ファイル暗号化ユーティリティ
   *** File Encryption/Decryption ***         1991.12.8. (c)ArtTECH
        
   使い方は次の通りです.
        
        C>cipher cmd key_word source_file target_file
        
        cmd -------- e  : Encipher/Encryption
                     ec :   with Check_Sum
                     d  : Decipher/Decryption
                     dc :   with Check_sum
        key_word --- any string less than 128 ch's
        file ------- Encryption/Decryption File