skeyinit1

Usage

Overview

skeyinit initializes the system so you can use S/Key one-time passwords to log in. The program will ask you to enter a secret passphrase which is used by skey(1) to generate one-time passwords: enter a phrase of several words in response. After the S/Key database has been updated, you can log in using either your regular password or using S/Key one-time passwords.

skeyinit requires you to type a secret passphrase, so it should be used only on a secure terminal. For example, on the console of a workstation or over an encrypted network session. If you are using skeyinit while logged in over an untrusted network, follow the instructions given below with the -s option.

Before initializing an S/Key entry, the user must authenticate using either a standard password or an S/Key challenge. To use a one-time password for initial authentication, skeyinit -a skey can be used. The user will then be presented with the standard S/Key challenge and allowed to proceed if it is correct.

skeyinit prints a sequence number and a one-time password. This password can't be used to log in; one-time passwords should be generated using skey(1) first. The one-time password printed by skeyinit can be used to verify if the right passphrase has been given to skey(1). The one-time password with the corresponding sequence number printed by skey(1) should match the one printed by skeyinit.

The options are as follows:

-a auth-type

Before an S/Key entry can be initialised, the user must authenticate themselves to the system. This option allows the authentication type to be specified, such as “passwd” or “skey”.

-D

Disables access to the S/Key database. Only the superuser may use the -D option.

-E

Enables access to the S/Key database. Only the superuser may use the -E option.

-md5 | -rmd160 | -sha1

Selects the hash algorithm: MD5, RMD-160 (160-bit Ripe Message Digest), or SHA1 (NIST Secure Hash Algorithm Revision 1).

-n count

Start the skey sequence at count (default is 100).

-r

Removes the user's S/Key entry.

-s

Secure mode. The user is expected to have already used a secure machine to generate the first one-time password. Without the -s option the system will assume you are directly connected over secure communications and prompt you for your secret passphrase. The -s option also allows one to set the seed and count for complete control of the parameters.

When the -s option is specified, skeyinit will try to authenticate the user via S/Key, instead of the default listed in /etc/login.conf. If a user has no entry in the S/Key database, an alternate authentication type must be specified via the -a option (see above). Entering a password or passphrase in plain text defeats the purpose of using “secure” mode.

You can use skeyinit -s in combination with the skey command to set the seed and count if you do not like the defaults. To do this run skeyinit -s in one window and put in your count and seed, then run skey(1) in another window to generate the correct 6 English words for that count and seed. You can then "cut-and-paste" or type the words into the skeyinit window.

-x

Displays one-time passwords in hexadecimal instead of ASCII.

user

The username to be changed/added. By default the current user is operated on.

Files

/etc/login.conf

file containing authentication types

/etc/skey

directory containing user entries for S/Key

Examples

$ skeyinit
Password: enter your regular password here
[Updating user with md5]
Old seed: [md5] host12377
Enter new secret passphrase: type a new passphrase here
Again secret passphrase: again
ID user skey is otp-md5 100 host12378
Next login password: CITE BREW IDLE CAIN ROD DOME
$ otp-md5 -n 3 100 host12378
Enter secret passphrase: type your passphrase here
98: WERE TUG EDDY GEAR GILL TEE
99: NEAR HA TILT FIN LONG SNOW
100: CITE BREW IDLE CAIN ROD DOME

The one-time password for the next login will have sequence number 99.

Diagnostics

skey disabled

/etc/skey does not exist or is not accessible by the user. The superuser may enable skeyinit via the -E flag.