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<title>Cryptography in OpenBSD</title>

<title>Cryptography in OpenBSD</title>

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<br>

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measures, including cryptography, work together."<br>

<br>

-- Bruce Schneier, author of "Applied Cryptography".

<h2><font color=#e00000>Cryptography</font><hr></h2>

<h2><font color="#e00000">Cryptography</font></h2>

<hr>

<strong>Index</strong><br>

<a href=#why>Why do we ship cryptography?</a>.<br>

<a href="#why">Why do we ship cryptography?</a>.<br>

<a href=#ssh>OpenSSH</a>.<br>

<a href="#ssh">OpenSSH</a>.<br>

<a href=#prng>Pseudo Random Number Generators</a> (PRNG): ARC4, ...<br>

<a href="#prng">Pseudo Random Number Generators</a> (PRNG): ARC4, ...<br>

<a href=#hash>Cryptographic Hash Functions</a>: MD5, SHA1, ...<br>

<a href="#hash">Cryptographic Hash Functions</a>: MD5, SHA1, ...<br>

<a href=#trans>Cryptographic Transforms</a>: DES, Blowfish, ...<br>

<a href="#trans">Cryptographic Transforms</a>: DES, Blowfish, ...<br>

<a href=#hardware>Cryptographic Hardware support</a><br>

<a href="#hardware">Cryptographic Hardware support</a><br>

<a href=#people>International Cryptographers wanted</a><br>

<a href="#people">International Cryptographers wanted</a><br>

<a href=#papers>Further Reading</a><br>

<a href="#papers">Further Reading</a><br>

<p>

<hr>

<h3><font color=#e00000>Why do we ship cryptography?</font></h3><p>

<h3><font color="#e00000">Why do we ship cryptography?</font></h3><p>

In three words: <strong>because we can</strong>.<p>

The OpenBSD project is based in Canada.<p>

The <a href=ECL.html>Export Control List of Canada</a>

The <a href="ECL.html">Export Control List of Canada</a>

places no significant restriction on the export of

cryptographic software, and is even more explicit about the free

export of freely-available cryptographic software. Marc Plumb has

done

some research to test the cryptographic laws</a>.

<p>

Hence the OpenBSD project has embedded cryptography into numerous places

in the operating system. We require that the cryptographic software we

use be <a href=policy.html>freely available and with good licenses</a>.

use be <a href="policy.html">freely available and with good licenses</a>.

We do not directly use cryptography with nasty patents.

We also require that such software is from countries with useful export

licenses because we do not wish to break the laws of any country.

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has been extended to make use of Kerberos as well.<p>

OpenBSD was the first operating system to ship with an IPsec stack.

We've been including IPsec since the OpenBSD 2.1 release in 1997.

Our fully conformant in-kernel IPsec stack, with hardware acceleration

based on a number of cards, and our own free ISAKMP daemon, is used as

one of the machines in the IPsec conformance testbed run by

<a href="http://www.vpnc.org">VPNC</a>.

<p>

Today cryptography is an important means for enhancing the <a

href=security.html>security</a> of an operating system. The

href="security.html">security</a> of an operating system. The

cryptography utilized in OpenBSD can be classified into various

aspects, described as follows.<p>

<h3><font color=#e00000>OpenSSH</font></h3><p>

<h3><font color="#e00000">OpenSSH</font></h3><p>

What is the first thing most people do after installing OpenBSD?

They install Secure Shell

(<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssh>ssh</a>)

(<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=ssh&sektion=1">ssh(1)</a>)

from the ports tree or the packages on the FTP sites. Until now, that is.<p>

As of the 2.6 release, OpenBSD contains

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<ul>

<li>

all components of a restrictive nature (i.e., patents, see

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ssl>ssl</a>)

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=ssl&sektion=8">ssl(8)</a>)

had been directly removed from the source code; any licensed or

patented components used external libraries.

</li>

<li>

had been updated to support ssh protocol 1.5.

</li>

<li>

contained added support for

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=kerberos>kerberos</a>

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=kerberos&sektion=1">kerberos(1)</a>

authentication and ticket passing.

</li>

<li>

supported one-time password authentication with

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=skey>skey</a>.

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=skey&sektion=1">skey(1)</a>.

</li>

</ul>

<p>

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About a year later, we extended OpenSSH to also do SSH 2 protocol, the

result being support for all 3 major SSH protocols: 1.3, 1.5, 2.0.

<h3><font color=#e00000>Pseudo Random Number Generators</font></h3><p>

<h3><font color="#e00000">Pseudo Random Number Generators</font></h3><p>

A Pseudo Random Number Generator (PRNG) provides applications with a stream of

numbers which have certain important properties for system security:<p>

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<li>random padding in IPsec esp_old packets.

<li>To generate salts for the various password algorithms.

<li>For generating fake S/Key challenges.

