Method and apparatus for multiple-iteration CMEA encryption and decryption for improved security for wireless telephone messages

US6266411A · kind A · utility

Assignee

• LUCENT TECHNOLOGIES INC. · US

Inventors

• Mark H. Etzel · Harvard, US
• Robert John Frank · Silver Spring, US
• Daniel Nelson Heer · Berlin, DE
• Robert Joseph McNelis · Columbia, US
• Semyon B. Mizikovsky · Morganville, US
• Robert J. Rance · Bradford, US
• R. Dale Shipp · Columbia, US

Key dates

• Filing date: Apr 13, 1998
• Grant date: Jul 24, 2001
• Expiry date: Apr 13, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2209/80
• WIPO field: Digital communication
• WIPO sector: Electrical engineering

Abstract

An enhanced CMEA encryption system suitable for use in wireless telephony. A plaintext message is introduced into the system and subjected to a first iteration of a CMEA process, using a first CMEA key to produce an intermediate ciphertext. The intermediate ciphertext is then subjected to a second iteration of the CMEA process using a second CMEA key to produce a final ciphertext. Additional security is achieved by subjecting the plaintext and intermediate ciphertext to input and output transformations before and after each iteration of the CMEA process. The CMEA iterations may be performed using an improved use of a tbox function which adds permutations to a message or intermediate crypto-processed data. Decryption is achieved by subjecting a ciphertext message to the reverse order of the steps used for encryption, replacing the input and output transformations by inverse output and inverse input transformations, respectively, as appropriate.