Annotation of www/crypto.html, Revision 1.16
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1.10 deraadt 4: <title>Cryptography in OpenBSD</title>
1.1 deraadt 5: <link rev=made href=mailto:www@openbsd.org>
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1.10 deraadt 7: <meta name="description" content="OpenBSD cryptography">
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10: <meta name="copyright" content="This document copyright 1997 by OpenBSD.">
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17: <p>
18: <h3><font color=#e00000><strong>OpenBSD Cryptography</strong></font></h3>
19: The OpenBSD project is based in Canada.<p>
20:
1.2 deraadt 21: The <a href=http://axion.physics.ubc.ca/ECL.html>Export Control
1.3 deraadt 22: List of Canada</a> 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
! 47: exportable KTH-based release from Sweden. Kerberos V support will
! 48: perhaps appear in 1999, but at present time a freely exportable
! 49: Kerberos V release does not exist.<p>
! 50:
1.15 deraadt 51: Today cryptography is an important means for enhancing the <a
52: href=security.html>security</a> of an operating system. The
53: cryptography utilized in OpenBSD can be classified into three
54: different aspects:<p>
1.10 deraadt 55:
56: <ul>
1.11 deraadt 57: <li><a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...
58: <li><a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...
59: <li><a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...
1.10 deraadt 60: </ul>
61:
62: <p>
63: <a name=prng>
64: <h3><font color=#e00000><strong>Pseudo Random Number Generators</strong></font></h3>
65: A Pseudo Random Number Generator (PRNG) provides applications with a stream of
66: numbers which have certain important properties for system security:<p>
67:
68: <ul>
1.11 deraadt 69: <li>It should be impossible for an outsider to predict the output of the
70: random number generator even with knowledge of previous output.
71: <li>The generated numbers should not have repeating patterns which means
72: the PRNG should have a very long cycle length.
1.10 deraadt 73: </ul>
74:
1.13 deraadt 75: A PRNG is normally just an algorithm where the same initial starting
76: values will yield the same sequence of outputs. On a multiuser
77: operating system there are many sources which allow seeding the PRNG
78: with random data. The OpenBSD kernel uses the mouse interrupt timing,
79: network data interrupt latency, inter-keypress timing and disk IO
80: information to fill an entropy pool. Random numbers are available for
81: kernel routines and are exported via devices to userland programs.
82: So far random numbers are used in the following places<p>
83:
1.10 deraadt 84: <ul>
1.14 deraadt 85: <li>Dynamic sin_port allocation in bind(2).
86: <li>PIDs of processes.
87: <li>RPC transaction IDs (XID).
88: <li>NFS RPC transaction IDs (XID).
89: <li>DNS Query-IDs.
90: <li>Inode generation numbers, see getfh(2) and fsirand(8).
91: <li>Timing perturbance in traceroute(1).
92: <li>Stronger temporary names for mktemp(3) and mkstemp(3)
93: <li>Randomness added to the TCP ISS value for protection against
94: spoofing attacks.
95: <li>To generate salts for the various password algorithms.
96: <li>For generating fake S/Key challenges.
1.10 deraadt 97: </ul>
1.1 deraadt 98:
1.10 deraadt 99: <p>
100: <a name=hash>
101: <h3><font color=#e00000><strong>Cryptographic Hash Functions</strong></font></h3>
102: A Hash Function compresses its input data to a string of
103: constant size. For a Cryptographic Hash Function it is infeasible to find
1.1 deraadt 104: <ul>
1.11 deraadt 105: <li>two inputs which have the same output (collision resistant),
106: <li>a different input for a given input with the same output
107: (2nd preimage resistant).
1.1 deraadt 108: </ul>
1.10 deraadt 109:
1.12 millert 110: In OpenBSD MD5, SHA1, and RIPEMD-160 are used as Cryptographic Hash Functions,
111: e.g.
1.10 deraadt 112: <ul>
1.14 deraadt 113: <li>In S/Key support to provide one time passwords.
114: <li>In <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>
1.10 deraadt 115: IPSec or Photuris</a> to authenticate the data origin of packets
116: and to ensure packet integrity.
1.14 deraadt 117: <li>For FreeBSD-style MD5 passwords (not enabled by default).
118: <li>For TCP SYN cookie support (not enabled by default).
1.10 deraadt 119: </ul>
120:
1.6 deraadt 121: <p>
1.10 deraadt 122: <a name=trans>
123: <h3><font color=#e00000><strong>Cryptographic Transforms</strong></font></h3>
1.11 deraadt 124: Cryptographic Transforms are used to encrypt and decrypt data. These
125: are normally used with an encryption key for data encryption and with
126: a decryption key for data decryption. The security of a Cryptographic
127: Transform should rely only on the keying material.<p>
1.6 deraadt 128:
1.11 deraadt 129: OpenBSD provides transforms like DES and Blowfish for the kernel and userland
130: programs, which are used in many places like
1.10 deraadt 131: <ul>
1.14 deraadt 132: <li>In libc for creating Blowfish passwords.
133: <li>In <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>IPSec</a>
134: to provide confidentiality for the network layer.
135: <li>In kerberized telnet.
136: <li>In Photuris to protect the exchanged packet content.
1.10 deraadt 137: </ul>
1.1 deraadt 138:
1.10 deraadt 139: <p>
1.1 deraadt 140: <hr>
1.10 deraadt 141: <a href=/index.html><img src=/back.gif border=0 alt=OpenBSD></a>
142: <a href=mailto:www@openbsd.org>www@openbsd.org</a>
143: <br>
1.16 ! deraadt 144: <small>$OpenBSD: crypto.html,v 1.15 1998/02/24 00:30:49 deraadt Exp $</small>
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