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15: <br>
16: <br>
17: <br>
18: "The mantra of any good security engineer is: "Security is a not a
19: product, but a process." It's more than designing strong cryptography
20: into a system; it's designing the entire system such that all security
21: measures, including cryptography, work together."<br>
22: <br>
23: -- Bruce Schneier, author of "Applied Cryptography".
24: <br clear=all>
1.37 deraadt 25: <h2><font color=#e00000>Cryptography</font><hr></h2>
1.32 deraadt 26:
27: <strong>Index</strong><br>
1.41 louis 28: <a href=#why>Why do we ship cryptography?</a>.<br>
1.40 deraadt 29: <a href=#ssh>SSH soon built in</a>.<br>
1.32 deraadt 30: <a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...<br>
31: <a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...<br>
32: <a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...<br>
33:
34: <a href=#people>International Cryptographers wanted</a><br>
1.33 deraadt 35: <a href=#papers>Further Reading</a><br>
1.1 deraadt 36: <p>
1.32 deraadt 37: <hr>
38:
39: <a name=why></a>
1.42 deraadt 40: <h3><font color=#e00000>Why do we ship cryptography?</font></h3><p>
1.32 deraadt 41:
42: In three words: <strong>because we can</strong>.<p>
43:
1.1 deraadt 44: The OpenBSD project is based in Canada.<p>
45:
1.23 deraadt 46: The <a href=ECL.html>Export Control List of Canada</a>
47: places no significant restriction on the export of
1.5 deraadt 48: cryptographic software, and is even more explicit about the free
49: export of freely-available cryptographic software. Marc Plumb has
50: done
1.2 deraadt 51: <a href=http://insight.mcmaster.ca/org/efc/pages/doc/crypto-export.html>
1.31 aaron 52: some research to test the cryptographic laws</a>.
1.2 deraadt 53: <p>
1.1 deraadt 54:
1.3 deraadt 55: Hence the OpenBSD project has embedded cryptography into numerous places
56: in the operating system. We require that the cryptographic software we
57: use be <a href=policy.html>freely available and with good licenses</a>.
1.32 deraadt 58: We do not directly use cryptography with nasty patents.
1.13 deraadt 59: We also require that such software is from countries with useful export
1.16 deraadt 60: licenses because we do not wish to break the laws of any country.
61: The cryptographic software components which we use currently were
62: written in Argentina, Australia, Canada, Germany, Greece, Norway, and
63: Sweden.
64: <p>
1.7 deraadt 65:
1.15 deraadt 66: When we create OpenBSD releases or snapshots we build our release
67: binaries in free countries to assure that the sources and binaries we
68: provide to users are free of tainting. In the past our release binary
69: builds have been done in Canada, Sweden, and Germany.<p>
70:
1.16 deraadt 71: OpenBSD ships with Kerberos IV included. The codebase we use is the
1.17 deraadt 72: exportable KTH-based release from Sweden. Our X11 source has been
73: extended to make use of Kerberos IV as well. Kerberos V support will
1.16 deraadt 74: perhaps appear in 1999, but at present time a freely exportable
75: Kerberos V release does not exist.<p>
76:
1.15 deraadt 77: Today cryptography is an important means for enhancing the <a
78: href=security.html>security</a> of an operating system. The
1.42 deraadt 79: cryptography utilized in OpenBSD can be classified into various
80: aspects, described as follows.<p>
1.10 deraadt 81:
1.39 louis 82: <a name=ssh></a>
1.42 deraadt 83: <h3><font color=#e00000>SSH soon built in</font></h3><p>
1.39 louis 84:
1.40 deraadt 85: What is the first thing most people do after installing OpenBSD?
