In regards to block cipher modes of operation, Output Feedba…
In regards to block cipher modes of operation, Output Feedback (OFB) and counter (CTR) both start with something and then encrypt it and then XOR the result with plaintext blocks to produce ciphertext blocks. Yet only one of these can be done in a way to get random access to a particular block of the ciphertext. a) Which one allows random access? b) Describe why it allows random access but the other one requires that additional work be done to get access to a particular block.
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