| 摘要 |
PURPOSE: To form a speech system in resistance even to an illegal action by comparing verification information generated by a verifying module with verification information generated from a terminal equipment in the continuity of speech. CONSTITUTION: When a user picks up a receiver 124 of a telephone set, a verifying module 108 receives an off-hook signal DT, and generates a random number being an initial verification value Ko. When the telephone set receives a verification signal corresponding to the value Ko, and receives a charge signal, only a sum corresponding to charge to be paid is subtracted from a valid balance in the memory of a card by a reader. When a new charge signal is transmitted in speech, the telephone set subtracts a new speech sum from the card, calculates a new verification value K'2 , and transmits it to the verifying module 108. At the same time, the verifying module 108 calculates a new verification K2 , and compares it with the received K'2 . Thus, a speech system can actually fulfill a condition necessary for safety guarantee.
|
