Homomorphic encryption makes it possible to generate aggregated insights about the encrypted data, without ever decrypting it. It remains fully encrypted all the time. Hence, it’s a ‘zero trust’ technique, in the manner that even the operator of the data clean room doesn’t have access to the plain data.
Just like other forms of encryption, homomorphic encryption uses a public key to encrypt the data. Unlike other forms of encryption, it uses an algebraic system to allow functions to be performed on the data while it’s encrypted. Then only the individual with the matching private key can access the unencrypted data after the functions and manipulation are complete. This allows the data to be and remain secure and private even when someone is using it.