xref: /freebsd/contrib/ntp/util/ntp-keygen.1ntp-keygenmdoc (revision c57c26179033f64c2011a2d2a904ee3fa62e826a)
1.Dd May 25 2024
2.Dt NTP_KEYGEN 1ntp-keygenmdoc User Commands
3.Os
4.\"  EDIT THIS FILE WITH CAUTION  (ntp-keygen-opts.mdoc)
5.\"
6.\"  It has been AutoGen-ed  May 25, 2024 at 12:04:46 AM by AutoGen 5.18.16
7.\"  From the definitions    ntp-keygen-opts.def
8.\"  and the template file   agmdoc-cmd.tpl
9.Sh NAME
10.Nm ntp-keygen
11.Nd Create a NTP host key
12.Sh SYNOPSIS
13.Nm
14.\" Mixture of short (flag) options and long options
15.Op Fl flags
16.Op Fl flag Op Ar value
17.Op Fl \-option\-name Ns Oo Oo Ns "=| " Oc Ns Ar value Oc
18.Pp
19All arguments must be options.
20.Pp
21.Sh DESCRIPTION
22This program generates cryptographic data files used by the NTPv4
23authentication and identification schemes.
24It can generate message digest keys used in symmetric key cryptography and,
25if the OpenSSL software library has been installed, it can generate host keys,
26signing keys, certificates, and identity keys and parameters used in Autokey
27public key cryptography.
28These files are used for cookie encryption,
29digital signature, and challenge/response identification algorithms
30compatible with the Internet standard security infrastructure.
31.Pp
32The message digest symmetric keys file is generated in a format
33compatible with NTPv3.
34All other files are in PEM\-encoded printable ASCII format,
35so they can be embedded as MIME attachments in email to other sites
36and certificate authorities.
37By default, files are not encrypted.
38.Pp
39When used to generate message digest symmetric keys, the program
40produces a file containing ten pseudo\-random printable ASCII strings
41suitable for the MD5 message digest algorithm included in the
42distribution.
43If the OpenSSL library is installed, it produces an additional ten
44hex\-encoded random bit strings suitable for SHA1, AES\-128\-CMAC, and
45other message digest algorithms.
46The message digest symmetric keys file must be distributed and stored
47using secure means beyond the scope of NTP itself.
48Besides the keys used for ordinary NTP associations, additional keys
49can be defined as passwords for the
50.Xr ntpq 1ntpqmdoc
51and
52.Xr ntpdc 1ntpdcmdoc
53utility programs.
54.Pp
55The remaining generated files are compatible with other OpenSSL
56applications and other Public Key Infrastructure (PKI) resources.
57Certificates generated by this program are compatible with extant
58industry practice, although some users might find the interpretation of
59X509v3 extension fields somewhat liberal.
60However, the identity keys are probably not compatible with anything
61other than Autokey.
62.Pp
63Some files used by this program are encrypted using a private password.
64The
65.Fl p
66option specifies the read password for local encrypted files and the
67.Fl q
68option the write password for encrypted files sent to remote sites.
69If no password is specified, the host name returned by the Unix
70.Xr hostname 1
71command, normally the DNS name of the host, is used as the the default read
72password, for convenience.
73The
74.Nm
75program prompts for the password if it reads an encrypted file
76and the password is missing or incorrect.
77If an encrypted file is read successfully and
78no write password is specified, the read password is used
79as the write password by default.
80.Pp
81The
82.Cm pw
83option of the
84.Ic crypto
85.Xr ntpd 1ntpdmdoc
86configuration command specifies the read
87password for previously encrypted local files.
88This must match the local read password used by this program.
89If not specified, the host name is used.
90Thus, if files are generated by this program without an explicit password,
91they can be read back by
92.Xr ntpd 1ntpdmdoc
93without specifying an explicit password but only on the same host.
94If the write password used for encryption is specified as the host name,
95these files can be read by that host with no explicit password.
96.Pp
97Normally, encrypted files for each host are generated by that host and
98used only by that host, although exceptions exist as noted later on
99this page.
100The symmetric keys file, normally called
101.Pa ntp.keys ,
102is usually installed in
103.Pa /etc .
104Other files and links are usually installed in
105.Pa /usr/local/etc ,
106which is normally in a shared filesystem in
107NFS\-mounted networks and cannot be changed by shared clients.
108In these cases, NFS clients can specify the files in another
109directory such as
110.Pa /etc
111using the
112.Ic keysdir
113.Xr ntpd 1ntpdmdoc
114configuration file command.
115.Pp
116This program directs commentary and error messages to the standard
117error stream
118.Pa stderr
119and remote files to the standard output stream
120.Pa stdout
121where they can be piped to other applications or redirected to files.
122The names used for generated files and links all begin with the
123string
124.Pa ntpkey\&*
125and include the file type, generating host and filestamp,
126as described in the
127.Sx "Cryptographic Data Files"
128section below.
129.Ss Running the Program
130The safest way to run the
131.Nm
132program is logged in directly as root.
133The recommended procedure is change to the
134.Ar keys
135directory, usually
136.Pa /usr/local/etc ,
137then run the program.
138.Pp
139To test and gain experience with Autokey concepts, log in as root and
140change to the
141.Ar keys
142directory, usually
143.Pa /usr/local/etc .
144When run for the first time, or if all files with names beginning with
145.Pa ntpkey\&*
146have been removed, use the
147.Nm
148command without arguments to generate a default
149.Cm RSA
150host key and matching
151.Cm RSA\-MD5
152certificate file with expiration date one year hence,
153which is all that is necessary in many cases.
