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Unformatted text preview: plain block = FP(LR) To encrypt or decrypt more than 64 bits there are four official modes (defined in FIPS PUB 81). One is to go through the above-described process for each block in succession. This is called Electronic Codebook (ECB) mode. A stronger method is to exclusive-or each plaintext block with the preceding ciphertext block prior to encryption. (The first block is exclusive-or'ed with a secret 64-bit initialization vector (IV).) This is called Cipher Block Chaining (CBC) mode. The other two modes are Output Feedback (OFB) and Cipher Feedback (CFB)....
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- Spring '12