| 摘要 |
PROBLEM TO BE SOLVED: To improve the security by employing the information processing unit provided with plural encryption means where kinds and contents of encryption differ from each other and selecting any of plural the encryption means based on an information content described in a header part of an electronic mail for encryption of a main text of the electronic mail being a transmission object. SOLUTION: Base addresses for plural kinds of encryption programs are stored in an encryption system entry table in an ROM 2. An MPU 1 extracts a character code stream in a SUBJECT column of header information of an electronic mail generated in an RAM 3, then acquires a base address for the encryption system entry table and generates a storage address of an encryption program by adding lower 2 digits of a sum of the character code stream to the base address. Then the encryption program corresponding to the storage address is acquired from the ROM 2 to encrypt main text information of the electronic mail generated in the RAM 3. Thus, decoding of the encrypted text is made difficult to enhance the security. |
