Worth noting: bitvm can also work in a security model where each sidechain user has a direct contract with a bridge operator and thus does not need to trust him or her. In this case the 1-of-N is a 1-of-2 and the user is among the 2, consequently the user only needs to trust themselves (and bitcoin's standard trust assumptions, e.g. they must assume miners are not censoring them).

See Unisob for more details: https://gist.github.com/supertestnet/5f262c632cbcd00348824aad5c289705