-.\" $OpenBSD: ssh-keygen.1,v 1.49 2001/09/05 06:23:07 deraadt Exp $
+.\" $OpenBSD: ssh-keygen.1,v 1.55 2002/11/26 02:35:30 stevesk Exp $
.\"
.\" -*- nroff -*-
.\"
.Nm ssh-keygen
.Op Fl q
.Op Fl b Ar bits
-.Op Fl t Ar type
+.Fl t Ar type
.Op Fl N Ar new_passphrase
.Op Fl C Ar comment
.Op Fl f Ar output_keyfile
generates, manages and converts authentication keys for
.Xr ssh 1 .
.Nm
-defaults to generating a RSA1 key for use by SSH protocol version 1.
-Specifying the
+can create RSA keys for use by SSH protocol version 1 and RSA or DSA
+keys for use by SSH protocol version 2. The type of key to be generated
+is specified with the
.Fl t
-option instead creates a key for use by SSH protocol version 2.
+option.
.Pp
Normally each user wishing to use SSH
with RSA or DSA authentication runs this once to create the authentication
The passphrase may be empty to indicate no passphrase
(host keys must have an empty passphrase), or it may be a string of
arbitrary length.
-Good passphrases are 10-30 characters long and are
+A passphrase is similar to a password, except it can be a phrase with a
+series of words, punctuation, numbers, whitespace, or any string of
+characters you want.
+Good passphrases are 10-30 characters long, are
not simple sentences or otherwise easily guessable (English
prose has only 1-2 bits of entropy per character, and provides very bad
-passphrases).
+passphrases), and contain a mix of upper and lowercase letters,
+numbers, and non-alphanumeric characters.
The passphrase can be changed later by using the
.Fl p
option.
.It Fl b Ar 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 slower.
+Generally, 1024 bits is considered sufficient.
The default is 1024 bits.
.It Fl c
Requests changing the comment in the private and public key files.
+This operation is only supported for RSA1 keys.
The program will prompt for the file containing the private keys, for
the passphrase if the key has one, and for the new comment.
.It Fl e
This option allows importing keys from several commercial
SSH implementations.
.It Fl l
-Show fingerprint of specified private or public key file.
+Show fingerprint of specified public key file.
+Private RSA1 keys are also supported.
+For RSA and DSA keys
+.Nm
+tries to find the matching public key file and prints its fingerprint.
.It Fl p
Requests changing the passphrase of a private key file instead of
creating a new private key.
or
.Dq dsa
for protocol version 2.
-The default is
-.Dq rsa1 .
.It Fl B
Show the bubblebabble digest of specified private or public key file.
.It Fl C Ar comment