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Polygraphic substitution cipher: the unit of substitution is a sequence of two or more letters rather than just one (e.g., Playfair cipher) Transposition cipher: the ciphertext is a permutation of the plaintext (e.g., rail fence cipher) Historical ciphers are not generally used as a standalone encryption technique because they are quite easy to ...
Because the pad, like all shared secrets, must be passed and kept secure, and the pad has to be at least as long as the message, there is often no point in using a one-time pad, as one can simply send the plain text instead of the pad (as both can be the same size and have to be sent securely). [18]
Unicity distance is a useful theoretical measure, but it does not say much about the security of a block cipher when attacked by an adversary with real-world (limited) resources. Consider a block cipher with a unicity distance of three ciphertext blocks.
The encrypted text then contains the IV, ciphertext, and authentication tag. GCM operation. For simplicity, a case with only a single block of additional authenticated data (labeled Auth Data 1) and two blocks of plaintext is shown. Encryption: A series of 128-bit counters is encrypted using the block cipher E with key K; this can occur in ...
The KG-84C contains all of the KG-84 and KG-84A modes, plus a variable update counter, improved HF performance, synchronous out-of-sync detection, asynchronous cipher text, plain text, bypass, and European TELEX protocol. The KG-84 (A/C) is certified to handle data at all levels of security.
By whether they work on blocks of symbols usually of a fixed size (block ciphers), or on a continuous stream of symbols (stream ciphers). By whether the same key is used for both encryption and decryption (symmetric key algorithms), or if a different key is used for each (asymmetric key algorithms). If the algorithm is symmetric, the key must ...
Encryption is an important tool but is not sufficient alone to ensure the security or privacy of sensitive information throughout its lifetime. Most applications of encryption protect information only at rest or in transit, leaving sensitive data in clear text and potentially vulnerable to improper disclosure during processing, such as by a ...
The Rail Fence cipher is a form of transposition cipher that gets its name from the way in which it is encoded. In the rail fence cipher, the plaintext is written downward and diagonally on successive "rails" of an imaginary fence, then moves up when it gets to the bottom. The message is then read off in rows.