ProtectedMemory for v2 pInvokes into SystemFunction040 and SystemFunction041 ... whatever those are? and i doubt those functions exist on CE :) all ProtectedMemory does is encrypt blocks of memory you pass in, so i cooked up my own internals using DES. this should be OK since ProtectedMemory is not supposed to be used outside of a single machine, although it can be used cross process. e.g. you could encrypt the memory in one process, then pass that encrypted memory to another process ... which would then decrypt that memory space. i THINK i have that working (with a hack) ... but i did not test it.
and ProtectedMemory allows for a SecureString. all i did was port the code from Hernan de Lahitte. it seems to be working, but i need to do a little more testing to be sure.