Digital Signatures, cont'd.

If you save a copy of
```
        S(me)
     {M}
```
then you can send it to someone else as proof to them that I said what you claim I did -- no one but I could have created that message.
You can further encrypt it for secrecy on the wire, just as I did when I sent it to you:
```
         S(me) P(third party)
     {{M}     }
```