Nortel Networks Corporation

Lawrence Gerard Dobranski

Michael C Lee

Method and system for encrypting streamed data employing fast set-up single use keys and self-synchronization. A transmitting handset produces a bitstream of voice data containing the session key and encrypted by an encryption signal based upon the session key. A receiving handset decrypts the incoming bitstream using the encryption signal and recognizes the session key, thereby establishing synchronization. The session key is derived from a seed by applying a first function to the seed. Following the call, the session key is converted into a new seed by application of a second function and the new seed is stored for use in the next call.

Method and system for encryption of streamed data

Method and apparatus for protecting processing elements from buffer overflow attacks are provided. The apparatus includes a memory stack for, upon execution of a jump to subroutine, storing a return address in a first location in a stack memory. A second location separate from the stack memory for storing an address of the first location and a third location separate from the stack memory for storing the return address itself are included. A first comparator upon completion of the subroutine, compares the address stored in the second location to the first location in the stack memory and a first interrupt generator provides an interrupt signal if locations are not the same. A second comparator looks at the return address stored in the third location and the return address stored in the first location in the stack memory and has a second interrupt generator for generating an interrupt signal if addresses are not the same. A further method and apparatus for protecting processing elements from buffer overflow attacks includes a memory stack for, upon execution of a jump to subroutine in a first processor, storing a return address in a first location in a stack memory and a second location separate from the stack memory for storing results for the subroutine operation. Also included is a second processor including routines for data manipulation associated with the subroutine, separate from the first processor and for storing any resultant data in the second location, which is readable by the first processor separate from the stack memory.

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Nepean, Canada

Lawrence Gerard Dobranski