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Building Secure Authentication Systems: Best Practices from Our Security Team

Eric Torres
10 min read
Building Secure Authentication Systems: Best Practices from Our Security Team

Security is paramount in modern applications. Our security experts share the authentication architecture we implement for enterprise clients, covering OAuth 2.0, JWT, MFA, and advanced threat protection measures.

Introduction

Authentication is the foundation of application security. A well-designed authentication system not only protects user data but also provides a seamless user experience. At CoreBytes, we've developed and refined our authentication architecture through years of implementing secure systems for clients in highly regulated industries such as finance, healthcare, and government.

In this article, we'll share our approach to building robust authentication systems that balance security, usability, and compliance requirements.

Core Authentication Principles

Before diving into specific technologies, it's important to understand the core principles that guide our authentication implementations:

Defense in Depth

We never rely on a single security control. Our authentication systems implement multiple layers of protection so that if one layer is compromised, others remain intact.

Least Privilege

Users and systems should only have access to the resources they need to perform their functions. This principle guides our authorization design, which works hand-in-hand with authentication.

Secure by Default

Our systems are configured with the most secure settings by default. Security should not depend on users or administrators making the right choices.

Usability Matters

Security measures that create significant friction will be circumvented. We design authentication flows that balance security with usability to ensure adoption.

Authentication Architecture

Our standard authentication architecture consists of several key components:

Identity Provider (IdP)

Rather than building authentication from scratch, we typically implement or integrate with a dedicated Identity Provider that specializes in secure authentication. This may be:

  • A cloud identity service (Auth0, Okta, AWS Cognito)
  • An enterprise identity solution (Azure AD, Ping Identity)
  • An open-source IdP (Keycloak) for self-hosted scenarios

OAuth 2.0 and OpenID Connect

We implement OAuth 2.0 and OpenID Connect (OIDC) as our standard protocols for authentication and authorization. These provide:

  • Standardized authentication flows for different application types
  • Separation of authentication from the application
  • Token-based authentication with limited scopes and lifetimes
  • Support for modern authentication patterns

JSON Web Tokens (JWT)

We use JWTs to securely transmit authentication and authorization information:

  • Digitally signed to prevent tampering
  • Encrypted when containing sensitive information
  • Short expiration times to limit the impact of token theft
  • Carefully designed claims to prevent information leakage

Multi-Factor Authentication (MFA)

We implement MFA for all sensitive applications, with options including:

  • Time-based One-Time Passwords (TOTP) via authenticator apps
  • Push notifications to mobile devices
  • Hardware security keys (FIDO2/WebAuthn)
  • Biometric authentication where appropriate

Advanced Security Measures

Beyond the core architecture, we implement several advanced security measures:

Adaptive Authentication

We implement risk-based authentication that adjusts security requirements based on contextual factors:

  • User location and IP reputation
  • Device recognition and health
  • Behavioral biometrics (typing patterns, mouse movements)
  • Time of access and previous usage patterns

Secure Session Management

Our session management includes:

  • Secure, HTTP-only, SameSite cookies
  • Token rotation strategies
  • Absolute and idle session timeouts
  • Concurrent session controls

Threat Protection

We implement multiple layers of threat protection:

  • Rate limiting and account lockout policies
  • CAPTCHA for suspicious login attempts
  • Credential stuffing protection
  • Real-time monitoring and alerting

Implementation Best Practices

When implementing authentication systems, we follow these best practices:

Password Policies

Our password policies follow NIST guidelines:

  • Minimum length of 12 characters
  • No arbitrary complexity requirements
  • Check against lists of compromised passwords
  • No forced periodic password changes

Secure Communication

All authentication traffic is protected:

  • TLS 1.2+ with strong cipher suites
  • Certificate pinning for mobile applications
  • Secure headers (HSTS, CSP, X-Frame-Options)

Logging and Monitoring

Comprehensive logging of authentication events:

  • Successful and failed authentication attempts
  • Password changes and account recovery
  • Permission changes and privilege escalation
  • Anomaly detection and alerting

Case Study: Financial Services Client

For a recent financial services client, we implemented a secure authentication system that included:

  • Integration with their existing Azure AD for employee access
  • A customer-facing authentication system using Auth0
  • Step-up authentication for high-value transactions
  • Hardware security key support for administrative access
  • Compliance with PSD2 Strong Customer Authentication requirements

The system successfully passed multiple security audits and penetration tests while maintaining a positive user experience.

Conclusion

Building secure authentication systems requires a combination of well-established protocols, modern security practices, and careful implementation. By following the architecture and best practices outlined in this article, you can create authentication systems that protect your users and your business while providing a seamless user experience.

Remember that security is a journey, not a destination. Regular security assessments, staying current with evolving threats, and continuous improvement are essential to maintaining a strong security posture.

ET

Eric Torres

Head of Security at CoreBytes

Eric leads the security practice at CoreBytes, bringing over 15 years of experience in application security and identity management. He holds CISSP and CISM certifications and regularly speaks at security conferences.

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