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1 .Dd June 23 2020
2 .Dt NTP_KEYGEN 1ntp-keygenmdoc User Commands
4 .\" EDIT THIS FILE WITH CAUTION (ntp-keygen-opts.mdoc)
6 .\" It has been AutoGen-ed June 23, 2020 at 02:21:05 AM by AutoGen 5.18.5
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
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
19 All arguments must be options.
21 .Sh DESCRIPTION
22 This program generates cryptographic data files used by the NTPv4
23 authentication and identification schemes.
24 It can generate message digest keys used in symmetric key cryptography and,
25 if the OpenSSL software library has been installed, it can generate host keys,
26 signing keys, certificates, and identity keys and parameters used in Autokey
27 public key cryptography.
28 These files are used for cookie encryption,
29 digital signature, and challenge/response identification algorithms
30 compatible with the Internet standard security infrastructure.
32 The message digest symmetric keys file is generated in a format
33 compatible with NTPv3.
34 All other files are in PEM\-encoded printable ASCII format,
35 so they can be embedded as MIME attachments in email to other sites
36 and certificate authorities.
37 By default, files are not encrypted.
39 When used to generate message digest symmetric keys, the program
40 produces a file containing ten pseudo\-random printable ASCII strings
41 suitable for the MD5 message digest algorithm included in the
43 If the OpenSSL library is installed, it produces an additional ten
44 hex\-encoded random bit strings suitable for SHA1, AES\-128\-CMAC, and
45 other message digest algorithms.
46 The message digest symmetric keys file must be distributed and stored
47 using secure means beyond the scope of NTP itself.
48 Besides the keys used for ordinary NTP associations, additional keys
49 can be defined as passwords for the
50 .Xr ntpq 1ntpqmdoc
52 .Xr ntpdc 1ntpdcmdoc
53 utility programs.
55 The remaining generated files are compatible with other OpenSSL
56 applications and other Public Key Infrastructure (PKI) resources.
57 Certificates generated by this program are compatible with extant
58 industry practice, although some users might find the interpretation of
59 X509v3 extension fields somewhat liberal.
60 However, the identity keys are probably not compatible with anything
61 other than Autokey.
63 Some files used by this program are encrypted using a private password.
65 .Fl p
66 option specifies the read password for local encrypted files and the
67 .Fl q
68 option the write password for encrypted files sent to remote sites.
69 If no password is specified, the host name returned by the Unix
70 .Xr hostname 1
71 command, normally the DNS name of the host, is used as the the default read
72 password, for convenience.
75 program prompts for the password if it reads an encrypted file
76 and the password is missing or incorrect.
77 If an encrypted file is read successfully and
78 no write password is specified, the read password is used
79 as the write password by default.
82 .Cm pw
83 option of the
84 .Ic crypto
85 .Xr ntpd 1ntpdmdoc
86 configuration command specifies the read
87 password for previously encrypted local files.
88 This must match the local read password used by this program.
89 If not specified, the host name is used.
90 Thus, if files are generated by this program without an explicit password,
91 they can be read back by
92 .Xr ntpd 1ntpdmdoc
93 without specifying an explicit password but only on the same host.
94 If the write password used for encryption is specified as the host name,
95 these files can be read by that host with no explicit password.
97 Normally, encrypted files for each host are generated by that host and
98 used only by that host, although exceptions exist as noted later on
99 this page.
100 The symmetric keys file, normally called
101 .Pa ntp.keys ,
102 is usually installed in
103 .Pa /etc .
104 Other files and links are usually installed in
105 .Pa /usr/local/etc ,
106 which is normally in a shared filesystem in
107 NFS\-mounted networks and cannot be changed by shared clients.
108 In these cases, NFS clients can specify the files in another
109 directory such as
110 .Pa /etc
111 using the
112 .Ic keysdir
113 .Xr ntpd 1ntpdmdoc
114 configuration file command.
116 This program directs commentary and error messages to the standard
117 error stream
118 .Pa stderr
119 and remote files to the standard output stream
120 .Pa stdout
121 where they can be piped to other applications or redirected to files.
122 The names used for generated files and links all begin with the
124 .Pa ntpkey\&*
125 and include the file type, generating host and filestamp,
126 as described in the
127 .Sx "Cryptographic Data Files"
128 section below.
129 .Ss Running the Program
130 The safest way to run the
132 program is logged in directly as root.
133 The recommended procedure is change to the
134 .Ar keys
135 directory, usually
136 .Pa /usr/local/etc ,
137 then run the program.
139 To test and gain experience with Autokey concepts, log in as root and
140 change to the
141 .Ar keys
142 directory, usually
143 .Pa /usr/local/etc .
144 When run for the first time, or if all files with names beginning with
145 .Pa ntpkey\&*
146 have been removed, use the
148 command without arguments to generate a default
149 .Cm RSA
150 host key and matching
151 .Cm RSA\-MD5
152 certificate file with expiration date one year hence,
153 which is all that is necessary in many cases.
154 The program also generates soft links from the generic names
155 to the respective files.
156 If run again without options, the program uses the
157 existing keys and parameters and generates a new certificate file with
158 new expiration date one year hence, and soft link.