154The program also generates soft links from the generic names
155to the respective files.
156If run again without options, the program uses the
157existing keys and parameters and generates a new certificate file with
158new expiration date one year hence, and soft link.
159.Pp
160The host key is used to encrypt the cookie when required and so must be
161.Cm RSA
162type.
163By default, the host key is also the sign key used to encrypt signatures.
164When necessary, a different sign key can be specified and this can be
165either
166.Cm RSA
167or
168.Cm DSA
169type.
170By default, the message digest type is
171.Cm MD5 ,
172but any combination
173of sign key type and message digest type supported by the OpenSSL library
174can be specified, including those using the
175.Cm AES128CMAC , MD2 , MD5 , MDC2 , SHA , SHA1
176and
177.Cm RIPE160
178message digest algorithms.
179However, the scheme specified in the certificate must be compatible
180with the sign key.
181Certificates using any digest algorithm are compatible with
182.Cm RSA
183sign keys;
184however, only
185.Cm SHA
186and
187.Cm SHA1
188certificates are compatible with
189.Cm DSA
190sign keys.
191.Pp
192Private/public key files and certificates are compatible with
193other OpenSSL applications and very likely other libraries as well.
194Certificates or certificate requests derived from them should be compatible
195with extant industry practice, although some users might find
196the interpretation of X509v3 extension fields somewhat liberal.
197However, the identification parameter files, although encoded
198as the other files, are probably not compatible with anything other than Autokey.
199.Pp
200Running the program as other than root and using the Unix
201.Xr su 1
202command
203to assume root may not work properly, since by default the OpenSSL library
204looks for the random seed file
205.Pa .rnd
206in the user home directory.
207However, there should be only one
208.Pa .rnd ,
209most conveniently
210in the root directory, so it is convenient to define the
211.Ev RANDFILE
212environment variable used by the OpenSSL library as the path to
213.Pa .rnd .
214.Pp
215Installing the keys as root might not work in NFS\-mounted
216shared file systems, as NFS clients may not be able to write
217to the shared keys directory, even as root.
218In this case, NFS clients can specify the files in another
219directory such as
220.Pa /etc
221using the
222.Ic keysdir
223.Xr ntpd 1ntpdmdoc
224configuration file command.
225There is no need for one client to read the keys and certificates
226of other clients or servers, as these data are obtained automatically
227by the Autokey protocol.
228.Pp
229Ordinarily, cryptographic files are generated by the host that uses them,
230but it is possible for a trusted agent (TA) to generate these files
231for other hosts; however, in such cases files should always be encrypted.
232The subject name and trusted name default to the hostname
233of the host generating the files, but can be changed by command line options.
234It is convenient to designate the owner name and trusted name
235as the subject and issuer fields, respectively, of the certificate.
236The owner name is also used for the host and sign key files,
237while the trusted name is used for the identity files.
238.Pp
239All files are installed by default in the keys directory
240.Pa /usr/local/etc ,
241which is normally in a shared filesystem
242in NFS\-mounted networks.
243The actual location of the keys directory
244and each file can be overridden by configuration commands,
245but this is not recommended.
246Normally, the files for each host are generated by that host
247and used only by that host, although exceptions exist
248as noted later on this page.
249.Pp
250Normally, files containing private values,
251including the host key, sign key and identification parameters,
252are permitted root read/write\-only;
253while others containing public values are permitted world readable.
254Alternatively, files containing private values can be encrypted
255and these files permitted world readable,
256which simplifies maintenance in shared file systems.
257Since uniqueness is insured by the
258.Ar hostname
259and
260.Ar filestamp
261file name extensions, the files for an NTP server and
262dependent clients can all be installed in the same shared directory.
263.Pp
264The recommended practice is to keep the file name extensions
265when installing a file and to install a soft link
266from the generic names specified elsewhere on this page
267to the generated files.
268This allows new file generations to be activated simply
269by changing the link.
270If a link is present,
271.Xr ntpd 1ntpdmdoc
272follows it to the file name to extract the
273.Ar filestamp .
274If a link is not present,
275.Xr ntpd 1ntpdmdoc
276extracts the
277.Ar filestamp
278from the file itself.
279This allows clients to verify that the file and generation times
280are always current.
281The
282.Nm
283program uses the same
284.Ar filestamp
285extension for all files generated
286at one time, so each generation is distinct and can be readily
287recognized in monitoring data.
288.Pp
289Run the command on as many hosts as necessary.
290Designate one of them as the trusted host (TH) using
291.Nm
292with the
293.Fl T
294option and configure it to synchronize from reliable Internet servers.
295Then configure the other hosts to synchronize to the TH directly or
296indirectly.
297A certificate trail is created when Autokey asks the immediately
298ascendant host towards the TH to sign its certificate, which is then
299provided to the immediately descendant host on request.
300All group hosts should have acyclic certificate trails ending on the TH.
301.Pp
302The host key is used to encrypt the cookie when required and so must be
303RSA type.
304By default, the host key is also the sign key used to encrypt
305signatures.
306A different sign key can be assigned using the
307.Fl S
308option and this can be either
309.Cm RSA
310or
311.Cm DSA
312type.
313By default, the signature
314message digest type is
315.Cm MD5 ,
316but any combination of sign key type and
317message digest type supported by the OpenSSL library can be specified
318using the
319.Fl c
320option.
