Our assignment asks us to convert an RSA speed in bytes per second to a DES speed in bytes per second. Our professor's treatment of this ("RSA is 100 times slower than DES") seems insufficient. Could anyone explain how this conversion is calculated?


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    $\begingroup$ You have not provided sufficient information. Firstly, different implementations of both algorithms have different speed. Secondly, what RSA padding is used? Thirdly, what size of the RSA modulus is assumed? Fourthly, what is the length of the plain text to be encrypted? $\endgroup$ – Henrick Hellström Mar 11 '13 at 14:37
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    $\begingroup$ Of related interest. $\endgroup$ – mikeazo Mar 11 '13 at 14:42
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    $\begingroup$ In addition to Henrick's questions, there's also the question of whether we're talking about RSA encryption or RSA decryption speed; those differ radically. $\endgroup$ – poncho Mar 11 '13 at 15:19
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    $\begingroup$ "convert an RSA speed in bytes per second to a DES speed in bytes per second" makes as much sense as "convert a tractor speed in meter per second to a jet speed in meter per second". $\endgroup$ – fgrieu Mar 11 '13 at 15:26
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    $\begingroup$ Find some website with benchmarks (or create your own). If the cost is given per-operation, instead of per-byte, then divide by the block size in bytes. $\endgroup$ – CodesInChaos Mar 11 '13 at 15:28

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