Terrapin attack and strict KEX

[DavisNT]

There is a recently published attack on SSH named Terrapin.

Is SSH.NET affected by Terrapin (does SSH.NET support any of the vulnerable encryption modes; does SSH.NET support the strict key exchange countermeasure)?

[Rob-Hague]

The library does not support ChaCha20-Poly1305 nor Encrypt-then-MAC (for better or worse), and does not support SSH extension negotiation (RFC8308)

[edwinvandeburgt]

Will Encrypt-then-MAC be supported (and when)?

Because one of the major cloud provider's SFTP-service isn't working anymore with the proposed security profile:

Amazon AWS FTPS policy

Profile 2022-03 still support the "normal" hashfunctions:
"SshMacs": [ "[email protected]", "[email protected]", "hmac-sha2-512", "hmac-sha2-256" ],

With profile 2023-05, only the EtM versions are supported:
"SshMacs": [ "[email protected]", "[email protected]" ],

Do you have a policy regarding attempting to remain compatibility of the library with the major Cloud providers Microsoft, Amazon and Google?

[DavisNT]

@scott-xu, @Rob-Hague Thank you very much!