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Output feedback (ofb)

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Output feedback system

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Output feedback (ofb)

  1. 1. Hasbi DİŞLEN 282607 Software Engineering
  2. 2.   In cryptography, output feedback (OFB) is a mode of operation for a block cipher. It has some similarities to the ciphertext feedback mode in that it permits encryption of differing block sizes, but has the key difference that the output of the encryption block function is the feedback (instead of the ciphertext). The XOR (exclusive OR) value of each plaintext block is created independently of both the plaintext and ciphertext. OFB
  3. 3.  Output feedback (OFB) is yet another variation on the same theme. The only difference is that the input to block N+1 is the output of the block cipher
  4. 4.   It is this mode that is used when there can be no tolerance for error propagation, as there are no chaining dependencies. Like the ciphertext feedback mode, it uses an initialization vector (IV). Changing the IV in the same plaintext block results in different ciphertext. In terms of error correction, output feedback can tolerate ciphertext bit errors, but is incapable of self-synchronization after losing ciphertext bits, as it disturbs the synchronization of the aligning keystream. A problem with output feedback is that the plaintext can be easily altered, but using a digital signature scheme can overcome this problem OFB
  5. 5.   Network Security Glossary  Security Management Glossary  Security threats and countermeasures Glossary Output Feedback (OFB) is part of the:

Output feedback system

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