I have read in a paper that Authenticated Encryption (by this I mean those that support GCM mode or ChaCha20 ciphers) are not supported in versions older than TLS 1.2?

I could not confirm this as the paper does not provide a reference. Can any expert confirm this information?


1 Answer 1


Pretty sure AES GCM is only defined for TLS 1.2. If you look at RFC 5288, it's titled "AES Galois Counter Mode (GCM) Cipher Suites for TLS" and it only defines suites for TLS 1.2:

The following cipher suites use the new authenticated encryption modes defined in TLS 1.2 with AES in Galois Counter Mode (GCM)

Later on it says

These cipher suites make use of the authenticated encryption with additional data defined in TLS 1.2 [RFC5246]. They MUST NOT be negotiated in older versions of TLS. Clients MUST NOT offer these cipher suites if they do not offer TLS 1.2 or later. Servers that select an earlier version of TLS MUST NOT select one of these cipher suites.

While this doesn't mean that a different, particularly a later, RFC couldn't have defined them, I can't see why one would have done so.

  • $\begingroup$ rfc7905 $\endgroup$
    – kelalaka
    Nov 12, 2018 at 17:00
  • $\begingroup$ Thanks. For readers: ChaCha20 is supported in TLS 1.2 and later. $\endgroup$
    – None
    Nov 12, 2018 at 17:04

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