<li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>

<li>In <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd&sektion=8">isakmpd(8)</a>

to provide liveness proof of key exchanges.

</ul>

<p>

<h3><font color=#e00000>Cryptographic Hash Functions</font></h3><p>

<h3><font color="#e00000">Cryptographic Hash Functions</font></h3><p>

A Hash Function compresses its input data to a string of

constant size. For a Cryptographic Hash Function it is infeasible to find:

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In OpenBSD MD5, SHA1, and RIPEMD-160 are used as Cryptographic Hash Functions,

e.g:<p>

<ul>

to provide one time passwords.

<li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>

<li>In <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec&sektion=4">IPsec(4)</a>

and

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd(8)</a>

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd&sektion=8">isakmpd(8)</a>

to authenticate the data origin of packets and to ensure packet integrity.

<li>For FreeBSD-style MD5 passwords (not enabled by default), see

passwd.conf(5)</a>

<li>For TCP SYN cookie support (not enabled by default), see

options(4)</a>

<li>In libssl for digital signing of messages.

</ul>

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<p>

<h3><font color=#e00000>Cryptographic Transforms</font></h3><p>

<h3><font color="#e00000">Cryptographic Transforms</font></h3><p>

Cryptographic Transforms are used to encrypt and decrypt data. These

are normally used with an encryption key for data encryption and with

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kernel and userland programs, which are used in many places like:<p>

<ul>

<li>In libc for creating

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=blf_key">Blowfish</a>

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=blf_key&sektion=3">Blowfish</a>

passwords. See also the <a href="papers/bcrypt-paper.ps">USENIX paper</a>

on this topic.

<li>In

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec>IPsec</a>

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=ipsec&sektion=4">IPsec(4)</a>

to provide confidentiality for the network layer.

<li>In Kerberos and a handful of kerberized applications, like

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=telnet>telnet</a>,

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=telnet&sektion=1">telnet(1)</a>,

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=cvs>cvs</a>,

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=cvs&sektion=1">cvs(1)</a>,

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rsh>rsh</a>,

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=rsh&sektion=1">rsh(1)</a>,

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rcp>rcp</a>,

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=rcp&sektion=1">rcp(1)</a>,

and

<a href=http://www.openbsd.org/cgi-bin/man.cgi?query=rlogin>rlogin</a>.

<a href="http://www.openbsd.org/cgi-bin/man.cgi?query=rlogin&sektion=1&manpath=OpenBSD+3.1">rlogin(1)</a>.

<li>In <a href=http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd>isakmpd</a>

<li>In <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=isakmpd&sektion=8">isakmpd(8)</a>

to protect the exchanges where IPsec key material is negotiated.

<li>In AFS to protect the messages passing over the network, providing

confidentiality of remote filesystem access.

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</ul>

<p>

<h3><font color=#e00000>Cryptographic Hardware Support</font></h3><p>

<h3><font color="#e00000">Cryptographic Hardware Support</font></h3><p>

OpenBSD, starting with 2.7, has begun supporting some cryptography hardware

such as accelerators and random number generators.

<ul>

IPsec crypto dequeue</a></b><br>

Our IPsec stack has been modified so that cryptographic functions get

done out-of-line. Most simple software IPsec stacks need to do

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these two components, as we have done. Actually, doing this gains some

performance even for the software case.

<p>

Hifn 7751</a></b><br>

Cards using the Hifn 7751 can be used as a symmetric cryptographic

accelerator, i.e., the

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crypto unlock algorithm).

<p>

Hifn 6500</a></b><br>

This device is an asymmetric crypto unit. It has support for RSA, DSA,

and DH algorithms, as well as other major big number functions. It also

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both the random number generator and big number unit are working.

<p>

Hifn 7814/7851/7854</a></b><br>

This device is a packet processor and asymmetric crypto unit. It has

support for RSA, DSA, and DH algorithms, as well as other major big number

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packet transforms).

<p>

Broadcom BCM5801/BCM5802/BCM5805/BCM5820/BCM5821/BCM5822

(or beta chip Bluesteelnet 5501/5601)</a></b><br>

Just after the OpenBSD 2.7 release, we succeeded at adding preliminary

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some undocumented interrupt handling requirements).

<p>

Securealink PCC-ISES</a></b><br>

The <a href="http://www.safenet-inc.com/technology/chips/safexcel_ises.asp">PCC-ISES</a> is

The <a href="http://www.securealink.com/pcc-ises.html">PCC-ISES</a> is

a new chipset from the Netherlands. We have received sample hardware

and documentation, and work on a driver is in progress. At the moment,

the driver is capable of feeding random numbers into the kernel entropy

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<li><b>SafeNet SafeXcel 2141</b><br>

We have received documentation and sample hardware for the

<a href="http://www.safenet-inc.com/technology/chips/safexcel_2141.asp">SafeNet</a>

<a href="http://www.safenet-inc.com/technology/chips/Chip2141.asp">SafeNet</a>

crypto cards. Work to support at least the symmetric cryptography of

these devices has started.

