16-page6 - ASCII that has printable characters. They load...

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• L&C’s example program in Section 5.2 encrypts and then decrypts a fxed message (declared as the initial value oF a string variable) using such a key cipher with a key oF length 7. Their key “letters” are small ints, which they add or subtract to the characters (viewed as numbers) to get diFFerent characters. They don’t bother with the wraparound, since adding or subtracting a small number From a letter in ASCII leaves you in the area oF
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Unformatted text preview: ASCII that has printable characters. They load their seven numbers into two queues oF Integers, and then use one to encode and one to decode. When they use a key letter, they replace it at the tail oF the queue, so they just rotate among the key letters. OF course they could have avoided the queues by keeping a count oF letters, and every time looking at array element key [count % 7]. But using the queue is simple and clear....
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This note was uploaded on 11/22/2011 for the course COMPSCI 187 taught by Professor Barrington during the Fall '11 term at UMass (Amherst).

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