108 lines
4.2 KiB
HTML
108 lines
4.2 KiB
HTML
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<?xml version="1.0" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>CMS_compress</title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<link rev="made" href="mailto:root@localhost" />
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</head>
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<body style="background-color: white">
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<!-- INDEX BEGIN -->
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<div name="index">
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<p><a name="__index__"></a></p>
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<ul>
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<li><a href="#name">NAME</a></li>
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<li><a href="#synopsis">SYNOPSIS</a></li>
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<li><a href="#description">DESCRIPTION</a></li>
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<li><a href="#return_values">RETURN VALUES</a></li>
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<li><a href="#see_also">SEE ALSO</a></li>
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<li><a href="#history">HISTORY</a></li>
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<li><a href="#copyright">COPYRIGHT</a></li>
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</ul>
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<hr name="index" />
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</div>
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<!-- INDEX END -->
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<p>
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</p>
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<hr />
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<h1><a name="name">NAME</a></h1>
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<p>CMS_compress - create a CMS CompressedData structure</p>
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<p>
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</p>
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<hr />
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<h1><a name="synopsis">SYNOPSIS</a></h1>
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<pre>
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#include <openssl/cms.h></pre>
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<pre>
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CMS_ContentInfo *CMS_compress(BIO *in, int comp_nid, unsigned int flags);</pre>
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<p>
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</p>
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<hr />
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<h1><a name="description">DESCRIPTION</a></h1>
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<p><code>CMS_compress()</code> creates and returns a CMS CompressedData structure. <strong>comp_nid</strong>
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is the compression algorithm to use or <strong>NID_undef</strong> to use the default
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algorithm (zlib compression). <strong>in</strong> is the content to be compressed.
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<strong>flags</strong> is an optional set of flags.</p>
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<p>The only currently supported compression algorithm is zlib using the NID
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NID_zlib_compression.</p>
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<p>If zlib support is not compiled into OpenSSL then <code>CMS_compress()</code> will return
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an error.</p>
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<p>If the <strong>CMS_TEXT</strong> flag is set MIME headers for type <strong>text/plain</strong> are
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prepended to the data.</p>
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<p>Normally the supplied content is translated into MIME canonical format (as
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required by the S/MIME specifications) if <strong>CMS_BINARY</strong> is set no translation
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occurs. This option should be used if the supplied data is in binary format
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otherwise the translation will corrupt it. If <strong>CMS_BINARY</strong> is set then
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<strong>CMS_TEXT</strong> is ignored.</p>
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<p>If the <strong>CMS_STREAM</strong> flag is set a partial <strong>CMS_ContentInfo</strong> structure is
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returned suitable for streaming I/O: no data is read from the BIO <strong>in</strong>.</p>
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<p>The compressed data is included in the CMS_ContentInfo structure, unless
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<strong>CMS_DETACHED</strong> is set in which case it is omitted. This is rarely used in
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practice and is not supported by <code>SMIME_write_CMS()</code>.</p>
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<p>If the flag <strong>CMS_STREAM</strong> is set the returned <strong>CMS_ContentInfo</strong> structure is
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<strong>not</strong> complete and outputting its contents via a function that does not
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properly finalize the <strong>CMS_ContentInfo</strong> structure will give unpredictable
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results.</p>
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<p>Several functions including <code>SMIME_write_CMS()</code>, i2d_CMS_bio_stream(),
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<code>PEM_write_bio_CMS_stream()</code> finalize the structure. Alternatively finalization
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can be performed by obtaining the streaming ASN1 <strong>BIO</strong> directly using
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<code>BIO_new_CMS()</code>.</p>
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<p>Additional compression parameters such as the zlib compression level cannot
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currently be set.</p>
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<p>
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</p>
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<hr />
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<h1><a name="return_values">RETURN VALUES</a></h1>
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<p><code>CMS_compress()</code> returns either a CMS_ContentInfo structure or NULL if an error
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occurred. The error can be obtained from <code>ERR_get_error(3)</code>.</p>
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<p>
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</p>
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<hr />
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<h1><a name="see_also">SEE ALSO</a></h1>
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<p><em>ERR_get_error(3)</em>, <em>CMS_uncompress(3)</em></p>
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<p>
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</p>
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<hr />
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<h1><a name="history">HISTORY</a></h1>
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<p>The <strong>CMS_STREAM</strong> flag was added in OpenSSL 1.0.0.</p>
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<p>
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</p>
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<hr />
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<h1><a name="copyright">COPYRIGHT</a></h1>
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<p>Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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</body>
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</html>
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