Symmetric-key Signatures CN5E by Tanenbaum & Wetherall, © Pearson Education- Prentice Hall and D. Wetherall, 2011 Alice and Bob each trust and share a
{"Image DocumentName": "Symmetric-key Signatures", "Image ImageDescription": "Alice and Bob each trust and share a key with Big Brother; Big Brother doesn\u2019t trust anyone. A=Alice, B=Bob, P=message, RA=random, t=time. RA and time protect against replays. Time lets very old messages be detected. For recent messages, RA can be checked to see if it has been used before. Only Alice can send this encrypted message to BB. Only BB can send this encrypted message to Bob. CN5E by Tanenbaum & Wetherall, \u00a9 Pearson Education-Prentice Hall and D. Wetherall, 2011.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}