1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2 <html> 3 <head> 4 <meta http-equiv="content-type" content="text/html;charset=iso-8859-1"> 5 <meta name="generator" content="HTML Tidy, see www.w3.org"> 6 <title>ntp-keygen - generate public and private keys</title> 7 <link href="scripts/style.css" type="text/css" rel="stylesheet"> 8 </head> 9 <body> 10 <h3><tt>ntp-keygen</tt> - generate public and private keys</h3> 11 <p><img src="pic/alice23.gif" alt="gif" align="left"><a href="http://www.eecis.udel.edu/%7emills/pictures.html">from <i>Alice's Adventures in Wonderland</i>, Lewis Carroll</a></p> 12 <p>Alice holds the key.</p> 13 <p>Last update: 14 <!-- #BeginDate format:En2m -->24-Jul-2018 07:27<!-- #EndDate --> 15 UTC</p> 16 <br clear="left"> 17 <h4>Related Links</h4> 18 <script type="text/javascript" language="javascript" src="scripts/manual.txt"></script> 19 <h4>Table of Contents</h4> 20 <ul> 21 <li class="inline"><a href="#synop">Synopsis</a></li> 22 <li class="inline"><a href="#descrip">Description</a></li> 23 <li class="inline"><a href="#run">Running the program</a></li> 24 <li class="inline"><a href="#cmd">Command Line Options</a></li> 25 <li class="inline"><a href="#rand">Random Seed File</a></li> 26 <li class="inline"><a href="#fmt">Cryptographic Data Files</a></li> 27 <li class="inline"><a href="#bug">Bugs</a></li> 28 </ul> 29 <hr> 30 <h4 id="synop">Synopsis</h4> 31 <p id="intro"><tt>ntp-keygen [ -deGHIMPT ] [ -b <i>modulus</i> ] [ -c [ RSA-MD2 | RSA-MD5 | RSA-SHA 32 | RSA-SHA1 | RSA-MDC2 | RSA-RIPEMD160 | DSA-SHA | DSA-SHA1 ] ] 33 [ -C <i>cipher</i> ] [-i <i>group</i> ] [ -l <em>days</em>] 34 [ -m <i>modulus</i> ] [ -p <i>passwd1</i> ] [ -q <i>passwd2</i> ] 35 [ -S [ RSA | DSA ] ] [ -s <i>host</i> ] [ -V <i>nkeys</i> ]</tt></p> 36 <h4 id="descrip">Description</h4> 37 <p>This program generates cryptographic data files used by the NTPv4 38 authentication and identity schemes. It can generate message digest keys 39 used in symmetric key cryptography and, if the OpenSSL software library 40 has been installed, it can generate host keys, sign keys, certificates, 41 and identity keys and parameters used by the Autokey public key 42 cryptography. The message digest keys file is generated in a format 43 compatible with NTPv3. All other files are in PEM-encoded printable ASCII 44 format so they can be embedded as MIME attachments in mail to other 45 sites.</p> 46 <p>When used to generate message digest keys, the program produces a file 47 containing ten pseudo-random printable ASCII strings suitable for the MD5 48 message digest algorithm included in the distribution. If the OpenSSL 49 library is installed, it produces an additional ten hex-encoded random bit 50 strings suitable for the SHA1, AES-128 CMAC, and other message digest 51 algorithms. The message digest keys file must be distributed and stored 52 using secure means beyond the scope of NTP itself. Besides the keys used 53 for ordinary NTP associations, additional keys can be defined as passwords 54 for the <tt><a href="ntpq.html">ntpq</a></tt> 55 and <tt><a href="ntpdc.html">ntpdc</a></tt> utility programs.</p> 56 <p>The remaining generated files are compatible with other OpenSSL 57 applications and other Public Key Infrastructure (PKI) 58 resources. Certificates generated by this program are compatible with 59 extant industry practice, although some users might find the 60 interpretation of X509v3 extension fields somewhat liberal. However, 61 the identity keys are probably not compatible with anything other than 62 Autokey.</p> 63 <p>Some files used by this program are encrypted using a private 64 password. The <tt>-p</tt> option specifies the password for local 65 encrypted files and the <tt>-q</tt> option the password for encrypted 66 files sent to remote sites. If no password is specified, the host name 67 returned by the Unix <tt>gethostname()</tt> function, normally the DNS 68 name of the host, is used.</p> 69 <p>The <tt>pw</tt> option of the <tt>crypto</tt> configuration command 70 specifies the read password for previously encrypted local files. 71 This must match the local password used by this program. If not 72 specified, the host name is used. Thus, if files are generated by 73 this program without password, they can be read back by <tt>ntpd</tt> 74 without password, but only on the same host.