[tor-relays] Re: Post-Quantum Cryptography in Tor's TLS Layer: Help needed!

[Alexander Hansen Færøy via tor-relays <tor-relays@xxxxxxxxxxxxxxxxxxxx>]

Hello Tor Relay Operators!

I did a scan of the network again yesterday. Here're the numbers that you can 
compare against our numbers from March:

Scan Stats:
   - 9707 relays were reachable.
   - 106 relays were unreachable.

Cipher Suites:
   - `TLS13_AES_256_GCM_SHA384`: 9517.
   - `TLS13_CHACHA20_POLY1305_SHA256`: 155.
   - `TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384`: 32.
   - `TLS13_AES_128_GCM_SHA256`: 3.

Key Exchange Groups:
   - `X25519`: 4827.
   - `X25519MLKEM768`: 4326.
   - `secp256r1`: 554.

Directory Authorities:
   - 10 out of 10 were reachable.
   - `TLS13_AES_256_GCM_SHA384` was used by all 10.
   - `X25519` was used by 5, and `X25519MLKEM768` was used by 5.

4326 / 9707 * 100 = 44.57% of the relays support PQC handshakes right now.

It's great to see that we have over 1000 more relays supporting PQC, but we are 
still a bit away from being able to enforce PQC in any possible manner here.

I've updated the list of relays and what they support here: 
https://ahf.me/tor-tls-pqc/2026-06-18/

If your relay does not yet support the `X25519MLKEM768` group, it would be 
really lovely if you could look into upgrading your TLS library (OpenSSL >= 
3.5.0 and LibreSSL >= 4.3.0) used by your relay.

Thanks all for running relays! <3

Cheers,
Alex

On 02/03/2026 14.29, Alexander Hansen Færøy via tor-relays wrote:
> The summary of yesterday's scan is as follows:
>
> Scan Stats:
>     - 9562 relays were reachable.
>     - 158 relays were unreachable.
>
> Cipher Suites:
>     - `TLS13_AES_256_GCM_SHA384`: 9352.
>     - `TLS13_CHACHA20_POLY1305_SHA256`: 165.
>     - `TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384`: 39.
>     - `TLS13_AES_128_GCM_SHA256`: 6.
>
> Key Exchange Groups:
>     - `X25519`: 5350.
>     - `X25519MLKEM768`: 3313.
>     - `secp256r1`: 899.
>
> Directory Authorities:
>     - 10 out of 10 were reachable.
>     - `TLS13_AES_256_GCM_SHA384` was used by all 10.
>     - `X25519` was used by 5, and `X25519MLKEM768` was used by 5.
>
> 3313 / 9562 * 100.0 = 34.65% of relays are supporting the `X25519MLKEM768` PQC
> handshake in the network right now.


--
Alexander Hansen Færøy
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