Of course, identity-swapping is quite easy to do for people in Eclipse Phase (take into account, however, that you will loose a lot of reputation from that... I'd rule that you will keep the value of the faction sponsoring the identity change, or people the player tells about... with the added risk of leaks, compromising the new Identity). However, there are a lot of ways to make it much more complicated. First of all, remember: enemy is a sub-plot, not a main plot. That means that the players will be in the middle of something when this comes (for example, infiltrated in the Jovian Republic, with minimal support and hardware...) and they are unable to switch identities, or at least not fully. Second, a new identity issued by Firewall because of this (an enemy of a player, and not because of a mission) will count as a favour by Firewall. So at least, the player spent a favour from one of his reps. And this might happen again in the future, by the way, so the players might feel some pressure about solving their problems (that is, the enemy... and how is that bastard finding their new identities!). Third, it will be a good excuse to add a new layer to the game, a little hard sometimes when you are dealing with players that keep a low profile while on mission and are used to be the hunters, with only the group of enemies in front of them. But if suddenly they have to watch their back, the game can be reoriented (at least for a time) in a spionage-themed one where the players act both as hunters and prey, like spies in enemy territory (Cold War books can be a really good source of inspiration for this. John le Carré's ones are quite good in that regard, even if we consider how slow-paced they are). Also, old-school spy books can have a deep impact in the game. After all, if you are used to life in a society as advanced as the one in EP, you won't usually look into thinks shown in that old books unless, of course, you are a Jovian Spy, or have skills like Interest (Cold-war era novels), Knowledge (20th century spionage), or similar stuff. Things like using some physical markings that would look inocuous to everybody, place small items where they will fall if that door/window is used, etc... (EP people would look for AR stuff, or hidden programs in the door's software!).