321.Pp
322The rules say cryptographic media should be generated with proventic
323filestamps, which means the host should already be synchronized before
324this program is run.
325This of course creates a chicken\-and\-egg problem
326when the host is started for the first time.
327Accordingly, the host time
328should be set by some other means, such as eyeball\-and\-wristwatch, at
329least so that the certificate lifetime is within the current year.
330After that and when the host is synchronized to a proventic source, the
331certificate should be re\-generated.
332.Pp
333Additional information on trusted groups and identity schemes is on the
334.Dq Autokey Public\-Key Authentication
335page.
336.Pp
337File names begin with the prefix
338.Pa ntpkey Ns _
339and end with the suffix
340.Pa _ Ns Ar hostname . Ar filestamp ,
341where
342.Ar hostname
343is the owner name, usually the string returned
344by the Unix
345.Xr hostname 1
346command, and
347.Ar filestamp
348is the NTP seconds when the file was generated, in decimal digits.
349This both guarantees uniqueness and simplifies maintenance
350procedures, since all files can be quickly removed
351by a
352.Ic rm Pa ntpkey\&*
353command or all files generated
354at a specific time can be removed by a
355.Ic rm Pa \&* Ns Ar filestamp
356command.
357To further reduce the risk of misconfiguration,
358the first two lines of a file contain the file name
359and generation date and time as comments.
360.Ss Trusted Hosts and Groups
361Each cryptographic configuration involves selection of a signature scheme
362and identification scheme, called a cryptotype,
363as explained in the
364.Sx Authentication Options
365section of
366.Xr ntp.conf 5 .
367The default cryptotype uses
368.Cm RSA
369encryption,
370.Cm MD5
371message digest
372and
373.Cm TC
374identification.
375First, configure a NTP subnet including one or more low\-stratum
376trusted hosts from which all other hosts derive synchronization
377directly or indirectly.
378Trusted hosts have trusted certificates;
379all other hosts have nontrusted certificates.
380These hosts will automatically and dynamically build authoritative
381certificate trails to one or more trusted hosts.
382A trusted group is the set of all hosts that have, directly or indirectly,
383a certificate trail ending at a trusted host.
384The trail is defined by static configuration file entries
385or dynamic means described on the
386.Sx Automatic NTP Configuration Options
387section of
388.Xr ntp.conf 5 .
389.Pp
390On each trusted host as root, change to the keys directory.
391To insure a fresh fileset, remove all
392.Pa ntpkey
393files.
394Then run
395.Nm
396.Fl T
397to generate keys and a trusted certificate.
398On all other hosts do the same, but leave off the
399.Fl T
400flag to generate keys and nontrusted certificates.
401When complete, start the NTP daemons beginning at the lowest stratum
402and working up the tree.
403It may take some time for Autokey to instantiate the certificate trails
404throughout the subnet, but setting up the environment is completely automatic.
405.Pp
406If it is necessary to use a different sign key or different digest/signature
407scheme than the default, run
408.Nm
409with the
410.Fl S Ar type
411option, where
412.Ar type
413is either
414.Cm RSA
415or
416.Cm DSA .
417The most frequent need to do this is when a
418.Cm DSA Ns \-signed
419certificate is used.
420If it is necessary to use a different certificate scheme than the default,
421run
422.Nm
423with the
424.Fl c Ar scheme
425option and selected
426.Ar scheme
427as needed.
428If
429.Nm
430is run again without these options, it generates a new certificate
431using the same scheme and sign key, and soft link.
432.Pp
433After setting up the environment it is advisable to update certificates
434from time to time, if only to extend the validity interval.
435Simply run
436.Nm
437with the same flags as before to generate new certificates
438using existing keys, and soft links.
439However, if the host or sign key is changed,
440.Xr ntpd 1ntpdmdoc
441should be restarted.
442When
443.Xr ntpd 1ntpdmdoc
444is restarted, it loads any new files and restarts the protocol.
445Other dependent hosts will continue as usual until signatures are refreshed,
446at which time the protocol is restarted.
447.Ss Identity Schemes
448As mentioned on the Autonomous Authentication page,
449the default
450.Cm TC
451identity scheme is vulnerable to a middleman attack.
452However, there are more secure identity schemes available,
453including
454.Cm PC , IFF , GQ
455and
456.Cm MV
457schemes described below.
458These schemes are based on a TA, one or more trusted hosts
459and some number of nontrusted hosts.
460Trusted hosts prove identity using values provided by the TA,
461while the remaining hosts prove identity using values provided
462by a trusted host and certificate trails that end on that host.
463The name of a trusted host is also the name of its sugroup
464and also the subject and issuer name on its trusted certificate.
465The TA is not necessarily a trusted host in this sense, but often is.
466.Pp
467In some schemes there are separate keys for servers and clients.
468A server can also be a client of another server,
469but a client can never be a server for another client.
470In general, trusted hosts and nontrusted hosts that operate
471as both server and client have parameter files that contain
472both server and client keys.
473Hosts that operate
474only as clients have key files that contain only client keys.
475.Pp
476The PC scheme supports only one trusted host in the group.
477On trusted host alice run
478.Nm
479.Fl P
480.Fl p Ar password
481to generate the host key file
482.Pa ntpkey Ns _ Cm RSA Pa key_alice. Ar filestamp
483and trusted private certificate file
484.Pa ntpkey Ns _ Cm RSA\-MD5 _ Pa cert_alice. Ar filestamp ,
485and soft links.
486Copy both files to all group hosts;
487they replace the files which would be generated in other schemes.
