CMS_compress - create a CMS CompressedData structure
#include <openssl/cms.h> CMS_ContentInfo *CMS_compress(BIO *in, int comp_nid, unsigned int flags);
CMS_compress(3openssl) OpenSSL CMS_compress(3openssl)
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.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | library/security/openssl |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
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().
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
https://www.openssl.org/source/openssl-1.0.2ze.tar.gz.
Further information about this software can be found on the open source
community website at https://www.openssl.org/.
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
CMS_compress() was added to OpenSSL 0.9.8 The CMS_STREAM flag was first
supported in OpenSSL 1.0.0.
1.0.2ze 2022-05-03 CMS_compress(3openssl)