The TLS handshake is a crucial process in establishing a secure connection between a client and a server. With the introduction of TLS 1.3, significant changes have been made, resulting in a faster and more secure handshake compared to previous versions. In this article, we will explore the key changes brought about by TLS 1.3 and their impact on web performance and security.
Contents
TLS 1.2 Handshake: A Two-Round Trip Process
To better understand the improvements in TLS 1.3, let’s first look at the TLS 1.2 handshake. The TLS 1.2 handshake requires two round trips to complete, involving multiple message exchanges between the client and the server. This handshake process establishes keys for encryption and verification, ensuring a secure connection.
TLS 1.3 Handshake: A Single Round Trip
TLS 1.3, on the other hand, revolutionizes the handshake process by reducing it to just a single round trip. This improvement significantly speeds up the connection establishment and reduces the time to first byte, resulting in a better web browsing experience.
TLS 1.3 achieves this efficiency by optimizing the message exchanges between the client and the server. In TLS 1.2, multiple messages were exchanged before the client and server could start sending encrypted application data. In TLS 1.3, however, the server can immediately start sending encrypted application data after the client hello, eliminating the need for additional round trips.
Improved Encryption for Privacy
Another significant change in TLS 1.3 is the increased emphasis on encryption. In TLS 1.2, only a few records were encrypted, leaving some information vulnerable to eavesdropping. TLS 1.3, on the other hand, encrypts almost all records, enhancing privacy and security.
This enhanced encryption paves the way for exciting new features such as encrypted Server Name Indication (ESNI) and encrypted Client Hello (ECH). ESNI allows the client to include the requested domain name in an encrypted form, preventing eavesdroppers from knowing which websites are being accessed. ECH takes it a step further by encrypting the entire Client Hello, providing even greater privacy during the handshake.
While these features are not yet formally standardized, TLS 1.3 lays the foundation for their implementation in the future, further enhancing privacy and security.
Mutual Authentication for Enhanced Security
TLS 1.3 also strengthens the authentication process by supporting mutual authentication. In TLS, usually only the server is authenticated through a certificate. Mutual authentication allows both the client and the server to exchange certificates, enhancing security.
To enable mutual authentication in TLS 1.3, the server sends a Certificate Request record along with the Server Hello, prompting the client to send its certificate along with a Certificate Verify record. This ensures that both the client and the server are authenticated, further securing the connection.
More Session Keys for Enhanced Security
In TLS 1.2, a limited number of session keys were generated, compromising cryptographic separation. TLS 1.3 addresses this issue by generating a larger number of session keys, each with perfect cryptographic separation.
TLS 1.3 generates separate session keys for different purposes, such as encrypting portions of the handshake, early data, and session resumption. This increased number of session keys enhances security and prevents compromise in one key from affecting the others.
In summary, TLS 1.3 brings significant improvements to the handshake process, reducing it to a single round trip and enhancing both speed and security. By optimizing message exchanges, encrypting most records, supporting mutual authentication, and generating more session keys, TLS 1.3 sets a new standard for secure communication on the web.
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FAQs
Q: What is the TLS handshake?
A: The TLS handshake is the process of establishing a secure connection between a client and a server. It involves multiple message exchanges to establish encryption keys and authentication.
Q: How many round trips does the TLS 1.3 handshake require?
A: The TLS 1.3 handshake only requires a single round trip, which significantly speeds up the connection establishment and reduces the time to first byte.
Q: How does TLS 1.3 improve privacy and security?
A: TLS 1.3 enhances privacy and security by encrypting almost all records exchanged during the handshake and supporting features like encrypted Server Name Indication (ESNI) and encrypted Client Hello (ECH). These features prevent eavesdroppers from accessing sensitive information and improve overall security.
Q: What is mutual authentication in TLS?
A: Mutual authentication in TLS allows both the client and the server to authenticate each other through the exchange of certificates. This strengthens the security of the connection by ensuring the identity of both parties.
Q: How does TLS 1.3 generate more session keys?
A: TLS 1.3 generates a larger number of session keys, each with perfect cryptographic separation, to enhance security. These keys are used for different purposes and prevent compromise in one key from affecting the others.
Conclusion
TLS 1.3 revolutionizes the handshake process, offering a faster and more secure connection establishment compared to previous versions. With improved privacy, enhanced authentication, and more session keys, TLS 1.3 sets a new standard for secure communication on the web. Stay tuned for more in-depth lessons on TLS 1.3 and its various features.
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