488On each host
489.Ar bob
490install a soft link from the generic name
491.Pa ntpkey_host_ Ns Ar bob
492to the host key file and soft link
493.Pa ntpkey_cert_ Ns Ar bob
494to the private certificate file.
495Note the generic links are on bob, but point to files generated
496by trusted host alice.
497In this scheme it is not possible to refresh
498either the keys or certificates without copying them
499to all other hosts in the group, and recreating the soft links.
500.Pp
501For the
502.Cm IFF
503scheme proceed as in the
504.Cm TC
505scheme to generate keys
506and certificates for all group hosts, then for every trusted host in the group,
507generate the
508.Cm IFF
509parameter file.
510On trusted host alice run
511.Nm
512.Fl T
513.Fl I
514.Fl p Ar password
515to produce her parameter file
516.Pa ntpkey_IFFpar_alice. Ns Ar filestamp ,
517which includes both server and client keys.
518Copy this file to all group hosts that operate as both servers
519and clients and install a soft link from the generic
520.Pa ntpkey_iff_alice
521to this file.
522If there are no hosts restricted to operate only as clients,
523there is nothing further to do.
524As the
525.Cm IFF
526scheme is independent
527of keys and certificates, these files can be refreshed as needed.
528.Pp
529If a rogue client has the parameter file, it could masquerade
530as a legitimate server and present a middleman threat.
531To eliminate this threat, the client keys can be extracted
532from the parameter file and distributed to all restricted clients.
533After generating the parameter file, on alice run
534.Nm
535.Fl e
536and pipe the output to a file or email program.
537Copy or email this file to all restricted clients.
538On these clients install a soft link from the generic
539.Pa ntpkey_iff_alice
540to this file.
541To further protect the integrity of the keys,
542each file can be encrypted with a secret password.
543.Pp
544For the
545.Cm GQ
546scheme proceed as in the
547.Cm TC
548scheme to generate keys
549and certificates for all group hosts, then for every trusted host
550in the group, generate the
551.Cm IFF
552parameter file.
553On trusted host alice run
554.Nm
555.Fl T
556.Fl G
557.Fl p Ar password
558to produce her parameter file
559.Pa ntpkey_GQpar_alice. Ns Ar filestamp ,
560which includes both server and client keys.
561Copy this file to all group hosts and install a soft link
562from the generic
563.Pa ntpkey_gq_alice
564to this file.
565In addition, on each host
566.Ar bob
567install a soft link
568from generic
569.Pa ntpkey_gq_ Ns Ar bob
570to this file.
571As the
572.Cm GQ
573scheme updates the
574.Cm GQ
575parameters file and certificate
576at the same time, keys and certificates can be regenerated as needed.
577.Pp
578For the
579.Cm MV
580scheme, proceed as in the
581.Cm TC
582scheme to generate keys
583and certificates for all group hosts.
584For illustration assume trish is the TA, alice one of several trusted hosts
585and bob one of her clients.
586On TA trish run
587.Nm
588.Fl V Ar n
589.Fl p Ar password ,
590where
591.Ar n
592is the number of revokable keys (typically 5) to produce
593the parameter file
594.Pa ntpkeys_MVpar_trish. Ns Ar filestamp
595and client key files
596.Pa ntpkeys_MVkey Ns Ar d _ Pa trish. Ar filestamp
597where
598.Ar d
599is the key number (0 \&<
600.Ar d
601\&<
602.Ar n ) .
603Copy the parameter file to alice and install a soft link
604from the generic
605.Pa ntpkey_mv_alice
606to this file.
607Copy one of the client key files to alice for later distribution
608to her clients.
609It does not matter which client key file goes to alice,
610since they all work the same way.
611Alice copies the client key file to all of her clients.
612On client bob install a soft link from generic
613.Pa ntpkey_mvkey_bob
614to the client key file.
615As the
616.Cm MV
617scheme is independent of keys and certificates,
618these files can be refreshed as needed.
619.Ss Command Line Options
620.Bl -tag -width indent
621.It Fl b Fl \-imbits Ns = Ar modulus
622Set the number of bits in the identity modulus for generating identity keys to
623.Ar modulus
624bits.
625The number of bits in the identity modulus defaults to 256, but can be set to
626values from 256 to 2048 (32 to 256 octets).
627Use the larger moduli with caution, as this can consume considerable computing
628resources and increases the size of authenticated packets.
629.It Fl c Fl \-certificate Ns = Ar scheme
630Select certificate signature encryption/message digest scheme.
631The
632.Ar scheme
633can be one of the following:
634.Cm RSA\-MD2 , RSA\-MD5 , RSA\-MDC2 , RSA\-SHA , RSA\-SHA1 , RSA\-RIPEMD160 , DSA\-SHA ,
635or
636.Cm DSA\-SHA1 .
637Note that
638.Cm RSA
639schemes must be used with an
640.Cm RSA
641sign key and
642.Cm DSA
643schemes must be used with a
644.Cm DSA
645sign key.
646The default without this option is
647.Cm RSA\-MD5 .
648If compatibility with FIPS 140\-2 is required, either the
649.Cm DSA\-SHA
650or
651.Cm DSA\-SHA1
652scheme must be used.
653.It Fl C Fl \-cipher Ns = Ar cipher
654Select the OpenSSL cipher to encrypt the files containing private keys.
655The default without this option is three\-key triple DES in CBC mode,
656.Cm des\-ede3\-cbc .
