Technology Google Chrome's new post-quantum cryptography may break TLS connections


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Thread author
May 29, 2023
Some Google Chrome users report having issues connecting to websites, servers, and firewalls after Chrome 124 was released last week with the new quantum-resistant X25519Kyber768 encapsulation mechanism enabled by default.
Google started testing the post-quantum secure TLS key encapsulation mechanism in August and has now enabled it in the latest Chrome version for all users.
The new version utilizes the Kyber768 quantum-resistant key agreement algorithm for TLS 1.3 and QUIC connections to protect Chrome TLS traffic against quantum cryptanalysis.
"After several months of experimentation for compatibility and performance impacts, we're launching a hybrid postquantum TLS key exchange to desktop platforms in Chrome 124," the Chrome Security Team explains.
"This protects users' traffic from so-called 'store now decrypt later' attacks, in which a future quantum computer could decrypt encrypted traffic recorded today."
Store now, decrypt later attacks are when attackers collect encrypted data and store it for the future when there may be new decryption methods, such as using quantum computers or encryption keys become available.
To protect against future attacks, companies have already started to add quantum-resistant encryption to their network stack to prevent these types of decryption strategies from working in the future. Some companies that have already introduced quantum-resistant algorithms include Apple, Signal, and Google.
However, as system admins have shared online since Google Chrome 124 and Microsoft Edge 124 started rolling out on desktop platforms last week, some web applications, firewalls, and servers will drop connections after the ClientHello TLS handshake.
The issue also affects security appliances, firewalls, networking middleware, and various network devices from multiple vendors (e.g., Fortinet, SonicWall, Palo Alto Networks, AWS).
"This appears to break the TLS handshake for servers that do not know what to do with the extra data in the client hello message," one admin said.

You'll get the error: "ERR_CONNECTION_RESET"

In Firefox the setting security.tls.enable_kyber in about:config is still set to false by default.
But it is enabled in Firefox Nightly (127)

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