BIO_new_CMS(3)

NAME

        BIO_new_CMS - CMS streaming filter BIO

SYNOPSIS

        #include <openssl/cms.h>

        BIO *BIO_new_CMS(BIO *out, CMS_ContentInfo *cms);

DESCRIPTION

       BIO_new_CMS() returns a streaming filter BIO chain based on cms. The
       output of the filter is written to out. Any data written to the chain
       is automatically translated to a BER format CMS structure of the appro-
       priate type.

NOTES

       The chain returned by this function behaves like a standard filter BIO.
       It supports non blocking I/O. Content is processed and streamed on the
       fly and not all held in memory at once: so it is possible to encode
       very large structures.  After all content has been written through the
       chain BIO_flush() must be called to finalise the structure.

       The CMS_STREAM flag must be included in the corresponding flags parame-
       ter of the cms creation function.

       If an application wishes to write additional data to out BIOs should be
       removed from the chain using BIO_pop() and freed with BIO_free() until
       out is reached. If no additional data needs to be written
       BIO_free_all() can be called to free up the whole chain.

       Any content written through the filter is used verbatim: no canonical
       translation is performed.

       It is possible to chain multiple BIOs to, for example, create a triple
       wrapped signed, enveloped, signed structure. In this case it is the
       applications responsibility to set the inner content type of any outer
       CMS_ContentInfo structures.

       Large numbers of small writes through the chain should be avoided as
       this will produce an output consisting of lots of OCTET STRING struc-
       tures. Prepending a BIO_f_buffer() buffering BIO will prevent this.

BUGS

       There is currently no corresponding inverse BIO: i.e. one which can
       decode a CMS structure on the fly.

RETURN VALUES

       BIO_new_CMS() returns a BIO chain when successful or NULL if an error
       occurred. The error can be obtained from ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), CMS_sign(3), CMS_encrypt(3)

HISTORY

       BIO_new_CMS() was added to OpenSSL 1.0.0

1.0.2t                            2019-09-10                    BIO_new_CMS(3)