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<title>CMS_encrypt</title>
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<ul id="index">
<li><a href="#NAME">NAME</a></li>
<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#NOTES">NOTES</a></li>
<li><a href="#NOTES1">NOTES</a></li>
<li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
<li><a href="#SEE-ALSO">SEE ALSO</a></li>
<li><a href="#HISTORY">HISTORY</a></li>
<li><a href="#COPYRIGHT">COPYRIGHT</a></li>
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<h1 id="NAME">NAME</h1>
<p>CMS_encrypt - create a CMS envelopedData structure</p>
<h1 id="SYNOPSIS">SYNOPSIS</h1>
<pre><code> #include <openssl/cms.h>
CMS_ContentInfo *CMS_encrypt(STACK_OF(X509) *certs, BIO *in,
const EVP_CIPHER *cipher, unsigned int flags);</code></pre>
<h1 id="DESCRIPTION">DESCRIPTION</h1>
<p>CMS_encrypt() creates and returns a CMS EnvelopedData structure. <b>certs</b> is a list of recipient certificates. <b>in</b> is the content to be encrypted. <b>cipher</b> is the symmetric cipher to use. <b>flags</b> is an optional set of flags.</p>
<h1 id="NOTES">NOTES</h1>
<p>Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this function.</p>
<p>EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use because most clients will support it.</p>
<p>The algorithm passed in the <b>cipher</b> parameter must support ASN1 encoding of its parameters.</p>
<p>Many browsers implement a "sign and encrypt" option which is simply an S/MIME envelopedData containing an S/MIME signed message. This can be readily produced by storing the S/MIME signed message in a memory BIO and passing it to CMS_encrypt().</p>
<p>The following flags can be passed in the <b>flags</b> parameter.</p>
<p>If the <b>CMS_TEXT</b> flag is set MIME headers for type <b>text/plain</b> are prepended to the data.</p>
<p>Normally the supplied content is translated into MIME canonical format (as required by the S/MIME specifications) if <b>CMS_BINARY</b> is set no translation occurs. This option should be used if the supplied data is in binary format otherwise the translation will corrupt it. If <b>CMS_BINARY</b> is set then <b>CMS_TEXT</b> is ignored.</p>
<p>OpenSSL will by default identify recipient certificates using issuer name and serial number. If <b>CMS_USE_KEYID</b> is set it will use the subject key identifier value instead. An error occurs if all recipient certificates do not have a subject key identifier extension.</p>
<p>If the <b>CMS_STREAM</b> flag is set a partial <b>CMS_ContentInfo</b> structure is returned suitable for streaming I/O: no data is read from the BIO <b>in</b>.</p>
<p>If the <b>CMS_PARTIAL</b> flag is set a partial <b>CMS_ContentInfo</b> structure is returned to which additional recipients and attributes can be added before finalization.</p>
<p>The data being encrypted is included in the CMS_ContentInfo structure, unless <b>CMS_DETACHED</b> is set in which case it is omitted. This is rarely used in practice and is not supported by SMIME_write_CMS().</p>
<h1 id="NOTES1">NOTES</h1>
<p>If the flag <b>CMS_STREAM</b> is set the returned <b>CMS_ContentInfo</b> structure is <b>not</b> complete and outputting its contents via a function that does not properly finalize the <b>CMS_ContentInfo</b> structure will give unpredictable results.</p>
<p>Several functions including SMIME_write_CMS(), i2d_CMS_bio_stream(), PEM_write_bio_CMS_stream() finalize the structure. Alternatively finalization can be performed by obtaining the streaming ASN1 <b>BIO</b> directly using BIO_new_CMS().</p>
<p>The recipients specified in <b>certs</b> use a CMS KeyTransRecipientInfo info structure. KEKRecipientInfo is also supported using the flag <b>CMS_PARTIAL</b> and CMS_add0_recipient_key().</p>
<p>The parameter <b>certs</b> may be NULL if <b>CMS_PARTIAL</b> is set and recipients added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key().</p>
<h1 id="RETURN-VALUES">RETURN VALUES</h1>
<p>CMS_encrypt() returns either a CMS_ContentInfo structure or NULL if an error occurred. The error can be obtained from ERR_get_error(3).</p>
<h1 id="SEE-ALSO">SEE ALSO</h1>
<p><a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>, <a href="../man3/CMS_decrypt.html">CMS_decrypt(3)</a></p>
<h1 id="HISTORY">HISTORY</h1>
<p>The <b>CMS_STREAM</b> flag was first supported in OpenSSL 1.0.0.</p>
<h1 id="COPYRIGHT">COPYRIGHT</h1>
<p>Copyright 2008-2018 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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