</p> 75 <p>Normally, encrypted files for each host are generated by that host 76 and used only by that host, although exceptions exist as noted later 77 on this page. The symmetric keys file, normally 78 called <tt>ntp.keys</tt>, is usually installed in <tt>/etc</tt>. 79 Other files and links are usually installed 80 in <tt>/usr/local/etc</tt>, which is normally in a shared filesystem 81 in NFS-mounted networks and cannot be changed by shared clients. The 82 location of the keys directory can be changed by the <tt>keysdir</tt> 83 configuration command in such cases. Normally, this is 84 in <tt>/etc</tt>.</p> 85 <p>This program directs commentary and error messages to the standard 86 error stream <tt>stderr</tt> and remote files to the standard output 87 stream <tt>stdout</tt> where they can be piped to other applications 88 or redirected to files. The names used for generated files and links 89 all begin with the string <tt>ntpkey</tt> and include the file type, 90 generating host and filestamp, as described in 91 the <a href="#fmt">Cryptographic Data Files</a> section below</p> 92 <h4 id="run">Running the Program</h4> 93 <p>To test and gain experience with Autokey concepts, log in as root and 94 change to the keys directory, usually <tt>/usr/local/etc</tt>. When 95 run for the first time, or if all files with names 96 beginning <tt>ntpkey</tt> have been removed, use 97 the <tt>ntp-keygen</tt> command without arguments to generate a 98 default RSA host key and matching RSA-MD5 certificate with expiration 99 date one year hence. If run again without options, the program uses 100 the existing keys and parameters and generates only a new certificate 101 with new expiration date one year hence.</p> 102 <p>Run the command on as many hosts as necessary. Designate one of them 103 as the trusted host (TH) using <tt>ntp-keygen</tt> with 104 the <tt>-T</tt> option and configure it to synchronize from reliable 105 Internet servers. Then configure the other hosts to synchronize to 106 the TH directly or indirectly. A certificate trail is created when 107 Autokey asks the immediately ascendant host towards the TH to sign its 108 certificate, which is then provided to the immediately descendant host 109 on request. All group hosts should have acyclic certificate trails 110 ending on the TH.</p> 111 <p>The host key is used to encrypt the cookie when required and so must 112 be RSA type. By default, the host key is also the sign key used to 113 encrypt signatures. A different sign key can be assigned using 114 the <tt>-S</tt> option and this can be either RSA or DSA type. By 115 default, the signature message digest type is MD5, but any combination 116 of sign key type and message digest type supported by the OpenSSL 117 library can be specified using the <tt>-c</tt> option.</p> 118 <p>The rules say cryptographic media should be generated with proventic 119 filestamps, which means the host should already be synchronized before 120 this program is run. This of course creates a chicken-and-egg problem 121 when the host is started for the first time. Accordingly, the host 122 time should be set by some other means, such as 123 eyeball-and-wristwatch, at least so that the certificate lifetime is 124 within the current year. After that and when the host is synchronized 125 to a proventic source, the certificate should be re-generated.</p> 126 <p>Additional information on trusted groups and identity schemes is on 127 the <a href="autokey.html">Autokey Public-Key Authentication</a> 128 page.</p> 129 <h4 id="cmd">Command Line Options</h4> 130 <dl> 131 <dt><tt>-b <i>modulus</i></tt></dt> 132 <dd>Set the modulus for generating identity keys to <i>modulus</i> 133 bits. The modulus defaults to 256, but can be set from 256 (32 134 octets) to 2048 (256 octets). Use the larger moduli with caution, 135 as this can consume considerable computing resources and increases 136 the size of authenticated packets.</dd> 137 <dt><tt>-c [ RSA-MD2 | RSA-MD5 | RSA-SHA | RSA-SHA1 | RSA-MDC2 | RSA-RIPEMD160 | DSA-SHA | DSA-SHA1 ]</tt></dt> 138 <dd>Select certificate digital signature and message digest scheme. 