openssh-2.1.1p1: ssh-keygen.1

[Ulrich Windl]

The manual page for ssh-keygen hides option "-d" almost: It's not 
listed in the usual way:

     The options are as follows:

     -b bits
             Specifies the number of bits in the key to create.  Minimum is
             512 bits.  Generally 1024 bits is considered sufficient, and key
             sizes above that no longer improve security but make things slow-
             er.  The default is 1024 bits.

     -c      Requests changing the comment in the private and public key
             files.  The program will prompt for the file containing 
the pri-
             vate keys, for passphrase if the key has one, and for the 
new
             comment.

     -f      Specifies the filename of the key file.

...

Regards,
Ulrich