The ibe.Ciphertext struct is missing serialization methods

[AnomalRoil]

Our ibe.Ciphertext struct can have variable size serialization, depending on the curve of the kyber.Point and the size of the hash used, etc.

kyber/encrypt/ibe/ibe.go

Lines 15 to 22 in 23debab

	type Ciphertext struct {
	// Random point rP
	U kyber.Point
	// Sigma attached to ID: sigma XOR H(rG_id)
	V []byte
	// ciphertext of the message M XOR H(sigma)
	W []byte
	}

It would be nice to have a "good way" of encoding it and decoding it.
Otherwise all the users have to go through the painful process of re-implementing something like that, e.g.:
https://github.com/drand/tlock/blob/24c8c6e1b288fcd1a703da1db5606800b4607337/tlock.go#L216-L234

[ineiti]

You can use https://github.com/dedis/protobuf for this - it's not a very good solution, but at least it handles all different types of kyber.Point, which is the difficult part here.
To make a generic (Un)Marshal method, you'd have to start with an identifier of the point-type, then have a switch/case list of points and unmarshal them.
Unfortunately the Point interface doesn't have a GroupName method, so you'd have to do either type reflection, or suppose that the code calling UnMarshal knows which group to use. Which might be a correct assumption to do.