Abstract: A portable telephone includes a nonvolatile memory, a microcomputer and a liquid crystal panel. The nonvolatile memory stores a plurality of conversion tables employed when an encrypted electronic mail is generated or decrypted. Upon reception of an entry of key information corresponding to any one of the plurality of conversion tables, the microcomputer selects the one conversion table from among the plurality of conversion tables stored in the nonvolatile memory based on the key information. The microcomputer encrypts an electronic mail or decrypts an encrypted electronic mail by referring to the selected conversion table to display the encrypted electronic mail or the decrypted electronic mail on the liquid crystal panel.

Abstract: A portable telephone comprises a nonvolatile memory, an operation unit, a liquid crystal panel and a microcomputer. The microcomputer is operable to: receive an encrypted electronic mail; store the received encrypted electronic mail in the nonvolatile memory; check whether or not a password input from the operation unit coincides with the password stored in the nonvolatile memory; decrypt the received encrypted electronic mail, with reference to the decryption table stored in the nonvolatile memory, to generate a decrypted electronic mail, if the password accepted by the operation unit coincides with the password stored in the nonvolatile memory; store temporarily the decrypted electronic mail; control the display of the decrypted electronic mail temporarily stored in the microcomputer on the liquid crystal panel; and delete the decrypted electronic mail temporarily stored in the microcomputer according to an order for stopping displaying the decrypted electronic mail on the liquid crystal panel.

Abstract: A portable telephone comprises a nonvolatile memory, an operation unit, a liquid crystal panel and a microcomputer. The microcomputer is operable to: creat a conversion table upon an input from an owner; receive an encrypted electronic mail; check whether or not a password accepted by the operation unit coincides with the password stored in the nonvolatile memory; decrypt the received encrypted electronic mail with reference to the conversion table to generate a decrypted electronic mail, if the password accepted by the operation unit coincides with the password stored in the nonvolatile memory; store temporarily the decrypted electronic mail; control the display of the decrypted electronic mail temporarily stored in the microcomputer on the liquid crystal panel; and delete the decrypted electronic mail temporarily stored in the microcomputer according to an order for stopping displaying the decrypted electronic mail on the liquid crystal display.