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16: <br>
17: <br>
18: <br>
19: "The mantra of any good security engineer is: "Security is a not a
20: product, but a process." It's more than designing strong cryptography
21: into a system; it's designing the entire system such that all security
22: measures, including cryptography, work together."<br>
23: <br>
24: -- Bruce Schneier, author of "Applied Cryptography".
25: <br clear=all>
1.37 deraadt 26: <h2><font color=#e00000>Cryptography</font><hr></h2>
1.32 deraadt 27:
28: <strong>Index</strong><br>
1.41 louis 29: <a href=#why>Why do we ship cryptography?</a>.<br>
1.47 provos 30: <a href=#ssh>OpenSSH</a>.<br>
1.32 deraadt 31: <a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...<br>
32: <a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...<br>
33: <a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...<br>
1.51 deraadt 34: <a href=#hardware>Cryptographic Hardware support</a><br>
1.32 deraadt 35: <a href=#people>International Cryptographers wanted</a><br>
1.33 deraadt 36: <a href=#papers>Further Reading</a><br>
1.1 deraadt 37: <p>
1.32 deraadt 38: <hr>
39:
40: <a name=why></a>
1.42 deraadt 41: <h3><font color=#e00000>Why do we ship cryptography?</font></h3><p>
1.32 deraadt 42:
43: In three words: <strong>because we can</strong>.<p>
44:
1.1 deraadt 45: The OpenBSD project is based in Canada.<p>
46:
1.23 deraadt 47: The <a href=ECL.html>Export Control List of Canada</a>
48: places no significant restriction on the export of
1.5 deraadt 49: cryptographic software, and is even more explicit about the free
50: export of freely-available cryptographic software. Marc Plumb has
51: done
1.2 deraadt 52: <a href=http://insight.mcmaster.ca/org/efc/pages/doc/crypto-export.html>
1.31 aaron 53: some research to test the cryptographic laws</a>.
1.2 deraadt 54: <p>
1.1 deraadt 55:
1.3 deraadt 56: Hence the OpenBSD project has embedded cryptography into numerous places
57: in the operating system. We require that the cryptographic software we
58: use be <a href=policy.html>freely available and with good licenses</a>.
1.32 deraadt 59: We do not directly use cryptography with nasty patents.
1.13 deraadt 60: We also require that such software is from countries with useful export
1.16 deraadt 61: licenses because we do not wish to break the laws of any country.
62: The cryptographic software components which we use currently were
63: written in Argentina, Australia, Canada, Germany, Greece, Norway, and
64: Sweden.
65: <p>
1.7 deraadt 66:
1.15 deraadt 67: When we create OpenBSD releases or snapshots we build our release
68: binaries in free countries to assure that the sources and binaries we
69: provide to users are free of tainting. In the past our release binary
70: builds have been done in Canada, Sweden, and Germany.<p>
71:
1.16 deraadt 72: OpenBSD ships with Kerberos IV included. The codebase we use is the
1.17 deraadt 73: exportable KTH-based release from Sweden. Our X11 source has been
74: extended to make use of Kerberos IV as well. Kerberos V support will
1.54 deraadt 75: appear sometime in 2000, but at present time a freely exportable
1.16 deraadt 76: Kerberos V release does not exist.<p>
77:
1.15 deraadt 78: Today cryptography is an important means for enhancing the <a
79: href=security.html>security</a> of an operating system. The
1.42 deraadt 80: cryptography utilized in OpenBSD can be classified into various
81: aspects, described as follows.<p>
1.10 deraadt 82:
1.39 louis 83: <a name=ssh></a>
1.47 provos 84: <h3><font color=#e00000>OpenSSH</font></h3><p>
1.39 louis 85:
1.40 deraadt 86: What is the first thing most people do after installing OpenBSD?
1.55 ! deraadt 87: They install Secure Shell
! 88: (<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssh>ssh</a>)
1.46 deraadt 89: from the ports tree or the packages on the FTP sites. Until now, that is.<p>
1.39 louis 90:
1.55 ! deraadt 91: As of the 2.6 release, OpenBSD contains
1.50 provos 92: <a href="http://www.openssh.com/">OpenSSH</a>, an absolutely free and
93: patent unencumbered version of ssh.
1.55 ! deraadt 94: As of the OpenBSD 2.6 release date,
! 95: <a href="http://www.openssh.com/">OpenSSH</a> interoperated with ssh
! 96: version 1 and had many added features,
1.47 provos 97: <ul>
98: <li>
99: all components of a restrictive nature (ie. patents, see
100: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssl>ssl</a>))
1.55 ! deraadt 101: had been directly removed from the source code; any licensed or
! 102: patented components used external libraries.
