Unformatted text preview: given only the ciphertext . This is usually the hardest task a cryptanalyst must do—of course Ceaser’s cipher is a trivial cipher. We discussed “Attacks on Cryptosystems” in class and gave a special name to this “attack”. What was it called? A ciphertext only attack. 3. The OneTime Pad. This is an encryption system that o±ers perfect secrecy . This means that (True or False): • given a plaintext, the corresponding ciphertext is random. TRUE • given a ciphertext, the corresponding plaintext is random. FALSE • the plaintext is random. FALSE • the ciphertext is random. TRUE Mike Burmester...
View
Full Document
 Fall '09
 Cryptography, Computer Security, Substitution cipher, Mike Burmester, Ceasar’s cipher, S→T →U →V, corresponding plaintext

Click to edit the document details