.\"     $NetBSD: skey.3,v 1.9 2008/04/30 13:10:52 martin Exp $
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Gregory McGarry.
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.Dd November 10, 2001
.Dt SKEY 3
.Os
.Sh NAME
.Nm skey ,
.Nm skeychallenge ,
.Nm skeylookup ,
.Nm skeygetnext ,
.Nm skeyverify ,
.Nm skeyzero ,
.Nm getskeyprompt ,
.Nm skey_set_algorithm ,
.Nm skey_get_algorithm ,
.Nm skey_haskey ,
.Nm skey_keyinfo ,
.Nm skey_passcheck ,
.Nm skey_authenticate
.Nd one-time password (OTP) library
.Sh LIBRARY
S/key One-Time Password Library (libskey, -lskey)
.Sh SYNOPSIS
.In skey.h
.Ft int
.Fn skeychallenge "struct skey *mp" "const char *name" "char *ss" \
"size_t sslen"
.Ft int
.Fn skeylookup "struct skey *mp" "const char *name"
.Ft int
.Fn skeygetnext "struct skey *mp"
.Ft int
.Fn skeyverify "struct skey *mp" "char *response"
.Ft int
.Fn skeyzero "struct skey *mp" "char *response"
.Ft int
.Fn getskeyprompt "struct skey *mp" "char *name" "char *prompt"
.Ft const char *
.Fn skey_set_algorithm "const char *new"
.Ft const char *
.Fn skey_get_algorithm "void"
.Ft int
.Fn skey_haskey "const char *username"
.Ft const char *
.Fn skey_keyinfo "const char *username"
.Ft int
.Fn skey_passcheck "const char *username" "char *passwd"
.Ft int
.Fn skey_authenticate "const char *username"
.Ft void
.Fn f "char *x"
.Ft int
.Fn keycrunch "char *result" "const char *seed" "const char *passwd"
.Ft void
.Fn rip "char *buf"
.Ft char *
.Fn readpass "char *buf " "int n"
.Ft char *
.Fn readskey "char *buf" "int n"
.Ft int
.Fn atob8 "char *out" "const char *in"
.Ft int
.Fn btoa8 "char *out" "const char *in"
.Ft int
.Fn htoi "int c"
.Ft const char *
.Fn skipspace "const char *cp"
.Ft void
.Fn backspace "char *buf"
.Ft void
.Fn sevenbit "char *buf"
.Ft char *
.Fn btoe "char *engout" "const char *c"
.Ft int
.Fn etob "char *out" "const char *e"
.Ft char *
.Fn put8 "char *out" "const char *s"
.Sh DESCRIPTION
The
.Nm
library provides routines for accessing
.Nx Ns 's
one-time password (OTP) authentication system.
.Pp
Most S/Key operations take a pointer to a
.Em struct skey ,
which should be considered as an opaque identifier.
.Sh FUNCTIONS
The following high-level functions are available:
.Bl -tag -width compact
.It Fn skeychallenge "mp" "name" "ss" "sslen"
Return a S/Key challenge for user
.Fa name .
If successful, the caller's skey structure
.Fa mp
is filled and 0 is returned.
If unsuccessful (e.g. if name is unknown),
\-1 is returned.
.It Fn skeylookup "mp" "name"
Find an entry for user
.Fa name
in the one-time password database.
Returns 0 if the entry is found and 1 if the entry is not found.
If an error occurs accessing the database, \-1 is returned.
.It Fn skeygetnext "mp"
Get the next entry in the one-time password database.
Returns 0 on success and the entry is stored in
.Ar mp
and 1 if no more entries are available.
If an error occurs accessing the database, \-1 is returned.
.It Fn skeyverify "mp" "response"
Verify response
.Fa response
to a S/Key challenge.
Returns 0 if the verification is successful and 1 if the verification failed.
If an error occurs accessing the database, \-1 is returned.
.It Fn skeyzero "mp" "response"
Comment out user's entry in the S/Key database.
Returns 0 on success and the database is updated,
otherwise \-1 is returned and the database remains unchanged.
.It Fn getskeyprompt "mp" "name" "prompt"
Issue a S/Key challenge for user
.Ar name .
If successful, fill in the caller's skey structure
.Fa mp
and return 0.
If unsuccessful (e.g. if name is unknown) \-1 is returned.
.El
.Pp
The following lower-level functions are available:
.Bl -tag -width compact
.It Fn skey_set_algorithm "new"
Set hash algorithm type.
Valid values for
.Fa new
are "md4", "md5" and "sha1".
.It Fn skey_get_algorithm "void"
Get current hash type.
.It Fn skey_haskey "username"
Returns 0 if the user
.Fa username
exists and 1 if the user doesn't exist.
Returns \-1 on file error.
.It Fn skey_keyinfo "username"
Returns the current sequence number and seed for user
.Ar username .
.It Fn skey_passcheck "username" "passwd"
Checks to see if answer is the correct one to the current challenge.
.It Fn skey_authenticate "username"
Used when calling program will allow input of the user's response to
the challenge.
Returns zero on success or \-1 on failure.
.El
.Pp
The following miscellaneous functions are available:
.Bl -tag -width compact
.It Fn f "x"
One-way function to take 8 bytes pointed to by
.Fa x
and return 8 bytes in place.
.It Fn keycrunch "char *result" "const char *seed" "const char *passwd"
Crunch a key.
.It Fn rip "buf"
Strip trailing CR/LF characters from a line of text
.Fa buf .
.It Fn readpass "buf" "n"
Read in secret passwd (turns off echo).
.It Fn readskey "buf" "n"
Read in an s/key OTP (does not turn off echo).
.It Fn atob8 "out" "in"
Convert 8-byte hex-ascii string
.Fa in
to binary array
.Fa out .
Returns 0 on success, \-1 on error.
.It Fn btoa8 "out" "in"
Convert 8-byte binary array
.Fa in
to hex-ascii string
.Fa out .
Returns 0 on success, \-1 on error.
.It Fn htoi "int c"
Convert hex digit to binary integer.
.It Fn skipspace "cp"
Skip leading spaces from the string
.Fa cp .
.It Fn backspace "buf"
Remove backspaced over characters from the string
.Fa buf .
.It Fn sevenbit "buf"
Ensure line
.Fa buf
is all seven bits.
.It Fn btoe "engout" "c"
Encode 8 bytes in
.Ar c
as a string of English words.
Returns a pointer to a static buffer in
.Fa engout .
.It Fn etob "out" "e"
Convert English to binary.
Returns 0 if the word is not in the database, 1 if all good words and
parity is valid, \-1 if badly formed input (i.e. \*[Gt] 4 char word)
and -2 if words are valid but parity is wrong.
.It Fn put8 "out" "s"
Display 8 bytes
.Fa s
as a series of 16-bit hex digits.
.El
.Sh FILES
.Bl -tag -width /usr/lib/libskey_p.a -compact
.It Pa /usr/lib/libskey.a
static skey library
.It Pa /usr/lib/libskey.so
dynamic skey library
.It Pa /usr/lib/libskey_p.a
static skey library compiled for profiling
.El
.Sh SEE ALSO
.Xr skey 1 ,
.Xr skeyaudit 1 ,
.Xr skeyinfo 1
.Sh BUGS
The
.Nm
library functions are not re-entrant or thread-safe.
.Pp
The
.Nm
library defines many poorly named functions which pollute the name space.