Annotation of www/crypto.html, Revision 1.11
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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.
1.3 deraadt 34: We also require that such software is from a countries with useful export
1.7 deraadt 35: licenses because we do not wish to break the laws of any country.<p>
36:
1.10 deraadt 37: When we make OpenBSD releases or snapshots we do our build processes
38: in free countries to assure that the sources and binaries we provide
39: to users are free of tainting. In the past our release binary builds
40: have been done in Canada, Sweden, and Germany.<p>
41:
42: Today cryptography is an important mean for enhancing the security
43: of an operating system. The cryptography utilized in OpenBSD
44: can be classified into three different aspects:<p>
45:
46: <ul>
1.11 ! deraadt 47: <li><a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...
! 48: <li><a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...
! 49: <li><a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...
1.10 deraadt 50: </ul>
51:
52: <p>
53: <a name=prng>
54: <h3><font color=#e00000><strong>Pseudo Random Number Generators</strong></font></h3>
55: A Pseudo Random Number Generator (PRNG) provides applications with a stream of
56: numbers which have certain important properties for system security:<p>
57:
58: <ul>
1.11 ! deraadt 59: <li>It should be impossible for an outsider to predict the output of the
! 60: random number generator even with knowledge of previous output.
! 61: <li>The generated numbers should not have repeating patterns which means
! 62: the PRNG should have a very long cycle length.
1.10 deraadt 63: </ul>
64:
65: Since a PRNG is normally just an algorithm where the same initial
66: starting values will yield the same output. On a multiuser operating
67: system there are many sources which allow seeding the PRNG with random
68: data. The OpenBSD kernel uses the mouse interrupt timing, network data
69: interrupt latency, inter-keypress timing and disk IO information to
70: fill an entropy pool. Random numbers are available for kernel
71: routines and are exported via devices to userland programs.
72: In OpenBSD random numbers are used in many places, such as<p>
73: <ul>
1.11 ! deraadt 74: <li>ports of a bound socket,
! 75: <li>PIDs of processes,
! 76: <li>RPC transaction IDs,
! 77: <li>DNS Query-IDs,
! 78: <li>inode generation numbers and
! 79: <li>password salts.
1.10 deraadt 80: </ul>
1.1 deraadt 81:
1.10 deraadt 82: <p>
83: <a name=hash>
84: <h3><font color=#e00000><strong>Cryptographic Hash Functions</strong></font></h3>
85: A Hash Function compresses its input data to a string of
86: constant size. For a Cryptographic Hash Function it is infeasible to find
1.1 deraadt 87: <ul>
1.11 ! deraadt 88: <li>two inputs which have the same output (collision resistant),
! 89: <li>a different input for a given input with the same output
! 90: (2nd preimage resistant).
1.1 deraadt 91: </ul>
1.10 deraadt 92:
93: In OpenBSD MD5 and SHA1 are used as Cryptographic Hash Functions, e.g.
94: <ul>
1.11 ! deraadt 95: <li>in S/Key to provide one time passwords,
! 96: <li>in <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>
1.10 deraadt 97: IPSec or Photuris</a> to authenticate the data origin of packets
98: and to ensure packet integrity.
99: </ul>
100:
1.6 deraadt 101: <p>
1.10 deraadt 102: <a name=trans>
103: <h3><font color=#e00000><strong>Cryptographic Transforms</strong></font></h3>
1.11 ! deraadt 104: Cryptographic Transforms are used to encrypt and decrypt data. These
! 105: are normally used with an encryption key for data encryption and with
! 106: a decryption key for data decryption. The security of a Cryptographic
! 107: Transform should rely only on the keying material.<p>
1.6 deraadt 108:
1.11 ! deraadt 109: OpenBSD provides transforms like DES and Blowfish for the kernel and userland
! 110: programs, which are used in many places like
1.10 deraadt 111: <ul>
1.11 ! deraadt 112: <li>in libc for creating Blowfish passwords,
! 113: <li>in <a href=http://wserver.physnet.uni-hamburg.de/provos/photuris/>IPSec</a>
1.10 deraadt 114: to provide confidentiality for the network layer,
1.11 ! deraadt 115: <li>in kerberized telnet,
! 116: <li>in Photuris to protect the exchanged packet content.
1.10 deraadt 117: </ul>
1.1 deraadt 118:
1.10 deraadt 119: <p>
1.1 deraadt 120: <hr>
1.10 deraadt 121: <a href=/index.html><img src=/back.gif border=0 alt=OpenBSD></a>
122: <a href=mailto:www@openbsd.org>www@openbsd.org</a>
123: <br>
1.11 ! deraadt 124: <small>$OpenBSD: crypto.html,v 1.10 1998/02/23 18:36:03 deraadt Exp $</small>
1.1 deraadt 125:
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127: </html>
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