Secure Shell (SSH) Protocol Parameters 2005-06-02 2025-01-21 Key Exchange Method Names curve25519-sha256 SHOULD diffie-hellman-group14-sha256 SHOULD diffie-hellman-group1-sha1 MUST NOT Encryption Algorithm Names chacha20-poly1305@openssh.com OpenSSH SHOULD aes128-ctr SHOULD aes256-ctr SHOULD 3des-cbc MUST NOT MAC Algorithm Names hmac-sha2-256 SHOULD hmac-sha2-512 SHOULD hmac-sha1 SHOULD NOT Compression Algorithm Names none MUST zlib MAY