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cms_compress(3ssl) [linux man page]

CMS_compress(3SSL)						      OpenSSL							CMS_compress(3SSL)

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

       CMS_compress() was added to OpenSSL 0.9.8 The CMS_STREAM flag was first supported in OpenSSL 1.0.0.

1.0.0e								    2009-09-30							CMS_compress(3SSL)

Check Out this Related Man Page

SMIME_write_CMS(3SSL)						      OpenSSL						     SMIME_write_CMS(3SSL)

NAME

	SMIME_write_CMS - convert CMS structure to S/MIME format.

SYNOPSIS

	#include <openssl/cms.h>

	int SMIME_write_CMS(BIO *out, CMS_ContentInfo *cms, BIO *data, int flags);

DESCRIPTION

       SMIME_write_CMS() adds the appropriate MIME headers to a CMS structure to produce an S/MIME message.

       out is the BIO to write the data to. cms is the appropriate CMS_ContentInfo structure. If streaming is enabled then the content must be
       supplied in the data argument. flags is an optional set of flags.

NOTES

       The following flags can be passed in the flags parameter.

       If CMS_DETACHED is set then cleartext signing will be used, this option only makes sense for SignedData where CMS_DETACHED is also set when
       CMS_sign() is called.

       If the CMS_TEXT flag is set MIME headers for type text/plain are added to the content, this only makes sense if CMS_DETACHED is also set.

       If the CMS_STREAM flag is set streaming is performed. This flag should only be set if CMS_STREAM was also set in the previous call to a
       CMS_ContentInfo creation function.

       If cleartext signing is being used and CMS_STREAM not set then the data must be read twice: once to compute the signature in CMS_sign() and
       once to output the S/MIME message.

       If streaming is performed the content is output in BER format using indefinite length constructed encoding except in the case of signed
       data with detached content where the content is absent and DER format is used.

BUGS

       SMIME_write_CMS() always base64 encodes CMS structures, there should be an option to disable this.

RETURN VALUES

       SMIME_write_CMS() returns 1 for success or 0 for failure.

SEE ALSO

       ERR_get_error(3), CMS_sign(3), CMS_verify(3), CMS_encrypt(3) CMS_decrypt(3)

HISTORY

       SMIME_write_CMS() was added to OpenSSL 0.9.8

1.0.1e								    2013-02-11						     SMIME_write_CMS(3SSL)
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