... The simple substitution with a shift of three is known as the Caesar’scipher because it was reputedly used with success by Julius Caesar.If we limit the simple substitution to shifts, then the ... 288possible keys, can she be moreclever? Assuming the underlying message is English, Trudy can make use of the English letter frequency counts in Figure 2.2 together with the frequency counts ... cryptography,• public key cryptography,•hash functions, andInformation Security: Principles and Practice, by Mark StampCopyright © 2006 John Wiley & Sons, Inc.11“c02” — 2005/9/21 — page...