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seal

Division Operator in SEAL

I didn't see any division function for Ciphertexts in evaluator. Can I use a negative exponent when using the evaluator.exponentiate() operation?

Solution

  • Division of a ciphertext or a plaintext by a ciphertext is not possible.

    It is possible to divide a ciphertext by a plaintext using e.g. FractionalEncoder: encode the inverse of the number you want to divide by and then multiply by that encoded inverse.

    In principle it is possible to compute all kinds of polynomial approximations for f(x) = 1/x and evaluate these for your ciphertext. In practice this doesn't seem to work well enough to make sense unless perhaps in some very very special situations.