125 lines
5.5 KiB
HTML
Executable File
125 lines
5.5 KiB
HTML
Executable File
<?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_encrypt</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_encrypt - create a CMS envelopedData 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_encrypt(STACK_OF(X509) *certs, BIO *in,
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const EVP_CIPHER *cipher, 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_encrypt()</code> creates and returns a CMS EnvelopedData structure. <strong>certs</strong>
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is a list of recipient certificates. <strong>in</strong> is the content to be encrypted.
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<strong>cipher</strong> is the symmetric cipher to use. <strong>flags</strong> is an optional set of flags.</p>
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<p>Only certificates carrying RSA, Diffie-Hellman or EC keys are supported by this
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function.</p>
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<p>EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use
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because most clients will support it.</p>
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<p>The algorithm passed in the <strong>cipher</strong> parameter must support ASN1 encoding of
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its parameters.</p>
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<p>Many browsers implement a "sign and encrypt" option which is simply an S/MIME
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envelopedData containing an S/MIME signed message. This can be readily produced
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by storing the S/MIME signed message in a memory BIO and passing it to
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<code>CMS_encrypt()</code>.</p>
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<p>The following flags can be passed in the <strong>flags</strong> parameter.</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>OpenSSL will by default identify recipient certificates using issuer name
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and serial number. If <strong>CMS_USE_KEYID</strong> is set it will use the subject key
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identifier value instead. An error occurs if all recipient certificates do not
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have a subject key identifier extension.</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>If the <strong>CMS_PARTIAL</strong> flag is set a partial <strong>CMS_ContentInfo</strong> structure is
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returned to which additional recipients and attributes can be added before
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finalization.</p>
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<p>The data being encrypted 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>The recipients specified in <strong>certs</strong> use a CMS KeyTransRecipientInfo info
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structure. KEKRecipientInfo is also supported using the flag <strong>CMS_PARTIAL</strong>
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and CMS_add0_recipient_key().</p>
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<p>The parameter <strong>certs</strong> may be NULL if <strong>CMS_PARTIAL</strong> is set and recipients
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added later using CMS_add1_recipient_cert() or CMS_add0_recipient_key().</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_encrypt()</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_decrypt(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 first supported 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 2008-2018 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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