657The
658.Ic openssl Fl h
659command provided with OpenSSL displays available ciphers.
660.It Fl d Fl \-debug\-level
661Increase debugging verbosity level.
662This option displays the cryptographic data produced in eye\-friendly billboards.
663.It Fl D Fl \-set\-debug\-level Ns = Ar level
664Set the debugging verbosity to
665.Ar level .
666This option displays the cryptographic data produced in eye\-friendly billboards.
667.It Fl e Fl \-id\-key
668Write the
669.Cm IFF
670or
671.Cm GQ
672public parameters from the
673.Ar IFFkey or GQkey
674client keys file previously specified
675as unencrypted data to the standard output stream
676.Pa stdout .
677This is intended for automatic key distribution by email.
678.It Fl G Fl \-gq\-params
679Generate a new encrypted
680.Cm GQ
681parameters and key file for the Guillou\-Quisquater (GQ) identity scheme.
682This option is mutually exclusive with the
683.Fl I
684and
685.Fl V
686options.
687.It Fl H Fl \-host\-key
688Generate a new encrypted
689.Cm RSA
690public/private host key file.
691.It Fl I Fl \-iffkey
692Generate a new encrypted
693.Cm IFF
694key file for the Schnorr (IFF) identity scheme.
695This option is mutually exclusive with the
696.Fl G
697and
698Fl V
699options.
700.It Fl i Fl \-ident Ns = Ar group
701Set the optional Autokey group name to
702.Ar group .
703This is used in the identity scheme parameter file names of
704.Cm IFF , GQ ,
705and
706.Cm MV
707client parameters files.
708In that role, the default is the host name if no group is provided.
709The group name, if specified using
710.Fl i
711or
712.Fl s
713following an
714.Ql @
715character, is also used in certificate subject and issuer names in the form
716.Ar host @ group
717and should match the group specified via
718.Ic crypto Cm ident
719or
720.Ic server Cm ident
721in the ntpd configuration file.
722.It Fl l Fl \-lifetime Ns = Ar days
723Set the lifetime for certificate expiration to
724.Ar days .
725The default lifetime is one year (365 days).
726.It Fl m Fl \-modulus Ns = Ar bits
727Set the number of bits in the prime modulus for generating files to
728.Ar bits .
729The modulus defaults to 512, but can be set from 256 to 2048 (32 to 256 octets).
730Use the larger moduli with caution, as this can consume considerable computing
731resources and increases the size of authenticated packets.
732.It Fl M Fl \-md5key
733Generate a new symmetric keys file containing 10
734.Cm MD5
735keys, and if OpenSSL is available, 10
736.Cm SHA
737keys.
738An
739.Cm MD5
740key is a string of 20 random printable ASCII characters, while a
741.Cm SHA
742key is a string of 40 random hex digits.
743The file can be edited using a text editor to change the key type or key content.
744This option is mutually exclusive with all other options.
745.It Fl p Fl \-password Ns = Ar passwd
746Set the password for reading and writing encrypted files to
747.Ar passwd .
748These include the host, sign and identify key files.
749By default, the password is the string returned by the Unix
750.Ic hostname
751command.
752.It Fl P Fl \-pvt\-cert
753Generate a new private certificate used by the
754.Cm PC
755identity scheme.
756By default, the program generates public certificates.
757Note: the PC identity scheme is not recommended for new installations.
758.It Fl q Fl \-export\-passwd Ns = Ar passwd
759Set the password for writing encrypted
760.Cm IFF , GQ and MV
761identity files redirected to
762.Pa stdout
763to
764.Ar passwd .
765In effect, these files are decrypted with the
766.Fl p
767password, then encrypted with the
768.Fl q
769password.
770By default, the password is the string returned by the Unix
771.Ic hostname
772command.
773.It Fl s Fl \-subject\-key Ns = Ar Oo host Oc Op @ Ar group
774Specify the Autokey host name, where
775.Ar host
776is the optional host name and
777.Ar group
778is the optional group name.
779The host name, and if provided, group name are used in
780.Ar host @ group
781form as certificate subject and issuer.
782Specifying
783.Fl s @ Ar group
784is allowed, and results in leaving the host name unchanged, as with
785.Fl i Ar group .
786The group name, or if no group is provided, the host name are also used in the
787file names of
788.Cm IFF , GQ ,
789and
790.Cm MV
791identity scheme client parameter files.
792If
793.Ar host
794is not specified, the default host name is the string returned by the Unix
795.Ic hostname
796command.
797.It Fl S Fl \-sign\-key Ns = Op Cm RSA | DSA
798Generate a new encrypted public/private sign key file of the specified type.
799By default, the sign key is the host key and has the same type.
800If compatibility with FIPS 140\-2 is required, the sign key type must be
801.Cm DSA .
802.It Fl T Fl \-trusted\-cert
803Generate a trusted certificate.
804By default, the program generates a non\-trusted certificate.
805.It Fl V Fl \-mv\-params Ar nkeys
806Generate
807.Ar nkeys
808encrypted server keys and parameters for the Mu\-Varadharajan (MV)
809identity scheme.
810This option is mutually exclusive with the
811.Fl I
812and
813.Fl G
814options.
815Note: support for this option should be considered a work in progress.
816.El
817.Ss Random Seed File
818All cryptographically sound key generation schemes must have means
819to randomize the entropy seed used to initialize
820the internal pseudo\-random number generator used
821by the library routines.
822The OpenSSL library uses a designated random seed file for this purpose.
