation Strategies

Regular key rotation schedules
Emergency rotation procedures
Backward compatibility periods
Automated rotation systems

// API Key Management System
class APIKeyManager {
  private static instance: APIKeyManager

  static getInstance(): APIKeyManager {
    if (!APIKeyManager.instance) {
      APIKeyManager.instance = new APIKeyManager()
    }
    return APIKeyManager.instance
  }

  // Generate secure API key
  generateAPIKey(userId: string, permissions: string[]): string {
    const keyId = crypto.randomBytes(8).toString('hex')
    const secretKey = crypto.randomBytes(32).toString('hex')

    // Store in database with hashed secret
    const hashedSecret = crypto.createHash('sha256').update(secretKey).digest('hex')

    // Store: { keyId, userId, hashedSecret, permissions, createdAt, lastUsed, usageCount }

    return `${keyId}.${secretKey}`
  }

  // Validate API key
  async validateAPIKey(apiKey: string): Promise<{ userId: string; permissions: string[] } | null> {
    const [keyId, secretKey] = apiKey.split('.')

    if (!keyId || !secretKey) {
      return null
    }

    // Get stored key data from database
    const keyData = await getAPIKeyFromDB(keyId)

    if (!keyData || !keyData.isActive) {
      return null
    }

    // Verify secret
    const hashedSecret = crypto.createHash('sha256').update(secretKey).digest('hex')
    if (hashedSecret !== keyData.hashedSecret) {
      return null
    }

    // Update usage statistics
    await updateAPIKeyUsage(keyId)

    return {
      userId: keyData.userId,
      permissions: keyData.permissions
    }
  }

  // Revoke API key
  async revokeAPIKey(keyId: string): Promise<void> {
    await revokeAPIKeyInDB(keyId)
  }

  // Get usage statistics
  async getAPIKeyStats(keyId: string): Promise<{
    usageCount: number
    lastUsed: Date
    requestsPerDay: number[]
  }> {
    return await getAPIKeyStatsFromDB(keyId)
  }
}

// Usage in middleware
function apiKeyAuth(req: any, res: any, next: any) {
  const apiKey = req.headers['x-api-key'] || req.query.api_key

  if (!apiKey) {
    return res.status(401).json({ error: 'API key required' })
  }

  const keyManager = APIKeyManager.getInstance()

  keyManager.validateAPIKey(apiKey).then(result => {
    if (!result) {
      return res.status(401).json({ error: 'Invalid API key' })
    }

    req.user = result
    next()
  }).catch(error => {
    res.status(500).json({ error: 'Authentication error' })
  })
}

Implementation Examples

Express.js Authentication Middleware

// Complete Express.js authentication middleware
import express from 'express'
import rateLimit from 'express-rate-limit'

const app = express()

// Rate limiting for authentication endpoints
const authLimiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // 5 attempts per window
  message: { error: 'Too many authentication attempts' },
  standardHeaders: true,
  legacyHeaders: false,
})

// Apply to authentication routes
app.post('/api/login', authLimiter, async (req, res) => {
  const { email, password } = req.body

  // Authenticate user
  const user = await authenticateUser(email, password)
  if (!user) {
    // Log failed attempt
    await logFailedAuth(email, req.ip)
    return res.status(401).json({ error: 'Invalid credentials' })
  }

  // Generate tokens
  const accessToken = generateJWT({
    userId: user.id,
    email: user.email,
    role: user.role,
    permissions: user.permissions
  })

  const refreshToken = generateRefreshToken(user.id)

  // Set HTTP-only cookie for refresh token
  res.cookie('refreshToken', refreshToken, {
    httpOnly: true,
    secure: process.env.NODE_ENV === 'production',
    sameSite: 'strict',
    maxAge: 30 * 24 * 60 * 60 * 1000 // 30 days
  })

  res.json({
    access_token: accessToken,
    token_type: 'Bearer',
    expires_in: 15 * 60,
    user: {
      id: user.id,
      email: user.email,
      role: user.role
    }
  })
})

