gistfile1.txt

Alice wishes to get some information from Bob.

Both Alice and Bob each have a key pair:

```
pk_alice (Alice's public key),   sk_alice (Alice's secret key)
pk_bob (Bob's public key),       sk_bob (Bob's secret key)
```

To get the information, Alice sends Bob a message consisting of:

- The identifier of the information to retrieve
- A symmetric key `symk` which is encrypted with `pk_bob` and signed by `sk_alice`

Bob verifies that `symk` was signed by Alice using `pk_alice`.

Bob then replies with the requested data, encrypted with `symk`, and signed by `sk_bob`.

Alice verifies that the returned data was signed by Bob using `pk_bob`.