according to an exemplary embodiment includes a key generation module 100 an encryption module 200 and a decryption module 300 the above mentioned compressed encryption means a technique which is designed to improve a structure in which only one bit is encrypted decrypted in the technique of the related art to encrypt decrypt multiple bit information to improve the space efficiency for storing a ciphertext the key generation module 100 receives a predetermined security parameter and a value of a compression ratio and generates a public key and a secret key for encrypting and decrypting plaintext information the general information is referred to as plaintext information and a method that hides contents of the plaintext is referred to as encryption the encrypted plaintext is referred to as a ciphertext and a method that converts the ciphertext into the plaintext is referred to as decryption the public key algorithm is an algorithm which uses different keys in encryption and decryption even though a third party knows an encryption key the third party cannot decrypt the ciphertext only a person who owns a decryption key decrypts the ciphertext therefore due to such a characteristic the encryption key is open and the decryption key is hidden the encryption key is referred to as a public key and the decryption key is referred to as a private key hereinafter a method that generates the public key and a secret key in the key generation module 100 will be described with reference to fig2 fig2 is a diagram illustrating a generating procedure of the secret key and.