823The file must be available when starting the NTP daemon and
824.Nm
825program.
826If a site supports OpenSSL or its companion OpenSSH,
827it is very likely that means to do this are already available.
828.Pp
829It is important to understand that entropy must be evolved
830for each generation, for otherwise the random number sequence
831would be predictable.
832Various means dependent on external events, such as keystroke intervals,
833can be used to do this and some systems have built\-in entropy sources.
834Suitable means are described in the OpenSSL software documentation,
835but are outside the scope of this page.
836.Pp
837The entropy seed used by the OpenSSL library is contained in a file,
838usually called
839.Pa .rnd ,
840which must be available when starting the NTP daemon
841or the
842.Nm
843program.
844The NTP daemon will first look for the file
845using the path specified by the
846.Cm randfile
847subcommand of the
848.Ic crypto
849configuration command.
850If not specified in this way, or when starting the
851.Nm
852program,
853the OpenSSL library will look for the file using the path specified
854by the
855.Ev RANDFILE
856environment variable in the user home directory,
857whether root or some other user.
858If the
859.Ev RANDFILE
860environment variable is not present,
861the library will look for the
862.Pa .rnd
863file in the user home directory.
864Since both the
865.Nm
866program and
867.Xr ntpd 1ntpdmdoc
868daemon must run as root, the logical place to put this file is in
869.Pa /.rnd
870or
871.Pa /root/.rnd .
872If the file is not available or cannot be written,
873the daemon exits with a message to the system log and the program
874exits with a suitable error message.
875.Ss Cryptographic Data Files
876All file formats begin with two nonencrypted lines.
877The first line contains the file name, including the generated host name
878and filestamp, in the format
879.Pa ntpkey_ Ns Ar key _ Ar name . Ar filestamp ,
880where
881.Ar key
882is the key or parameter type,
883.Ar name
884is the host or group name and
885.Ar filestamp
886is the filestamp (NTP seconds) when the file was created.
887By convention,
888.Ar key
889names in generated file names include both upper and lower case
890characters, while
891.Ar key
892names in generated link names include only lower case characters.
893The filestamp is not used in generated link names.
894The second line contains the datestamp in conventional Unix
895.Pa date
896format.
897Lines beginning with
898.Ql #
899are considered comments and ignored by the
900.Nm
901program and
902.Xr ntpd 1ntpdmdoc
903daemon.
904.Pp
905The remainder of the file contains cryptographic data, encoded first using ASN.1
906rules, then encrypted if necessary, and finally written in PEM\-encoded
907printable ASCII text, preceded and followed by MIME content identifier lines.
908.Pp
909The format of the symmetric keys file, ordinarily named
910.Pa ntp.keys ,
911is somewhat different than the other files in the interest of backward compatibility.
912Ordinarily, the file is generated by this program, but it can be constructed
913and edited using an ordinary text editor.
914.Bd -literal -unfilled -offset center
915# ntpkey_MD5key_bk.ntp.org.3595864945
916# Thu Dec 12 19:22:25 2013
9171  MD5 L";Nw<\`.I<f4U0)247"i  # MD5 key
9182  MD5 &>l0%XXK9O'51VwV<xq~  # MD5 key
9193  MD5 lb4zLW~d^!K:]RsD'qb6  # MD5 key
9204  MD5 Yue:tL[+vR)M\`n~bY,'?  # MD5 key
9215  MD5 B;fx'Kgr/&4ZTbL6=RxA  # MD5 key
9226  MD5 4eYwa\`o}3i@@V@..R9!l  # MD5 key
9237  MD5 \`A.([h+;wTQ|xfi%Sn_!  # MD5 key
9248  MD5 45:V,r4]l6y^JH6"Sh?F  # MD5 key
9259  MD5 3\-5vcn*6l29DS?Xdsg)*  # MD5 key
92610 MD5 2late4Me              # MD5 key
92711 SHA1 a27872d3030a9025b8446c751b4551a7629af65c  # SHA1 key
92812 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74  # SHA1 key
92913 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9  # SHA1 key
93014 SHA  a5332809c8878dd3a5b918819108a111509aeceb  # SHA  key
93115 MD2  2fe16c88c760ff2f16d4267e36c1aa6c926e6964  # MD2  key
93216 MD4  b2691811dc19cfc0e2f9bcacd74213f29812183d  # MD4  key
93317 MD5  e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c  # MD5  key
93418 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc  # MDC2 key
93519 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2  # RIPEMD160 key
93620 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878  # AES128CMAC key
937.Ed
938.D1 Figure 1. Typical Symmetric Key File
939.Pp
940Figure 1 shows a typical symmetric keys file used by the reference
941implementation.
942Following the header the keys are entered one per line in the format
943.D1 Ar keyno Ar type Ar key
944where
945.Ar keyno
946is a positive integer in the range 1\-65535;
947.Ar type
948is the key type for the message digest algorithm, which in the absence of the
949OpenSSL library must be
950.Cm MD5
951to designate the MD5 message digest algorithm;
952if the OpenSSL library is installed, the key type can be any
953message digest algorithm supported by that library;
954however, if compatibility with FIPS 140\-2 is required,
955the key type must be either
956.Cm SHA
957or
958.Cm SHA1 ;
959.Ar key
960is the key itself,
961which is a printable ASCII string 20 characters or less in length:
962each character is chosen from the 93 printable characters
963in the range 0x21 through 0x7e (
964.Ql !
965through
966.Ql ~
967\&) excluding space and the
968.Ql #
969character, and terminated by whitespace or a
970.Ql #
971character.
