п»їOnline Ciphers and the Hash-CBC Construction.
We initiate a study of on-line ciphers. These are ciphers that can take input plaintexts of large and varying lengths and will output the ith block of the ciphertext after having processed only the first i blocks of the plaintext. Such ciphers permit length-preserving encryption of a data stream with only a single pass through the data. We provide security definitions for this primitive and study its basic properties. We then provide attacks on some possible candidates, including CBC with fixed IV. Finally we provide a construction called HCBC which is based on a given block cipher E and a family of AXU functions. HCBC is proven secure against chosen-plaintext attacks assuming that E is a PRP secure against chosen-plaintext attacks.
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Lecture Notes in Computer Science.
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Lecture Notes in Computer Science.
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Lecture Notes in Computer Science.
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Lecture Notes in Computer Science.
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Cryptography and Communications.
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Authenticated encryption provides confidentiality and integrity in the same one-pass process, by computing a Message Authentication Code (MAC) at almost no cost over generating keystream. This is natively more efficient than providing confidentiality then authentication in separate passes. The argument as to whether compute MAC (on plaintext) then encrypt, encrypt then compute MAC (on ciphertext), or simultaneously encrypt and compute MAC (on plaintext, then encrypt plaintext and append MAC to ciphertext) was settled by Bellare and Namprempre [1] who showed that computing a MAC of the ciphertext best satisfies security properties of the typical scheme. HKC is a new stream cipher with a built in MAC routine that provides вЂencrypt then MAC’. HKC uses a 256-bit key to provide 256 bits of security. Its native environment is a processor that operates on 64-bit words, although it is also efficient in other environments. HKC is a family of Stream-Cipher-Based Authenticated Encryption algor.
