File: C:/Ruby27-x64/share/doc/ruby/html/OpenSSL/Digest.html
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<h3>Table of Contents</h3>
<ul class="link-list" role="directory">
<li><a href="#class-OpenSSL::Digest-label-Mapping+between+Digest+class+and+sn-2Fln">Mapping between Digest class and sn/ln</a>
<li><a href="#class-OpenSSL::Digest-label-MD2">MD2</a>
<li><a href="#class-OpenSSL::Digest-label-MD4">MD4</a>
<li><a href="#class-OpenSSL::Digest-label-MD5">MD5</a>
<li><a href="#class-OpenSSL::Digest-label-SHA">SHA</a>
<li><a href="#class-OpenSSL::Digest-label-SHA-1">SHA-1</a>
<li><a href="#class-OpenSSL::Digest-label-SHA-224">SHA-224</a>
<li><a href="#class-OpenSSL::Digest-label-SHA-256">SHA-256</a>
<li><a href="#class-OpenSSL::Digest-label-SHA-384">SHA-384</a>
<li><a href="#class-OpenSSL::Digest-label-SHA-512">SHA-512</a>
<li><a href="#class-OpenSSL::Digest-label-Hashing+a+file">Hashing a file</a>
<li><a href="#class-OpenSSL::Digest-label-Hashing+several+pieces+of+data+at+once">Hashing several pieces of data at once</a>
<li><a href="#class-OpenSSL::Digest-label-Reuse+a+Digest+instance">Reuse a Digest instance</a>
</ul>
</div>
<div id="class-metadata">
<div id="parent-class-section" class="nav-section">
<h3>Parent</h3>
<p class="link">OpenSSL::Digest::Class
</div>
<!-- Method Quickref -->
<div id="method-list-section" class="nav-section">
<h3>Methods</h3>
<ul class="link-list" role="directory">
<li class="calls-super" ><a href="#method-c-digest">::digest</a>
<li ><a href="#method-c-new">::new</a>
<li ><a href="#method-i-3C-3C">#<<</a>
<li ><a href="#method-i-block_length">#block_length</a>
<li ><a href="#method-i-digest_length">#digest_length</a>
<li ><a href="#method-i-finish">#finish</a>
<li ><a href="#method-i-initialize_copy">#initialize_copy</a>
<li ><a href="#method-i-name">#name</a>
<li ><a href="#method-i-reset">#reset</a>
<li ><a href="#method-i-update">#update</a>
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<main role="main" aria-labelledby="class-OpenSSL::Digest">
<h1 id="class-OpenSSL::Digest" class="class">
class OpenSSL::Digest
</h1>
<section class="description">
<p><a href="Digest.html"><code>OpenSSL::Digest</code></a> allows you to compute message digests (sometimes interchangeably called “hashes”) of arbitrary data that are cryptographically secure, i.e. a <a href="Digest.html"><code>Digest</code></a> implements a secure one-way function.</p>
<p>One-way functions offer some useful properties. E.g. given two distinct inputs the probability that both yield the same output is highly unlikely. Combined with the fact that every message digest algorithm has a fixed-length output of just a few bytes, digests are often used to create unique identifiers for arbitrary data. A common example is the creation of a unique id for binary documents that are stored in a database.</p>
<p>Another useful characteristic of one-way functions (and thus the name) is that given a digest there is no indication about the original data that produced it, i.e. the only way to identify the original input is to “brute-force” through every possible combination of inputs.</p>
<p>These characteristics make one-way functions also ideal companions for public key signature algorithms: instead of signing an entire document, first a hash of the document is produced with a considerably faster message digest algorithm and only the few bytes of its output need to be signed using the slower public key algorithm. To validate the integrity of a signed document, it suffices to re-compute the hash and verify that it is equal to that in the signature.</p>
<p>Among the supported message digest algorithms are:</p>
<ul><li>
<p>SHA, SHA1, SHA224, SHA256, SHA384 and SHA512</p>
</li><li>
<p>MD2, MD4, MDC2 and MD5</p>
</li><li>
<p>RIPEMD160</p>
</li><li>
<p>DSS, DSS1 (Pseudo algorithms to be used for DSA signatures. DSS is equal to SHA and DSS1 is equal to SHA1)</p>
</li></ul>
<p>For each of these algorithms, there is a sub-class of <a href="Digest.html"><code>Digest</code></a> that can be instantiated as simply as e.g.</p>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA1</span>.<span class="ruby-identifier">new</span>
</pre>
<h3 id="class-OpenSSL::Digest-label-Mapping+between+Digest+class+and+sn-2Fln">Mapping between <a href="Digest.html"><code>Digest</code></a> class and sn/ln<span><a href="#class-OpenSSL::Digest-label-Mapping+between+Digest+class+and+sn-2Fln">¶</a> <a href="#top">↑</a></span></h3>
<p>The sn (short names) and ln (long names) are defined in <openssl/object.h> and <openssl/obj_mac.h>. They are textual representations of ASN.1 OBJECT IDENTIFIERs. Each supported digest algorithm has an OBJECT IDENTIFIER associated to it and those again have short/long names assigned to them. E.g. the OBJECT IDENTIFIER for SHA-1 is 1.3.14.3.2.26 and its sn is “SHA1” and its ln is “sha1”.</p>
<h4 id="class-OpenSSL::Digest-label-MD2">MD2<span><a href="#class-OpenSSL::Digest-label-MD2">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: MD2</p>
</li><li>
