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CMS_COMPRESS(3)			    OpenSSL		       CMS_COMPRESS(3)

NAME
       CMS_compress - create a CMS CompressedData structure

SYNOPSIS
	#include <openssl/cms.h>

	CMS_ContentInfo	*CMS_compress(BIO *in, int comp_nid, unsigned int flags);

DESCRIPTION
       CMS_compress() creates and returns a CMS	CompressedData structure.
       comp_nid	is the compression algorithm to	use or NID_undef to use	the
       default algorithm (zlib compression). in	is the content to be
       compressed.  flags is an	optional set of	flags.

NOTES
       The only	currently supported compression	algorithm is zlib using	the
       NID NID_zlib_compression.

       If zlib support is not compiled into OpenSSL then CMS_compress()	will
       return an error.

       If the CMS_TEXT flag is set MIME	headers	for type text/plain are
       prepended to the	data.

       Normally	the supplied content is	translated into	MIME canonical format
       (as required by the S/MIME specifications) if CMS_BINARY	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
       CMS_BINARY is set then CMS_TEXT is ignored.

       If the CMS_STREAM flag is set a partial CMS_ContentInfo structure is
       returned	suitable for streaming I/O: no data is read from the BIO in.

       The compressed data is included in the CMS_ContentInfo structure,
       unless CMS_DETACHED is set in which case	it is omitted. This is rarely
       used in practice	and is not supported by	SMIME_write_CMS().

NOTES
       If the flag CMS_STREAM is set the returned CMS_ContentInfo structure is
       not complete and	outputting its contents	via a function that does not
       properly	finalize the CMS_ContentInfo structure will give unpredictable
       results.

       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 BIO
       directly	using BIO_new_CMS().

       Additional compression parameters such as the zlib compression level
       cannot currently	be set.

RETURN VALUES
       CMS_compress() returns either a CMS_ContentInfo structure or NULL if an
       error occurred. The error can be	obtained from ERR_get_error(3).

SEE ALSO
       ERR_get_error(3), CMS_uncompress(3)

HISTORY
       The CMS_STREAM flag was added in	OpenSSL	1.0.0.

COPYRIGHT
       Copyright 2008-2016 The OpenSSL Project Authors.	All Rights Reserved.

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

1.1.1a				  2018-11-20		       CMS_COMPRESS(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | NOTES | RETURN VALUES | SEE ALSO | HISTORY | COPYRIGHT

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