HOMOMORFISK KRYPTERINGSANORDNING OG FREMGANGSMÅDE TIL OPERATION DERAF

An encryption device includes: a parameter generating circuit configured to generate an encryption parameter including a number of initial valid bits based on an operation scenario; an encryption circuit configured to generate a cipher text by encrypting a plain text received from the outside, based on the encryption parameter; an operation circuit configured to generate a final cipher text by performing a plurality of operations on the cipher text according to the operation scenario and tag, to the final cipher text, history information of the operations performed on the final cipher text; and a decryption circuit configured to generate a decrypted plain text by decrypting the final cipher text and output a number of reliable bits of the decrypted plain text based on the history information.