<p>ln: md2</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-MD4">MD4<span><a href="#class-OpenSSL::Digest-label-MD4">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: MD4</p>
</li><li>
<p>ln: md4</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-MD5">MD5<span><a href="#class-OpenSSL::Digest-label-MD5">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: MD5</p>
</li><li>
<p>ln: md5</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA">SHA<span><a href="#class-OpenSSL::Digest-label-SHA">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA</p>
</li><li>
<p>ln: SHA</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA-1">SHA-1<span><a href="#class-OpenSSL::Digest-label-SHA-1">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA1</p>
</li><li>
<p>ln: sha1</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA-224">SHA-224<span><a href="#class-OpenSSL::Digest-label-SHA-224">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA224</p>
</li><li>
<p>ln: sha224</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA-256">SHA-256<span><a href="#class-OpenSSL::Digest-label-SHA-256">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA256</p>
</li><li>
<p>ln: sha256</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA-384">SHA-384<span><a href="#class-OpenSSL::Digest-label-SHA-384">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA384</p>
</li><li>
<p>ln: sha384</p>
</li></ul>
<h4 id="class-OpenSSL::Digest-label-SHA-512">SHA-512<span><a href="#class-OpenSSL::Digest-label-SHA-512">¶</a> <a href="#top">↑</a></span></h4>
<ul><li>
<p>sn: SHA512</p>
</li><li>
<p>ln: sha512</p>
</li></ul>
<p>“Breaking” a message digest algorithm means defying its one-way function characteristics, i.e. producing a collision or finding a way to get to the original data by means that are more efficient than brute-forcing etc. Most of the supported digest algorithms can be considered broken in this sense, even the very popular MD5 and SHA1 algorithms. Should security be your highest concern, then you should probably rely on SHA224, SHA256, SHA384 or SHA512.</p>
<h3 id="class-OpenSSL::Digest-label-Hashing+a+file">Hashing a file<span><a href="#class-OpenSSL::Digest-label-Hashing+a+file">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">data</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'document'</span>)
<span class="ruby-identifier">sha256</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</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">digest</span> = <span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">digest</span>(<span class="ruby-identifier">data</span>)
</pre>
<h3 id="class-OpenSSL::Digest-label-Hashing+several+pieces+of+data+at+once">Hashing several pieces of data at once<span><a href="#class-OpenSSL::Digest-label-Hashing+several+pieces+of+data+at+once">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">data1</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'file1'</span>)
<span class="ruby-identifier">data2</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'file2'</span>)
<span class="ruby-identifier">data3</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'file3'</span>)
<span class="ruby-identifier">sha256</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</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-operator"><<</span> <span class="ruby-identifier">data1</span>
<span class="ruby-identifier">sha256</span> <span class="ruby-operator"><<</span> <span class="ruby-identifier">data2</span>
<span class="ruby-identifier">sha256</span> <span class="ruby-operator"><<</span> <span class="ruby-identifier">data3</span>
<span class="ruby-identifier">digest</span> = <span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">digest</span>
</pre>
<h3 id="class-OpenSSL::Digest-label-Reuse+a+Digest+instance">Reuse a <a href="Digest.html"><code>Digest</code></a> instance<span><a href="#class-OpenSSL::Digest-label-Reuse+a+Digest+instance">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">data1</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'file1'</span>)
<span class="ruby-identifier">sha256</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</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">digest1</span> = <span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">digest</span>(<span class="ruby-identifier">data1</span>)
<span class="ruby-identifier">data2</span> = <span class="ruby-constant">File</span>.<span class="ruby-identifier">read</span>(<span class="ruby-string">'file2'</span>)
<span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">reset</span>
<span class="ruby-identifier">digest2</span> = <span class="ruby-identifier">sha256</span>.<span class="ruby-identifier">digest</span>(<span class="ruby-identifier">data2</span>)
</pre>
</section>
<section id="5Buntitled-5D" class="documentation-section">
<section id="public-class-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Class Methods</h3>
</header>
<div id="method-c-digest" class="method-detail ">
<div class="method-heading">