// Protected route middleware
function requireAuth(req: any, res: any, next: any) {
  const authHeader = req.headers.authorization

  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({ error: 'Authentication required' })
  }

  const token = authHeader.split(' ')[1]

  try {
    const decoded = verifyJWT(token)
    req.user = decoded

    // Check if user still has required permissions
    if (!hasRequiredPermissions(decoded.permissions, req.route.permissions)) {
      return res.status(403).json({ error: 'Insufficient permissions' })
    }

    next()
  } catch (error) {
    return res.status(401).json({ error: 'Invalid token' })
  }
}

// Usage
app.get('/api/protected', requireAuth, (req, res) => {
  res.json({
    message: 'Access granted',
    user: req.user,
    data: 'sensitive data'
  })
})

Python FastAPI Implementation

# FastAPI Authentication Example
from fastapi import FastAPI, Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
import jwt
import time
from typing import List, Optional

app = FastAPI()
security = HTTPBearer()

# JWT configuration
JWT_SECRET = "your-secret-key"
JWT_ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 15

class User:
    def __init__(self, user_id: str, email: str, permissions: List[str]):
        self.user_id = user_id
        self.email = email
        self.permissions = permissions

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = time.time() + expires_delta
    else:
        expire = time.time() + (15 * 60)  # 15 minutes

    to_encode.update({"exp": expire, "type": "access"})
    encoded_jwt = jwt.encode(to_encode, JWT_SECRET, algorithm=JWT_ALGORITHM)
    return encoded_jwt

def verify_token(credentials: HTTPAuthorizationCredentials = Depends(security)):
    try:
        payload = jwt.decode(
            credentials.credentials,
            JWT_SECRET,
            algorithms=[JWT_ALGORITHM]
        )

        if payload.get("type") != "access":
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid token type"
            )

        user_id: str = payload.get("user_id")
        if user_id is None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Invalid token"
            )

        # Get user from database
        user = get_user_from_db(user_id)
        if not user:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="User not found"
            )

        return user

    except jwt.ExpiredSignatureError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Token has expired"
        )
    except jwt.JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token"
        )

@app.post("/login")
async def login(email: str, password: str):
    # Authenticate user
    user = authenticate_user(email, password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect email or password"
        )

    # Create access token
    token_data = {
        "user_id": user.user_id,
        "email": user.email,
        "permissions": user.permissions
    }

    access_token = create_access_token(token_data)

    return {
        "access_token": access_token,
        "token_type": "bearer",
        "expires_in": 15 * 60
    }

@app.get("/protected")
async def protected_route(current_user: User = Depends(verify_token)):
    return {
        "message": "Access granted",
        "user": current_user.email,
        "permissions": current_user.permissions
    }

@app.get("/admin")
async def admin_route(current_user: User = Depends(verify_token)):
    if "admin" not in current_user.permissions:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin access required"
        )

    return {"message": "Admin access granted"}

Monitoring and Alerting

Authentication Metrics

// Authentication monitoring middleware
function authMonitoring(req: any, res: any, next: any) {
  const startTime = Date.now()

  // Track request metrics
  res.on('finish', () => {
    const duration = Date.now() - startTime
    const statusCode = res.statusCode
    const endpoint = req.route?.path || req.path
    const method = req.method
    const userAgent = req.get('User-Agent')
    const ip = req.ip

    // Send metrics to monitoring system
    sendMetrics({
      metric: 'api_auth_request',
      value: 1,
      tags: {
        endpoint,
        method,
        status_code: statusCode,
        user_agent: userAgent,
        ip_address: ip,
        duration_ms: duration
      }
    })

    // Alert on suspicious patterns
    if (statusCode === 401 && duration < 100) {
      // Rapid failed authentication attempts
      alertSuspiciousActivity(ip, 'rapid_auth_failures')
    }

    if (statusCode === 429) {
      // Rate limiting triggered
      alertSuspiciousActivity(ip, 'rate_limit_exceeded')
    }
  })

  next()
}

// Anomaly detection
async function detectAuthAnomalies() {
  // Check for unusual patterns
  const anomalies = await checkAuthPatterns()

  for (const anomaly of anomalies) {
    await alertSecurityTeam({
      type: 'auth_anomaly',
      severity: anomaly.severity,
      description: anomaly.description,
      affected_users: anomaly.userIds,
      timestamp: new Date()
    })
  }
}

