1275970Scy\input texinfo @c -*-texinfo-*- 2275970Scy@c %**start of header 3275970Scy@setfilename ntp-keygen.info 4275970Scy@settitle Ntp-keygen User's Manual 5275970Scy@include ../sntp/include/version.texi 6275970Scy@paragraphindent 2 7275970Scy@c %**end of header 8275970Scy 9275970Scy@ifinfo 10275970ScyThis file documents the use of the NTP Project's @code{ntp-keygen} 11275970Scyprogram, which generates various keys for @code{ntpd}, 12275970Scy@end ifinfo 13275970Scy 14275970Scy@direntry 15275970Scy* ntp-keygen: (ntp-keygen). NTP Key Generation 16275970Scy@end direntry 17275970Scy 18275970Scy@titlepage 19275970Scy@title NTP Key Generation User's Manual 20275970Scy@subtitle ntp-keygen, version @value{VERSION}, @value{UPDATED} 21275970Scy@c @author Max @email{foo@ntp.org} 22275970Scy@end titlepage 23275970Scy 24275970Scy@c @page 25275970Scy@c @vskip 0pt plus 1filll 26275970Scy 27275970Scy@shortcontents 28275970Scy 29275970Scy@menu 30275970Scy* Description:: 31275970Scy* ntp-keygen Invocation:: Invoking ntp-keygen 32275970Scy* Running the Program:: 33275970Scy* Random Seed File:: 34275970Scy* Cryptographic Data Files:: 35275970Scy@end menu 36275970Scy 37275970Scy@node Top, Description, (dir), (dir) 38275970Scy@top NTP Key Generation Program User Manual 39275970Scy 40275970ScyThis document describes the use of the NTP Project's @code{ntp-keygen} 41275970Scyprogram, that generates cryptographic data files used by the NTPv4 42275970Scyauthentication and identity schemes. 43275970ScyIt can generate message digest keys used in symmetric key cryptography and, 44275970Scyif the OpenSSL software 45275970Scylibrary has been installed, it can generate host keys, sign keys, 46275970Scycertificates, and identity keys and parameters used by the Autokey 47275970Scypublic key cryptography. 48275970ScyThe message digest keys file is generated in a 49275970Scyformat compatible with NTPv3. 50275970ScyAll other files are in PEM-encoded 51275970Scyprintable ASCII format so they can be embedded as MIME attachments in 52275970Scymail to other sites. 53275970Scy 54275970ScyThis document applies to version @value{VERSION} of @code{ntp-keygen}. 55275970Scy 56275970Scy@node Description, Running the Program, Top, Top 57275970Scy@comment node-name, next, previous, up 58275970Scy@section Description 59275970Scy 60275970ScyThis program generates cryptographic data files used by the NTPv4 61275970Scyauthentication and identity schemes. It can generate message digest 62275970Scykeys used in symmetric key cryptography and, if the OpenSSL software 63275970Scylibrary has been installed, it can generate host keys, sign keys, 64275970Scycertificates, and identity keys and parameters used by the Autokey 65275970Scypublic key cryptography. The message digest keys file is generated in a 66275970Scyformat compatible with NTPv3. All other files are in PEM-encoded 67275970Scyprintable ASCII format so they can be embedded as MIME attachments in 68275970Scymail to other sites. 69275970Scy 70275970ScyWhen used to generate message digest keys, the program produces a file 71275970Scycontaining ten pseudo-random printable ASCII strings suitable for the 72275970ScyMD5 message digest algorithm included in the distribution. 73275970ScyIf the 74275970ScyOpenSSL library is installed, it produces an additional ten hex-encoded 75275970Scyrandom bit strings suitable for the SHA1 and other message digest 76275970Scyalgorithms. 77275970ScyThe message digest keys file must be distributed and stored 78275970Scyusing secure means beyond the scope of NTP itself. 79275970ScyBesides the keys 80275970Scyused for ordinary NTP associations, additional keys can be defined as 81275970Scypasswords for the ntpq and ntpdc utility programs. 82275970Scy 83275970ScyThe remaining generated files are compatible with other OpenSSL 84275970Scyapplications and other Public Key Infrastructure (PKI) resources. 85275970ScyCertificates generated by this program are compatible with extant 86275970Scyindustry practice, although some users might find the interpretation of 87275970ScyX509v3 extension fields somewhat liberal. 88275970ScyHowever, the identity keys 89275970Scyare probably not compatible with anything other than Autokey. 