160 The host key is used to encrypt the cookie when required and so must be
161 .Cm RSA
163 By default, the host key is also the sign key used to encrypt signatures.
164 When necessary, a different sign key can be specified and this can be
166 .Cm RSA
168 .Cm DSA
170 By default, the message digest type is
171 .Cm MD5 ,
172 but any combination
173 of sign key type and message digest type supported by the OpenSSL library
174 can be specified, including those using the
175 .Cm AES128CMAC , MD2 , MD5 , MDC2 , SHA , SHA1
177 .Cm RIPE160
178 message digest algorithms.
179 However, the scheme specified in the certificate must be compatible
180 with the sign key.
181 Certificates using any digest algorithm are compatible with
182 .Cm RSA
183 sign keys;
184 however, only
185 .Cm SHA
187 .Cm SHA1
188 certificates are compatible with
189 .Cm DSA
190 sign keys.
192 Private/public key files and certificates are compatible with
193 other OpenSSL applications and very likely other libraries as well.
194 Certificates or certificate requests derived from them should be compatible
195 with extant industry practice, although some users might find
196 the interpretation of X509v3 extension fields somewhat liberal.
197 However, the identification parameter files, although encoded
198 as the other files, are probably not compatible with anything other than Autokey.
200 Running the program as other than root and using the Unix
201 .Xr su 1
203 to assume root may not work properly, since by default the OpenSSL library
204 looks for the random seed file
205 .Pa .rnd
206 in the user home directory.
207 However, there should be only one
208 .Pa .rnd ,
209 most conveniently
210 in the root directory, so it is convenient to define the
211 .Ev RANDFILE
212 environment variable used by the OpenSSL library as the path to
213 .Pa .rnd .
215 Installing the keys as root might not work in NFS\-mounted
216 shared file systems, as NFS clients may not be able to write
217 to the shared keys directory, even as root.
218 In this case, NFS clients can specify the files in another
219 directory such as
220 .Pa /etc
221 using the
222 .Ic keysdir
223 .Xr ntpd 1ntpdmdoc
224 configuration file command.
225 There is no need for one client to read the keys and certificates
226 of other clients or servers, as these data are obtained automatically
227 by the Autokey protocol.
229 Ordinarily, cryptographic files are generated by the host that uses them,
230 but it is possible for a trusted agent (TA) to generate these files
231 for other hosts; however, in such cases files should always be encrypted.
232 The subject name and trusted name default to the hostname
233 of the host generating the files, but can be changed by command line options.
234 It is convenient to designate the owner name and trusted name
235 as the subject and issuer fields, respectively, of the certificate.
236 The owner name is also used for the host and sign key files,
237 while the trusted name is used for the identity files.
239 All files are installed by default in the keys directory
240 .Pa /usr/local/etc ,
241 which is normally in a shared filesystem
242 in NFS\-mounted networks.
243 The actual location of the keys directory
244 and each file can be overridden by configuration commands,
245 but this is not recommended.
246 Normally, the files for each host are generated by that host
247 and used only by that host, although exceptions exist
248 as noted later on this page.
250 Normally, files containing private values,
251 including the host key, sign key and identification parameters,
252 are permitted root read/write\-only;
253 while others containing public values are permitted world readable.
254 Alternatively, files containing private values can be encrypted
255 and these files permitted world readable,
256 which simplifies maintenance in shared file systems.
257 Since uniqueness is insured by the
258 .Ar hostname
260 .Ar filestamp
261 file name extensions, the files for an NTP server and
262 dependent clients can all be installed in the same shared directory.
264 The recommended practice is to keep the file name extensions
265 when installing a file and to install a soft link
266 from the generic names specified elsewhere on this page
267 to the generated files.
268 This allows new file generations to be activated simply
269 by changing the link.
270 If a link is present,
271 .Xr ntpd 1ntpdmdoc
272 follows it to the file name to extract the
273 .Ar filestamp .
274 If a link is not present,
275 .Xr ntpd 1ntpdmdoc
276 extracts the
277 .Ar filestamp
278 from the file itself.
279 This allows clients to verify that the file and generation times
280 are always current.
283 program uses the same
284 .Ar filestamp
285 extension for all files generated
286 at one time, so each generation is distinct and can be readily
287 recognized in monitoring data.
289 Run the command on as many hosts as necessary.
290 Designate one of them as the trusted host (TH) using
292 with the
293 .Fl T
294 option and configure it to synchronize from reliable Internet servers.
295 Then configure the other hosts to synchronize to the TH directly or
297 A certificate trail is created when Autokey asks the immediately
298 ascendant host towards the TH to sign its certificate, which is then
299 provided to the immediately descendant host on request.
300 All group hosts should have acyclic certificate trails ending on the TH.
302 The host key is used to encrypt the cookie when required and so must be
303 RSA type.
304 By default, the host key is also the sign key used to encrypt
306 A different sign key can be assigned using the
307 .Fl S
308 option and this can be either
309 .Cm RSA
311 .Cm DSA
313 By default, the signature
314 message digest type is
315 .Cm MD5 ,
316 but any combination of sign key type and
317 message digest type supported by the OpenSSL library can be specified
318 using the
319 .Fl c
322 The rules say cryptographic media should be generated with proventic
323 filestamps, which means the host should already be synchronized before
324 this program is run.
325 This of course creates a chicken\-and\-egg problem
326 when the host is started for the first time.
