Commedia dell’Arte

In the XVI^th Century, a new style a theater flourished in Italy. In The Commedia dell’Arte: A Study in Italian Popular Comedy, Winifred Smith says: “A commedia dell’arte was always in part the transitory creation of the individual actors who played it; the plot was known to each member of the troupe, so well-known, indeed, that an entrance or an exit was never missed, but the dialog was chiefly left to be struck out by the suggestion of the moment.” The art then comes in the flexible presentation of the play and it takes a level of improvisation by the actors to tell the story while at the same time remaining in character and also remaining true to the plot. In A Short History of the Drama, Martha Fletcher Bellinger notes about the commedia dell’arte: “The actors had to find the proper words to make the tears flow or the laughter ring; they had to catch the sallies of their fellow-actors on the wing, and return them with prompt repartee. The dialogue must go like a merry game of ball or spirited sword-play, with ease and without a pause.” Compared to the scripted play, interactions contain the increased threat that comes with the need for the actors to find inspiration. To lower their anxiety, Smith notes that “each player possessed a book which he filled with compositions either original or borrowed, suitable for his rôle.” The unknown of impromptu interactions is widespread, and the actors’ approach to it in the commedia dell’arte is also very common. To come back to the military’s preparedness to threat confrontation, the sweat expensed at the training field is said to be the blood saved at the battlefield. Similarly, athletes in group sports rehearse extensively all sorts of plays to be ready with alternatives when the big game comes. Each of us has discovered how studying for exams gets one ready for the curved balls to come. So we see a common thread of preparing from the unknown by building a set of ready answers to use as the threats come by.

In the computer world, threats of impromptu interactions are named exceptions. An elaborate formal framework allows exceptions to be specified at several levels, where each exception can raise one of more generality. For example, a computer program may regularly access a file, perhaps a spreadsheet for content needed for processing. Under normal operations, the computer just finds the file in its hard drive and opens it to read its data, just as we might fetch a file from our cabinet in the office. However, there can be situations, for the computer just as for us humans, where the file is not there. Did somebody borrow it? Am I looking in the right cabinet? Do I remember incorrectly the name of the file? The number of possible reasons can be quite large, and we can’t in advance try to list all the possibilities for error. First, these exceptions are unlikely, and second, there are always some errors that we will not anticipate. Therefore, before reading the file, the application just signals the system that it is ready for an interaction that contains the threat of not performing as expected, by setting an exception. If the threat materializes, say the file is not found, the raised exception is said to be caught and the computer attempts to fix the problem with whatever solutions it has in its arsenal; for example, it may decide to try substituting a new file for the one that has disappeared, or it can prompt the user for information. If none of these solutions work (there is no new file, or the user is not answering), then it may decide that the task is too hard, and it may throw a higher exception. The higher exception is then caught by a supervisory part of the program that may decide to try more drastic solutions, like just shutting down operations. In the same way, if the clerk doesn’t find a file in the cabinet, then perhaps it is time to call the manager to present the situation.

If we consider now our secure core reinforced with a fingerprint sensor, it should be anticipated that the sensor could be attacked, for example by presenting a fake finger, or by tampering electronically with the sensor, or by trying to modify the signal between the sensor and the secure core processing unit. Again, the possibilities are many, and therefore the secure core will set an exception which will react with a set of tried solutions, like just ignoring the entry if a fake finger is suspected, or more drastically, shutting down the sensor altogether if electronic tampering is

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