// Scheduled anomaly detection (run every 5 minutes)
setInterval(detectAuthAnomalies, 5 * 60 * 1000)

Security Monitoring Dashboard

-- Authentication metrics queries for monitoring

-- Failed authentication attempts by IP (last hour)
SELECT
  ip_address,
  COUNT(*) as attempts,
  MIN(created_at) as first_attempt,
  MAX(created_at) as last_attempt
FROM auth_logs
WHERE status = 'failed'
  AND created_at > NOW() - INTERVAL '1 hour'
GROUP BY ip_address
HAVING COUNT(*) > 10
ORDER BY attempts DESC;

-- Successful authentication trends
SELECT
  DATE_TRUNC('hour', created_at) as hour,
  COUNT(*) as auth_count,
  COUNT(DISTINCT user_id) as unique_users
FROM auth_logs
WHERE status = 'success'
  AND created_at > NOW() - INTERVAL '24 hours'
GROUP BY 1
ORDER BY 1;

-- Geographic authentication patterns
SELECT
  country,
  COUNT(*) as auth_count,
  COUNT(DISTINCT ip_address) as unique_ips,
  AVG(auth_count) OVER (PARTITION BY country) as avg_auth_per_ip
FROM (
  SELECT
    ip_address,
    get_country_by_ip(ip_address) as country,
    COUNT(*) as auth_count
  FROM auth_logs
  WHERE status = 'success'
    AND created_at > NOW() - INTERVAL '24 hours'
  GROUP BY ip_address
) ip_auth
GROUP BY country
ORDER BY auth_count DESC;

Security Considerations

Comprehensive security requires attention to multiple aspects of authentication implementation.

Transport Security

HTTPS Requirements

TLS 1.2 minimum (prefer TLS 1.3)
Strong cipher suites
Certificate validation
HSTS implementation

Header Security

Secure authentication headers
Avoid credentials in URLs
Implement CORS properly
Use security headers

Rate Limiting and Abuse Prevention

Implementation Strategies

Token bucket algorithms
Sliding window counters
Distributed rate limiting
Adaptive rate limiting

Monitoring and Detection

Failed authentication tracking
Suspicious pattern detection
Automated response systems
Security incident logging

Security Monitoring Dashboard

Multi-Factor Authentication

MFA Implementation

Time-based OTP (TOTP)
SMS-based verification
Hardware security keys
Biometric authentication

Risk-Based Authentication

Device fingerprinting
Geolocation analysis
Behavioral analytics
Adaptive security measures

Conclusion

Effective API authentication requires a multi-layered approach combining appropriate authentication methods, robust security practices, and continuous monitoring. Success depends on understanding your specific requirements, implementing industry best practices, and maintaining security awareness throughout the development lifecycle.

Secure your APIs with our comprehensive Authentication Service, featuring OAuth 2.0, JWT, and advanced security monitoring capabilities.

API Authentication Best Practices: Securing Your Endpoints

Table of Contents

Table of Contents

API Authentication Best Practices: Securing Your Endpoints

Authentication Fundamentals

Core Authentication Principles

Common Authentication Challenges

Authentication Methods

Basic Authentication

Bearer Token Authentication

OAuth 2.0 Implementation

OAuth 2.0 Flows

OAuth Implementation Best Practices

Proof-of-Possession and mTLS

JWT Best Practices

JWT Structure and Security

Key Management and JWKS

Rotation and Revocation

JWT Implementation Guidelines

API Key Management

API Key Best Practices

Key Lifecycle Management

Implementation Examples

Express.js Authentication Middleware

Python FastAPI Implementation

Monitoring and Alerting

Authentication Metrics

Security Monitoring Dashboard

Security Considerations

Transport Security

Rate Limiting and Abuse Prevention

Multi-Factor Authentication

Conclusion