327 Accordingly, the host time
328 should be set by some other means, such as eyeball\-and\-wristwatch, at
329 least so that the certificate lifetime is within the current year.
330 After that and when the host is synchronized to a proventic source, the
331 certificate should be re\-generated.
333 Additional information on trusted groups and identity schemes is on the
334 .Dq Autokey Public\-Key Authentication
337 File names begin with the prefix
338 .Pa ntpkey Ns _
339 and end with the suffix
340 .Pa _ Ns Ar hostname . Ar filestamp ,
342 .Ar hostname
343 is the owner name, usually the string returned
344 by the Unix
345 .Xr hostname 1
346 command, and
347 .Ar filestamp
348 is the NTP seconds when the file was generated, in decimal digits.
349 This both guarantees uniqueness and simplifies maintenance
350 procedures, since all files can be quickly removed
351 by a
352 .Ic rm Pa ntpkey\&*
353 command or all files generated
354 at a specific time can be removed by a
355 .Ic rm Pa \&* Ns Ar filestamp
357 To further reduce the risk of misconfiguration,
358 the first two lines of a file contain the file name
359 and generation date and time as comments.
360 .Ss Trusted Hosts and Groups
361 Each cryptographic configuration involves selection of a signature scheme
362 and identification scheme, called a cryptotype,
363 as explained in the
364 .Sx Authentication Options
365 section of
366 .Xr ntp.conf 5 .
367 The default cryptotype uses
368 .Cm RSA
370 .Cm MD5
371 message digest
373 .Cm TC
375 First, configure a NTP subnet including one or more low\-stratum
376 trusted hosts from which all other hosts derive synchronization
377 directly or indirectly.
378 Trusted hosts have trusted certificates;
379 all other hosts have nontrusted certificates.
380 These hosts will automatically and dynamically build authoritative
381 certificate trails to one or more trusted hosts.
382 A trusted group is the set of all hosts that have, directly or indirectly,
383 a certificate trail ending at a trusted host.
384 The trail is defined by static configuration file entries
385 or dynamic means described on the
386 .Sx Automatic NTP Configuration Options
387 section of
388 .Xr ntp.conf 5 .
390 On each trusted host as root, change to the keys directory.
391 To insure a fresh fileset, remove all
392 .Pa ntpkey
394 Then run
396 .Fl T
397 to generate keys and a trusted certificate.
398 On all other hosts do the same, but leave off the
399 .Fl T
400 flag to generate keys and nontrusted certificates.
401 When complete, start the NTP daemons beginning at the lowest stratum
402 and working up the tree.
403 It may take some time for Autokey to instantiate the certificate trails
404 throughout the subnet, but setting up the environment is completely automatic.
406 If it is necessary to use a different sign key or different digest/signature
407 scheme than the default, run
409 with the
410 .Fl S Ar type
411 option, where
412 .Ar type
413 is either
414 .Cm RSA
416 .Cm DSA .
417 The most frequent need to do this is when a
418 .Cm DSA Ns \-signed
419 certificate is used.
420 If it is necessary to use a different certificate scheme than the default,
423 with the
424 .Fl c Ar scheme
425 option and selected
426 .Ar scheme
427 as needed.
430 is run again without these options, it generates a new certificate
431 using the same scheme and sign key, and soft link.
433 After setting up the environment it is advisable to update certificates
434 from time to time, if only to extend the validity interval.
435 Simply run
437 with the same flags as before to generate new certificates
438 using existing keys, and soft links.
439 However, if the host or sign key is changed,
440 .Xr ntpd 1ntpdmdoc
441 should be restarted.
443 .Xr ntpd 1ntpdmdoc
444 is restarted, it loads any new files and restarts the protocol.
445 Other dependent hosts will continue as usual until signatures are refreshed,
446 at which time the protocol is restarted.
447 .Ss Identity Schemes
448 As mentioned on the Autonomous Authentication page,
449 the default
450 .Cm TC
451 identity scheme is vulnerable to a middleman attack.
452 However, there are more secure identity schemes available,
454 .Cm PC , IFF , GQ
456 .Cm MV
457 schemes described below.
458 These schemes are based on a TA, one or more trusted hosts
459 and some number of nontrusted hosts.
460 Trusted hosts prove identity using values provided by the TA,
461 while the remaining hosts prove identity using values provided
462 by a trusted host and certificate trails that end on that host.
463 The name of a trusted host is also the name of its sugroup
464 and also the subject and issuer name on its trusted certificate.
465 The TA is not necessarily a trusted host in this sense, but often is.
467 In some schemes there are separate keys for servers and clients.
468 A server can also be a client of another server,
469 but a client can never be a server for another client.
470 In general, trusted hosts and nontrusted hosts that operate
471 as both server and client have parameter files that contain
472 both server and client keys.
473 Hosts that operate
474 only as clients have key files that contain only client keys.
476 The PC scheme supports only one trusted host in the group.
477 On trusted host alice run
479 .Fl P
480 .Fl p Ar password
481 to generate the host key file
482 .Pa ntpkey Ns _ Cm RSA Pa key_alice. Ar filestamp
483 and trusted private certificate file
484 .Pa ntpkey Ns _ Cm RSA\-MD5 _ Pa cert_alice. Ar filestamp ,
485 and soft links.
486 Copy both files to all group hosts;
487 they replace the files which would be generated in other schemes.