<span class="method-name">digest</span><span
class="method-args">(name, data)</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Return the hash value computed with <em>name</em> <a href="Digest.html"><code>Digest</code></a>. <em>name</em> is either the long name or short name of a supported digest algorithm.</p>
<h3 id="method-c-digest-label-Examples">Examples<span><a href="#method-c-digest-label-Examples">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span>.<span class="ruby-identifier">digest</span>(<span class="ruby-string">"SHA256"</span>, <span class="ruby-string">"abc"</span>)
</pre>
<p>which is equivalent to:</p>
<pre class="ruby"><span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</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">"abc"</span>)
</pre>
<div class="method-calls-super">
Calls superclass method
</div>
<div class="method-source-code" id="digest-source">
<pre><span class="ruby-comment"># File ext/openssl/lib/openssl/digest.rb, line 34</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword">self</span>.<span class="ruby-identifier ruby-title">digest</span>(<span class="ruby-identifier">name</span>, <span class="ruby-identifier">data</span>)
<span class="ruby-keyword">super</span>(<span class="ruby-identifier">data</span>, <span class="ruby-identifier">name</span>)
<span class="ruby-keyword">end</span></pre>
</div>
</div>
</div>
<div id="method-c-new" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
new(string [, data]) → Digest
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Creates a <a href="Digest.html"><code>Digest</code></a> instance based on <em>string</em>, which is either the ln (long name) or sn (short name) of a supported digest algorithm.</p>
<p>If <em>data</em> (a <a href="../String.html"><code>String</code></a>) is given, it is used as the initial input to the <a href="Digest.html"><code>Digest</code></a> instance, i.e.</p>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span>.<span class="ruby-identifier">new</span>(<span class="ruby-string">'sha256'</span>, <span class="ruby-string">'digestdata'</span>)
</pre>
<p>is equivalent to</p>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span>.<span class="ruby-identifier">new</span>(<span class="ruby-string">'sha256'</span>)
<span class="ruby-identifier">digest</span>.<span class="ruby-identifier">update</span>(<span class="ruby-string">'digestdata'</span>)
</pre>
<div class="method-source-code" id="new-source">
<pre>static VALUE
ossl_digest_initialize(int argc, VALUE *argv, VALUE self)
{
EVP_MD_CTX *ctx;
const EVP_MD *md;
VALUE type, data;
rb_scan_args(argc, argv, "11", &type, &data);
md = ossl_evp_get_digestbyname(type);
if (!NIL_P(data)) StringValue(data);
TypedData_Get_Struct(self, EVP_MD_CTX, &ossl_digest_type, ctx);
if (!ctx) {
RTYPEDDATA_DATA(self) = ctx = EVP_MD_CTX_new();
if (!ctx)
ossl_raise(eDigestError, "EVP_MD_CTX_new");
}
if (!EVP_DigestInit_ex(ctx, md, NULL))
ossl_raise(eDigestError, "Digest initialization failed");
if (!NIL_P(data)) return ossl_digest_update(self, data);
return self;
}</pre>
</div>
</div>
</div>
</section>
<section id="public-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Instance Methods</h3>
</header>
<div id="method-i-3C-3C" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name"><<</span><span
class="method-args">(p1)</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Digest.html#method-i-update">update</a>
</div>
</div>
<div id="method-i-block_length" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
block_length → integer
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the block length of the digest algorithm, i.e. the length in bytes of an individual block. Most modern algorithms partition a message to be digested into a sequence of fix-sized blocks that are processed consecutively.</p>
<h3 id="method-i-block_length-label-Example">Example<span><a href="#method-i-block_length-label-Example">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA1</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">puts</span> <span class="ruby-identifier">digest</span>.<span class="ruby-identifier">block_length</span> <span class="ruby-comment"># => 64</span>
</pre>
<div class="method-source-code" id="block_length-source">
<pre>static VALUE
ossl_digest_block_length(VALUE self)
{
EVP_MD_CTX *ctx;
GetDigest(self, ctx);
return INT2NUM(EVP_MD_CTX_block_size(ctx));
}</pre>
</div>
</div>
</div>
<div id="method-i-digest_length" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
digest_length → integer
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the output size of the digest, i.e. the length in bytes of the final message digest result.</p>
<h3 id="method-i-digest_length-label-Example">Example<span><a href="#method-i-digest_length-label-Example">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA1</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">puts</span> <span class="ruby-identifier">digest</span>.<span class="ruby-identifier">digest_length</span> <span class="ruby-comment"># => 20</span>