139 Note that RSA schemes must be used with an RSA sign key and DSA 140 schemes must be used with a DSA sign key. The default without this 141 option is <tt>RSA-MD5</tt>. If compatibility with FIPS 140-2 is 142 required, either the <tt>DSA-SHA</tt> or <tt>DSA-SHA1</tt> scheme 143 must be used.</dd> 144 <dt><tt>-C <i>cipher</i></tt></dt> 145 <dd>Select the OpenSSL cipher to use for password-protected keys. 146 The <tt>openssl -h</tt> command provided with OpenSSL displays 147 available ciphers. The default without this option 148 is <tt>des-ede3-cbc</tt>.</dd> 149 <dt><tt>-d</tt></dt> 150 <dd>Enable debugging. This option displays the cryptographic data 151 produced for eye-friendly billboards.</dd> 152 <dt><tt>-e</tt></dt> 153 <dd>Extract the IFF or GQ public parameters from the <tt>IFFkey</tt> 154 or <tt>GQkey</tt> keys file previously specified. Send the 155 unencrypted data to the standard output stream <tt>stdout</tt>.</dd> 156 <dt><tt>-G</tt></dt> 157 <dd>Generate a new encrypted GQ key file for the Guillou-Quisquater 158 (GQ) identity scheme. This option is mutually exclusive with 159 the <tt>-I</tt> and <tt>-V</tt> options.</dd> 160 <dt><tt>-H</tt></dt> 161 <dd>Generate a new encrypted RSA public/private host key file.</dd> 162 <dt><tt>-i <i>group</i></tt></dt> 163 <dd>Set the optional Autokey group name to <tt><i>group</i></tt>. This 164 is used in the identity scheme parameter file names. In that role, 165 the default is the host name if no group is provided. The group 166 name, if specified using <tt>-i</tt> or using <tt>-s</tt> following 167 an <tt>@</tt> character, is also used in certificate subject and 168 issuer names in the form <tt><i>host</i>@<i>group</i></tt> and 169 should match the group specified via <tt>crypto ident</tt> 170 or <tt>server ident</tt> in ntpd's configuration file.</dd> 171 <dt><tt>-I</tt></dt> 172 <dd>Generate a new encrypted IFF key file for the Schnorr (IFF) 173 identity scheme. This option is mutually exclusive with 174 the <tt>-G</tt> and <tt>-V</tt> options.</dd> 175 <dt><tt>-l <i>days</i></tt></dt> 176 <dd>Set the lifetime for certificates to <tt><i>days</i></tt>. The 177 default lifetime is one year (365 d).</dd> 178 <dt><tt>-m <i>modulus</i></tt></dt> 179 <dd>Set the modulus for generating files to <i>modulus</i> bits. The 180 modulus defaults to 512, but can be set from 256 (32 octets) to 2048 181 (256 octets). Use the larger moduli with caution, as this can 182 consume considerable computing resources and increases the size of 183 authenticated packets.</dd> 184 <dt><tt>-M</tt></dt> 185 <dd>Generate a new keys file containing 10 MD5 keys and 10 SHA keys. 186 An MD5 key is a string of 20 random printable ASCII characters, 187 while a SHA key is a string of 40 random hex digits. The file can be 188 edited using a text editor to change the key type or key content. 189 This option is mutually exclusive with all other options.</dd> 190 <dt><tt>-P</tt></dt> 191 <dd>Generate a new private certificate used by the PC identity scheme. 192 By default, the program generates public certificates. Note: the PC 193 identity scheme is not recommended for new installations.</dd> 194 <dt><tt>-p <i>passwd</i></tt></dt> 195 <dd>Set the password for reading and writing encrypted files 196 to <tt><i>passwd</i></tt>. These include the host, sign and 197 identify key files. By default, the password is the string returned 198 by the Unix <tt>gethostname()</tt> routine.</dd> 199 <dt><tt>-q <i>passwd</i></tt></dt> 200 <dd>Set the password for writing encrypted IFF, GQ and MV identity 201 files redirected to <tt>stdout</tt> to <tt><i>passwd</i></tt>=. In 202 effect, these files are decrypted with the <tt>-p</tt> password, 203 then encrypted with the <tt>-q</tt> password. By default, the 204 password is the string returned by the Unix <tt>gethostname()</tt> 205 routine.</dd> 206 <dt><tt>-S [ RSA | DSA ]</tt></dt> 207 <dd>Generate a new encrypted public/private sign key file of the 208 specified type. By default, the sign key is the host key and has 209 the same type. If compatibly with FIPS 140-2 is required, the sign 210 key type must be <tt>DSA</tt>.