International Business Machines Corporation

Byron Allen Williams

Andrew W Spyker

An apparatus and method for ensuring data integrity of unauthenticated code is provided. With the apparatus and method, a hash value of unauthenticated code is embedded in associated automatically authenticated code. When the automatically authenticated code is downloaded and executed, the automatically authenticated code may require that the unauthenticated code also be downloaded for proper execution of the automatically authenticated code on a particular client device. The unauthenticated code can be downloaded and its integrity verified by generating a hash value of the unauthenticated code and comparing the generated hash value to a hash value embedded in the automatically authenticated code. If there is a match, the unauthenticated code is verified. If there is not a match, the unauthenticated code has been corrupted during transmission and is not verified. As a result, the unauthenticated code is not used by the client device. The download of the unauthenticated code can then be attempted again and the verification process repeated.

Apparatus and method for ensuring data integrity of unauthenticated code

A priority queue structure and algorithm for managing the structure which in most cases performs in constant time. In other words, most of the time the inventive algorithm performs its work in an amount of time that is independent on the number of priority classes or elements that exist in the queue. The queue itself consists of a linked list of elements ordered into subqueues corresponding to priority classes, with higher priority subqueues appearing earlier in the queue. An array of priority pointers contains an entry for each subqueue that points to the last element of each subqueue. Elements are removed for processing from the top of the queue. Removal takes constant time. Items are inserted into an appropriate subqueue by linking it at the end of its respective subqueue. The only case that requires a variable amount of time depending on the length of the queue and the number of priority classes occurs when an item is added to an empty subqueue which is of lower priority than the element at the top of the queue. All subsequent additions to that subqueue consume constant time until the subqueue becomes empty once again. A feature of the invention prevents the possibility of perpetually locking out lower priority items in the queue by promoting the priority of a preempted item residing directly below a newly inserted item on the queue.

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Chapel Hill, NC, United States of America

Byron Allen Williams