1.46 ! deraadt 86: They install Secure Shell (
! 87: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssh>ssh</a>)
! 88: from the ports tree or the packages on the FTP sites. Until now, that is.<p>
1.39 louis 89:
90: This is still very much a work in progress, but we found an innovative way
1.40 deraadt 91: around the RSA patent. We are taking a free license release of ssh and
92: OpenBSD-ifying it. We will get around the USA-based RSA patent by providing
93: an easy way to automatically download and install a RSA-enabled package
1.41 louis 94: containing shared library versions of libcrypto and libssl. These packages
1.40 deraadt 95: are based on OpenSSL. People living outside the USA can freely use the
96: RSA patented code, while people inside the USA can freely use it for
97: non-commercial purposes. It appears as if companies inside the USA can
98: use the RSA libraries too, as long as RSA is not used in a profit generating
99: role.<p>
1.39 louis 100:
1.40 deraadt 101: But this way almost everyone will get ssh built-in.<p>
1.39 louis 102:
1.18 deraadt 103: <a name=prng></a>
1.42 deraadt 104: <h3><font color=#e00000>Pseudo Random Number Generators</font></h3><p>
1.32 deraadt 105:
1.10 deraadt 106: A Pseudo Random Number Generator (PRNG) provides applications with a stream of
107: numbers which have certain important properties for system security:<p>
108:
109: <ul>
1.11 deraadt 110: <li>It should be impossible for an outsider to predict the output of the
111: random number generator even with knowledge of previous output.
112: <li>The generated numbers should not have repeating patterns which means
113: the PRNG should have a very long cycle length.
1.10 deraadt 114: </ul>
1.32 deraadt 115: <p>
1.10 deraadt 116:
1.13 deraadt 117: A PRNG is normally just an algorithm where the same initial starting
118: values will yield the same sequence of outputs. On a multiuser
119: operating system there are many sources which allow seeding the PRNG
120: with random data. The OpenBSD kernel uses the mouse interrupt timing,
121: network data interrupt latency, inter-keypress timing and disk IO
122: information to fill an entropy pool. Random numbers are available for
123: kernel routines and are exported via devices to userland programs.
1.36 deraadt 124: So far random numbers are used in the following places:<p>
1.13 deraadt 125:
1.10 deraadt 126: <ul>
1.14 deraadt 127: <li>Dynamic sin_port allocation in bind(2).
128: <li>PIDs of processes.
1.26 aaron 129: <li>IP datagram IDs.
1.14 deraadt 130: <li>RPC transaction IDs (XID).
131: <li>NFS RPC transaction IDs (XID).
132: <li>DNS Query-IDs.
133: <li>Inode generation numbers, see getfh(2) and fsirand(8).
1.31 aaron 134: <li>Timing perturbance in traceroute(8).
1.14 deraadt 135: <li>Stronger temporary names for mktemp(3) and mkstemp(3)
136: <li>Randomness added to the TCP ISS value for protection against
137: spoofing attacks.
1.29 deraadt 138: <li>random padding in IPSEC esp_old packets.
1.14 deraadt 139: <li>To generate salts for the various password algorithms.
140: <li>For generating fake S/Key challenges.
1.44 provos 141: <li>In <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>photurisd</a>
1.28 angelos 142: and <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>
143: to provide liveness proof of key exchanges.
1.10 deraadt 144: </ul>
1.1 deraadt 145:
1.10 deraadt 146: <p>
1.18 deraadt 147: <a name=hash></a>
1.42 deraadt 148: <h3><font color=#e00000>Cryptographic Hash Functions</font></h3><p>
1.32 deraadt 149:
1.10 deraadt 150: A Hash Function compresses its input data to a string of
1.36 deraadt 151: constant size. For a Cryptographic Hash Function it is infeasible to find:
152:
1.1 deraadt 153: <ul>
1.11 deraadt 154: <li>two inputs which have the same output (collision resistant),
155: <li>a different input for a given input with the same output
156: (2nd preimage resistant).
1.1 deraadt 157: </ul>
1.32 deraadt 158: <p>
1.10 deraadt 159:
1.12 millert 160: In OpenBSD MD5, SHA1, and RIPEMD-160 are used as Cryptographic Hash Functions,
1.36 deraadt 161: e.g:<p>
1.10 deraadt 162: <ul>
1.27 deraadt 163: <li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=skey>S/Key</a>
164: to provide one time passwords.
165: <li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>,
1.44 provos 166: <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>photurisd</a>
1.27 deraadt 167: and
168: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd(8)</a>
169: to authenticate the data origin of packets and to ensure packet integrity.
170: <li>For FreeBSD-style MD5 passwords (not enabled by default), see
171: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=passwd.conf&sektion=5>
172: passwd.conf(5)</a>
173: <li>For TCP SYN cookie support (not enabled by default), see
174: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=options&sektion=4>
175: options(4)</a>
1.24 niklas 176: <li>In libssl for digital signing of messages.
