Multi-party key-switch eval-key generation

Generates an eval key that switches ciphertexts encrypted under sk_orig into a form decryptable by sk_new, starting from an existing eval key that carries the key-switch auxiliary information. Used by threshold protocols to route partial decryptions across a re-keyed party set.

Usage

multi_key_switch_gen(cc, sk_orig, sk_new, eval_key)

Arguments

cc

A CryptoContext

sk_orig

The original party's PrivateKey

sk_new

The new party's PrivateKey

eval_key

An EvalKey carrying key-switch auxiliary data

Value

An EvalKey suitable for routing through multi_add_eval_keys() to combine with other parties' key-switch shares