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=head1 NAME

CMS_final, CMS_final_digest - finalise a CMS_ContentInfo structure

=head1 SYNOPSIS

 #include <openssl/cms.h>

 int CMS_final(CMS_ContentInfo *cms, BIO *data, BIO *dcont, unsigned int flags);
 int CMS_final_digest(CMS_ContentInfo *cms, const unsigned char *md,
                      unsigned int mdlen, BIO *dcont, unsigned int flags);

=head1 DESCRIPTION

CMS_final() finalises the structure B<cms>. Its purpose is to perform any
operations necessary on B<cms> (digest computation for example) and set the
appropriate fields. The parameter B<data> contains the content to be
processed. The B<dcont> parameter contains a BIO to write content to after
processing: this is only used with detached data and will usually be set to
NULL.

CMS_final_digest() finalises the structure B<cms> using a pre-computed digest,
rather than computing the digest from the original data.

=head1 NOTES

These functions will normally be called when the B<CMS_PARTIAL> flag is used. It
should only be used when streaming is not performed because the streaming
I/O functions perform finalisation operations internally.

To sign a pre-computed digest, L<CMS_sign(3)> or CMS_sign_ex() is called
with the B<data> parameter set to NULL before the CMS structure is finalised
with the digest provided to CMS_final_digest() in binary form.
When signing a pre-computed digest, the security relies on the digest and its
computation from the original message being trusted.

=head1 RETURN VALUES

CMS_final() and CMS_final_digest() return 1 for success or 0 for failure.

=head1 SEE ALSO

L<ERR_get_error(3)>, L<CMS_sign(3)>,
L<CMS_encrypt(3)>

=head1 HISTORY

CMS_final_digest() was added in OpenSSL 3.1.

=head1 COPYRIGHT

Copyright 2008-2022 The OpenSSL Project Authors. All Rights Reserved.

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
L<https://www.openssl.org/source/license.html>.

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