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CMS_COMPRESS(3) FreeBSD Library Functions Manual 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. Currently, the default algorithm NID_zlib_compression is the only supported algorithm. If zlib support is not compiled in, CMS_compress() always returns an error. in provides the content to be compressed. Any of the following flags (OR'ed together) can be passed in the flags parameter: CMS_TEXT Prepend MIME headers for type text/plain to the data. CMS_BINARY Do not translate the supplied content into MIME canonical format, even though that is required by the S/MIME specifications. This option should be used if the supplied data is in binary format. Otherwise, the translation will corrupt it. If CMS_BINARY is set, CMS_TEXT is ignored. CMS_STREAM Return a partial CMS_ContentInfo structure suitable for streaming I/O: no data is read from in. Several functions including SMIME_write_CMS(3), i2d_CMS_bio_stream(3), or PEM_write_bio_CMS_stream(3) can be used to finalize the structure. Alternatively, finalization can be performed by obtaining the streaming ASN1 BIO directly using BIO_new_CMS(3). Outputting the contents of the CMS_ContentInfo structure via a function that does not properly finalize it will give unpredictable results. CMS_DETACHED Do not include the compressed data in the CMS_ContentInfo structure. This is rarely used in practice and is not supported by SMIME_write_CMS(3). 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 CMS_ContentInfo_new(3), CMS_uncompress(3) STANDARDS RFC 3274: Compressed Data Content Type for Cryptographic Message Syntax (CMS) HISTORY CMS_compress() first appeared in OpenSSL 0.9.8h and has been available since OpenBSD 6.7. The CMS_STREAM flag first appeared in OpenSSL 1.0.0. FreeBSD 14.1-RELEASE-p8 November 2, 2019 FreeBSD 14.1-RELEASE-p8