Function CMSEncode 

pub unsafe extern "C" fn CMSEncode(
    signers: CFTypeRef,
    recipients: CFTypeRef,
    eContentType: *const SecAsn1Oid,
    detachedContent: Boolean,
    signedAttributes: CMSSignedAttributes,
    content: *const c_void,
    contentLen: usize,
    encodedContentOut: *mut CFDataRef,
) -> OSStatus

Apple SDK function CMSEncode.