1.47 provos 103: </li>
104: <li>
1.55 ! deraadt 105: had been updated to support ssh protocol 1.5.
1.47 provos 106: </li>
107: <li>
1.55 ! deraadt 108: contained added support for
1.47 provos 109: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=kerberos>kerberos</a>
110: authentication and ticket passing.
111: </li>
112: <li>
1.55 ! deraadt 113: supported one-time password authentication with
1.47 provos 114: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=skey>skey</a>.
115: </li>
116: </ul>
117: <p>
118:
1.55 ! deraadt 119: Roughly, we took a free license release of ssh and OpenBSD-ifyed it.
! 120: We get around the USA-based RSA patent by providing an easy way to
1.47 provos 121: automatically download and install a RSA-enabled package containing
122: shared library versions of libcrypto and libssl. These packages are
123: based on OpenSSL. People living outside the USA can freely use the
1.40 deraadt 124: RSA patented code, while people inside the USA can freely use it for
1.47 provos 125: non-commercial purposes. It appears as if companies inside the USA
126: can use the RSA libraries too, as long as RSA is not used in a profit
127: generating role.<p>
1.39 louis 128:
1.55 ! deraadt 129: But this way almost everyone will get ssh built into their OS.<p>
! 130:
! 131: <strong>NEW! OpenSSH supports protocol 2.0!</strong><p>
! 132:
! 133: Recently, we have extended OpenSSH so that it also does SSH 2 protocol.
! 134: Having a ssh daemon which can do all 3 major SSH protocols
! 135: (1.3, 1.5, 2.0) permits us much flexibility. Protocol 2.0 does not
! 136: use RSA for it's public key cryptography, relying instead on the DH
! 137: and DSA algorithms. In OpenBSD 2.7 -- which will ship with the new
! 138: OpenSSH -- you get protocol 2.0 support right out of the box! If
! 139: you wish to also support protocol 1.3 and 1.5, you simply add the
! 140: RSA package (as described our
! 141: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssl>ssl</a>
! 142: manual page), and restart the daemon.
1.39 louis 143:
1.18 deraadt 144: <a name=prng></a>
1.42 deraadt 145: <h3><font color=#e00000>Pseudo Random Number Generators</font></h3><p>
1.32 deraadt 146:
1.10 deraadt 147: A Pseudo Random Number Generator (PRNG) provides applications with a stream of
148: numbers which have certain important properties for system security:<p>
149:
150: <ul>
1.11 deraadt 151: <li>It should be impossible for an outsider to predict the output of the
152: random number generator even with knowledge of previous output.
153: <li>The generated numbers should not have repeating patterns which means
154: the PRNG should have a very long cycle length.
1.10 deraadt 155: </ul>
1.32 deraadt 156: <p>
1.10 deraadt 157:
1.13 deraadt 158: A PRNG is normally just an algorithm where the same initial starting
159: values will yield the same sequence of outputs. On a multiuser
160: operating system there are many sources which allow seeding the PRNG
161: with random data. The OpenBSD kernel uses the mouse interrupt timing,
162: network data interrupt latency, inter-keypress timing and disk IO
163: information to fill an entropy pool. Random numbers are available for
164: kernel routines and are exported via devices to userland programs.
1.36 deraadt 165: So far random numbers are used in the following places:<p>
1.13 deraadt 166:
1.10 deraadt 167: <ul>
1.14 deraadt 168: <li>Dynamic sin_port allocation in bind(2).
169: <li>PIDs of processes.
1.26 aaron 170: <li>IP datagram IDs.
1.14 deraadt 171: <li>RPC transaction IDs (XID).
172: <li>NFS RPC transaction IDs (XID).
173: <li>DNS Query-IDs.
174: <li>Inode generation numbers, see getfh(2) and fsirand(8).
1.31 aaron 175: <li>Timing perturbance in traceroute(8).
1.14 deraadt 176: <li>Stronger temporary names for mktemp(3) and mkstemp(3)
177: <li>Randomness added to the TCP ISS value for protection against
178: spoofing attacks.
1.29 deraadt 179: <li>random padding in IPSEC esp_old packets.
1.14 deraadt 180: <li>To generate salts for the various password algorithms.
181: <li>For generating fake S/Key challenges.
1.44 provos 182: <li>In <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>photurisd</a>
1.28 angelos 183: and <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>
184: to provide liveness proof of key exchanges.
1.10 deraadt 185: </ul>
1.1 deraadt 186:
1.10 deraadt 187: <p>
1.18 deraadt 188: <a name=hash></a>
1.42 deraadt 189: <h3><font color=#e00000>Cryptographic Hash Functions</font></h3><p>
1.32 deraadt 190:
1.10 deraadt 191: A Hash Function compresses its input data to a string of
1.36 deraadt 192: constant size. For a Cryptographic Hash Function it is infeasible to find:
193:
1.1 deraadt 194: <ul>
1.11 deraadt 195: <li>two inputs which have the same output (collision resistant),
196: <li>a different input for a given input with the same output
197: (2nd preimage resistant).
