Annotation of www/crypto.html, Revision 1.26
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1.10 deraadt 4: <title>Cryptography in OpenBSD</title>
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1.10 deraadt 7: <meta name="description" content="OpenBSD cryptography">
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1.22 deraadt 15: <img alt="[OpenBSD]" height=200 width=200 SRC="images/blowfish.jpg">
1.1 deraadt 16:
17: <p>
18: <h3><font color=#e00000><strong>OpenBSD Cryptography</strong></font></h3>
19: The OpenBSD project is based in Canada.<p>
20:
1.23 deraadt 21: The <a href=ECL.html>Export Control List of Canada</a>
22: places no significant restriction on the export of
1.5 deraadt 23: cryptographic software, and is even more explicit about the free
24: export of freely-available cryptographic software. Marc Plumb has
25: done
1.2 deraadt 26: <a href=http://insight.mcmaster.ca/org/efc/pages/doc/crypto-export.html>
1.5 deraadt 27: some research to test the cryptographic laws.</a>
1.2 deraadt 28: <p>
1.1 deraadt 29:
1.3 deraadt 30: Hence the OpenBSD project has embedded cryptography into numerous places
31: in the operating system. We require that the cryptographic software we
32: use be <a href=policy.html>freely available and with good licenses</a>.
1.4 deraadt 33: We do not use cryptography with nasty patents.
1.13 deraadt 34: We also require that such software is from countries with useful export
1.16 deraadt 35: licenses because we do not wish to break the laws of any country.
36: The cryptographic software components which we use currently were
37: written in Argentina, Australia, Canada, Germany, Greece, Norway, and
38: Sweden.
39: <p>
1.7 deraadt 40:
1.15 deraadt 41: When we create OpenBSD releases or snapshots we build our release
42: binaries in free countries to assure that the sources and binaries we
43: provide to users are free of tainting. In the past our release binary
44: builds have been done in Canada, Sweden, and Germany.<p>
45:
1.16 deraadt 46: OpenBSD ships with Kerberos IV included. The codebase we use is the
1.17 deraadt 47: exportable KTH-based release from Sweden. Our X11 source has been
48: extended to make use of Kerberos IV as well. Kerberos V support will
1.16 deraadt 49: perhaps appear in 1999, but at present time a freely exportable
50: Kerberos V release does not exist.<p>
51:
1.15 deraadt 52: Today cryptography is an important means for enhancing the <a
53: href=security.html>security</a> of an operating system. The
54: cryptography utilized in OpenBSD can be classified into three
55: different aspects:<p>
1.10 deraadt 56:
57: <ul>
1.11 deraadt 58: <li><a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...
59: <li><a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...
60: <li><a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...
1.10 deraadt 61: </ul>
62:
63: <p>
1.18 deraadt 64: <a name=prng></a>
1.10 deraadt 65: <h3><font color=#e00000><strong>Pseudo Random Number Generators</strong></font></h3>
66: A Pseudo Random Number Generator (PRNG) provides applications with a stream of
67: numbers which have certain important properties for system security:<p>
68:
69: <ul>
1.11 deraadt 70: <li>It should be impossible for an outsider to predict the output of the
71: random number generator even with knowledge of previous output.
72: <li>The generated numbers should not have repeating patterns which means
73: the PRNG should have a very long cycle length.
1.10 deraadt 74: </ul>
75:
1.13 deraadt 76: A PRNG is normally just an algorithm where the same initial starting
77: values will yield the same sequence of outputs. On a multiuser
78: operating system there are many sources which allow seeding the PRNG
79: with random data. The OpenBSD kernel uses the mouse interrupt timing,
80: network data interrupt latency, inter-keypress timing and disk IO
81: information to fill an entropy pool. Random numbers are available for
82: kernel routines and are exported via devices to userland programs.
83: So far random numbers are used in the following places<p>
84:
1.10 deraadt 85: <ul>
1.14 deraadt 86: <li>Dynamic sin_port allocation in bind(2).
87: <li>PIDs of processes.
