Finally, there is a line saying "Private-MAC: " plus a hex representation of a HMAC-SHA-1 of: string name of algorithm ("ssh-dss", "ssh-rsa") string encryption
type string comment string public-blob string private-plaintext (the plaintext version of the private part, including the final padding) The key to the MAC is
itself a SHA-1 hash of: data "putty-private-key-file-mac-key" data passphrase (An empty passphrase is used for unencrypted keys.)