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homenc / HElib

HElib is an open-source software library that implements homomorphic encryption. It supports the BGV scheme with bootstrapping and the Approximate Number CKKS scheme. HElib also includes optimizations for efficient homomorphic evaluation, focusing on effective use of ciphertext packing techniques and on the Gentry-Halevi-Smart optimizations.
https://homenc.github.io/HElib
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Multiplication under different keys #369

Open merryu opened 3 years ago

merryu commented 3 years ago

I want to know if you considered multiplication under different secret keys. Assume we have c3 = c1 * c2, which means c3 is the tensor product of c1 and c2, and c1 is under secret key s1, c2 is under secret key s2, can we decrypt c3 with s3 = s1 * s_2, I computed this and think it may work, but I know from your code that this operation is not allowed( I read code carefully and I have read the design document). Is my computation wrong or this operation is hard to do ?

jlhcrawford commented 3 years ago

There is ongoing research into multi-key homomorphic encryption: https://dl.acm.org/doi/abs/10.1145/2213977.2214086