<p>

3com 3cr990</a></b><br>

3com gave us a driver to support the ethernet component of this chipset,

and based on that, we have written our own ethernet driver. This driver

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documentation).

<p>

Intel 82802AB/82802AC Firmware Hub RNG</a></b><br>

The 82802 FWH chip (found on i810, i820, i840, i850, and i860 motherboards)

contains a random number generator (RNG). High-performance IPsec

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<p>

<b>If people wish to help with writing drivers,

<p>

<h3><font color=#e00000>International Cryptographers Wanted</font></h3><p>

<h3><font color="#e00000">International Cryptographers Wanted</font></h3><p>

Of course, our project needs people to work on these systems. If any

non-American cryptographer who meets the constraints listed earlier is

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please contact us.<p>

<p>

<h3><font color=#e00000>Further Reading</font></h3><p>

<h3><font color="#e00000">Further Reading</font></h3><p>

A number of papers have been written by OpenBSD team members, about

cryptographic changes they have done in OpenBSD. The postscript

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<ul>

<li>A Future-Adaptable Password Scheme.<br>

<a href=events.html#usenix99>Usenix 1999</a>,

<a href="events.html#usenix99">Usenix 1999</a>,

by <a href=mailto:provos@openbsd.org>Niels Provos</a>,

by <a href="mailto:provos@openbsd.org">Niels Provos</a>,

<a href=mailto:dm@openbsd.org>David Mazieres</a>.<br>

<a href="mailto:dm@openbsd.org">David Mazieres</a>.<br>

<a href=papers/bcrypt-paper.ps>paper</a> and

<a href="papers/bcrypt-paper.ps">paper</a> and

<a href=papers/bcrypt-slides.ps>slides</a>.

<a href="papers/bcrypt-slides.ps">slides</a>.

<p>

<li>Cryptography in OpenBSD: An Overview.<br>

<a href=events.html#usenix99>Usenix 1999</a>,

<a href="events.html#usenix99">Usenix 1999</a>,

by <a href=mailto:deraadt@openbsd.org>Theo de Raadt</a>,

by <a href="mailto:deraadt@openbsd.org">Theo de Raadt</a>,

<a href=mailto:niklas@openbsd.org>Niklas Hallqvist</a>,

<a href="mailto:niklas@openbsd.org">Niklas Hallqvist</a>,

<a href=mailto:art@openbsd.org>Artur Grabowski</a>,

<a href="mailto:art@openbsd.org">Artur Grabowski</a>,

<a href=mailto:angelos@openbsd.org>Angelos D. Keromytis</a>,

<a href="mailto:angelos@openbsd.org">Angelos D. Keromytis</a>,

<a href=mailto:provos@openbsd.org>Niels Provos</a>.<br>

<a href="mailto:provos@openbsd.org">Niels Provos</a>.<br>

<a href=papers/crypt-paper.ps>paper</a> and

<a href="papers/crypt-paper.ps">paper</a> and

<a href=papers/crypt-slides.ps>slides</a>.

<a href="papers/crypt-slides.ps">slides</a>.

<p>

<li>Implementing Internet Key Exchange (IKE).<br>

<a href=events.html#usenix2000>Usenix 2000</a>,

<a href="events.html#usenix2000">Usenix 2000</a>,

by <a href=mailto:niklas@openbsd.org>Niklas Hallqvist</a> and

by <a href="mailto:niklas@openbsd.org">Niklas Hallqvist</a> and

<a href=mailto:angelos@openbsd.org>Angelos D. Keromytis</a>.<br>

<a href="mailto:angelos@openbsd.org">Angelos D. Keromytis</a>.<br>

<a href=papers/ikepaper.ps>paper</a> and

<a href="papers/ikepaper.ps">paper</a> and

<a href=papers/ikeslides.ps>slides</a>.

<a href="papers/ikeslides.ps">slides</a>.

<p>

<li>Encrypting Virtual Memory</a><br>

<li>Encrypting Virtual Memory.<br>

<a href=events.html#sec2000>Usenix Security 2000</a>,

<a href="events.html#sec2000">Usenix Security 2000</a>,

<a href=mailto:provos@openbsd.org>Niels Provos</a>.<br>

<a href="mailto:provos@openbsd.org">Niels Provos</a>.<br>

<a href=papers/swapencrypt.ps>paper</a> and

<a href="papers/swapencrypt.ps">paper</a> and

<a href=papers/swapencrypt-slides.ps>slides</a>.

<a href="papers/swapencrypt-slides.ps">slides</a>.

</ul>

<p>

<hr>

<a href=mailto:www@openbsd.org>www@openbsd.org</a>

<a href="mailto:www@openbsd.org">www@openbsd.org</a>

<br>

<small>$OpenBSD$</small>