972An OpenSSL key consists of a hex\-encoded ASCII string of 40 characters, which
973is truncated as necessary.
974.Pp
975Note that the keys used by the
976.Xr ntpq 1ntpqmdoc
977and
978.Xr ntpdc 1ntpdcmdoc
979programs
980are checked against passwords requested by the programs
981and entered by hand, so it is generally appropriate to specify these keys
982in human readable ASCII format.
983.Pp
984The
985.Nm
986program generates a symmetric keys file
987.Pa ntpkey_MD5key_ Ns Ar hostname Ns . Ns Ar filestamp .
988Since the file contains private shared keys,
989it should be visible only to root and distributed by secure means
990to other subnet hosts.
991The NTP daemon loads the file
992.Pa ntp.keys ,
993so
994.Nm
995installs a soft link from this name to the generated file.
996Subsequently, similar soft links must be installed by manual
997or automated means on the other subnet hosts.
998While this file is not used with the Autokey Version 2 protocol,
999it is needed to authenticate some remote configuration commands
1000used by the
1001.Xr ntpq 1ntpqmdoc
1002and
1003.Xr ntpdc 1ntpdcmdoc
1004utilities.
1005.Sh "OPTIONS"
1006.Bl -tag
1007.It  Fl b Ar imbits , Fl \-imbits Ns = Ns Ar imbits
1008identity modulus bits.
1009This option takes an integer number as its argument.
1010The value of
1011.Ar imbits
1012is constrained to being:
1013.in +4
1014.nf
1015.na
1016in the range  256 through 2048
1017.fi
1018.in -4
1019.sp
1020The number of bits in the identity modulus.  The default is 512.
1021.It  Fl c Ar scheme , Fl \-certificate Ns = Ns Ar scheme
1022certificate scheme.
1023.sp
1024scheme is one of
1025RSA\-MD2, RSA\-MD5, RSA\-MDC2, RSA\-SHA, RSA\-SHA1, RSA\-RIPEMD160,
1026DSA\-SHA, or DSA\-SHA1.
1027.sp
1028Select the certificate signature encryption/message digest scheme.
1029Note that RSA schemes must be used with a RSA sign key and DSA
1030schemes must be used with a DSA sign key.  The default without
1031this option is RSA\-MD5.
1032.It  Fl C Ar cipher , Fl \-cipher Ns = Ns Ar cipher
1033privatekey cipher.
1034.sp
1035Select the cipher which is used to encrypt the files containing
1036private keys.  The default is three\-key triple DES in CBC mode,
1037equivalent to "\fB\-C des\-ede3\-cbc\fP".  The openssl tool lists ciphers
1038available in "\fBopenssl \-h\fP" output.
1039.It  Fl d , Fl \-debug\-level
1040Increase debug verbosity level.
1041This option may appear an unlimited number of times.
1042.sp
1043.It  Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number
1044Set the debug verbosity level.
1045This option may appear an unlimited number of times.
1046This option takes an integer number as its argument.
1047.sp
1048.It  Fl e , Fl \-id\-key
1049Write IFF or GQ identity keys.
1050.sp
1051Write the public parameters from the IFF or GQ client keys to
1052the standard output.
1053This is intended for automatic key distribution by email.
1054.It  Fl G , Fl \-gq\-params
1055Generate GQ parameters and keys.
1056.sp
1057Generate parameters and keys for the GQ identification scheme,
1058obsoleting any that may exist.
1059.It  Fl H , Fl \-host\-key
1060generate RSA host key.
1061.sp
1062Generate new host keys, obsoleting any that may exist.
1063.It  Fl I , Fl \-iffkey
1064generate IFF parameters.
1065.sp
1066Generate parameters for the IFF identification scheme, obsoleting
1067any that may exist.
1068.It  Fl i Ar group , Fl \-ident Ns = Ns Ar group
1069set Autokey group name.
1070.sp
1071Set the optional Autokey group name to name.  This is used in
1072the file name of IFF, GQ, and MV client parameters files.  In
1073that role, the default is the host name if this option is not
1074provided.  The group name, if specified using \fB\-i/\-\-ident\fP or
1075using \fB\-s/\-\-subject\-name\fP following an '\fB@\fP' character,
1076is also a part of the self\-signed host certificate subject and
1077issuer names in the form \fBhost@group\fP and should match the
1078\'\fBcrypto ident\fP' or '\fBserver ident\fP' configuration in the
1079\fBntpd\fP configuration file.
1080.It  Fl l Ar lifetime , Fl \-lifetime Ns = Ns Ar lifetime
1081set certificate lifetime.
1082This option takes an integer number as its argument.
1083.sp
1084Set the certificate expiration to lifetime days from now.
1085.It  Fl m Ar modulus , Fl \-modulus Ns = Ns Ar modulus
1086prime modulus.
1087This option takes an integer number as its argument.
1088The value of
1089.Ar modulus
1090is constrained to being:
1091.in +4
1092.nf
1093.na
1094in the range  256 through 2048
1095.fi
1096.in -4
1097.sp
1098The number of bits in the prime modulus.  The default is 512.
1099.It  Fl M , Fl \-md5key
1100generate symmetric keys.
1101.sp
1102Generate symmetric keys, obsoleting any that may exist.
1103.It  Fl P , Fl \-pvt\-cert
1104generate PC private certificate.
1105.sp
1106Generate a private certificate.  By default, the program generates
1107public certificates.