90275970Scy 91275970ScySome files used by this program are encrypted using a private password. 92275970ScyThe @code{-p} option specifies the password for local encrypted files and the 93275970Scy@code{-q} option the password for encrypted files sent to remote sites. 94275970ScyIf no password is specified, the host name returned by the Unix 95275970Scy@code{gethostname()} function, normally the DNS name of the host, is used. 96275970Scy 97275970ScyThe @kbd{pw} option of the @code{crypto} configuration command 98275970Scyspecifies the read password for previously encrypted local files. 99275970ScyThis must match the local password used by this program. 100275970ScyIf not specified, the host name is used. 101275970ScyThus, if files are generated by this program without password, 102275970Scythey can be read back by ntpd without password, but only on the same 103275970Scyhost. 104275970Scy 105275970ScyNormally, encrypted files for each host are generated by that host and 106275970Scyused only by that host, although exceptions exist as noted later on 107275970Scythis page. 108275970ScyThe symmetric keys file, normally called @code{ntp.keys}, is 109275970Scyusually installed in @code{/etc}. 110275970ScyOther files and links are usually installed 111275970Scyin @code{/usr/local/etc}, which is normally in a shared filesystem in 112275970ScyNFS-mounted networks and cannot be changed by shared clients. 113275970ScyThe location of the keys directory can be changed by the keysdir 114275970Scyconfiguration command in such cases. 115275970ScyNormally, this is in @code{/etc}. 116275970Scy 117275970ScyThis program directs commentary and error messages to the standard 118275970Scyerror stream @code{stderr} and remote files to the standard output stream 119275970Scy@code{stdout} where they can be piped to other applications or redirected to 120275970Scyfiles. 121275970ScyThe names used for generated files and links all begin with the 122275970Scystring @code{ntpkey} and include the file type, 123275970Scygenerating host and filestamp, 124275970Scyas described in the @ref{Cryptographic Data Files} section below. 125275970Scy 126275970Scy@node Running the Program, Random Seed File, Description, Top 127275970Scy@comment node-name, next, previous, up 128275970Scy@section Running the Program 129275970Scy 130275970ScyTo test and gain experience with Autokey concepts, log in as root and 131275970Scychange to the keys directory, usually @code{/usr/local/etc}. 132275970ScyWhen run for the 133275970Scyfirst time, or if all files with names beginning @code{ntpkey}] have been 134275970Scyremoved, use the @code{ntp-keygen} command without arguments to generate a 135275970Scydefault RSA host key and matching RSA-MD5 certificate with expiration 136275970Scydate one year hence. 137275970ScyIf run again without options, the program uses the 138275970Scyexisting keys and parameters and generates only a new certificate with 139275970Scynew expiration date one year hence. 140275970Scy 141275970ScyRun the command on as many hosts as necessary. 142275970ScyDesignate one of them as the trusted host (TH) using @code{ntp-keygen} 143275970Scywith the @code{-T} option and configure 144275970Scyit to synchronize from reliable Internet servers. 145275970ScyThen configure the other hosts to synchronize to the TH directly or indirectly. 146275970ScyA certificate trail is created when Autokey asks the immediately 147275970Scyascendant host towards the TH to sign its certificate, which is then 148275970Scyprovided to the immediately descendant host on request. 149275970ScyAll group hosts should have acyclic certificate trails ending on the TH. 150275970Scy 151275970ScyThe host key is used to encrypt the cookie when required and so must be 152275970ScyRSA type. 153275970ScyBy default, the host key is also the sign key used to encrypt signatures. 154275970ScyA different sign key can be assigned using the @code{-S} option 155275970Scyand this can be either RSA or DSA type. 156275970ScyBy default, the signature 157275970Scymessage digest type is MD5, but any combination of sign key type and 158275970Scymessage digest type supported by the OpenSSL library can be specified 159275970Scyusing the @code{-c} option. 