Ciphers & Algorithms

This page lists the cryptographic algorithms supported by ZestSSH for SSH connections.

Key Exchange Algorithms

Algorithm	Notes
`curve25519-sha256`	Recommended. Modern elliptic curve.
`[email protected]`	Same as above, alternate identifier.
`ecdh-sha2-nistp256`	NIST P-256 curve.
`ecdh-sha2-nistp384`	NIST P-384 curve.
`ecdh-sha2-nistp521`	NIST P-521 curve.
`diffie-hellman-group-exchange-sha256`	DH group exchange with SHA-256.
`diffie-hellman-group16-sha512`	4096-bit DH group.
`diffie-hellman-group14-sha256`	2048-bit DH group with SHA-256.
`diffie-hellman-group14-sha1`	Legacy. 2048-bit DH with SHA-1.

Ciphers (Encryption)

Cipher	Notes
`[email protected]`	Recommended. Fast and secure.
`[email protected]`	AES-256 in GCM mode. Authenticated encryption.
`[email protected]`	AES-128 in GCM mode. Authenticated encryption.
`aes256-ctr`	AES-256 in CTR mode.
`aes192-ctr`	AES-192 in CTR mode.
`aes128-ctr`	AES-128 in CTR mode.

MAC Algorithms

MAC (Message Authentication Code) algorithms are used with non-AEAD ciphers (CTR mode). GCM and ChaCha20-Poly1305 ciphers have built-in authentication.

Algorithm	Notes
`[email protected]`	Encrypt-then-MAC. Recommended.
`[email protected]`	Encrypt-then-MAC with SHA-512.
`hmac-sha2-256`	Standard HMAC-SHA-256.
`hmac-sha2-512`	Standard HMAC-SHA-512.
`hmac-sha1`	Legacy. For older server compatibility.

Host Key Types

Type	Notes
`ssh-ed25519`	Recommended. Modern, fast, secure.
`ecdsa-sha2-nistp256`	NIST P-256 curve.
`ecdsa-sha2-nistp384`	NIST P-384 curve.
`ecdsa-sha2-nistp521`	NIST P-521 curve.
`rsa-sha2-512`	RSA with SHA-512 signature.
`rsa-sha2-256`	RSA with SHA-256 signature.
`ssh-rsa`	Legacy RSA with SHA-1. For older servers only.

Client Key Types

Keys that can be generated or imported in ZestSSH:

Type	Generation	Import
Ed25519	Yes	Yes (OpenSSH PEM)
ECDSA	Yes	Yes (OpenSSH PEM)
RSA 4096	Yes	Yes (OpenSSH PEM, PuTTY .ppk)
RSA 2048	Yes	Yes (OpenSSH PEM, PuTTY .ppk)