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Review of the paper The paper's goal is to offload to a server the computation of the inverse of a (non-singular) $n\times n$ matrix $X$ of (the floating-point approximation of) real numbers, while keeping $X$ and $X^{-1}$ confidential. Towards that goal, the paper's method is to draw a secret key consisting of two random permutations and $2n$ non-zero ...


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Here are some hints on how it's done on Mega: The password provided is passed through a KDF to derive a key, that is used to en-/decrypt the master key (later provided by the server through an API call). To bring it down to the crucial bits: The KDF applies $2^{16}$ rounds of AES-128 with it. The details can be found in the function prepare_key() of the ...


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If you are looking for something that is faster than AES, there are several options. HOWEVER (and this is a big one) if AES-NI instructions (hardware acceleration) are available to you, there is nothing that can come close. My computer is a few years old, and I get 3100MiB/s in CTR mode. That is 3 gigabytes every second. That is faster than the network ...


2

Salsa/ChaCha and the other eSTREAM winners are likely to be the "fastest but still secure" options today. Don't forget authentication of course. Reduced-round ChaCha/Poly1305 is likely to be the fastest software-only option, due to tuned implementations in the libsodium and NaCl libraries. UPDATED: The following slide deck has good info on state of the art ...


1

Use AES-128, the instruction set in most CPU's (AES-NI) speeds up the encryption and does not put to much load on your CPU. I would use CBC but there might be better mode operations for encrypting files. Also don't forget to use a MAC. Using a one time pad (OTP) is nice but what you're doing is not an OTP it's more a Vigenère cipher. If you were to use OTP ...



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