2023-12-17
In today's interconnected world, ensuring the security and authenticity of data and communication is of utmost importance. Engineers and IT professionals often find themselves navigating a complex landscape of security protocols and mechanisms. One such mechanism that plays a critical role in securing network communications is Mutual Transport Layer Security (mTLS). This blog post is aimed at engineers and professionals seeking to
Mutual Transport Layer Security (mTLS, mutual TLS) serves as a robust mechanism for mutual authentication between services, a concept often referred to as two-way authentication. The core objective of mTLS is to ensure that the parties at each end of a connection are genuinely who they claim to be. This mTLS authentication process operates within the framework of a Zero Trust security model, which is designed to verify the identities of devices, servers, workloads and API connections.
In the context of Zero Trust, the fundamental assumption is that threats can exist both within and outside the network. This makes automatic trust in any connection unwise. Instead, the Zero Trust model employs the principle of least-privilege access, which means granting each party only the specific access permissions they require. This approach restricts each user's access to only the information and resources they are explicitly authorized to access.
Within the realm of Mutual TLS, a connection can only be established if each party successfully exchanges, verifies, and trusts the certificate (identity) presented by the other party.
While SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols used to secure network communications, mTLS introduces an extra layer of authentication. Here's how they differ:
SSL (Secure Sockets Layer): SSL was the precursor to TLS and was developed in the mid-1990s. It was primarily used to secure data transfer between a client (e.g., a web browser) and a server (e.g., a web server). However, SSL is no longer considered secure due to vulnerabilities like POODLE and BEAST. TLS has largely replaced SSL in modern security practices.
TLS (Transport Layer Security): TLS, the successor to SSL, provides secure communication between two parties over a network. It ensures data confidentiality, integrity, and authentication. TLS is widely used to secure various types of network connections, including web traffic (HTTPS), email (SMTP/IMAP/POP), and more. TLS primarily focuses on securing the connection between a client and a server.
mTLS (Mutual Transport Layer Security): mTLS is an extension of TLS that adds an extra layer of authentication. While TLS primarily focuses on the server authenticating itself to the client (ensuring the client is connecting to the correct server), mTLS extends this security by requiring the client to authenticate itself to the server as well. This mutual authentication ensures that both parties in the communication are who they claim to be. mTLS is commonly used in scenarios where both the client and server need to prove their identities.
The choice between TLS and mTLS depends on the specific security requirements of the network application. TLS is suitable for scenarios where a client-server model is in place, and the client simply needs to ensure the server's authenticity and secure communication. On the other hand, mTLS is ideal when both the client and server must authenticate themselves to each other. It provides an additional layer of security, making it suitable for microservices and IoT device communications, API connections, and other situations where two-way authentication is necessary.
Transport Layer Security (TLS) is a cryptographic protocol that secures communication over a network, such as the Internet. TLS ensures data confidentiality, integrity, and authentication between two parties, typically a client and a server. The key components of how TLS works include:
TLS encrypts and secures communication between a client and server using these components, ensuring that data remains confidential and untampered during transmission over potentially untrusted networks like the Internet.
The main steps between the client and server in a mutual TLS handshake.
Public trust in TLS relies on the hierarchical structure of Certificate Authorities (CAs) and the proper issuance and management of certificates. The CA/Browser Forum, a consortium of CAs and web browser vendors, plays a crucial role in shaping the standards, guidelines, and minimum requirements for the issuance and management of these publicly trusted digital certificates. This includes defining certificate policies and baseline requirements, guidelines for extended validation certificates, code signing certificates, S/MIME, validation and revocation processes, root and intermediate CA certificate management, and more. Public trust in TLS certificates is maintained through adherence to these industry-wide standards and best practices.
Private trust with TLS or mTLS is used to establish secure communication within a “closed” network or application ecosystem without relying on publicly trusted CAs. This approach gives organizations complete control over the certificate issuance process, making it suitable for use cases where the trust relationships are known in advance. Examples of these situations are IoT, corporate networks, DevOps, and service meshes in containerized environments, among others.
Managing private trust involving “closed” ecosystems with multiple stakeholders does not have to be complex. Private trust, certificates issued by one or several private Certificate Authority (CA) and PKIs, are often used in such environments. Here's how it can work in two example scenarios:
A PKI hierarchy with an offline root CA, policy/intermediate CAs, and issuing CAs for different types of certificates. For optimal security, registration and issuance of certificates should be separated from the CA (signing) by Registration Authorities (RAs). CA services such as CRLs and OCSPs are also separate.
