Demystifying SSL/TLS Handshake

Navigating the complex world of cybersecurity can be a daunting task for many, and at the heart of this intricate landscape lies the enigmatic realm of Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL). Understanding Transport Layer Security (TLS) and Secure Sockets Layer (SSL) becomes crucial for me when dealing with OpenShift components and troubleshooting application failures. OpenShift, as a container orchestration platform, relies on secure communication for the seamless functioning of its components and the applications it hosts. Here's how a solid grasp of TLS/SSL is indispensable in this context:

1. Secure Communication in OpenShift: OpenShift employs TLS/SSL to establish secure communication channels between its various components. These components, including the OpenShift API server, etcd, and the nodes, communicate sensitive information over the network. Understanding TLS/SSL is essential to configuring these communication channels securely, ensuring data integrity, confidentiality, and authenticity within the OpenShift cluster.
2. Certificates and Authentication: TLS/SSL certificates play a vital role in authenticating the identity of OpenShift components. When troubleshooting application failures, having a good understanding of certificate management becomes crucial. Misconfigurations, expired certificates, or issues with the certificate authorities can lead to communication failures between components, impacting the overall stability of the OpenShift cluster.
3. Route Security in OpenShift: OpenShift uses Routes to expose services to the external world. These routes often involve TLS termination for secure communication between clients and applications. Troubleshooting issues with these routes, such as certificate mismatches or misconfigurations, requires a comprehensive understanding of TLS/SSL concepts.
4. Debugging Application Failures: In a containerized environment like OpenShift, applications often communicate over secure connections. When an application fails, understanding the role of TLS/SSL in these communication pathways is vital. Errors related to certificate validation, cipher suites, or encryption protocols may be at the heart of application failures. A solid grasp of TLS/SSL enables effective debugging and resolution of these issues.
5. Integration with External Systems: Many applications hosted on OpenShift interact with external systems and services. These interactions often involve secure connections using TLS/SSL. Understanding how to configure and troubleshoot these connections ensures seamless communication with external entities, preventing potential failures or security vulnerabilities.
6. Security Policies and Compliance: OpenShift allows the enforcement of security policies, including those related to TLS/SSL configurations. Understanding TLS/SSL is essential for aligning OpenShift deployments with security best practices and compliance requirements. This knowledge becomes particularly crucial in regulated industries where adherence to security standards is mandatory.

TLS/SSL?

A Secure Sockets Layer (SSL) / Transport Layer Security (TLS) handshake is the process of creating a safe and secure encrypted communication channel between the client (user’s browser) and the server (webserver).

SSL/TLS handshake involves several exchanges between the client and the server:

• Choose a protocol (TLS) version.
• Select a cipher suite.
• Verify each other by exchanging and confirming digital certificates.
• Create session keys to use symmetric encryption after the handshake is complete.

SSL/TLS Terminology

Cipher Suite:

A cipher suite is a collection of cryptographic algorithms used to establish a secure connection between the client and server. During the SSL/TLS handshake, both the client and host computer agree upon an encryption method from the cipher suites to create keys and encrypt information. The cipher suite contains digital signature algorithms, hash functions for checking if the data in transit is modified, asymmetric encryption algorithms for the handshake, and symmetric encryption algorithm to maintain session security.

Key Exchange:

TLS key exchange allows two parties to use a cryptographic algorithm by exchanging cryptographic keys. For example, a symmetric session key is generated during SSL/TLS handshake before an encrypted message is transmitted. RSA and Diffie-Hellman-Merkle are the top key exchange algorithms used.

Symmetric Encryption:

Symmetric encryption encrypts and decrypts using the same (one) key. Compared to asymmetric cryptography, this is more efficient – it needs less encryption time, uses fewer resources, and can transfer large volumes of data, while also maintaining confidentiality. Cipher text is the same or smaller than the plain text.

Asymmetric Encryption:

Asymmetric encryption uses two keys: a public and a private key. This means a message encrypted with a public key can only be decrypted with the corresponding private key. It provides better security as the keys are never shared and allows the user to authenticate data using digital signatures. It is slower than symmetric encryption and can only be utilized for small amounts of data. Cipher text is the same or larger than plain text.

Digital signature

A digital signature is a way of verification to authenticate that the sender is actually the sender of the payload. A digital signature serves three purposes:

1. Authentication: A digital signature helps the client verify that the message was sent by the claimed sender.
2. Non-repudiation: The sender cannot deny having sent the message later on.
3.  Integrity: A digital signature ensures that the message was not altered in transit.

In our case of SSL/TLS handshake, the Document is replaced with a digital certificate, so the client can later both check the identity of the server and verify it. 

SSL/TLS Handshake Steps

Finally, the TLS/SSL handshake steps:

• Step 1: The SSL/TLS client will send the server a “ClientHello” message that details the client’s configuration settings, including the SSL/TLS version, the cipher suites it supports, the data compression technique it employs, and a string of random data referred to as “client random.”
• Step 2: The SSL/TLS server sends back a “ServerHello” message containing its own public key, digital certificate, session identifier, the cryptographic algorithm agreement (selected by the server from the client-supplied list of algorithms), and the “server random”.
• Step 3: The client performs authentication by contacting the server’s certificate authority (CA) to validate the web server’s digital certificate. This confirms the authenticity of the web server, thus, establishing trust.
• Step 4: During the ClientKeyExchange step, the client extracts the public key from the verified certificate and generates a new random sequence called the premaster secret. The premaster secret is then encrypted using the extracted public key and is sent to the server.
• Step 5: The SSL/TLS server decrypts the premaster secret using its private key.
• Step 6: Both the client and the server now use the premaster secret to configure a shared secret key.
• Step 7: Next, the client sends an encrypted “finished” message using the shared secret key. This message says that the client’s part of the handshake is complete.
• Step 8: Finally, an encrypted “finished” message is sent back to the client from the server using the previously agreed shared secret key, which indicates the end of the server’s side of the handshake.
• Step 9: Once the SSL/TLS handshake and negotiation is done, the server and the client communication continues, i.e., they begin to share files and messages using the session keys (symmetric encryption).

In conclusion, delving into the intricacies of Transport Layer Security (TLS) and Secure Sockets Layer (SSL) has proven to be a transformative journey, especially for those navigating the dynamic realm of OpenShift components and troubleshooting application failures. As we unravel the layers of cryptographic protocols, it becomes evident that a profound understanding of TLS/SSL is not just a theoretical necessity but a practical imperative in the context of modern container orchestration.