1.10 deraadt 177: </ul>
1.32 deraadt 178: <p>
1.10 deraadt 179:
1.6 deraadt 180: <p>
1.18 deraadt 181: <a name=trans></a>
1.42 deraadt 182: <h3><font color=#e00000>Cryptographic Transforms</font></h3><p>
1.32 deraadt 183:
1.11 deraadt 184: Cryptographic Transforms are used to encrypt and decrypt data. These
185: are normally used with an encryption key for data encryption and with
186: a decryption key for data decryption. The security of a Cryptographic
187: Transform should rely only on the keying material.<p>
1.6 deraadt 188:
1.24 niklas 189: OpenBSD provides transforms like DES, 3DES, Blowfish and Cast for the
1.36 deraadt 190: kernel and userland programs, which are used in many places like:<p>
1.10 deraadt 191: <ul>
1.27 deraadt 192: <li>In libc for creating
193: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=blf_key>Blowfish</a>
1.33 deraadt 194: passwords. See also the <a href=papers/bcrypt-paper.ps>USENIX paper</a>
195: on this topic.
1.27 deraadt 196: <li>In
197: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>
198: to provide confidentiality for the network layer.
199: <li>In Kerberos and a handful of kerberized applications, like
200: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=telnet>telnet</a>,
201: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=cvs>cvs</a>,
202: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rsh>rsh</a>,
203: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rcp>rcp</a>,
204: and
205: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rlogin>rlogin</a>.
1.44 provos 206: <li>In <a href=http://www.physnet.uni-hamburg.de/provos/photuris/>
1.27 deraadt 207: photurisd</a> and
208: <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>
209: to protect the exchanges where IPsec key material is negotiated.
1.24 niklas 210: <li>In AFS to protect the messages passing over the network, providing
1.27 deraadt 211: confidentiality of remote filesystem access.
1.24 niklas 212: <li>In libssl to let applications communicate over the de-facto standard
213: cryptographically secure SSL protocol.
1.10 deraadt 214: </ul>
1.1 deraadt 215:
1.10 deraadt 216: <p>
1.32 deraadt 217: <a name=people></a>
1.42 deraadt 218: <h3><font color=#e00000>International Cryptographers Wanted</font></h3><p>
1.32 deraadt 219:
220: Of course, our project needs people to work on these systems. If any
221: non-American cryptographer who meets the constraints listed earlier is
222: interested in helping out with embedded cryptography in OpenBSD,
223: please contact us.<p>
224:
1.33 deraadt 225: <p>
226: <a name=papers></a>
1.42 deraadt 227: <h3><font color=#e00000>Further Reading</font></h3><p>
1.33 deraadt 228:
229: A number of papers have been written by OpenBSD team members, about
230: cryptographic changes they have done in OpenBSD. The postscript
1.34 deraadt 231: versions of these documents are available as follows.<p>
1.33 deraadt 232:
233: <ul>
1.43 deraadt 234: <li>A Future-Adaptable Password Scheme.<br>
235: by <a href=mailto:provos@openbsd.org>Niels Provos<a/>,
236: <a href=mailto:dm@openbsd.org>David Mazieres</a>.<br>
1.33 deraadt 237: <a href=papers/bcrypt-paper.ps>paper</a> and
238: <a href=papers/bcrypt-slides.ps>slides</a>.
1.43 deraadt 239: <p>
240: <li>Cryptography in OpenBSD: An Overview.<br>
241: by <a href=mailto:deraadt@openbsd.org>Theo de Raadt</a>,
242: <a href=mailto:niklas@openbsd.org>Niklas Hallqvist</a>,
243: <a href=mailto:art@openbsd.org>Artur Grabowski</a>,
244: <a href=mailto:angelos@openbsd.org>Angelos D. Keromytis</a>,
245: <a href=mailto:provos@openbsd.org>Niels Provos</a>.<br>
1.33 deraadt 246: <a href=papers/crypt-paper.ps>paper</a> and
247: <a href=papers/crypt-slides.ps>slides</a>.
248: </ul>
249:
1.32 deraadt 250: <p>
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