Is the GHS key-switching method implemented in OpenFHE?

Library Questions
1

Hello.

I was wondering if the GHS (Gentry–Halevi–Smart) key-switching method described in Revisiting Homomorphic Encryption Schemes for Finite Fields is implemented in OpenFHE. I could only find the BV and Hybrid methods, so I’m curious whether GHS has not been adopted in OpenFHE.

If GHS is not implemented, could you share the reason (no practical advantage over Hybrid, or other technical reasons)?

Thank you.

2

GHS is a special case of Hybrid key switching when the number of large digits is set to 1 (it can be set via SetNumLargeDigits). In many cases, a configuration with 3 digits is more performant as it increases the size of ciphertext modulus size (in bits) only by one-third (rather than twice, as in the case of GHS key switching).

1 Like
3

Thank you for your answer.