CHACHA20-POLY1305 cipher

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Post by kevdog » Fri Oct 15, 2021 11:32 am
Hi I'm using Viscosity 1.94 as an OpenVPN client connecting to an OpenVPN server running pfSense 2.5.2. I control both the server and client. I have installed on my MacBook openvpn 2.5.4 and I'm aware on pfSense openvpn = 2.5.4. I'm not sure what version of openvpn comes bundled with however.

I was configuring both client and server to use TLS 1.3 and was attempting use the data-cipher of CHACHA20-POLY1305 (I entered this under the data-ciphers option under advanced).

When trying to connect to remote server, viscosity just gives an error that CHACHA20-POLY1305 is unsupported. I'm not sure if this means on the client or server.

Within pfsense I have Data Encryption Algorithms of: CHACHA20-POLY1305, AES-256-GCM, AES-128-GCM. I believe the CHACHA20-POLY1305 cipher is supported since its listed as one of the available options.

Just trying to get some confirmation on whether CHACHA is supported with Viscosity.


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Post by James » Fri Oct 15, 2021 2:49 pm
Hi kevdog,

Use of this cipher requires OpenVPN 2.5, which the latest Viscosity beta version supports. You can find instructions in the article below for how to use the latest beta version: ... -versions/

We expect to have version 1.10 fully released once macOS 12 comes out of beta.

James Bekkema
Viscosity Developer



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Joined: Fri Oct 15, 2021 12:09 am

Post by kevdog » Fri Oct 15, 2021 11:52 pm
Thanks for info -- I just went ahead and starting using viscosity's beta version and all is well. Thanks for information.
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