Importance

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Abstract

A method for initiating secure communications between two stations. In this method, a first portion of a session data encryption key (DEK1) is randomly generated by an EDU in one of the stations. The DEK1 is then encrypted using a key exchange key (KEK) selected from a table as a function of a check value determined by applying the DEK1 to encrypt a predefined zero function. The encrypted DEK1 is transmitted to the other station, along with an encrypted EDU ID number for the station that generated the DEK1 and a cyclic redundancy check (CRC) value of the KEK table. The encrypted table entry value used to define the KEK is decrypted at the other station, and a check is made to determine if the KEK table CRC and the EDU ID are correct. If not, communication is terminated. Otherwise, the second portion of the data encryption key (DEK2) is generated by the station that received the first portion, and encrypted by it using a different KEK value selected from the table for transmission to the other station, along with the EDU ID of the station then transmitting. The encrypted DEK2 is decrypted at the other station and a check made of the EDU ID. Both stations logically XOR the values of DEK1 and DEK2 together to determine the session data encryption key (DEK), which is used to encrypt and decrypt all further transmissions between the two stations during the current session.

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First Claim