</dd> 211 <dt><tt>-s <i>host</i>[@<i>group</i>]</tt></dt> 212 <dd>Specify the Autokey host name, where <tt><i>host</i></tt> is the 213 host name and <tt><i>group</i></tt> is the optional group name. The 214 host name, and if provided, group name are used 215 in <tt><i>host</i>@<i>group</i></tt> form as certificate subject and 216 issuer. Specifying <tt>-s @<i>group</i></tt> is allowed, and 217 results in leaving the host name unchanged, as 218 with <tt>-i <i>group</i></tt>. The group name, or if no group is 219 provided, the host name are also used in the file names of IFF, GQ, 220 and MV identity scheme parameter files. If <tt><i>host</i></tt> is 221 not specified, the default host name is the string returned by 222 the <tt>gethostname()</tt> routine.</dd> 223 <dt><tt>-T</tt></dt> 224 <dd>Generate a trusted certificate. By default, the program generates 225 nontrusted certificates.</dd> 226 <dt><tt>-V <i>nkeys</i></tt></dt> 227 <dd>Generate <tt>nkeys</tt> encrypted server keys for the 228 Mu-Varadharajan (MV) identity scheme. This option is mutually 229 exclusive with the <tt>-I</tt> and <tt>-G</tt> options. Note: 230 support for this option should be considered a work in 231 progress.</dd> 232 </dl> 233 <h4 id="rand">Random Seed File</h4> 234 <p>All cryptographically sound key generation schemes must have means to 235 randomize the entropy seed used to initialize the internal 236 pseudo-random number generator used by the OpenSSL library routines. 237 If a site supports <tt>ssh</tt>, it is very likely that means to do 238 this are already available. The entropy seed used by the OpenSSL 239 library is contained in a file, usually called <tt>.rnd</tt>, which 240 must be available when starting the <tt>ntp-keygen</tt> program 241 or <tt>ntpd</tt> daemon.</p> 242 <p>The OpenSSL library looks for the file using the path specified by 243 the <tt>RANDFILE</tt> environment variable in the user home directory, 244 whether root or some other user. If the <tt>RANDFILE</tt> environment 245 variable is not present, the library looks for the <tt>.rnd</tt> file 246 in the user home directory. Since both the <tt>ntp-keygen</tt> 247 program and <tt>ntpd</tt> daemon must run as root, the logical place 248 to put this file is in <tt>/.rnd</tt> or <tt>/root/.rnd</tt>. If the 249 file is not available or cannot be written, the program exits with a 250 message to the system log.</p> 251 <h4 id="fmt">Cryptographic Data Files</h4> 252 <p>File and link names are in the 253 form <tt>ntpkey_<i>key</i>_<i>name</i>.<i>fstamp</i></tt>, 254 where <tt><i>key</i></tt> is the key or parameter 255 type, <tt><i>name</i></tt> is the host or group name 256 and <tt><i>fstamp</i></tt> is the filestamp (NTP seconds) when the 257 file was created). By convention, <em><tt>key</tt></em> names in 258 generated file names include both upper and lower case characters, 259 while <em><tt>key</tt></em> names in generated link names include only 260 lower case characters. The filestamp is not used in generated link 261 names.</p> 262 <p>The <em><tt>key</tt></em> name is a string defining the cryptographic 263 key type. Key types include public/private keys <tt>host</tt> 264 and <tt>sign</tt>, certificate <tt>cert</tt> and several 265 challenge/response key types. By convention, client files used for 266 challenges have a <tt>par</tt> subtype, as in the IFF 267 challenge <tt>IFFpar</tt>, while server files for responses have 268 a <tt>key</tt> subtype, as in the GQ response <tt>GQkey</tt>.</p> 269 <p>All files begin with two nonencrypted lines. The first line contains 270 the file name in the 271 format <tt>ntpkey_<i>key</i>_<i>host</i>.<i>fstamp</i></tt>. The second 272 line contains the datestamp in conventional Unix <tt>date</tt> format. 273 Lines beginning with <tt>#</tt> are ignored.</p> 274 <p>The remainder of the file contains cryptographic data encoded first 275 using ASN.1 rules, then encrypted using the DES-CBC algorithm with 276 given password and finally written in PEM-encoded printable ASCII text 277 preceded and followed by MIME content identifier lines.</p> 278 <p>The format of the symmetric keys file, ordinarily 279 named <tt>ntp.keys,</tt> is somewhat different than the other files in 280 the interest of backward compatibility. Ordinarily, the file is 281 generated by this program, but it can be constructed and edited using 282 an ordinary text editor.