# Functional Encryption (for Non Experts)

I recently stumbled across "How to Run Turing Machines on Encrypted Data".

Given that it's now possible to run turing machines on encrypted data, what open problems remain in the realm of Functional Encryption?

(It seems like for every problem in Functional Encryption, one would just say: well, design a TM to compute the function, encrypt the data, then use the above scheme.)

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My guess would be speed. It looks like asymptotically their scheme is pretty good, but by looking at how they construct their system, they probably have large constant factors in there that would kill performance in the real world. Implementation is probably non-trivial too. –  mikeazo Mar 3 at 16:13

Another possibility is security against adversaries that can choose the Turing $\hspace{1.46 in}$ machines after seeing the challenge ciphertext. $\;$ –  Ricky Demer Mar 7 at 21:20