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<h3>Table of Contents</h3>
<ul class="link-list" role="directory">
<li><a href="#module-Digest-label-Examples">Examples</a>
<li><a href="#module-Digest-label-Digest+algorithms">Digest algorithms</a>
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<!-- Method Quickref -->
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<h3>Methods</h3>
<ul class="link-list" role="directory">
<li ><a href="#method-c-bubblebabble">::bubblebabble</a>
<li ><a href="#method-c-hexencode">::hexencode</a>
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<h1 id="module-Digest" class="module">
module Digest
</h1>
<section class="description">
<p>This module provides a framework for message digest libraries.</p>
<p>You may want to look at <a href="OpenSSL/Digest.html"><code>OpenSSL::Digest</code></a> as it supports more algorithms.</p>
<p>A cryptographic hash function is a procedure that takes data and returns a fixed bit string: the hash value, also known as <em>digest</em>. <a href="Hash.html"><code>Hash</code></a> functions are also called one-way functions, it is easy to compute a digest from a message, but it is infeasible to generate a message from a digest.</p>
<h2 id="module-Digest-label-Examples">Examples<span><a href="#module-Digest-label-Examples">¶</a> <a href="#top">↑</a></span></h2>
<pre class="ruby"><span class="ruby-identifier">require</span> <span class="ruby-string">'digest'</span>
<span class="ruby-comment"># Compute a complete digest</span>
<span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">digest</span> <span class="ruby-string">'message'</span> <span class="ruby-comment">#=> "\xABS\n\x13\xE4Y..."</span>
<span class="ruby-identifier">sha256</span> = <span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">digest</span> <span class="ruby-string">'message'</span> <span class="ruby-comment">#=> "\xABS\n\x13\xE4Y..."</span>
<span class="ruby-comment"># Other encoding formats</span>
<span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">hexdigest</span> <span class="ruby-string">'message'</span> <span class="ruby-comment">#=> "ab530a13e459..."</span>
<span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">base64digest</span> <span class="ruby-string">'message'</span> <span class="ruby-comment">#=> "q1MKE+RZFJgr..."</span>
<span class="ruby-comment"># Compute digest by chunks</span>
<span class="ruby-identifier">md5</span> = <span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">MD5</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">md5</span>.<span class="ruby-identifier">update</span> <span class="ruby-string">'message1'</span>
<span class="ruby-identifier">md5</span> <span class="ruby-operator"><<</span> <span class="ruby-string">'message2'</span> <span class="ruby-comment"># << is an alias for update</span>
<span class="ruby-identifier">md5</span>.<span class="ruby-identifier">hexdigest</span> <span class="ruby-comment">#=> "94af09c09bb9..."</span>
<span class="ruby-comment"># Compute digest for a file</span>
<span class="ruby-identifier">sha256</span> = <span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">file</span> <span class="ruby-string">'testfile'</span>
<span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">hexdigest</span>
</pre>
<p>Additionally digests can be encoded in “bubble babble” format as a sequence of consonants and vowels which is more recognizable and comparable than a hexadecimal digest.</p>
<pre class="ruby"><span class="ruby-identifier">require</span> <span class="ruby-string">'digest/bubblebabble'</span>
<span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">bubblebabble</span> <span class="ruby-string">'message'</span> <span class="ruby-comment">#=> "xopoh-fedac-fenyh-..."</span>
</pre>
<p>See the bubble babble specification at <a href="http://web.mit.edu/kenta/www/one/bubblebabble/spec/jrtrjwzi/draft-huima-01.txt">web.mit.edu/kenta/www/one/bubblebabble/spec/jrtrjwzi/draft-huima-01.txt</a>.</p>
<h2 id="module-Digest-label-Digest+algorithms"><a href="Digest.html"><code>Digest</code></a> algorithms<span><a href="#module-Digest-label-Digest+algorithms">¶</a> <a href="#top">↑</a></span></h2>
<p>Different digest algorithms (or hash functions) are available:</p>
<dl class="rdoc-list note-list"><dt><a href="Digest/MD5.html"><code>MD5</code></a>
<dd>
<p>See RFC 1321 The <a href="Digest/MD5.html"><code>MD5</code></a> Message-Digest Algorithm</p>
</dd><dt>RIPEMD-160
<dd>
<p>As <a href="Digest/RMD160.html"><code>Digest::RMD160</code></a>. See <a href="http://homes.esat.kuleuven.be/~bosselae/ripemd160.html">homes.esat.kuleuven.be/~bosselae/ripemd160.html</a>.</p>
</dd><dt><a href="Digest/SHA1.html"><code>SHA1</code></a>
<dd>
<p>See FIPS 180 Secure <a href="Hash.html"><code>Hash</code></a> Standard.</p>
</dd><dt>SHA2 family
<dd>
<p>See FIPS 180 Secure <a href="Hash.html"><code>Hash</code></a> Standard which defines the following algorithms:</p>
<ul><li>
<p>SHA512</p>
</li><li>
<p>SHA384</p>
</li><li>
<p>SHA256</p>
</li></ul>
</dd></dl>
<p>The latest versions of the FIPS publications can be found here: <a href="http://csrc.nist.gov/publications/PubsFIPS.html">csrc.nist.gov/publications/PubsFIPS.html</a>.</p>
</section>
<section id="5Buntitled-5D" class="documentation-section">
<section class="constants-list">
<header>
<h3>Constants</h3>
</header>
<dl>
<dt id="REQUIRE_MUTEX">REQUIRE_MUTEX
<dd><p>A mutex for Digest().</p>
</dl>
</section>
<section id="public-class-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Class Methods</h3>
</header>
<div id="method-c-bubblebabble" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
bubblebabble(string) → bubblebabble_string
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns a BubbleBabble encoded version of a given <em>string</em>.</p>
<div class="method-source-code" id="bubblebabble-source">
<pre>static VALUE
rb_digest_s_bubblebabble(VALUE klass, VALUE str)
{
return bubblebabble_str_new(str);
}</pre>
</div>
</div>
</div>
<div id="method-c-hexencode" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
hexencode(string) → hexencoded_string
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Generates a hex-encoded version of a given <em>string</em>.</p>
<div class="method-source-code" id="hexencode-source">
<pre>static VALUE
rb_digest_s_hexencode(VALUE klass, VALUE str)
{
return hexencode_str_new(str);
}</pre>
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