488 On each host
489 .Ar bob
490 install a soft link from the generic name
491 .Pa ntpkey_host_ Ns Ar bob
492 to the host key file and soft link
493 .Pa ntpkey_cert_ Ns Ar bob
494 to the private certificate file.
495 Note the generic links are on bob, but point to files generated
496 by trusted host alice.
497 In this scheme it is not possible to refresh
498 either the keys or certificates without copying them
499 to all other hosts in the group, and recreating the soft links.
501 For the
502 .Cm IFF
503 scheme proceed as in the
504 .Cm TC
505 scheme to generate keys
506 and certificates for all group hosts, then for every trusted host in the group,
507 generate the
508 .Cm IFF
509 parameter file.
510 On trusted host alice run
512 .Fl T
513 .Fl I
514 .Fl p Ar password
515 to produce her parameter file
516 .Pa ntpkey_IFFpar_alice. Ns Ar filestamp ,
517 which includes both server and client keys.
518 Copy this file to all group hosts that operate as both servers
519 and clients and install a soft link from the generic
520 .Pa ntpkey_iff_alice
521 to this file.
522 If there are no hosts restricted to operate only as clients,
523 there is nothing further to do.
524 As the
525 .Cm IFF
526 scheme is independent
527 of keys and certificates, these files can be refreshed as needed.
529 If a rogue client has the parameter file, it could masquerade
530 as a legitimate server and present a middleman threat.
531 To eliminate this threat, the client keys can be extracted
532 from the parameter file and distributed to all restricted clients.
533 After generating the parameter file, on alice run
535 .Fl e
536 and pipe the output to a file or email program.
537 Copy or email this file to all restricted clients.
538 On these clients install a soft link from the generic
539 .Pa ntpkey_iff_alice
540 to this file.
541 To further protect the integrity of the keys,
542 each file can be encrypted with a secret password.
544 For the
545 .Cm GQ
546 scheme proceed as in the
547 .Cm TC
548 scheme to generate keys
549 and certificates for all group hosts, then for every trusted host
550 in the group, generate the
551 .Cm IFF
552 parameter file.
553 On trusted host alice run
555 .Fl T
556 .Fl G
557 .Fl p Ar password
558 to produce her parameter file
559 .Pa ntpkey_GQpar_alice. Ns Ar filestamp ,
560 which includes both server and client keys.
561 Copy this file to all group hosts and install a soft link
562 from the generic
563 .Pa ntpkey_gq_alice
564 to this file.
565 In addition, on each host
566 .Ar bob
567 install a soft link
568 from generic
569 .Pa ntpkey_gq_ Ns Ar bob
570 to this file.
571 As the
572 .Cm GQ
573 scheme updates the
574 .Cm GQ
575 parameters file and certificate
576 at the same time, keys and certificates can be regenerated as needed.
578 For the
579 .Cm MV
580 scheme, proceed as in the
581 .Cm TC
582 scheme to generate keys
583 and certificates for all group hosts.
584 For illustration assume trish is the TA, alice one of several trusted hosts
585 and bob one of her clients.
586 On TA trish run
588 .Fl V Ar n
589 .Fl p Ar password ,
591 .Ar n
592 is the number of revokable keys (typically 5) to produce
593 the parameter file
594 .Pa ntpkeys_MVpar_trish. Ns Ar filestamp
595 and client key files
596 .Pa ntpkeys_MVkey Ns Ar d _ Pa trish. Ar filestamp
598 .Ar d
599 is the key number (0 \&<
600 .Ar d
602 .Ar n ) .
603 Copy the parameter file to alice and install a soft link
604 from the generic
605 .Pa ntpkey_mv_alice
606 to this file.
607 Copy one of the client key files to alice for later distribution
608 to her clients.
609 It does not matter which client key file goes to alice,
610 since they all work the same way.
611 Alice copies the client key file to all of her clients.
612 On client bob install a soft link from generic
613 .Pa ntpkey_mvkey_bob
614 to the client key file.
615 As the
616 .Cm MV
617 scheme is independent of keys and certificates,
618 these 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
622 Set the number of bits in the identity modulus for generating identity keys to
623 .Ar modulus
625 The number of bits in the identity modulus defaults to 256, but can be set to
626 values from 256 to 2048 (32 to 256 octets).
627 Use the larger moduli with caution, as this can consume considerable computing
628 resources and increases the size of authenticated packets.
629 .It Fl c Fl \-certificate Ns = Ar scheme
630 Select certificate signature encryption/message digest scheme.
632 .Ar scheme
633 can be one of the following:
634 .Cm RSA\-MD2 , RSA\-MD5 , RSA\-MDC2 , RSA\-SHA , RSA\-SHA1 , RSA\-RIPEMD160 , DSA\-SHA ,
636 .Cm DSA\-SHA1 .
637 Note that
638 .Cm RSA
639 schemes must be used with an
640 .Cm RSA
641 sign key and
642 .Cm DSA
643 schemes must be used with a
644 .Cm DSA
645 sign key.
646 The default without this option is
647 .Cm RSA\-MD5 .
648 If compatibility with FIPS 140\-2 is required, either the
649 .Cm DSA\-SHA
651 .Cm DSA\-SHA1
652 scheme must be used.
653 .It Fl C Fl \-cipher Ns = Ar cipher
654 Select the OpenSSL cipher to encrypt the files containing private keys.
655 The default without this option is three\-key triple DES in CBC mode,
656 .Cm des\-ede3\-cbc .
658 .Ic openssl Fl h
659 command provided with OpenSSL displays available ciphers.
660 .It Fl d Fl \-debug\-level
661 Increase debugging verbosity level.
662 This option displays the cryptographic data produced in eye\-friendly billboards.
663 .It Fl D Fl \-set\-debug\-level Ns = Ar level
664 Set the debugging verbosity to
665 .Ar level .
666 This option displays the cryptographic data produced in eye\-friendly billboards.
667 .It Fl e Fl \-id\-key
668 Write the
669 .Cm IFF
671 .Cm GQ
672 public parameters from the
673 .Ar IFFkey or GQkey
674 client keys file previously specified
675 as unencrypted data to the standard output stream
676 .Pa stdout .
677 This is intended for automatic key distribution by email.
678 .It Fl G Fl \-gq\-params
679 Generate a new encrypted
680 .Cm GQ
681 parameters and key file for the Guillou\-Quisquater (GQ) identity scheme.
682 This option is mutually exclusive with the
683 .Fl I
685 .Fl V
687 .It Fl H Fl \-host\-key
688 Generate a new encrypted
689 .Cm RSA
690 public/private host key file.
691 .It Fl I Fl \-iffkey
692 Generate a new encrypted
693 .Cm IFF
694 key file for the Schnorr (IFF) identity scheme.
695 This option is mutually exclusive with the
696 .Fl G
698 Fl V
700 .It Fl i Fl \-ident Ns = Ar group
701 Set the optional Autokey group name to
702 .Ar group .
703 This is used in the identity scheme parameter file names of
704 .Cm IFF , GQ ,
706 .Cm MV
707 client parameters files.
708 In that role, the default is the host name if no group is provided.
709 The group name, if specified using
710 .Fl i
712 .Fl s
713 following an
714 .Ql @
715 character, is also used in certificate subject and issuer names in the form
716 .Ar host @ group
717 and should match the group specified via
718 .Ic crypto Cm ident
720 .Ic server Cm ident
721 in the ntpd configuration file.
722 .It Fl l Fl \-lifetime Ns = Ar days
723 Set the lifetime for certificate expiration to
724 .Ar days .
725 The default lifetime is one year (365 days).
726 .It Fl m Fl \-modulus Ns = Ar bits
727 Set the number of bits in the prime modulus for generating files to
728 .Ar bits .
729 The modulus defaults to 512, but can be set from 256 to 2048 (32 to 256 octets).
730 Use the larger moduli with caution, as this can consume considerable computing
731 resources and increases the size of authenticated packets.
732 .It Fl M Fl \-md5key
733 Generate a new symmetric keys file containing 10
734 .Cm MD5
735 keys, and if OpenSSL is available, 10
736 .Cm SHA
739 .Cm MD5
740 key is a string of 20 random printable ASCII characters, while a
741 .Cm SHA
742 key is a string of 40 random hex digits.
743 The file can be edited using a text editor to change the key type or key content.
744 This option is mutually exclusive with all other options.
745 .It Fl p Fl \-password Ns = Ar passwd
746 Set the password for reading and writing encrypted files to
747 .Ar passwd .
748 These include the host, sign and identify key files.
749 By default, the password is the string returned by the Unix
750 .Ic hostname
752 .It Fl P Fl \-pvt\-cert
753 Generate a new private certificate used by the
754 .Cm PC
755 identity scheme.
756 By default, the program generates public certificates.
757 Note: the PC identity scheme is not recommended for new installations.
758 .It Fl q Fl \-export\-passwd Ns = Ar passwd
759 Set the password for writing encrypted
760 .Cm IFF , GQ and MV
761 identity files redirected to
762 .Pa stdout
764 .Ar passwd .
765 In effect, these files are decrypted with the
766 .Fl p
767 password, then encrypted with the
768 .Fl q
770 By default, the password is the string returned by the Unix
771 .Ic hostname
773 .It Fl s Fl \-subject\-key Ns = Ar Oo host Oc Op @ Ar group
774 Specify the Autokey host name, where
775 .Ar host
776 is the optional host name and
777 .Ar group
778 is the optional group name.
779 The host name, and if provided, group name are used in
780 .Ar host @ group
781 form as certificate subject and issuer.
783 .Fl s @ Ar group
784 is allowed, and results in leaving the host name unchanged, as with
785 .Fl i Ar group .
786 The group name, or if no group is provided, the host name are also used in the
787 file names of
788 .Cm IFF , GQ ,
790 .Cm MV
791 identity scheme client parameter files.
793 .Ar host
794 is not specified, the default host name is the string returned by the Unix
795 .Ic hostname
797 .It Fl S Fl \-sign\-key Ns = Op Cm RSA | DSA
798 Generate a new encrypted public/private sign key file of the specified type.
799 By default, the sign key is the host key and has the same type.
800 If compatibility with FIPS 140\-2 is required, the sign key type must be
801 .Cm DSA .
802 .It Fl T Fl \-trusted\-cert
803 Generate a trusted certificate.
804 By default, the program generates a non\-trusted certificate.
805 .It Fl V Fl \-mv\-params Ar nkeys
807 .Ar nkeys
808 encrypted server keys and parameters for the Mu\-Varadharajan (MV)
809 identity scheme.
810 This option is mutually exclusive with the
811 .Fl I
813 .Fl G
815 Note: support for this option should be considered a work in progress.
817 .Ss Random Seed File
818 All cryptographically sound key generation schemes must have means
819 to randomize the entropy seed used to initialize
820 the internal pseudo\-random number generator used
821 by the library routines.
822 The OpenSSL library uses a designated random seed file for this purpose.
823 The file must be available when starting the NTP daemon and
826 If a site supports OpenSSL or its companion OpenSSH,
827 it is very likely that means to do this are already available.
829 It is important to understand that entropy must be evolved
830 for each generation, for otherwise the random number sequence
831 would be predictable.
832 Various means dependent on external events, such as keystroke intervals,
833 can be used to do this and some systems have built\-in entropy sources.
834 Suitable means are described in the OpenSSL software documentation,
835 but are outside the scope of this page.
837 The entropy seed used by the OpenSSL library is contained in a file,
838 usually called
839 .Pa .rnd ,
840 which must be available when starting the NTP daemon
841 or the
844 The NTP daemon will first look for the file
845 using the path specified by the
846 .Cm randfile
847 subcommand of the
848 .Ic crypto
849 configuration command.
850 If not specified in this way, or when starting the
853 the OpenSSL library will look for the file using the path specified
854 by the
855 .Ev RANDFILE
856 environment variable in the user home directory,
857 whether root or some other user.
858 If the
859 .Ev RANDFILE
860 environment variable is not present,
861 the library will look for the
862 .Pa .rnd
863 file in the user home directory.
864 Since both the
866 program and
867 .Xr ntpd 1ntpdmdoc
868 daemon must run as root, the logical place to put this file is in
869 .Pa /.rnd
871 .Pa /root/.rnd .
872 If the file is not available or cannot be written,
873 the daemon exits with a message to the system log and the program
874 exits with a suitable error message.
875 .Ss Cryptographic Data Files
876 All file formats begin with two nonencrypted lines.
877 The first line contains the file name, including the generated host name
878 and filestamp, in the format
879 .Pa ntpkey_ Ns Ar key _ Ar name . Ar filestamp ,
881 .Ar key
882 is the key or parameter type,
883 .Ar name
884 is the host or group name and
885 .Ar filestamp
886 is the filestamp (NTP seconds) when the file was created.
887 By convention,
888 .Ar key
889 names in generated file names include both upper and lower case
890 characters, while
891 .Ar key
892 names in generated link names include only lower case characters.
893 The filestamp is not used in generated link names.
894 The second line contains the datestamp in conventional Unix
895 .Pa date
897 Lines beginning with
898 .Ql #
899 are considered comments and ignored by the
901 program and
902 .Xr ntpd 1ntpdmdoc
905 The remainder of the file contains cryptographic data, encoded first using ASN.1
906 rules, then encrypted if necessary, and finally written in PEM\-encoded
907 printable ASCII text, preceded and followed by MIME content identifier lines.
909 The format of the symmetric keys file, ordinarily named
910 .Pa ntp.keys ,
911 is somewhat different than the other files in the interest of backward compatibility.
912 Ordinarily, the file is generated by this program, but it can be constructed
913 and 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
917 1 MD5 L";Nw<\`.I<f4U0)247"i # MD5 key
918 2 MD5 &>l0%XXK9O'51VwV<xq~ # MD5 key
919 3 MD5 lb4zLW~d^!K:]RsD'qb6 # MD5 key
920 4 MD5 Yue:tL[+vR)M\`n~bY,'? # MD5 key
921 5 MD5 B;fx'Kgr/&4ZTbL6=RxA # MD5 key
922 6 MD5 4eYwa\`o}3i@@V@..R9!l # MD5 key
923 7 MD5 \`A.([h+;wTQ|xfi%Sn_! # MD5 key
924 8 MD5 45:V,r4]l6y^JH6"Sh?F # MD5 key
925 9 MD5 3\-5vcn*6l29DS?Xdsg)* # MD5 key
926 10 MD5 2late4Me # MD5 key
927 11 SHA1 a27872d3030a9025b8446c751b4551a7629af65c # SHA1 key
928 12 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74 # SHA1 key
929 13 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9 # SHA1 key
930 14 SHA a5332809c8878dd3a5b918819108a111509aeceb # SHA key
931 15 MD2 2fe16c88c760ff2f16d4267e36c1aa6c926e6964 # MD2 key
932 16 MD4 b2691811dc19cfc0e2f9bcacd74213f29812183d # MD4 key
933 17 MD5 e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c # MD5 key
934 18 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc # MDC2 key
935 19 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2 # RIPEMD160 key
936 20 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878 # AES128CMAC key
938 .D1 Figure 1. Typical Symmetric Key File
940 Figure 1 shows a typical symmetric keys file used by the reference
942 Following the header the keys are entered one per line in the format
943 .D1 Ar keyno Ar type Ar key
945 .Ar keyno
946 is a positive integer in the range 1\-65535;
947 .Ar type
948 is the key type for the message digest algorithm, which in the absence of the
949 OpenSSL library must be
950 .Cm MD5
951 to designate the MD5 message digest algorithm;
952 if the OpenSSL library is installed, the key type can be any
953 message digest algorithm supported by that library;
954 however, if compatibility with FIPS 140\-2 is required,
955 the key type must be either
956 .Cm SHA
958 .Cm SHA1 ;
959 .Ar key
960 is the key itself,
961 which is a printable ASCII string 20 characters or less in length:
962 each character is chosen from the 93 printable characters
963 in the range 0x21 through 0x7e (
964 .Ql !
966 .Ql ~
967 \&) excluding space and the
968 .Ql #
969 character, and terminated by whitespace or a
970 .Ql #
972 An OpenSSL key consists of a hex\-encoded ASCII string of 40 characters, which
973 is truncated as necessary.
975 Note that the keys used by the
976 .Xr ntpq 1ntpqmdoc
978 .Xr ntpdc 1ntpdcmdoc
980 are checked against passwords requested by the programs
981 and entered by hand, so it is generally appropriate to specify these keys
982 in human readable ASCII format.
986 program generates a symmetric keys file
987 .Pa ntpkey_MD5key_ Ns Ar hostname Ns . Ns Ar filestamp .
988 Since the file contains private shared keys,
989 it should be visible only to root and distributed by secure means
990 to other subnet hosts.
991 The NTP daemon loads the file
992 .Pa ntp.keys ,
995 installs a soft link from this name to the generated file.
996 Subsequently, similar soft links must be installed by manual
997 or automated means on the other subnet hosts.
998 While this file is not used with the Autokey Version 2 protocol,
999 it is needed to authenticate some remote configuration commands
1000 used by the
1001 .Xr ntpq 1ntpqmdoc
1003 .Xr ntpdc 1ntpdcmdoc
1005 .Sh "OPTIONS"
1006 .Bl -tag
1007 .It Fl b Ar imbits , Fl \-imbits Ns = Ns Ar imbits
1008 identity modulus bits.
1009 This option takes an integer number as its argument.
1010 The value of
1011 .Ar imbits
1012 is constrained to being:
1013 .in +4
1016 in the range 256 through 2048
1018 .in -4
1020 The number of bits in the identity modulus. The default is 256.
1021 .It Fl c Ar scheme , Fl \-certificate Ns = Ns Ar scheme
1022 certificate scheme.
1024 scheme is one of
1025 RSA\-MD2, RSA\-MD5, RSA\-MDC2, RSA\-SHA, RSA\-SHA1, RSA\-RIPEMD160,
1026 DSA\-SHA, or DSA\-SHA1.
1028 Select the certificate signature encryption/message digest scheme.
1029 Note that RSA schemes must be used with a RSA sign key and DSA
1030 schemes must be used with a DSA sign key. The default without
1031 this option is RSA\-MD5.
1032 .It Fl C Ar cipher , Fl \-cipher Ns = Ns Ar cipher
1033 privatekey cipher.
1035 Select the cipher which is used to encrypt the files containing
1036 private keys. The default is three\-key triple DES in CBC mode,
1037 equivalent to "\fB\-C des\-ede3\-cbc\fP". The openssl tool lists ciphers
1038 available in "\fBopenssl \-h\fP" output.
1039 .It Fl d , Fl \-debug\-level
1040 Increase debug verbosity level.
1041 This option may appear an unlimited number of times.
1043 .It Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number
1044 Set the debug verbosity level.
1045 This option may appear an unlimited number of times.
1046 This option takes an integer number as its argument.
1048 .It Fl e , Fl \-id\-key
1049 Write IFF or GQ identity keys.
1051 Write the public parameters from the IFF or GQ client keys to
1052 the standard output.
1053 This is intended for automatic key distribution by email.
1054 .It Fl G , Fl \-gq\-params
1055 Generate GQ parameters and keys.
1057 Generate parameters and keys for the GQ identification scheme,
1058 obsoleting any that may exist.
1059 .It Fl H , Fl \-host\-key
1060 generate RSA host key.
1062 Generate new host keys, obsoleting any that may exist.
1063 .It Fl I , Fl \-iffkey
1064 generate IFF parameters.
1066 Generate parameters for the IFF identification scheme, obsoleting
1067 any that may exist.
1068 .It Fl i Ar group , Fl \-ident Ns = Ns Ar group
1069 set Autokey group name.
1071 Set the optional Autokey group name to name. This is used in
1072 the file name of IFF, GQ, and MV client parameters files. In
1073 that role, the default is the host name if this option is not
1074 provided. The group name, if specified using \fB\-i/\-\-ident\fP or
1075 using \fB\-s/\-\-subject\-name\fP following an '\fB@\fP' character,
1076 is also a part of the self\-signed host certificate subject and
1077 issuer 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
1081 set certificate lifetime.
1082 This option takes an integer number as its argument.
1084 Set the certificate expiration to lifetime days from now.
1085 .It Fl m Ar modulus , Fl \-modulus Ns = Ns Ar modulus
1086 prime modulus.
1087 This option takes an integer number as its argument.
1088 The value of
1089 .Ar modulus
1090 is constrained to being:
1091 .in +4
1094 in the range 256 through 2048
1096 .in -4
1098 The number of bits in the prime modulus. The default is 512.
1099 .It Fl M , Fl \-md5key
1100 generate symmetric keys.
1102 Generate symmetric keys, obsoleting any that may exist.
1103 .It Fl P , Fl \-pvt\-cert
1104 generate PC private certificate.
1106 Generate a private certificate. By default, the program generates
1107 public certificates.
1108 .It Fl p Ar passwd , Fl \-password Ns = Ns Ar passwd
1109 local private password.
1111 Local files containing private data are encrypted with the
1112 DES\-CBC algorithm and the specified password. The same password
1113 must be specified to the local ntpd via the "crypto pw password"
1114 configuration command. The default password is the local
1116 .It Fl q Ar passwd , Fl \-export\-passwd Ns = Ns Ar passwd
1117 export IFF or GQ group keys with password.
1119 Export IFF or GQ identity group keys to the standard output,
1120 encrypted with the DES\-CBC algorithm and the specified password.
1121 The 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
1125 set host and optionally group name.
1127 Set the Autokey host name, and optionally, group name specified
1128 following an '\fB@\fP' character. The host name is used in the file
1129 name of generated host and signing certificates, without the
1130 group name. The host name, and if provided, group name are used
1131 in \fBhost@group\fP form for the host certificate subject and issuer
1132 fields. Specifying '\fB\-s @group\fP' is allowed, and results in
1133 leaving the host name unchanged while appending \fB@group\fP to the
1134 subject and issuer fields, as with \fB\-i group\fP. The group name, or
1135 if not provided, the host name are also used in the file names
1136 of IFF, GQ, and MV client parameter files.
1137 .It Fl S Ar sign , Fl \-sign\-key Ns = Ns Ar sign
1138 generate sign key (RSA or DSA).
1140 Generate a new sign key of the designated type, obsoleting any
1141 that may exist. By default, the program uses the host key as the
1142 sign key.
1143 .It Fl T , Fl \-trusted\-cert
1144 trusted certificate (TC scheme).
1146 Generate a trusted certificate. By default, the program generates
1147 a non\-trusted certificate.
1148 .It Fl V Ar num , Fl \-mv\-params Ns = Ns Ar num
1149 generate <num> MV parameters.
1150 This option takes an integer number as its argument.
1152 Generate parameters and keys for the Mu\-Varadharajan (MV)
1153 identification scheme.
1154 .It Fl v Ar num , Fl \-mv\-keys Ns = Ns Ar num
1155 update <num> MV keys.
1156 This option takes an integer number as its argument.
1158 This option has not been fully documented.
1159 .It Fl \&? , Fl \-help
1160 Display usage information and exit.
1161 .It Fl \&! , Fl \-more\-help
1162 Pass the extended usage information through a pager.
1163 .It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc
1164 Save the option state to \fIcfgfile\fP. The default is the \fIlast\fP
1165 configuration file listed in the \fBOPTION PRESETS\fP section, below.
1166 The command will exit after updating the config file.
1167 .It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts
1168 Load options from \fIcfgfile\fP.
1169 The \fIno\-load\-opts\fP form will disable the loading
1170 of earlier config/rc/ini files. \fI\-\-no\-load\-opts\fP is handled early,
1171 out of order.
1172 .It Fl \-version Op Brq Ar v|c|n
1173 Output version of program and exit. The default mode is `v', a simple
1174 version. The `c' mode will print copyright information and `n' will
1175 print the full copyright notice.
1177 .Sh "OPTION PRESETS"
1178 Any option that is not marked as \fInot presettable\fP may be preset
1179 by loading values from configuration ("RC" or ".INI") file(s) and values from
1180 environment variables named:
1182 \fBNTP_KEYGEN_<option\-name>\fP or \fBNTP_KEYGEN\fP
1185 The environmental presets take precedence (are processed later than)
1186 the configuration files.
1187 The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
1188 If any of these are directories, then the file \fI.ntprc\fP
1189 is searched for within those directories.
1190 .Sh USAGE
1191 .Sh "ENVIRONMENT"
1192 See \fBOPTION PRESETS\fP for configuration environment variables.
1193 .Sh "FILES"
1194 See \fBOPTION PRESETS\fP for configuration files.
1195 .Sh "EXIT STATUS"
1196 One of the following exit values will be returned:
1197 .Bl -tag
1198 .It 0 " (EXIT_SUCCESS)"
1199 Successful program execution.
1200 .It 1 " (EXIT_FAILURE)"
1201 The operation failed or the command syntax was not valid.
1202 .It 66 " (EX_NOINPUT)"
1203 A specified configuration file could not be loaded.
1204 .It 70 " (EX_SOFTWARE)"
1205 libopts had an internal operational error. Please report
1206 it to autogen\-firstname.lastname@example.org. Thank you.
1208 .Sh "AUTHORS"
1209 The University of Delaware and Network Time Foundation
1210 .Sh "COPYRIGHT"
1211 Copyright (C) 1992\-2020 The University of Delaware and Network Time Foundation all rights reserved.
1212 This program is released under the terms of the NTP license, <http://ntp.org/license>.
1213 .Sh BUGS
1214 It can take quite a while to generate some cryptographic values.
1216 Please report bugs to http://bugs.ntp.org .
1218 Please send bug reports to: http://bugs.ntp.org, email@example.com
1219 .Sh NOTES
1220 Portions of this document came from FreeBSD.
1222 This manual page was \fIAutoGen\fP\-erated from the \fBntp\-keygen\fP
1223 option definitions.