Secure File Transfer: A Computational Analog To The Furniture Moving Paradigm


Selim G. Akl


One of the most compelling illustrations of the power of parallelism is the furniture-moving paradigm. In it, a large item of furniture needs to be moved from one place to another. A single mover, working alone, must take the item apart, move each piece separately, and then reassemble the item at the new location, taking a long time to complete the job. By contrast, four movers can simply lift the item and quickly move it to its new location. Thus, the time required to accomplish the task is reduced by a factor significantly larger than four.

This paper describes a computational analog to the furniture-moving paradigm. The computation in question is concerned with transferring a computer file from one computer system to another over an insecure communications channel. The file contains private or sensitive information whose secrecy and integrity need to be maintained. Cryptography is used to obtain a digital signature of the file, thereby protecting its integrity, and then encrypting it to ensure its secrecy. If the file transfer is performed sequentially, the file and its digital signature need to be broken into blocks, each of which is signed and encrypted individually then transmitted. At the receiving end, each block is checked for authenticity, then the original file is reassembled and its digital signature verified. On the other hand, performing the file transfer in parallel allows the entire file and its digital signature to be sent as a whole in one step. Consequently, the parallel solution speeds up the sequential one by a factor that is superlinear in the number of processors used.


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