Key Support

Supported Key Types

Prompt currently supports keys of the following key types for both host key verification and client key exchange in both PEM and OpenSSH formats( where applicable):

  • DSA
  • Ed25519
  • RSA


Prompt 3 now supports client key exchange FIDO2 keys in the following formats:

  • Ed25519-SK

Supported Exchange/Security Methods


  • diffie-hellman-group-exchange-sha1
  • diffie-hellman-group14-sha1
  • diffie-hellman-group1-sha1
  • diffie-hellman-group-exchange-sha256
  • ecdh-sha2-nistp256
  • ecdh-sha2-nistp384
  • ecdh-sha2-nistp521


  • aes128-ctr
  • aes192-ctr
  • aes256-ctr
  • aes128-cbc
  • aes192-cbc
  • aes256-cbc
  • blowfish-cbc
  • arcfour
  • arcfour128
  • cast128-cbc
  • 3des-cbc


Troubleshooting Key Import

  • To address issues importing your private key, make sure you are importing the private key, and that it is in a supported format listed above.

  • If Prompt detects a public key (ex., or anything that doesn’t exactly match the format of supported private keys, it won’t offer to let you import from the clipboard.

  • If you already have a PuTTY key (in the PPK format), you can convert it by following these instructions under “Dealing with Private Keys in Other Formats”, then import the resulting OpenSSH private key into Prompt.

Learn more about keys

This article was last updated on October 23, 2023