160275970Scy 161275970ScyThe rules say cryptographic media should be generated with proventic 162275970Scyfilestamps, which means the host should already be synchronized before 163275970Scythis program is run. 164275970ScyThis of course creates a chicken-and-egg problem 165275970Scywhen the host is started for the first time. 166275970ScyAccordingly, the host time 167275970Scyshould be set by some other means, such as eyeball-and-wristwatch, at 168275970Scyleast so that the certificate lifetime is within the current year. 169275970ScyAfter that and when the host is synchronized to a proventic source, the 170275970Scycertificate should be re-generated. 171275970Scy 172275970ScyAdditional information on trusted groups and identity schemes is on the 173275970ScyAutokey Public-Key Authentication page. 174275970Scy 175275970Scy@include invoke-ntp-keygen.texi 176275970Scy 177275970Scy@node Random Seed File, Cryptographic Data Files, Running the Program, Top 178275970Scy@comment node-name, next, previous, up 179275970Scy@section Random Seed File 180275970Scy 181275970ScyAll cryptographically sound key generation schemes must have means to 182275970Scyrandomize the entropy seed used to initialize the internal 183275970Scypseudo-random number generator used by the OpenSSL library routines. 184275970ScyIf a site supports ssh, it is very likely that means to do this are 185275970Scyalready available. 186275970ScyThe entropy seed used by the OpenSSL library is contained in a file, 187275970Scyusually called @code{.rnd}, which must be available when 188275970Scystarting the @code{ntp-keygen} program or @code{ntpd} daemon. 189275970Scy 190275970ScyThe OpenSSL library looks for the file using the path specified by the 191275970Scy@code{RANDFILE} environment variable in the user home directory, whether root 192275970Scyor some other user. 193275970ScyIf the @code{RANDFILE} environment variable is not 194275970Scypresent, the library looks for the @code{.rnd} file in the user home 195275970Scydirectory. 196275970ScySince both the @code{ntp-keygen} program and @code{ntpd} daemon must run 197275970Scyas root, the logical place to put this file is in @code{/.rnd} or 198275970Scy@code{/root/.rnd}. 199275970ScyIf the file is not available or cannot be written, the program exits 200275970Scywith a message to the system log. 201275970Scy 202275970Scy@node Cryptographic Data Files, , Random Seed File, Top 203275970Scy@comment node-name, next, previous, up 204275970Scy@section Cryptographic Data Files 205275970Scy 206275970ScyFile and link names are in the @code{form ntpkey_key_name.fstamp}, 207275970Scywhere @code{key} is the key or parameter type, 208275970Scy@code{name} is the host or group name and 209275970Scy@code{fstamp} is the filestamp (NTP seconds) when the file was created). 210275970ScyBy convention, key names in generated file names include both upper and 211275970Scylower case characters, while key names in generated link names include 212275970Scyonly lower case characters. The filestamp is not used in generated link 213275970Scynames. 214275970Scy 215275970ScyThe key name is a string defining the cryptographic key type. 216275970ScyKey types include public/private keys host and sign, certificate cert 217275970Scyand several challenge/response key types. 218275970ScyBy convention, client files used for 219275970Scychallenges have a par subtype, as in the IFF challenge IFFpar, while 220275970Scyserver files for responses have a key subtype, as in the GQ response 221275970ScyGQkey. 222275970Scy 223275970ScyAll files begin with two nonencrypted lines. The first line contains 224275970Scythe file name in the format @code{ntpkey_key_host.fstamp}. 225275970ScyThe second line contains the datestamp in conventional Unix date format. 226275970ScyLines beginning with @code{#} are ignored. 227275970Scy 228275970ScyThe remainder of the file contains cryptographic data encoded first 229275970Scyusing ASN.1 rules, then encrypted using the DES-CBC algorithm with 230275970Scygiven password and finally written in PEM-encoded printable ASCII text 231275970Scypreceded and followed by MIME content identifier lines. 