1.26 ! aaron 88: <li>IP datagram IDs.
1.14 deraadt 89: <li>RPC transaction IDs (XID).
90: <li>NFS RPC transaction IDs (XID).
91: <li>DNS Query-IDs.
92: <li>Inode generation numbers, see getfh(2) and fsirand(8).
93: <li>Timing perturbance in traceroute(1).
94: <li>Stronger temporary names for mktemp(3) and mkstemp(3)
95: <li>Randomness added to the TCP ISS value for protection against
96: spoofing attacks.
97: <li>To generate salts for the various password algorithms.
98: <li>For generating fake S/Key challenges.
1.24 niklas 99: <li>In isakmpd to provide liveness proof of key exchanges.
1.10 deraadt 100: </ul>
1.1 deraadt 101:
1.10 deraadt 102: <p>
1.18 deraadt 103: <a name=hash></a>
1.10 deraadt 104: <h3><font color=#e00000><strong>Cryptographic Hash Functions</strong></font></h3>
105: A Hash Function compresses its input data to a string of
106: constant size. For a Cryptographic Hash Function it is infeasible to find
1.1 deraadt 107: <ul>
1.11 deraadt 108: <li>two inputs which have the same output (collision resistant),
109: <li>a different input for a given input with the same output
110: (2nd preimage resistant).
1.1 deraadt 111: </ul>
1.10 deraadt 112:
1.12 millert 113: In OpenBSD MD5, SHA1, and RIPEMD-160 are used as Cryptographic Hash Functions,
114: e.g.
1.10 deraadt 115: <ul>
1.14 deraadt 116: <li>In S/Key support to provide one time passwords.
1.24 niklas 117: <li>In IPsec, <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>
118: photurisd</a> and isakmpd to authenticate the data origin of packets
1.10 deraadt 119: and to ensure packet integrity.
1.14 deraadt 120: <li>For FreeBSD-style MD5 passwords (not enabled by default).
121: <li>For TCP SYN cookie support (not enabled by default).
1.24 niklas 122: <li>In libssl for digital signing of messages.
1.10 deraadt 123: </ul>
124:
1.6 deraadt 125: <p>
1.18 deraadt 126: <a name=trans></a>
1.10 deraadt 127: <h3><font color=#e00000><strong>Cryptographic Transforms</strong></font></h3>
1.11 deraadt 128: Cryptographic Transforms are used to encrypt and decrypt data. These
129: are normally used with an encryption key for data encryption and with
130: a decryption key for data decryption. The security of a Cryptographic
131: Transform should rely only on the keying material.<p>
1.6 deraadt 132:
1.24 niklas 133: OpenBSD provides transforms like DES, 3DES, Blowfish and Cast for the
134: kernel and userland programs, which are used in many places like
1.10 deraadt 135: <ul>
1.14 deraadt 136: <li>In libc for creating Blowfish passwords.
1.24 niklas 137: <li>In IPsec to provide confidentiality for the network layer.
1.25 niklas 138: <li>In Kerberos and a handful of kerberized applications, like telnet, cvs
139: rsh, rcp & rlogin.
1.24 niklas 140: <li>In <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>
141: photurisd</a> and isakmpd to protect the exchanges where IPsec key
142: material is negotiated.
143: <li>In AFS to protect the messages passing over the network, providing
144: confidentiality of remote filesystem access.
145: <li>In libssl to let applications communicate over the de-facto standard
146: cryptographically secure SSL protocol.
1.10 deraadt 147: </ul>
1.1 deraadt 148:
1.10 deraadt 149: <p>
1.1 deraadt 150: <hr>
1.19 pauls 151: <a href=/index.html><img height=24 width=24 src=back.gif border=0 alt=OpenBSD></a>
1.10 deraadt 152: <a href=mailto:www@openbsd.org>www@openbsd.org</a>
153: <br>
1.26 ! aaron 154: <small>$OpenBSD: crypto.html,v 1.25 1998/12/01 08:22:06 niklas Exp $</small>
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