2. Establishing multiple distinct Private PKIs each hosted and managed by different stakeholders in the eco-system.
This scenario is the same as above except that these PKIs need to establish mutual trust during the definition and set up of the PKIs, either by
The private trust model can be used to create an eco-system encompassing stakeholders, applications, servers, APIs, devices, users, etc. The trust model is based on agreed security policies, procedures etc. Operationally each stakeholder can host its own PKI and CAs or they can all rely on a common service provider.
Managing private trust in a larger ecosystem involving suppliers and users requires the establishment of a Private PKI with clear governance, certificate issuance policies, and secure practices.
The PKI becomes the central authority for managing trust and security within the ecosystem, enabling secure interactions between devices and entities.
Stakeholder device certificate issuance and secure communication:
TLS-based authentication and secure communication necessitate the verification of certificate authenticity and validity, along with validating the CA trust chains towards the PKI services. Additionally, the PKI service plays a crucial role in ensuring the seamless renewal or updating of certificates upon expiration or revocation.
Certificate Distribution and Management:
Trust Relationships:
Security and Compliance:
Monitoring and Revocation:
Scalability and Interoperability:
Documentation and Policies:
In controlled testing environments, tools like Open SSL can generate self-signed certificates. However, their practicality diminishes in production settings for several reasons:
It is advisable to refrain from relying on self-signed certificates in the presence of viable alternatives. Instead, consider establishing a robust PKI from the outset, ensuring scalability and facilitating seamless migration or reconstruction in a production setting. This approach promotes long-term reliability and avoids the pitfalls associated with self-signed certificates.
mTLS is widely used across various sectors where data security, privacy, and authentication are paramount concerns. Some notable use cases for mTLS include:
TLS plays a crucial role in securing telecommunications networks, particularly within the 3rd Generation Partnership Project (3GPP) standards. 3GPP is responsible for developing standards for mobile telecommunications, including GSM, 3G, 4G (LTE), and 5G networks. TLS is used in 3GPP networks to secure signaling and control planes, facilitate authentication and key exchange, ensure privacy and data security, interwork with other networks, authenticate mobile devices, secure management interfaces, and ensure roaming and interconnect security.
Mutual Transport Layer Security (mTLS) is extensively used to secure communication between microservices and containers in cloud-native environments. In such ecosystems, certificates are generated and distributed to each microservice, and mTLS ensures secure communication. Service meshes, which manage and secure communication between microservices, often rely on mTLS for added security. Key components of mTLS for microservices include certificate generation and distribution, TLS handshake and authentication, secure communication, automatic sidecar proxy integration, service discovery and load balancing, certificate rotation and lifecycle management, security policies and compliance, key management, and monitoring and revocation.
Service meshes are designed to enhance the observability, security, and reliability of microservices-based applications. Several standards and specifications have emerged in the service mesh ecosystem to promote interoperability, consistency, and best practices. Some notable standards and projects in the service mesh space include Envoy Proxy, Istio and Linkerd. These projects and standards play a crucial role in ensuring the secure and efficient operation of service meshes and their use of mTLS for mutual authentication and secure communications.
Mutual Transport Layer Security (mTLS) is a vital component of modern network security, enabling secure communication and authentication in a variety of contexts, from web security to IoT, enterprise networks, and telecommunications. Engineers and IT professionals must understand the role of mTLS in their security strategies and make informed choices regarding its implementation and need for certificate and management. Whether in public trust scenarios with trusted CAs or private trust environments using private PKIs, mTLS and the quality of the certificates used play a pivotal role in ensuring the confidentiality, integrity, and authenticity of data and communication in today's digital landscape.
Do you need to issue private trust certificates for mutual TLS today?
Then you can start with the open-source PKI and Certificate Authority EJBCA and create your TLS client or server certificates by following our best practices video tutorials. With EJBCA, you can start small and scale as your use case grows.
You can manually issue client and server TLS certificates or automate the issuing process by integrating with the EJBCA REST API. More information, hands-on video tutorials, and guides: Issue TLS and mTLS certificates.
For more information on related topics, see the following links: