MFV ntp 4.2.8p1 (r258945, r275970, r276091, r276092, r276093, r278284)

Thanks to roberto for providing pointers to wedge this into HEAD.

Approved by:	roberto

1 files changed, 1071 insertions, 0 deletions

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+.Dd February 4 2015
+.Dt NTP_KEYGEN @NTP_KEYGEN_MS@ User Commands
+.Os
+.\"  EDIT THIS FILE WITH CAUTION  (ntp-keygen-opts.mdoc)
+.\"
+.\"  It has been AutoGen-ed  February  4, 2015 at 02:44:02 AM by AutoGen 5.18.5pre4
+.\"  From the definitions    ntp-keygen-opts.def
+.\"  and the template file   agmdoc-cmd.tpl
+.Sh NAME
+.Nm ntp-keygen
+.Nd Create a NTP host key
+.Sh SYNOPSIS
+.Nm
+.\" Mixture of short (flag) options and long options
+.Op Fl flags
+.Op Fl flag Op Ar value
+.Op Fl \-option\-name Ns Oo Oo Ns "=| " Oc Ns Ar value Oc
+.Pp
+All arguments must be options.
+.Pp
+.Sh DESCRIPTION
+This program generates cryptographic data files used by the NTPv4
+authentication and identification schemes.
+It generates MD5 key files used in symmetric key cryptography.
+In addition, if the OpenSSL software library has been installed,
+it generates keys, certificate and identity files used in public key
+cryptography.
+These files are used for cookie encryption,
+digital signature and challenge/response identification algorithms
+compatible with the Internet standard security infrastructure.
+.Pp
+All files are in PEM\-encoded printable ASCII format,
+so they can be embedded as MIME attachments in mail to other sites
+and certificate authorities.
+By default, files are not encrypted.
+.Pp
+When used to generate message digest keys, the program produces a file
+containing ten pseudo\-random printable ASCII strings suitable for the
+MD5 message digest algorithm included in the distribution.
+If the OpenSSL library is installed, it produces an additional ten
+hex\-encoded random bit strings suitable for the SHA1 and other message
+digest algorithms.
+The message digest keys file must be distributed and stored
+using secure means beyond the scope of NTP itself.
+Besides the keys used for ordinary NTP associations, additional keys
+can be defined as passwords for the
+.Xr ntpq @NTPQ_MS@
+and
+.Xr ntpdc @NTPDC_MS@
+utility programs.
+.Pp
+The remaining generated files are compatible with other OpenSSL
+applications and other Public Key Infrastructure (PKI) resources.
+Certificates generated by this program are compatible with extant
+industry practice, although some users might find the interpretation of
+X509v3 extension fields somewhat liberal.
+However, the identity keys are probably not compatible with anything
+other than Autokey.
+.Pp
+Some files used by this program are encrypted using a private password.
+The
+.Fl p
+option specifies the password for local encrypted files and the
+.Fl q
+option the password for encrypted files sent to remote sites.
+If no password is specified, the host name returned by the Unix
+.Fn gethostname
+function, normally the DNS name of the host is used.
+.Pp
+The
+.Ar pw
+option of the
+.Ar crypto
+configuration command specifies the read
+password for previously encrypted local files.
+This must match the local password used by this program.
+If not specified, the host name is used.
+Thus, if files are generated by this program without password,
+they can be read back by
+.Ar ntpd
+without password but only on the same host.
+.Pp
+Normally, encrypted files for each host are generated by that host and
+used only by that host, although exceptions exist as noted later on
+this page.
+The symmetric keys file, normally called
+.Ar ntp.keys ,
+is usually installed in
+.Pa /etc .
+Other files and links are usually installed in
+.Pa /usr/local/etc ,
+which is normally in a shared filesystem in
+NFS\-mounted networks and cannot be changed by shared clients.
+The location of the keys directory can be changed by the
+.Ar keysdir
+configuration command in such cases.
+Normally, this is in
+.Pa /etc .
+.Pp
+This program directs commentary and error messages to the standard
+error stream
+.Ar stderr
+and remote files to the standard output stream
+.Ar stdout
+where they can be piped to other applications or redirected to files.
+The names used for generated files and links all begin with the
+string
+.Ar ntpkey
+and include the file type, generating host and filestamp,
+as described in the
+.Dq Cryptographic Data Files
+section below.
+.Ss Running the Program
+To test and gain experience with Autokey concepts, log in as root and
+change to the keys directory, usually
+.Pa /usr/local/etc 
+When run for the first time, or if all files with names beginning with
+.Ar ntpkey
+have been removed, use the
+.Nm
+command without arguments to generate a
+default RSA host key and matching RSA\-MD5 certificate with expiration
+date one year hence.
+If run again without options, the program uses the
+existing keys and parameters and generates only a new certificate with
+new expiration date one year hence.
+.Pp
+Run the command on as many hosts as necessary.
+Designate one of them as the trusted host (TH) using
+.Nm
+with the
+.Fl T
+option and configure it to synchronize from reliable Internet servers.
+Then configure the other hosts to synchronize to the TH directly or
+indirectly.
+A certificate trail is created when Autokey asks the immediately
+ascendant host towards the TH to sign its certificate, which is then
+provided to the immediately descendant host on request.
+All group hosts should have acyclic certificate trails ending on the TH.
+.Pp
+The host key is used to encrypt the cookie when required and so must be
+RSA type.
+By default, the host key is also the sign key used to encrypt
+signatures.
+A different sign key can be assigned using the
+.Fl S
+option and this can be either RSA or DSA type.
+By default, the signature
+message digest type is MD5, but any combination of sign key type and
+message digest type supported by the OpenSSL library can be specified
+using the
+.Fl c
+option.
+The rules say cryptographic media should be generated with proventic
+filestamps, which means the host should already be synchronized before
+this program is run.
+This of course creates a chicken\-and\-egg problem
+when the host is started for the first time.
+Accordingly, the host time
+should be set by some other means, such as eyeball\-and\-wristwatch, at
+least so that the certificate lifetime is within the current year.
+After that and when the host is synchronized to a proventic source, the
+certificate should be re\-generated.
+.Pp
+Additional information on trusted groups and identity schemes is on the
+.Dq Autokey Public\-Key Authentication
+page.
+.Pp
+The
+.Xr ntpd @NTPD_MS@
+configuration command
+.Ic crypto pw Ar password
+specifies the read password for previously encrypted files.
+The daemon expires on the spot if the password is missing
+or incorrect.
+For convenience, if a file has been previously encrypted,
+the default read password is the name of the host running
+the program.
+If the previous write password is specified as the host name,
+these files can be read by that host with no explicit password.
+.Pp
+File names begin with the prefix
+.Cm ntpkey_
+and end with the postfix
+.Ar _hostname.filestamp ,
+where
+.Ar hostname
+is the owner name, usually the string returned
+by the Unix gethostname() routine, and
+.Ar filestamp
+is the NTP seconds when the file was generated, in decimal digits.
+This both guarantees uniqueness and simplifies maintenance
+procedures, since all files can be quickly removed
+by a
+.Ic rm ntpkey\&*
+command or all files generated
+at a specific time can be removed by a
+.Ic rm
+.Ar \&*filestamp
+command.
+To further reduce the risk of misconfiguration,
+the first two lines of a file contain the file name
+and generation date and time as comments.
+.Pp
+All files are installed by default in the keys directory
+.Pa /usr/local/etc ,
+which is normally in a shared filesystem
+in NFS\-mounted networks.
+The actual location of the keys directory
+and each file can be overridden by configuration commands,
+but this is not recommended.
+Normally, the files for each host are generated by that host
+and used only by that host, although exceptions exist
+as noted later on this page.
+.Pp
+Normally, files containing private values,
+including the host key, sign key and identification parameters,
+are permitted root read/write\-only;
+while others containing public values are permitted world readable.
+Alternatively, files containing private values can be encrypted
+and these files permitted world readable,
+which simplifies maintenance in shared file systems.
+Since uniqueness is insured by the hostname and
+file name extensions, the files for a NFS server and
+dependent clients can all be installed in the same shared directory.
+.Pp
+The recommended practice is to keep the file name extensions
+when installing a file and to install a soft link
+from the generic names specified elsewhere on this page
+to the generated files.
+This allows new file generations to be activated simply
+by changing the link.
+If a link is present, ntpd follows it to the file name
+to extract the filestamp.
+If a link is not present,
+.Xr ntpd @NTPD_MS@
+extracts the filestamp from the file itself.
+This allows clients to verify that the file and generation times
+are always current.
+The
+.Nm
+program uses the same timestamp extension for all files generated
+at one time, so each generation is distinct and can be readily
+recognized in monitoring data.
+.Ss Running the program
+The safest way to run the
+.Nm
+program is logged in directly as root.
+The recommended procedure is change to the keys directory,
+usually
+.Pa /usr/local/etc ,
+then run the program.
+When run for the first time,
+or if all
+.Cm ntpkey
+files have been removed,
+the program generates a RSA host key file and matching RSA\-MD5 certificate file,
+which is all that is necessary in many cases.
+The program also generates soft links from the generic names
+to the respective files.
+If run again, the program uses the same host key file,
+but generates a new certificate file and link.
+.Pp
+The host key is used to encrypt the cookie when required and so must be RSA type.
+By default, the host key is also the sign key used to encrypt signatures.
+When necessary, a different sign key can be specified and this can be
+either RSA or DSA type.
+By default, the message digest type is MD5, but any combination
+of sign key type and message digest type supported by the OpenSSL library
+can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2
+and RIPE160 message digest algorithms.
+However, the scheme specified in the certificate must be compatible
+with the sign key.
+Certificates using any digest algorithm are compatible with RSA sign keys;
+however, only SHA and SHA1 certificates are compatible with DSA sign keys.
+.Pp
+Private/public key files and certificates are compatible with
+other OpenSSL applications and very likely other libraries as well.
+Certificates or certificate requests derived from them should be compatible
+with extant industry practice, although some users might find
+the interpretation of X509v3 extension fields somewhat liberal.
+However, the identification parameter files, although encoded
+as the other files, are probably not compatible with anything other than Autokey.
+.Pp
+Running the program as other than root and using the Unix
+.Ic su
+command
+to assume root may not work properly, since by default the OpenSSL library
+looks for the random seed file
+.Cm .rnd
+in the user home directory.
+However, there should be only one
+.Cm .rnd ,
+most conveniently
+in the root directory, so it is convenient to define the
+.Cm $RANDFILE
+environment variable used by the OpenSSL library as the path to
+.Cm /.rnd .
+.Pp
+Installing the keys as root might not work in NFS\-mounted
+shared file systems, as NFS clients may not be able to write
+to the shared keys directory, even as root.
+In this case, NFS clients can specify the files in another
+directory such as
+.Pa /etc
+using the
+.Ic keysdir
+command.
+There is no need for one client to read the keys and certificates
+of other clients or servers, as these data are obtained automatically
+by the Autokey protocol.
+.Pp
+Ordinarily, cryptographic files are generated by the host that uses them,
+but it is possible for a trusted agent (TA) to generate these files
+for other hosts; however, in such cases files should always be encrypted.
+The subject name and trusted name default to the hostname
+of the host generating the files, but can be changed by command line options.
+It is convenient to designate the owner name and trusted name
+as the subject and issuer fields, respectively, of the certificate.
+The owner name is also used for the host and sign key files,
+while the trusted name is used for the identity files.
+.Pp
+All files are installed by default in the keys directory
+.Pa /usr/local/etc ,
+which is normally in a shared filesystem
+in NFS\-mounted networks.
+The actual location of the keys directory
+and each file can be overridden by configuration commands,
+but this is not recommended.
+Normally, the files for each host are generated by that host
+and used only by that host, although exceptions exist
+as noted later on this page.
+.Pp
+Normally, files containing private values,
+including the host key, sign key and identification parameters,
+are permitted root read/write\-only;
+while others containing public values are permitted world readable.
+Alternatively, files containing private values can be encrypted
+and these files permitted world readable,
+which simplifies maintenance in shared file systems.
+Since uniqueness is insured by the hostname and
+file name extensions, the files for a NFS server and
+dependent clients can all be installed in the same shared directory.
+.Pp
+The recommended practice is to keep the file name extensions
+when installing a file and to install a soft link
+from the generic names specified elsewhere on this page
+to the generated files.
+This allows new file generations to be activated simply
+by changing the link.
+If a link is present, ntpd follows it to the file name
+to extract the filestamp.
+If a link is not present,
+.Xr ntpd @NTPD_MS@
+extracts the filestamp from the file itself.
+This allows clients to verify that the file and generation times
+are always current.
+The
+.Nm
+program uses the same timestamp extension for all files generated
+at one time, so each generation is distinct and can be readily
+recognized in monitoring data.
+.Ss Running the program
+The safest way to run the
+.Nm
+program is logged in directly as root.
+The recommended procedure is change to the keys directory,
+usually
+.Pa /usr/local/etc ,
+then run the program.
+When run for the first time,
+or if all
+.Cm ntpkey
+files have been removed,
+the program generates a RSA host key file and matching RSA\-MD5 certificate file,
+which is all that is necessary in many cases.
+The program also generates soft links from the generic names
+to the respective files.
+If run again, the program uses the same host key file,
+but generates a new certificate file and link.
+.Pp
+The host key is used to encrypt the cookie when required and so must be RSA type.
+By default, the host key is also the sign key used to encrypt signatures.
+When necessary, a different sign key can be specified and this can be
+either RSA or DSA type.
+By default, the message digest type is MD5, but any combination
+of sign key type and message digest type supported by the OpenSSL library
+can be specified, including those using the MD2, MD5, SHA, SHA1, MDC2
+and RIPE160 message digest algorithms.
+However, the scheme specified in the certificate must be compatible
+with the sign key.
+Certificates using any digest algorithm are compatible with RSA sign keys;
+however, only SHA and SHA1 certificates are compatible with DSA sign keys.
+.Pp
+Private/public key files and certificates are compatible with
+other OpenSSL applications and very likely other libraries as well.
+Certificates or certificate requests derived from them should be compatible
+with extant industry practice, although some users might find
+the interpretation of X509v3 extension fields somewhat liberal.
+However, the identification parameter files, although encoded
+as the other files, are probably not compatible with anything other than Autokey.
+.Pp
+Running the program as other than root and using the Unix
+.Ic su
+command
+to assume root may not work properly, since by default the OpenSSL library
+looks for the random seed file
+.Cm .rnd
+in the user home directory.
+However, there should be only one
+.Cm .rnd ,
+most conveniently
+in the root directory, so it is convenient to define the
+.Cm $RANDFILE
+environment variable used by the OpenSSL library as the path to
+.Cm /.rnd .
+.Pp
+Installing the keys as root might not work in NFS\-mounted
+shared file systems, as NFS clients may not be able to write
+to the shared keys directory, even as root.
+In this case, NFS clients can specify the files in another
+directory such as
+.Pa /etc
+using the
+.Ic keysdir
+command.
+There is no need for one client to read the keys and certificates
+of other clients or servers, as these data are obtained automatically
+by the Autokey protocol.
+.Pp
+Ordinarily, cryptographic files are generated by the host that uses them,
+but it is possible for a trusted agent (TA) to generate these files
+for other hosts; however, in such cases files should always be encrypted.
+The subject name and trusted name default to the hostname
+of the host generating the files, but can be changed by command line options.
+It is convenient to designate the owner name and trusted name
+as the subject and issuer fields, respectively, of the certificate.
+The owner name is also used for the host and sign key files,
+while the trusted name is used for the identity files.
+seconds.
+seconds.
+s Trusted Hosts and Groups
+Each cryptographic configuration involves selection of a signature scheme
+and identification scheme, called a cryptotype,
+as explained in the
+.Sx Authentication Options
+section of
+.Xr ntp.conf 5 .
+The default cryptotype uses RSA encryption, MD5 message digest
+and TC identification.
+First, configure a NTP subnet including one or more low\-stratum
+trusted hosts from which all other hosts derive synchronization
+directly or indirectly.
+Trusted hosts have trusted certificates;
+all other hosts have nontrusted certificates.
+These hosts will automatically and dynamically build authoritative
+certificate trails to one or more trusted hosts.
+A trusted group is the set of all hosts that have, directly or indirectly,
+a certificate trail ending at a trusted host.
+The trail is defined by static configuration file entries
+or dynamic means described on the
+.Sx Automatic NTP Configuration Options
+section of
+.Xr ntp.conf 5 .
+.Pp
+On each trusted host as root, change to the keys directory.
+To insure a fresh fileset, remove all
+.Cm ntpkey
+files.
+Then run
+.Nm
+.Fl T
+to generate keys and a trusted certificate.
+On all other hosts do the same, but leave off the
+.Fl T
+flag to generate keys and nontrusted certificates.
+When complete, start the NTP daemons beginning at the lowest stratum
+and working up the tree.
+It may take some time for Autokey to instantiate the certificate trails
+throughout the subnet, but setting up the environment is completely automatic.
+.Pp
+If it is necessary to use a different sign key or different digest/signature
+scheme than the default, run
+.Nm
+with the
+.Fl S Ar type
+option, where
+.Ar type
+is either
+.Cm RSA
+or
+.Cm DSA .
+The most often need to do this is when a DSA\-signed certificate is used.
+If it is necessary to use a different certificate scheme than the default,
+run
+.Nm
+with the
+.Fl c Ar scheme
+option and selected
+.Ar scheme
+as needed.
+f
+.Nm
+is run again without these options, it generates a new certificate
+using the same scheme and sign key.
+.Pp
+After setting up the environment it is advisable to update certificates
+from time to time, if only to extend the validity interval.
+Simply run
+.Nm
+with the same flags as before to generate new certificates
+using existing keys.
+However, if the host or sign key is changed,
+.Xr ntpd @NTPD_MS@
+should be restarted.
+When
+.Xr ntpd @NTPD_MS@
+is restarted, it loads any new files and restarts the protocol.
+Other dependent hosts will continue as usual until signatures are refreshed,
+at which time the protocol is restarted.
+.Ss Identity Schemes
+As mentioned on the Autonomous Authentication page,
+the default TC identity scheme is vulnerable to a middleman attack.
+However, there are more secure identity schemes available,
+including PC, IFF, GQ and MV described on the
+.Qq Identification Schemes
+page
+(maybe available at
+.Li http://www.eecis.udel.edu/%7emills/keygen.html ) .
+These schemes are based on a TA, one or more trusted hosts
+and some number of nontrusted hosts.
+Trusted hosts prove identity using values provided by the TA,
+while the remaining hosts prove identity using values provided
+by a trusted host and certificate trails that end on that host.
+The name of a trusted host is also the name of its sugroup
+and also the subject and issuer name on its trusted certificate.
+The TA is not necessarily a trusted host in this sense, but often is.
+.Pp
+In some schemes there are separate keys for servers and clients.
+A server can also be a client of another server,
+but a client can never be a server for another client.
+In general, trusted hosts and nontrusted hosts that operate
+as both server and client have parameter files that contain
+both server and client keys.
+Hosts that operate
+only as clients have key files that contain only client keys.
+.Pp
+The PC scheme supports only one trusted host in the group.
+On trusted host alice run
+.Nm
+.Fl P
+.Fl p Ar password
+to generate the host key file
+.Pa ntpkey_RSAkey_ Ns Ar alice.filestamp
+and trusted private certificate file
+.Pa ntpkey_RSA\-MD5_cert_ Ns Ar alice.filestamp .
+Copy both files to all group hosts;
+they replace the files which would be generated in other schemes.
+On each host bob install a soft link from the generic name
+.Pa ntpkey_host_ Ns Ar bob
+to the host key file and soft link
+.Pa ntpkey_cert_ Ns Ar bob
+to the private certificate file.
+Note the generic links are on bob, but point to files generated
+by trusted host alice.
+In this scheme it is not possible to refresh
+either the keys or certificates without copying them
+to all other hosts in the group.
+.Pp
+For the IFF scheme proceed as in the TC scheme to generate keys
+and certificates for all group hosts, then for every trusted host in the group,
+generate the IFF parameter file.
+On trusted host alice run
+.Nm
+.Fl T
+.Fl I
+.Fl p Ar password
+to produce her parameter file
+.Pa ntpkey_IFFpar_ Ns Ar alice.filestamp ,
+which includes both server and client keys.
+Copy this file to all group hosts that operate as both servers
+and clients and install a soft link from the generic
+.Pa ntpkey_iff_ Ns Ar alice
+to this file.
+If there are no hosts restricted to operate only as clients,
+there is nothing further to do.
+As the IFF scheme is independent
+of keys and certificates, these files can be refreshed as needed.
+.Pp
+If a rogue client has the parameter file, it could masquerade
+as a legitimate server and present a middleman threat.
+To eliminate this threat, the client keys can be extracted
+from the parameter file and distributed to all restricted clients.
+After generating the parameter file, on alice run
+.Nm
+.Fl e
+and pipe the output to a file or mail program.
+Copy or mail this file to all restricted clients.
+On these clients install a soft link from the generic
+.Pa ntpkey_iff_ Ns Ar alice
+to this file.
+To further protect the integrity of the keys,
+each file can be encrypted with a secret password.
+.Pp
+For the GQ scheme proceed as in the TC scheme to generate keys
+and certificates for all group hosts, then for every trusted host
+in the group, generate the IFF parameter file.
+On trusted host alice run
+.Nm
+.Fl T
+.Fl G
+.Fl p Ar password
+to produce her parameter file
+.Pa ntpkey_GQpar_ Ns Ar alice.filestamp ,
+which includes both server and client keys.
+Copy this file to all group hosts and install a soft link
+from the generic
+.Pa ntpkey_gq_ Ns Ar alice
+to this file.
+In addition, on each host bob install a soft link
+from generic
+.Pa ntpkey_gq_ Ns Ar bob
+to this file.
+As the GQ scheme updates the GQ parameters file and certificate
+at the same time, keys and certificates can be regenerated as needed.
+.Pp
+For the MV scheme, proceed as in the TC scheme to generate keys
+and certificates for all group hosts.
+For illustration assume trish is the TA, alice one of several trusted hosts
+and bob one of her clients.
+On TA trish run
+.Nm
+.Fl V Ar n
+.Fl p Ar password ,
+where
+.Ar n
+is the number of revokable keys (typically 5) to produce
+the parameter file
+.Pa ntpkeys_MVpar_ Ns Ar trish.filestamp
+and client key files
+.Pa ntpkeys_MVkeyd_ Ns Ar trish.filestamp
+where
+.Ar d
+is the key number (0 \&<
+.Ar d
+\&<
+.Ar n ) .
+Copy the parameter file to alice and install a soft link
+from the generic
+.Pa ntpkey_mv_ Ns Ar alice
+to this file.
+Copy one of the client key files to alice for later distribution
+to her clients.
+It doesn't matter which client key file goes to alice,
+since they all work the same way.
+Alice copies the client key file to all of her cliens.
+On client bob install a soft link from generic
+.Pa ntpkey_mvkey_ Ns Ar bob
+to the client key file.
+As the MV scheme is independent of keys and certificates,
+these files can be refreshed as needed.
+.Ss Command Line Options
+.Bl -tag -width indent
+.It Fl c Ar scheme
+Select certificate message digest/signature encryption scheme.
+The
+.Ar scheme
+can be one of the following:
+. Cm RSA\-MD2 , RSA\-MD5 , RSA\-SHA , RSA\-SHA1 , RSA\-MDC2 , RSA\-RIPEMD160 , DSA\-SHA ,
+or
+.Cm DSA\-SHA1 .
+Note that RSA schemes must be used with a RSA sign key and DSA
+schemes must be used with a DSA sign key.
+The default without this option is
+.Cm RSA\-MD5 .
+.It Fl d
+Enable debugging.
+This option displays the cryptographic data produced in eye\-friendly billboards.
+.It Fl e
+Write the IFF client keys to the standard output.
+This is intended for automatic key distribution by mail.
+.It Fl G
+Generate parameters and keys for the GQ identification scheme,
+obsoleting any that may exist.
+.It Fl g
+Generate keys for the GQ identification scheme
+using the existing GQ parameters.
+If the GQ parameters do not yet exist, create them first.
+.It Fl H
+Generate new host keys, obsoleting any that may exist.
+.It Fl I
+Generate parameters for the IFF identification scheme,
+obsoleting any that may exist.
+.It Fl i Ar name
+Set the suject name to
+.Ar name .
+This is used as the subject field in certificates
+and in the file name for host and sign keys.
+.It Fl M
+Generate MD5 keys, obsoleting any that may exist.
+.It Fl P
+Generate a private certificate.
+By default, the program generates public certificates.
+.It Fl p Ar password
+Encrypt generated files containing private data with
+.Ar password
+and the DES\-CBC algorithm.
+.It Fl q
+Set the password for reading files to password.
+.It Fl S Oo Cm RSA | DSA Oc
+Generate a new sign key of the designated type,
+obsoleting any that may exist.
+By default, the program uses the host key as the sign key.
+.It Fl s Ar name
+Set the issuer name to
+.Ar name .
+This is used for the issuer field in certificates
+and in the file name for identity files.
+.It Fl T
+Generate a trusted certificate.
+By default, the program generates a non\-trusted certificate.
+.It Fl V Ar nkeys
+Generate parameters and keys for the Mu\-Varadharajan (MV) identification scheme.
+.El
+.Ss Random Seed File
+All cryptographically sound key generation schemes must have means
+to randomize the entropy seed used to initialize
+the internal pseudo\-random number generator used
+by the library routines.
+The OpenSSL library uses a designated random seed file for this purpose.
+The file must be available when starting the NTP daemon and
+.Nm
+program.
+If a site supports OpenSSL or its companion OpenSSH,
+it is very likely that means to do this are already available.
+.Pp
+It is important to understand that entropy must be evolved
+for each generation, for otherwise the random number sequence
+would be predictable.
+Various means dependent on external events, such as keystroke intervals,
+can be used to do this and some systems have built\-in entropy sources.
+Suitable means are described in the OpenSSL software documentation,
+but are outside the scope of this page.
+.Pp
+The entropy seed used by the OpenSSL library is contained in a file,
+usually called
+.Cm .rnd ,
+which must be available when starting the NTP daemon
+or the
+.Nm
+program.
+The NTP daemon will first look for the file
+using the path specified by the
+.Ic randfile
+subcommand of the
+.Ic crypto
+configuration command.
+If not specified in this way, or when starting the
+.Nm
+program,
+the OpenSSL library will look for the file using the path specified
+by the
+.Ev RANDFILE
+environment variable in the user home directory,
+whether root or some other user.
+If the
+.Ev RANDFILE
+environment variable is not present,
+the library will look for the
+.Cm .rnd
+file in the user home directory.
+If the file is not available or cannot be written,
+the daemon exits with a message to the system log and the program
+exits with a suitable error message.
+.Ss Cryptographic Data Files
+All other file formats begin with two lines.
+The first contains the file name, including the generated host name
+and filestamp.
+The second contains the datestamp in conventional Unix date format.
+Lines beginning with # are considered comments and ignored by the
+.Nm
+program and
+.Xr ntpd @NTPD_MS@
+daemon.
+Cryptographic values are encoded first using ASN.1 rules,
+then encrypted if necessary, and finally written PEM\-encoded
+printable ASCII format preceded and followed by MIME content identifier lines.
+.Pp
+The format of the symmetric keys file is somewhat different
+than the other files in the interest of backward compatibility.
+Since DES\-CBC is deprecated in NTPv4, the only key format of interest
+is MD5 alphanumeric strings.
+Following hte heard the keys are
+entered one per line in the format
+.D1 Ar keyno type key
+where
+.Ar keyno
+is a positive integer in the range 1\-65,535,
+.Ar type
+is the string MD5 defining the key format and
+.Ar key
+is the key itself,
+which is a printable ASCII string 16 characters or less in length.
+Each character is chosen from the 93 printable characters
+in the range 0x21 through 0x7f excluding space and the
+.Ql #
+character.
+.Pp
+Note that the keys used by the
+.Xr ntpq @NTPQ_MS@
+and
+.Xr ntpdc @NTPDC_MS@
+programs
+are checked against passwords requested by the programs
+and entered by hand, so it is generally appropriate to specify these keys
+in human readable ASCII format.
+.Pp
+The
+.Nm
+program generates a MD5 symmetric keys file
+.Pa ntpkey_MD5key_ Ns Ar hostname.filestamp .
+Since the file contains private shared keys,
+it should be visible only to root and distributed by secure means
+to other subnet hosts.
+The NTP daemon loads the file
+.Pa ntp.keys ,
+so
+.Nm
+installs a soft link from this name to the generated file.
+Subsequently, similar soft links must be installed by manual
+or automated means on the other subnet hosts.
+While this file is not used with the Autokey Version 2 protocol,
+it is needed to authenticate some remote configuration commands
+used by the
+.Xr ntpq @NTPQ_MS@
+and
+.Xr ntpdc @NTPDC_MS@
+utilities.
+.Sh "OPTIONS"
+.Bl -tag
+.It  Fl b Ar imbits , Fl \-imbits Ns = Ns Ar imbits 
+identity modulus bits.
+This option takes an integer number as its argument.
+The value of
+.Ar imbits
+is constrained to being:
+.in +4
+.nf
+.na
+in the range  256 through 2048
+.fi
+.in -4
+.sp
+The number of bits in the identity modulus.  The default is 256.
+.It  Fl c Ar scheme , Fl \-certificate Ns = Ns Ar scheme 
+certificate scheme.
+.sp
+scheme is one of
+RSA\-MD2, RSA\-MD5, RSA\-SHA, RSA\-SHA1, RSA\-MDC2, RSA\-RIPEMD160,
+DSA\-SHA, or DSA\-SHA1.
+.sp
+Select the certificate message digest/signature encryption scheme.
+Note that RSA schemes must be used with a RSA sign key and DSA
+schemes must be used with a DSA sign key.  The default without
+this option is RSA\-MD5.
+.It  Fl C Ar cipher , Fl \-cipher Ns = Ns Ar cipher 
+privatekey cipher.
+.sp
+Select the cipher which is used to encrypt the files containing
+private keys.  The default is three\-key triple DES in CBC mode,
+equivalent to "@code{\-C des\-ede3\-cbc".  The openssl tool lists ciphers
+available in "\fBopenssl \-h\fP" output.
+.It  Fl d , Fl \-debug\-level 
+Increase debug verbosity level.
+This option may appear an unlimited number of times.
+.sp
+.It  Fl D Ar number , Fl \-set\-debug\-level Ns = Ns Ar number 
+Set the debug verbosity level.
+This option may appear an unlimited number of times.
+This option takes an integer number as its argument.
+.sp
+.It  Fl e , Fl \-id\-key 
+Write IFF or GQ identity keys.
+.sp
+Write the IFF or GQ client keys to the standard output.  This is
+intended for automatic key distribution by mail.
+.It  Fl G , Fl \-gq\-params 
+Generate GQ parameters and keys.
+.sp
+Generate parameters and keys for the GQ identification scheme,
+obsoleting any that may exist.
+.It  Fl H , Fl \-host\-key 
+generate RSA host key.
+.sp
+Generate new host keys, obsoleting any that may exist.
+.It  Fl I , Fl \-iffkey 
+generate IFF parameters.
+.sp
+Generate parameters for the IFF identification scheme, obsoleting
+any that may exist.
+.It  Fl i Ar group , Fl \-ident Ns = Ns Ar group 
+set Autokey group name.
+.sp
+Set the optional Autokey group name to name.  This is used in
+the file name of IFF, GQ, and MV client parameters files.  In
+that role, the default is the host name if this option is not
+provided.  The group name, if specified using \fB\-i/\-\-ident\fP or
+using \fB\-s/\-\-subject\-name\fP following an '\fB@\fP' character,
+is also a part of the self\-signed host certificate's subject and
+issuer names in the form \fBhost@group\fP and should match the
+\'\fBcrypto ident\fP' or '\fBserver ident\fP' configuration in
+\fBntpd\fP's configuration file. 
+.It  Fl l Ar lifetime , Fl \-lifetime Ns = Ns Ar lifetime 
+set certificate lifetime.
+This option takes an integer number as its argument.
+.sp
+Set the certificate expiration to lifetime days from now.
+.It  Fl M , Fl \-md5key 
+generate MD5 keys.
+.sp
+Generate MD5 keys, obsoleting any that may exist.
+.It  Fl m Ar modulus , Fl \-modulus Ns = Ns Ar modulus 
+modulus.
+This option takes an integer number as its argument.
+The value of
+.Ar modulus
+is constrained to being:
+.in +4
+.nf
+.na
+in the range  256 through 2048
+.fi
+.in -4
+.sp
+The number of bits in the prime modulus.  The default is 512.
+.It  Fl P , Fl \-pvt\-cert 
+generate PC private certificate.
+.sp
+Generate a private certificate.  By default, the program generates
+public certificates.
+.It  Fl p Ar passwd , Fl \-password Ns = Ns Ar passwd 
+local private password.
+.sp
+Local files containing private data are encrypted with the
+DES\-CBC algorithm and the specified password.  The same password
+must be specified to the local ntpd via the "crypto pw password"
+configuration command.  The default password is the local
+hostname.
+.It  Fl q Ar passwd , Fl \-export\-passwd Ns = Ns Ar passwd 
+export IFF or GQ group keys with password.
+.sp
+Export IFF or GQ identity group keys to the standard output,
+encrypted with the DES\-CBC algorithm and the specified password.
+The same password must be specified to the remote ntpd via the
+"crypto pw password" configuration command.  See also the option
+-\-id\-key (\-e) for unencrypted exports.
+.It  Fl S Ar sign , Fl \-sign\-key Ns = Ns Ar sign 
+generate sign key (RSA or DSA).
+.sp
+Generate a new sign key of the designated type, obsoleting any
+that may exist.  By default, the program uses the host key as the
+sign key.
+.It  Fl s Ar host@group , Fl \-subject\-name Ns = Ns Ar host@group 
+set host and optionally group name.
+.sp
+Set the Autokey host name, and optionally, group name specified
+following an '\fB@\fP' character.  The host name is used in the file
+name of generated host and signing certificates, without the
+group name.  The host name, and if provided, group name are used
+in \fBhost@group\fP form for the host certificate's subject and issuer
+fields.  Specifying '\fB\-s @group\fP' is allowed, and results in
+leaving the host name unchanged while appending \fB@group\fP to the
+subject and issuer fields, as with \fB\-i group\fP.  The group name, or
+if not provided, the host name are also used in the file names
+of IFF, GQ, and MV client parameter files.
+.It  Fl T , Fl \-trusted\-cert 
+trusted certificate (TC scheme).
+.sp
+Generate a trusted certificate.  By default, the program generates
+a non\-trusted certificate.
+.It  Fl V Ar num , Fl \-mv\-params Ns = Ns Ar num 
+generate <num> MV parameters.
+This option takes an integer number as its argument.
+.sp
+Generate parameters and keys for the Mu\-Varadharajan (MV)
+identification scheme.
+.It  Fl v Ar num , Fl \-mv\-keys Ns = Ns Ar num 
+update <num> MV keys.
+This option takes an integer number as its argument.
+.sp
+This option has not been fully documented.
+.It Fl \&? , Fl \-help
+Display usage information and exit.
+.It Fl \&! , Fl \-more\-help
+Pass the extended usage information through a pager.
+.It Fl > Oo Ar cfgfile Oc , Fl \-save\-opts Oo Ns = Ns Ar cfgfile Oc
+Save the option state to \fIcfgfile\fP.  The default is the \fIlast\fP
+configuration file listed in the \fBOPTION PRESETS\fP section, below.
+The command will exit after updating the config file.
+.It Fl < Ar cfgfile , Fl \-load\-opts Ns = Ns Ar cfgfile , Fl \-no\-load\-opts
+Load options from \fIcfgfile\fP.
+The \fIno\-load\-opts\fP form will disable the loading
+of earlier config/rc/ini files.  \fI\-\-no\-load\-opts\fP is handled early,
+out of order.
+.It Fl \-version Op Brq Ar v|c|n
+Output version of program and exit.  The default mode is `v', a simple
+version.  The `c' mode will print copyright information and `n' will
+print the full copyright notice.
+.El
+.Sh "OPTION PRESETS"
+Any option that is not marked as \fInot presettable\fP may be preset
+by loading values from configuration ("RC" or ".INI") file(s) and values from
+environment variables named:
+.nf
+  \fBNTP_KEYGEN_<option\-name>\fP or \fBNTP_KEYGEN\fP
+.fi
+.ad
+The environmental presets take precedence (are processed later than)
+the configuration files.
+The \fIhomerc\fP files are "\fI$HOME\fP", and "\fI.\fP".
+If any of these are directories, then the file \fI.ntprc\fP
+is searched for within those directories.
+.Sh USAGE
+The
+.Fl p Ar password
+option specifies the write password and
+.Fl q Ar password
+option the read password for previously encrypted files.
+The
+.Nm
+program prompts for the password if it reads an encrypted file
+and the password is missing or incorrect.
+If an encrypted file is read successfully and
+no write password is specified, the read password is used
+as the write password by default.
+.Sh "ENVIRONMENT"
+See \fBOPTION PRESETS\fP for configuration environment variables.
+.Sh "FILES"
+See \fBOPTION PRESETS\fP for configuration files.
+.Sh "EXIT STATUS"
+One of the following exit values will be returned:
+.Bl -tag
+.It 0 " (EXIT_SUCCESS)"
+Successful program execution.
+.It 1 " (EXIT_FAILURE)"
+The operation failed or the command syntax was not valid.
+.It 66 " (EX_NOINPUT)"
+A specified configuration file could not be loaded.
+.It 70 " (EX_SOFTWARE)"
+libopts had an internal operational error.  Please report
+it to autogen\-users@lists.sourceforge.net.  Thank you.
+.El
+.Sh "AUTHORS"
+The University of Delaware and Network Time Foundation
+.Sh "COPYRIGHT"
+Copyright (C) 1992\-2015 The University of Delaware and Network Time Foundation all rights reserved.
+This program is released under the terms of the NTP license, <http://ntp.org/license>.
+.Sh BUGS
+It can take quite a while to generate some cryptographic values,
+from one to several minutes with modern architectures
+such as UltraSPARC and up to tens of minutes to an hour
+with older architectures such as SPARC IPC.
+.Pp
+Please report bugs to http://bugs.ntp.org .
+.Pp
+Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org
+.Sh NOTES
+Portions of this document came from FreeBSD.
+.Pp
+This manual page was \fIAutoGen\fP\-erated from the \fBntp\-keygen\fP
+option definitions.