</p> 283 <table> 284 <caption style="caption-side: bottom;"> 285 Figure 1. Typical Symmetric Key File 286 </caption> 287 <tr><td style="border: 1px solid black; border-spacing: 0;"> 288 <pre style="color:grey;"> 289 # ntpkey_MD5key_bk.ntp.org.3595864945 290 # Thu Dec 12 19:22:25 2013 291 292 1 MD5 L";Nw<`.I<f4U0)247"i # MD5 key 293 2 MD5 &>l0%XXK9O'51VwV<xq~ # MD5 key 294 3 MD5 lb4zLW~d^!K:]RsD'qb6 # MD5 key 295 4 MD5 Yue:tL[+vR)M`n~bY,'? # MD5 key 296 5 MD5 B;fxlKgr/&4ZTbL6=RxA # MD5 key 297 6 MD5 4eYwa`o}3i@@V (a] ..R9!l # MD5 key 298 7 MD5 `A.([h+;wTQ|xfi%Sn_! # MD5 key 299 8 MD5 45:V,r4]l6y^JH6.Sh?F # MD5 key 300 9 MD5 3-5vcn*6l29DS?Xdsg)* # MD5 key 301 10 MD5 2late4Me # MD5 key 302 11 SHA1 a27872d3030a9025b8446c751b4551a7629af65c # SHA1 key 303 12 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74 # SHA1 key 304 13 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9 # SHA1 key 305 14 SHA a5332809c8878dd3a5b918819108a111509aeceb # SHA key 306 15 MD2 2fe16c88c760ff2f16d4267e36c1aa6c926e6964 # MD2 key 307 16 MD4 b2691811dc19cfc0e2f9bcacd74213f29812183d # MD4 key 308 17 MD5 e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c # MD5 key 309 18 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc # MDC2 key 310 19 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2 # RIPEMD160 key 311 20 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878 # AES128CMAC key 312 21 MD5 sampo 10.1.2.3/24 313 </pre></td></tr></table> 314 <p>Figure 1 shows a typical symmetric keys file used by the reference 315 implementation. Each line of the file contains three or four fields, 316 first an integer between 1 and 65535, inclusive, representing the key 317 identifier used in the <tt>server</tt> and <tt>peer</tt> configuration 318 commands. Second is the key type for the message digest algorithm, 319 which in the absence of the OpenSSL library must be <tt>MD5</tt> to 320 designate the MD5 message digest algorithm. If the OpenSSL library is 321 installed, the key type can be any message digest algorithm supported 322 by that library. However, if compatibility with FIPS 140-2 is 323 required, the key type must be either <tt>SHA</tt> or <tt>SHA1</tt>. 324 The key type can be changed using an ASCII text editor.</p> 325 <p>The third field is the key.</p> 326 <p>An MD5 key consists of a printable ASCII string less than or equal to 327 16 characters and terminated by whitespace or a # character. An 328 OpenSSL key consists of a hex-encoded ASCII string of 40 characters, 329 which is truncated as necessary.</p> 330 <p>Note that the keys used by the <tt>ntpq</tt> and <tt>ntpdc</tt> 331 programs are checked against passwords requested by the programs and 332 entered by hand, so it is generally appropriate to specify these keys 333 in human readable ASCII format.</p> 334 <p>The optional fourth field is one or more IPs, with each IP separated 335 with a comma. An IP may end with an optional <tt>/subnetbits</tt> 336 suffix, which limits the acceptance of the key identifier to packets 337 claiming to be from the described IP space.</p> 338 <p>The <tt>ntp-keygen</tt> program generates a MD5 symmetric keys 339 file <tt>ntpkey_MD5key_<i>hostname.filestamp</i></tt>. Since the file 340 contains private shared keys, it should be visible only to root and 341 distributed by secure means to other subnet hosts. The NTP daemon 342 loads the file <tt>ntp.keys</tt>, so <tt>ntp-keygen</tt> installs a 343 soft link from this name to the generated file. Subsequently, similar 344 soft links must be installed by manual or automated means on the other 345 subnet hosts. While this file is not used with the Autokey Version 2 346 protocol, it is needed to authenticate some remote configuration 347 commands used by the <a href="ntpq.html"><tt>ntpq</tt></a> 348 and <a href="ntpdc.html"><tt>ntpdc</tt></a> utilities.</p> 349 <h4 id="bug">Bugs</h4> 350 <p>It can take quite a while to generate some cryptographic values.</p> 351 <hr> 352 <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 353 </body> 354 </html> 355
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