1ae771770SStanislav Sedov<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2ae771770SStanislav Sedov<html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"> 3ae771770SStanislav Sedov<title>Heimdal crypto library: DES - Data Encryption Standard crypto interface</title> 4ae771770SStanislav Sedov<link href="doxygen.css" rel="stylesheet" type="text/css"> 5ae771770SStanislav Sedov<link href="tabs.css" rel="stylesheet" type="text/css"> 6ae771770SStanislav Sedov</head><body> 7ae771770SStanislav Sedov<p> 8ae771770SStanislav Sedov<a href="http://www.h5l.org/"><img src="http://www.h5l.org/keyhole-heimdal.png" alt="keyhole logo"/></a> 9ae771770SStanislav Sedov</p> 10ae771770SStanislav Sedov<!-- end of header marker --> 11ae771770SStanislav Sedov<!-- Generated by Doxygen 1.5.6 --> 12ae771770SStanislav Sedov<div class="navigation" id="top"> 13ae771770SStanislav Sedov <div class="tabs"> 14ae771770SStanislav Sedov <ul> 15ae771770SStanislav Sedov <li><a href="index.html"><span>Main Page</span></a></li> 16ae771770SStanislav Sedov <li><a href="modules.html"><span>Modules</span></a></li> 17ae771770SStanislav Sedov <li><a href="examples.html"><span>Examples</span></a></li> 18ae771770SStanislav Sedov </ul> 19ae771770SStanislav Sedov </div> 20ae771770SStanislav Sedov <div class="navpath"><a class="el" href="index.html">Heimdal crypto library</a> 21ae771770SStanislav Sedov </div> 22ae771770SStanislav Sedov</div> 23ae771770SStanislav Sedov<div class="contents"> 24ae771770SStanislav Sedov<h1><a class="anchor" name="page_des">DES - Data Encryption Standard crypto interface </a></h1>See the library functions here: <a class="el" href="group__hcrypto__des.html">DES crypto functions</a><p> 25ae771770SStanislav SedovDES was created by IBM, modififed by NSA and then adopted by NBS (now NIST) and published ad FIPS PUB 46 (updated by FIPS 46-1).<p> 26ae771770SStanislav SedovSince the 19th May 2005 DES was withdrawn by NIST and should no longer be used. See <a class="el" href="page_evp.html">EVP - generic crypto interface</a> for replacement encryption algorithms and interfaces.<p> 27ae771770SStanislav SedovRead more the iteresting history of DES on Wikipedia <a href="http://www.wikipedia.org/wiki/Data_Encryption_Standard">http://www.wikipedia.org/wiki/Data_Encryption_Standard</a> .<h2><a class="anchor" name="des_keygen"> 28ae771770SStanislav SedovDES key generation</a></h2> 29ae771770SStanislav SedovTo generate a DES key safely you have to use the code-snippet below. This is because the <a class="el" href="group__hcrypto__des.html#gd70d485549f7444589f3283e938c0258">DES_random_key()</a> can fail with an abort() in case of and failure to start the random generator.<p> 30ae771770SStanislav SedovThere is a replacement function <a class="el" href="group__hcrypto__des.html#gcd3642bcd8a7e93ea977786e5b540d5f">DES_new_random_key()</a>, however that function does not exists in OpenSSL.<p> 31ae771770SStanislav Sedov<div class="fragment"><pre class="fragment"> DES_cblock key; 32ae771770SStanislav Sedov <span class="keywordflow">do</span> { 33ae771770SStanislav Sedov <span class="keywordflow">if</span> (RAND_rand(&key, <span class="keyword">sizeof</span>(key)) != 1) 34ae771770SStanislav Sedov <span class="keywordflow">goto</span> failure; 35ae771770SStanislav Sedov <a class="code" href="group__hcrypto__des.html#g4179bef43ceb72cc2034f39e7d2d5ae4">DES_set_odd_parity</a>(key); 36ae771770SStanislav Sedov } <span class="keywordflow">while</span> (<a class="code" href="group__hcrypto__des.html#g0d8a49cafee4be6cd3922bfb6323fd2d">DES_is_weak_key</a>(&key)); 37ae771770SStanislav Sedov</pre></div><h2><a class="anchor" name="des_impl"> 38ae771770SStanislav SedovDES implementation history</a></h2> 39ae771770SStanislav SedovThere was no complete BSD licensed, fast, GPL compatible implementation of DES, so Love wrote the part that was missing, fast key schedule setup and adapted the interface to the orignal libdes.<p> 40ae771770SStanislav SedovThe document that got me started for real was "Efficient Implementation of the Data Encryption Standard" by Dag Arne Osvik. I never got to the PC1 transformation was working, instead I used table-lookup was used for all key schedule setup. The document was very useful since it de-mystified other implementations for me.<p> 41ae771770SStanislav SedovThe core DES function (SBOX + P transformation) is from Richard Outerbridge public domain DES implementation. My sanity is saved thanks to his work. Thank you Richard. </div> 42ae771770SStanislav Sedov<hr size="1"><address style="text-align: right;"><small> 43*cf771f22SStanislav SedovGenerated on Wed Jan 11 14:07:38 2012 for Heimdal crypto library by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.6</small></address> 44ae771770SStanislav Sedov</body> 45ae771770SStanislav Sedov</html> 46
