Key Exchange Security

Supported Key Types

Prompt currently supports OpenSSH private keys but not keys in other formats, and is expecting the private half of either an RSA, DSA or ECDSA key pair (ex., id_rsa or id_dsa  or  id_ecdsa ). If it detects a public key (ex., or anything that doesn’t exactly match the format of an RSA or DSA private key, 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 the Dealing with Private Keys in Other Formats section, then import the resulting OpenSSH private key into Prompt.

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


  • sha2-512
  • sha2-256
  • sha1
  • sha1 96
  • ripemd160

Last updated February 16, 2016