in a searchable cipher system , the security of ciphertext , the optimization of the size of ciphertext and the optimization of the network traffic are not examined enough . a registration client deposits encrypted data acquired by compressing the size of a search tag created for a search by a stochastic encryption using a mask by a hash value and an output value of a homomorphic function in a server , a search client similarly stochastically encrypts a search keyword and transmits it to the management server as a search keyword acquired by encrypting only a part of the encrypted data , the search client requests the management server to search data to be searched without making the management server release a mask by random numbers of the encrypted data and the encrypted keyword , the search client detects a wrong search in a search result , and decrypts the search result .