secrecy: how should one use SecretBytesMut?

[fjarri]

Perhaps I do not understand something, but how can one use the current API to actually mutate the insides of the secret? In my case, I want to create a secret random seed, so I write

let key = SecretBytesMut::new(BytesMut::zeroed(32));
OsRng.fill_bytes(key.expose_secret().as_mut());

Which results in a "cannot borrow as mutable" for key.expose_secret().as_mut(). Which I understand - expose_secret() returns an immutable reference - but how to get a mutable access to the bytes then?

[jymchng]

You might want to build the bytes first before moving it into the new constructor since the constructor consumes the value.

[fjarri]

Thanks for reminding me, this will be closed (or rather invalidated) by #1140.