sign
Description:
Attempts to sign the content MIME part with userid's private key using the ctx signing context.
If successful, a new multipart/signed object is returned.
Parameters:
| ctx | |
| entity |
MIME part to sign |
| userid |
user id to sign with |
Returns:
|
a new MultipartSigned object on success or
null on fail. If signing fails, an exception will be set on |