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.IX Title "CMS_ADD_STANDARD_SMIMECAP_EX 3ssl"
.TH CMS_ADD_STANDARD_SMIMECAP_EX 3ssl 2026-10-23 4.1.0 OpenSSL
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.nh
.SH NAME
CMS_add_standard_smimecap_ex, CMS_add_standard_smimecap,
CMS_add_smimecap, CMS_add_simple_smimecap
\&\- CMS SMIMECapabilities attribute utilities
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/cms.h>
\&
\& int CMS_add_standard_smimecap_ex(STACK_OF(X509_ALGOR) **smcap,
\&                                  OSSL_LIB_CTX *libctx, const char *propq);
\& int CMS_add_standard_smimecap(STACK_OF(X509_ALGOR) **smcap);
\&
\& int CMS_add_smimecap(CMS_SignerInfo *si, STACK_OF(X509_ALGOR) *algs);
\& int CMS_add_simple_smimecap(STACK_OF(X509_ALGOR) **algs,
\&                             int algnid, int keysize);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\fBCMS_add_standard_smimecap_ex()\fR populates \fB*smcap\fR with the set of
algorithms that should be advertised in an SMIMECapabilities signed
attribute.  Only algorithms that are available in the providers
associated with \fBlibctx\fR and the property query string \fBpropq\fR are
included, so the list accurately reflects what the caller can actually
use.  If \fBlibctx\fR is NULL the default library context is used.  If
\&\fB*smcap\fR is NULL a new \fBSTACK_OF(X509_ALGOR)\fR is allocated; otherwise
entries are appended to the existing stack.
.PP
The candidate algorithms, listed in preference order, are: AES\-256\-CBC,
GOST R 34.11\-2012 (256\-bit), GOST R 34.11\-2012 (512\-bit), GOST R
34.11\-94, GOST 28147\-89, AES\-192\-CBC, AES\-128\-CBC, DES\-EDE3\-CBC,
RC2\-CBC (128\-bit key), RC2\-CBC (64\-bit key), DES\-CBC, and RC2\-CBC
(40\-bit key).  Algorithms not available in the active providers
(for example, RC2 and DES when only the default provider is loaded)
are silently omitted.
.PP
\&\fBCMS_add_standard_smimecap()\fR is a wrapper that calls
\&\fBCMS_add_standard_smimecap_ex()\fR with a NULL library context and NULL
property query string.
.PP
\&\fBCMS_add_smimecap()\fR adds a pre\-built stack of algorithm identifiers
\&\fBalgs\fR as the SMIMECapabilities signed attribute on the
\&\fBCMS_SignerInfo\fR \fBsi\fR.
.PP
\&\fBCMS_add_simple_smimecap()\fR appends a single algorithm entry to \fB*algs\fR.
\&\fBalgnid\fR is the NID of the algorithm and \fBkeysize\fR is the key size in
bits, or \-1 if the algorithm does not use a variable key size.
.SH NOTES
.IX Header "NOTES"
Applications that need accurate capability advertisements should use
\&\fBCMS_add_standard_smimecap_ex()\fR, passing the same \fBlibctx\fR and \fBpropq\fR
used for the rest of the CMS operation.  This ensures that only
algorithms genuinely available to the application are listed.
.PP
\&\fBCMS_add1_signer()\fR calls \fBCMS_add_standard_smimecap_ex()\fR internally using
the library context associated with the CMS_ContentInfo structure, so
applications that use \fBCMS_add1_signer()\fR without \fBCMS_NOSMIMECAP\fR do not
need to call these functions directly.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
All functions return 1 for success or 0 for failure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBCMS_add1_signer\fR\|(3), \fBCMS_sign\fR\|(3), \fBOSSL_LIB_CTX\fR\|(3)
.SH HISTORY
.IX Header "HISTORY"
\&\fBCMS_add_standard_smimecap_ex()\fR was added in OpenSSL 4.1.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2026 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (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
<https://www.openssl.org/source/license.html>.