1.1 deraadt 198: </ul>
1.32 deraadt 199: <p>
1.10 deraadt 200:
1.12 millert 201: In OpenBSD MD5, SHA1, and RIPEMD-160 are used as Cryptographic Hash Functions,
1.36 deraadt 202: e.g:<p>
1.10 deraadt 203: <ul>
1.27 deraadt 204: <li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=skey>S/Key</a>
205: to provide one time passwords.
206: <li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>,
1.44 provos 207: <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>photurisd</a>
1.27 deraadt 208: and
209: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd(8)</a>
210: to authenticate the data origin of packets and to ensure packet integrity.
211: <li>For FreeBSD-style MD5 passwords (not enabled by default), see
212: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=passwd.conf&sektion=5>
213: passwd.conf(5)</a>
214: <li>For TCP SYN cookie support (not enabled by default), see
215: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=options&sektion=4>
216: options(4)</a>
1.24 niklas 217: <li>In libssl for digital signing of messages.
1.10 deraadt 218: </ul>
1.32 deraadt 219: <p>
1.10 deraadt 220:
1.6 deraadt 221: <p>
1.18 deraadt 222: <a name=trans></a>
1.42 deraadt 223: <h3><font color=#e00000>Cryptographic Transforms</font></h3><p>
1.32 deraadt 224:
1.11 deraadt 225: Cryptographic Transforms are used to encrypt and decrypt data. These
226: are normally used with an encryption key for data encryption and with
227: a decryption key for data decryption. The security of a Cryptographic
228: Transform should rely only on the keying material.<p>
1.6 deraadt 229:
1.24 niklas 230: OpenBSD provides transforms like DES, 3DES, Blowfish and Cast for the
1.36 deraadt 231: kernel and userland programs, which are used in many places like:<p>
1.10 deraadt 232: <ul>
1.27 deraadt 233: <li>In libc for creating
234: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=blf_key>Blowfish</a>
1.33 deraadt 235: passwords. See also the <a href=papers/bcrypt-paper.ps>USENIX paper</a>
236: on this topic.
1.27 deraadt 237: <li>In
238: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>
239: to provide confidentiality for the network layer.
240: <li>In Kerberos and a handful of kerberized applications, like
241: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=telnet>telnet</a>,
242: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=cvs>cvs</a>,
243: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rsh>rsh</a>,
244: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rcp>rcp</a>,
245: and
246: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rlogin>rlogin</a>.
1.44 provos 247: <li>In <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>
1.27 deraadt 248: photurisd</a> and
249: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>
250: to protect the exchanges where IPsec key material is negotiated.
1.24 niklas 251: <li>In AFS to protect the messages passing over the network, providing
1.27 deraadt 252: confidentiality of remote filesystem access.
1.24 niklas 253: <li>In libssl to let applications communicate over the de-facto standard
254: cryptographically secure SSL protocol.
1.10 deraadt 255: </ul>
1.1 deraadt 256:
1.10 deraadt 257: <p>
1.51 deraadt 258: <a name=hardware></a>
259: <h3><font color=#e00000>Cryptographic Hardware Support</font></h3><p>
260:
261: OpenBSD starting with 2.7 supports some limited cryptography hardware.
262: <ul>
263: <li><b>IPSEC crypto dequeue</b><br>
264: Our IPSEC stack has been modified so that cryptographic functions get
265: done out-of-line. Most simple software IPSEC stacks need to do
266: cryptography when processing each packet. This results in syncronous
267: performance. To use hardware properly and speedily one needs to seperate
268: these two components, as we have done. Actually, doing this gains some
269: performance even for the software case.
270: <p>
271: <li><b>HiFn 7751</b><br>
1.53 deraadt 272: Cards using the <a href="http://www.hifn.com/products/7751.htm">HiFn 7751</a>
273: can be used as a cryptographic accelerator (ie.
1.51 deraadt 274: <a href="http://www.powercrypt.com">PowerCrypt</a>).
