Unformatted text preview: nrecoverable. CFB: OFB/Counter: Security: Security: + Plaintext patterns are concealed. + Plaintext patterns are concealed. + Input to the block cipher is + Input to the block cipher is randomized. randomized. + More than one message can be + More than one message can be encrypted with the same key provided encrypted with the same key, that a different IV is used. provided that a different IV is used. +/ Plaintext is somewhat difficult to  Plaintext is very easy to manipulate, manipulate;blocks can be removed any change in ciphertext directly from the beginning and end of the affects the plaintext. message, bits of the first block can be changed, and repetition allows some controlled changes. Efficiency: + Speed is the same as the block cipher.  Ciphertext is the same size as the plaintext, not counting the IV. +/ Encryption is not parallelizable; decryption is parallelizable and has a randomaccess property.  Some preprocessing is possible before a block is seen; the previous ciphertext block can be encrypted. +/ Encryption is not parallelizable; decryption is parallelizable and has a randomaccess property. Faulttolerance:  A ciphertext error affects the corresponding bit of plaintext and the next full block. +Synchronization errors of full block sizes are recoverable. 1bit CFB can recover from the addition or loss of single bits. Efficiency: + Speed is the same as the block cipher.  Ciphertext is the same size as the plaintext, not counting the IV. + Processing is possible before the message is seen. /+ OFB processing is not parallelizable; counter processing is parallelizable. Faulttolerance: + A ciphertext error affects only the corresponding bit of plaintext. Synchronization error is unrecoverable. Previous Table of Contents Next Products  Contact Us  About Us  Privacy  Ad Info  Home Use of this site is subject to certain Terms & Conditions, Copyright © 19962000 EarthWeb Inc. All rights reserved. Reproduction whole or in part in any form or medium without express written permission of EarthWeb is pr...
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 Fall '10
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 Cryptography, Bruce Schneier, Applied Cryptography, EarthWeb, Search Search Tips

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