1108.It  Fl p Ar passwd , Fl \-password Ns = Ns Ar passwd
1109local private password.
1110.sp
1111Local files containing private data are encrypted with the
1112DES\-CBC algorithm and the specified password.  The same password
1113must be specified to the local ntpd via the "crypto pw password"
1114configuration command.  The default password is the local
1115hostname.
1116.It  Fl q Ar passwd , Fl \-export\-passwd Ns = Ns Ar passwd
1117export IFF or GQ group keys with password.
1118.sp
1119Export IFF or GQ identity group keys to the standard output,
1120encrypted with the DES\-CBC algorithm and the specified password.
1121The same password must be specified to the remote ntpd via the
1122"crypto pw password" configuration command.  See also the option
1123-\-id\-key (\-e) for unencrypted exports.
1124.It  Fl s Ar host@group , Fl \-subject\-name Ns = Ns Ar host@group
1125set host and optionally group name.
1126.sp
1127Set the Autokey host name, and optionally, group name specified
1128following an '\fB@\fP' character.  The host name is used in the file
1129name of generated host and signing certificates, without the
1130group name.  The host name, and if provided, group name are used
1131in \fBhost@group\fP form for the host certificate subject and issuer
1132fields.  Specifying '\fB\-s @group\fP' is allowed, and results in
1133leaving the host name unchanged while appending \fB@group\fP to the
1134subject and issuer fields, as with \fB\-i group\fP.  The group name, or
1135if not provided, the host name are also used in the file names
1136of IFF, GQ, and MV client parameter files.
1137.It  Fl S Ar sign , Fl \-sign\-key Ns = Ns Ar sign
1138generate sign key (RSA or DSA).
1139.sp
1140Generate a new sign key of the designated type, obsoleting any
1141that may exist.  By default, the program uses the host key as the
1142sign key.
1143.It  Fl T , Fl \-trusted\-cert
1144trusted certificate (TC scheme).
1145.sp
1146Generate a trusted certificate.  By default, the program generates
1147a non\-trusted certificate.
1148.It  Fl V Ar num , Fl \-mv\-params Ns = Ns Ar num
1149generate <num> MV parameters.
1150This option takes an integer number as its argument.
1151.sp
1152Generate parameters and keys for the Mu\-Varadharajan (MV)
1153identification scheme.
1154.It  Fl v Ar num , Fl \-mv\-keys Ns = Ns Ar num
1155update <num> MV keys.
1156This option takes an integer number as its argument.
1157.sp
1158This option has not been fully documented.
1159.It Fl \&? , Fl \-help
1160Display usage information and exit.
1161.It Fl \&! , Fl \-more\-help
1162Pass the extended usage information through a pager.
1163.It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc
1164Save the option state to \fIcfgfile\fP.  The default is the \fIlast\fP
1165configuration file listed in the \fBOPTION PRESETS\fP section, below.
1166The command will exit after updating the config file.
1167.It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts
1168Load options from \fIcfgfile\fP.
1169The \fIno\-load\-opts\fP form will disable the loading
1170of earlier config/rc/ini files.  \fI\-\-no\-load\-opts\fP is handled early,
1171out of order.
1172.It Fl \-version Op Brq Ar v|c|n
1173Output version of program and exit.  The default mode is `v', a simple
1174version.  The `c' mode will print copyright information and `n' will
1175print the full copyright notice.
1176.El
1177.Sh "OPTION PRESETS"
1178Any option that is not marked as \fInot presettable\fP may be preset
1179by loading values from configuration ("RC" or ".INI") file(s) and values from
1180environment variables named:
1181.nf
1182  \fBNTP_KEYGEN_<option\-name>\fP or \fBNTP_KEYGEN\fP
1183.fi
1184.ad
1185The environmental presets take precedence (are processed later than)
1186the configuration files.
1187The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
1188If any of these are directories, then the file \fI.ntprc\fP
1189is searched for within those directories.
1190.Sh USAGE
1191.Sh "ENVIRONMENT"
1192See \fBOPTION PRESETS\fP for configuration environment variables.
1193.Sh "FILES"
1194See \fBOPTION PRESETS\fP for configuration files.
1195.Sh "EXIT STATUS"
1196One of the following exit values will be returned:
1197.Bl -tag
1198.It 0 " (EXIT_SUCCESS)"
1199Successful program execution.
1200.It 1 " (EXIT_FAILURE)"
1201The operation failed or the command syntax was not valid.
1202.It 66 " (EX_NOINPUT)"
1203A specified configuration file could not be loaded.
1204.It 70 " (EX_SOFTWARE)"
1205libopts had an internal operational error.  Please report
1206it to autogen\-users@lists.sourceforge.net.  Thank you.
1207.El
1208.Sh "AUTHORS"
1209The University of Delaware and Network Time Foundation
1210.Sh "COPYRIGHT"
1211Copyright (C) 1992\-2024 The University of Delaware and Network Time Foundation all rights reserved.
1212This program is released under the terms of the NTP license, <http://ntp.org/license>.
1213.Sh BUGS
1214It can take quite a while to generate some cryptographic values.
1215.Pp
1216Please report bugs to http://bugs.ntp.org .
1217.Pp
1218Please send bug reports to: https://bugs.ntp.org, bugs@ntp.org
1219.Sh NOTES
1220Portions of this document came from FreeBSD.
1221.Pp
1222This manual page was \fIAutoGen\fP\-erated from the \fBntp\-keygen\fP
1223option definitions.
1224