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Brief Full Advanced Search Search Tips (Publisher: John Wiley & Sons, Inc.) Author(s): Bruce Schneier ISBN: 0471128457 Publication Date: 01/01/96 Search this book:
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----------- There are other techniques for message broadcasting, some of which avoid the previous problem. These are discussed in Section 22.7. TABLE 3.3 Three-Key Message Encryption Encrypted with Keys: KA KB KC KA and KB KA and KC KB and KC Must be Decrypted with Keys: KB and KC KA and KC KA and KB KC KB KA 3.6 Secret Splitting
Imagine that you’ve invented a new, extra gooey, extra sweet, cream filling or a burger sauce that is even more tasteless than your competitors’. This is important; you have to keep it secret. You could tell only your most trusted employees the exact mixture of ingredients, but what if one of them defects to the competition? There goes the secret, and before long every grease palace on the block will be making burgers with sauce as tasteless as yours. This calls for secret splitting. There are ways to take a message and divide it up into pieces . Each piece by itself means nothing, but put them together and the message appears. If the message is the recipe and each employee has a piece, then only together can they make the sauce. If any employee resigns with his single piece of the recipe, his information is useless by itself. The simplest sharing scheme splits a message between two people. Here’s a protocol in which Trent can split a message between Alice and Bob: (1) Trent generates a random-bit string, R, the same length as the message, M. (2) Trent XORs M with R to generate S. M•R=S (3) Trent gives R...
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