275: Current performance using a single Hifn 7751 on each end of a tunnel
276: is 63Mbit/sec for 3DES/SHA1 ESP, nearly a 600% improvement over
277: using a P3/550 cpu. Further improvements are under way to resolve a
278: few more issues, but as of April 13, 2000 the code is considered
1.53 deraadt 279: stable. We wrote our own driver for supporting this chip, rather
280: than using the (USA-written)
281: <a href="http://www.powercrypt.com">powercrypt</a> driver, as well
282: our driver links in properly to the IPSEC stack<p>
283: The 7751 is now considered slow by industry standards and many vendors
284: have faster chips (even HiFn now has a faster but more expensive
285: chip). We are moving towards supporting other chips such as:
286: <p>
287: <ul>
288: <li><a href="http://www.ire.com/OEM/OEMTechnologyDefault.htm">IRE 2141</a>
289: <li><a href="http://www.bluesteelnet.com/product.html">Bluesteelnet 5501</a>
290: <li><a href="http://www.pcc.pijnenburg.nl/pcc-ises.htm">Pijnenburg PCC-ISES</a>
291: <li>perhaps the
292: <a href="http://www.3com.com/promotions/3c990promo/index.html">3com 3c990</a>
293: <li>and others
294: </ul>
295: <p>
296: IRE and Bluesteelnet in particular have already been very
1.51 deraadt 297: friendly, and have given us all the information we need to support their
1.53 deraadt 298: hardware. Other vendors are on our list, but we are focusing on the
299: fast+cheap solutions first.
1.52 deraadt 300: Intel (and 3com to a lesser degree) don't yet fully understand how
301: they could benefit from giving us documentation for their cryptography
302: cards, so feel free to contact them independently and encourage them.
303: <p>
304: If people wish to help with writing drivers,
1.51 deraadt 305: <a href=#people>come and help us</a>.
306: <p>
307: <li><b>Intel 82802AB/82802AC Firmware Hub RNG</b><br>
308: The 82802 FWH chip (found on i810, i820, and i840 motherboards) contains
309: a random number generator (RNG). High-performance IPSEC requires more
310: random number entropy. As of April 10, 2000, we support the RNG. We
311: will add support for other RNG's found on crypto chips.
1.52 deraadt 312: <p>
313: <li><b>OpenSSL</b><br>
314: We have grand schemes for supporting crypto cards that can do RSA or DSA,
315: and exporting the functions of all crypto cards to OpenSSL so that
316: userland programs (ie. <a href="http://www.openssh.com">ssh</a>,
317: <a href="http://www.modssl.org/">apache https</a>, etc)
318: can benefit.
1.51 deraadt 319: </ul>
320:
321: <p>
1.32 deraadt 322: <a name=people></a>
1.42 deraadt 323: <h3><font color=#e00000>International Cryptographers Wanted</font></h3><p>
1.32 deraadt 324:
325: Of course, our project needs people to work on these systems. If any
326: non-American cryptographer who meets the constraints listed earlier is
327: interested in helping out with embedded cryptography in OpenBSD,
328: please contact us.<p>
329:
1.33 deraadt 330: <p>
331: <a name=papers></a>
1.42 deraadt 332: <h3><font color=#e00000>Further Reading</font></h3><p>
1.33 deraadt 333:
334: A number of papers have been written by OpenBSD team members, about
335: cryptographic changes they have done in OpenBSD. The postscript
1.34 deraadt 336: versions of these documents are available as follows.<p>
1.33 deraadt 337:
338: <ul>
1.43 deraadt 339: <li>A Future-Adaptable Password Scheme.<br>
1.49 deraadt 340: <a href=events.html#usenix99>Usenix 1999</a>,
1.43 deraadt 341: by <a href=mailto:provos@openbsd.org>Niels Provos<a/>,
342: <a href=mailto:dm@openbsd.org>David Mazieres</a>.<br>
1.33 deraadt 343: <a href=papers/bcrypt-paper.ps>paper</a> and
344: <a href=papers/bcrypt-slides.ps>slides</a>.
1.43 deraadt 345: <p>
346: <li>Cryptography in OpenBSD: An Overview.<br>
1.49 deraadt 347: <a href=events.html#usenix99>Usenix 1999</a>,
1.43 deraadt 348: by <a href=mailto:deraadt@openbsd.org>Theo de Raadt</a>,
349: <a href=mailto:niklas@openbsd.org>Niklas Hallqvist</a>,
350: <a href=mailto:art@openbsd.org>Artur Grabowski</a>,
351: <a href=mailto:angelos@openbsd.org>Angelos D. Keromytis</a>,
352: <a href=mailto:provos@openbsd.org>Niels Provos</a>.<br>
1.33 deraadt 353: <a href=papers/crypt-paper.ps>paper</a> and
354: <a href=papers/crypt-slides.ps>slides</a>.
355: </ul>
356:
1.32 deraadt 357: <p>
1.1 deraadt 358: <hr>
1.19 pauls 359: <a href=/index.html><img height=24 width=24 src=back.gif border=0 alt=OpenBSD></a>
1.10 deraadt 360: <a href=mailto:www@openbsd.org>www@openbsd.org</a>
361: <br>
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1.1 deraadt 363:
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