Add CMS_compress() docs.

=pod

=head1 NAME

CMS_compress - create a CMS CompressedData structure

=head1 SYNOPSIS

 #include <openssl/cms.h>

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

=head1 DESCRIPTION

CMS_compress() creates and returns a CMS CompressedData structure. B<comp_nid>

is the compression algorithm to use or B<NID_undef> to use the default

algorithms (zlib compression). B<in> is the content to be compressed.

B<flags> is an optional set of flags.

=head1 NOTES

The only currently supported compression algorithm is zlib using the NID

NID_zlib_compression.

If zlib support is not compiled into OpenSSL this CMS_compress() will return

an error.

If the B<CMS_TEXT> flag is set MIME headers for type B<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 B<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 B<CMS_BINARY> is set then

B<CMS_TEXT> is ignored.

If the B<CMS_STREAM> flag is set a partial B<CMS_ContentInfo> structure is

returned suitable for streaming I/O: no data is read from the BIO B<in>.

The compressed data is included in the CMS_ContentInfo structure, unless

B<CMS_DETACHED> is set in which case it is omitted. This is rarely used in

practice and is not supported by SMIME_write_CMS().

=head1 NOTES

If the flag B<CMS_STREAM> is set the returned B<CMS_ContentInfo> structure is

B<not> complete and outputting its contents via a function that does not

properly finalize the B<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 B<BIO> directly using

BIO_new_CMS().

=head1 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).

=head1 SEE ALSO

L<ERR_get_error(3)|ERR_get_error(3)>, L<CMS_uncompress(3)|CMS_uncompress(3)>

=head1 HISTORY

CMS_compress() was added to OpenSSL 0.9.8

The B<CMS_STREAM> flag was first supported in OpenSSL 0.9.9.

=cut

=head1 NAME

CMS_sign - create a CMS signedData structure

CMS_sign - create a CMS SignedData structure

=head1 SYNOPSIS

=head1 DESCRIPTION

CMS_sign() creates and returns a CMS signedData structure. B<signcert> is

CMS_sign() creates and returns a CMS SignedData structure. B<signcert> is

the certificate to sign with, B<pkey> is the corresponsding private key.

B<certs> is an optional additional set of certificates to include in the CMS

structure (for example any intermediate CAs in the chain). Any or all of

occurs. This option should be used if the supplied data is in binary format

otherwise the translation will corrupt it.

The signedData structure includes several CMS signedAttributes including the

The SignedData structure includes several CMS signedAttributes including the

signing time, the CMS content type and the supported list of ciphers in an

SMIMECapabilities attribute. If B<CMS_NOATTR> is set then no signedAttributes

will be used. If B<CMS_NOSMIMECAP> is set then just the SMIMECapabilities are

=head1 NAME

CMS_verify - verify a CMS signedData structure

CMS_verify - verify a CMS SignedData structure

=head1 SYNOPSIS

=head1 DESCRIPTION

CMS_verify() verifies a CMS signedData structure. B<cms> is the CMS_ContentInfo

CMS_verify() verifies a CMS SignedData structure. B<cms> is the CMS_ContentInfo

structure to verify. B<certs> is a set of certificates in which to search for

the signer's certificate. B<store> is a trusted certficate store (used for

chain verification). B<indata> is the signed data if the content is not

Normally the verify process proceeds as follows.

Initially some sanity checks are performed on B<cms>. The type of B<cms> must

be signedData. There must be at least one signature on the data and if

be SignedData. There must be at least one signature on the data and if

the content is detached B<indata> cannot be B<NULL>.

An attempt is made to locate all the signer's certificates, first looking in