232275970Scy 233275970ScyThe format of the symmetric keys file, ordinarily named @code{ntp.keys}, 234275970Scyis somewhat different than the other files in the interest of backward 235275970Scycompatibility. 236275970ScyOrdinarily, the file is generated by this program, but 237275970Scyit can be constructed and edited using an ordinary text editor. 238275970Scy 239275970Scy@example 240275970Scy# ntpkey_MD5key_hms.local.3564038757 241275970Scy# Sun Dec 9 02:45:57 2012 242275970Scy 243275970Scy 1 MD5 "]!ghT%O;3)WJ,/Nc:>I # MD5 key 244275970Scy 2 MD5 lu+H^tF46BKR-6~p{V_5 # MD5 key 245275970Scy 3 MD5 :lnoVsE%Y}z*avh%EtNC # MD5 key 246275970Scy 4 MD5 |fdZrf0sF~@PHZ;w-i^V # MD5 key 247275970Scy 5 MD5 IyAG>O"}y"LmCRS!*bHC # MD5 key 248275970Scy 6 MD5 ">e\A@>hT/661ri52,,H # MD5 key 249275970Scy 7 MD5 c9x=M'CfLxax9v)PV-si # MD5 key 250275970Scy 8 MD5 E|=jvFVov?Bn|Ev=&aK\ # MD5 key 251275970Scy 9 MD5 T!c4UT&`(m$+m+B6,`Q0 # MD5 key 252275970Scy10 MD5 JVF/1=)=IFbHbJQz..Cd # MD5 key 253275970Scy11 SHA1 6dea311109529e436c2b4fccae9bc753c16d1b48 # SHA1 key 254275970Scy12 SHA1 7076f373d86c4848c59ff8046e49cb7d614ec394 # SHA1 key 255275970Scy13 SHA1 5f48b1b60591eb01b7cf1d33b7774f08d20262d3 # SHA1 key 256275970Scy14 SHA1 eed5ab9d9497319ec60cf3781d52607e76720178 # SHA1 key 257275970Scy15 SHA1 f283562611a04c964da8126296f5f8e58c3f85de # SHA1 key 258275970Scy16 SHA1 1930da171297dd63549af50b29449de17dcf341f # SHA1 key 259275970Scy17 SHA1 fee892110358cd4382322b889869e750db8e8a8f # SHA1 key 260275970Scy18 SHA1 b5520c9fadd7ad3fd8bfa061c8821b65d029bb37 # SHA1 key 261275970Scy19 SHA1 8c74fb440ec80f453ec6aaa62b9baed0ab723b92 # SHA1 key 262275970Scy20 SHA1 6bc05f734306a189326000970c19b3910f403795 # SHA1 key 263275970Scy@end example 264275970Scy 265275970Scy Figure 1. Typical Symmetric Key File 266275970Scy 267275970ScyFigure 1 shows a typical symmetric keys file used by the reference 268275970Scyimplementation. 269275970ScyEach line of the file contains three fields, first an 270275970Scyinteger between 1 and 65534, inclusive, representing the key identifier 271275970Scyused in the server and peer configuration commands. 272275970ScyNext is the key type for the message digest algorithm, 273275970Scywhich in the absence of the 274275970ScyOpenSSL library must be MD5 to designate the MD5 message digest 275275970Scyalgorithm. 276275970ScyIf the OpenSSL library is installed, the key type can be any 277275970Scymessage digest algorithm supported by that library. 278275970ScyHowever, if 279275970Scycompatibility with FIPS 140-2 is required, the key type must be either 280275970ScySHA or SHA1. 281275970ScyThe key type can be changed using an ASCII text editor. 282275970Scy 283275970ScyAn MD5 key consists of a printable ASCII string less than or equal to 284275970Scy16 characters and terminated by whitespace or a # character. 285275970ScyAn OpenSSL 286275970Scykey consists of a hex-encoded ASCII string of 40 characters, which is 287275970Scytruncated as necessary. 288275970Scy 289275970ScyNote that the keys used by the @code{ntpq} and @code{ntpdc} programs are 290275970Scychecked against passwords requested by the programs and entered by hand, 291275970Scyso it 292275970Scyis generally appropriate to specify these keys in human readable ASCII 293275970Scyformat. 294275970Scy 295275970ScyThe @code{ntp-keygen} program generates a MD5 symmetric keys file 296275970Scy@code{ntpkey_MD5key_hostname.filestamp}. 297275970ScySince the file contains private 298275970Scyshared keys, it should be visible only to root and distributed by 299275970Scysecure means to other subnet hosts. 300275970ScyThe NTP daemon loads the file @code{ntp.keys}, so @code{ntp-keygen} 301275970Scyinstalls a soft link from this name to the generated file. 302275970ScySubsequently, similar soft links must be installed by 303275970Scymanual or automated means on the other subnet hosts. 304275970ScyWhile this file is 305275970Scynot used with the Autokey Version 2 protocol, it is needed to 306275970Scyauthenticate some remote configuration commands used by the @code{ntpq} and 307275970Scy@code{ntpdc} utilities. 308