</pre>
<div class="method-source-code" id="digest_length-source">
<pre>static VALUE
ossl_digest_size(VALUE self)
{
EVP_MD_CTX *ctx;
GetDigest(self, ctx);
return INT2NUM(EVP_MD_CTX_size(ctx));
}</pre>
</div>
</div>
</div>
<div id="method-i-initialize_copy" class="method-detail ">
<div class="method-heading">
<span class="method-name">initialize_copy</span><span
class="method-args">(p1)</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<div class="method-source-code" id="initialize_copy-source">
<pre>static VALUE
ossl_digest_copy(VALUE self, VALUE other)
{
EVP_MD_CTX *ctx1, *ctx2;
rb_check_frozen(self);
if (self == other) return self;
TypedData_Get_Struct(self, EVP_MD_CTX, &ossl_digest_type, ctx1);
if (!ctx1) {
RTYPEDDATA_DATA(self) = ctx1 = EVP_MD_CTX_new();
if (!ctx1)
ossl_raise(eDigestError, "EVP_MD_CTX_new");
}
GetDigest(other, ctx2);
if (!EVP_MD_CTX_copy(ctx1, ctx2)) {
ossl_raise(eDigestError, NULL);
}
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-name" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
name → string
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the sn of this <a href="Digest.html"><code>Digest</code></a> algorithm.</p>
<h3 id="method-i-name-label-Example">Example<span><a href="#method-i-name-label-Example">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</span><span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA512</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">puts</span> <span class="ruby-identifier">digest</span>.<span class="ruby-identifier">name</span> <span class="ruby-comment"># => SHA512</span>
</pre>
<div class="method-source-code" id="name-source">
<pre>static VALUE
ossl_digest_name(VALUE self)
{
EVP_MD_CTX *ctx;
GetDigest(self, ctx);
return rb_str_new2(EVP_MD_name(EVP_MD_CTX_md(ctx)));
}</pre>
</div>
</div>
</div>
<div id="method-i-reset" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
reset → self
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Resets the <a href="Digest.html"><code>Digest</code></a> in the sense that any <a href="Digest.html#method-i-update"><code>Digest#update</code></a> that has been performed is abandoned and the <a href="Digest.html"><code>Digest</code></a> is set to its initial state again.</p>
<div class="method-source-code" id="reset-source">
<pre>static VALUE
ossl_digest_reset(VALUE self)
{
EVP_MD_CTX *ctx;
GetDigest(self, ctx);
if (EVP_DigestInit_ex(ctx, EVP_MD_CTX_md(ctx), NULL) != 1) {
ossl_raise(eDigestError, "Digest initialization failed.");
}
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-update" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
update(string) → aString
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Not every message digest can be computed in one single pass. If a message digest is to be computed from several subsequent sources, then each may be passed individually to the <a href="Digest.html"><code>Digest</code></a> instance.</p>
<h3 id="method-i-update-label-Example">Example<span><a href="#method-i-update-label-Example">¶</a> <a href="#top">↑</a></span></h3>
<pre class="ruby"><span class="ruby-identifier">digest</span> = <span class="ruby-constant">OpenSSL</span><span class="ruby-operator">::</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">digest</span>.<span class="ruby-identifier">update</span>(<span class="ruby-string">'First input'</span>)
<span class="ruby-identifier">digest</span> <span class="ruby-operator"><<</span> <span class="ruby-string">'Second input'</span> <span class="ruby-comment"># equivalent to digest.update('Second input')</span>
<span class="ruby-identifier">result</span> = <span class="ruby-identifier">digest</span>.<span class="ruby-identifier">digest</span>
</pre>
<div class="method-source-code" id="update-source">
<pre>VALUE
ossl_digest_update(VALUE self, VALUE data)
{
EVP_MD_CTX *ctx;
StringValue(data);
GetDigest(self, ctx);
if (!EVP_DigestUpdate(ctx, RSTRING_PTR(data), RSTRING_LEN(data)))
ossl_raise(eDigestError, "EVP_DigestUpdate");
return self;
}</pre>
</div>
</div>
<div class="aliases">
Also aliased as: <a href="Digest.html#method-i-3C-3C"><<</a>
</div>
</div>
</section>
<section id="private-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Private Instance Methods</h3>
</header>
<div id="method-i-finish" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
finish → aString
</span>
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</div>
<div class="method-description">
<div class="method-source-code" id="finish-source">
<pre>static VALUE
ossl_digest_finish(int argc, VALUE *argv, VALUE self)
{
EVP_MD_CTX *ctx;
VALUE str;
int out_len;
GetDigest(self, ctx);
rb_scan_args(argc, argv, "01", &str);
out_len = EVP_MD_CTX_size(ctx);
if (NIL_P(str)) {
str = rb_str_new(NULL, out_len);
} else {
StringValue(str);
rb_str_resize(str, out_len);
}
if (!EVP_DigestFinal_ex(ctx, (unsigned char *)RSTRING_PTR(str), NULL))
ossl_raise(eDigestError, "EVP_DigestFinal_ex");
return str;
}</pre>
</div>
</div>
</div>
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