Block Cipher Modes Of Operation
In cryptography, modes of operation is the procedure of enabling the repeated and secure use of a block cipher under a single key. A block cipher by itself allows encryption only of a single data block of the cipher's block length. When targeting a variable-length message, the data must first be partitioned into separate cipher blocks. Typically, the last block must also be extended to match the cipher's block length using a suitable padding scheme. A mode of operation describes the process of encrypting each of these blocks, and generally uses randomization based on an additional input value, often called an initialization vector, to allow doing so safely.
Modes of operation have primarily been defined for encryption and authentication. Historically, encryption modes have been studied extensively in regard to their error propagation properties under various scenarios of data modification. Later development regarded integrity protection as an entirely separate cryptographic goal from encryption. Some modern modes of operation combine encryption and authentication in an efficient way, and are known as authenticated encryption modes.
While modes of operation are commonly associated with symmetric encryption, they may also be applied to public-key encryption primitives such as RSA in principle (though in practice public-key encryption of longer messages is generally realized using hybrid encryption).
Read more about Block Cipher Modes Of Operation: History and Standardization, Initialization Vector (IV), Padding, Electronic Codebook (ECB), Cipher-block Chaining (CBC), Propagating Cipher-block Chaining (PCBC), Cipher Feedback (CFB), Output Feedback (OFB), Counter (CTR), Error Propagation, Authenticated Encryption, Other Modes and Other Cryptographic Primitives
Famous quotes containing the words block, cipher, modes and/or operation:
“Of course I lie to people. But I lie altruistically—for our mutual good. The lie is the basic building block of good manners. That may seem mildly shocking to a moralist—but then what isn’t?”
—Quentin Crisp (b. 1908)
“It is not an arbitrary “decree of God,” but in the nature of man, that a veil shuts down on the facts of to-morrow; for the soul will not have us read any other cipher than that of cause and effect. By this veil, which curtains events, it instructs the children of men to live in to-day.”
—Ralph Waldo Emerson (1803–1882)
“Of the modes of persuasion furnished by the spoken word there are three kinds. The first kind depends on the personal character of the speaker; the second on putting the audience into a certain frame of mind; the third on the proof, provided by the words of the speech itself.”
—Aristotle (384–323 B.C.)
“An absolute can only be given in an intuition, while all the rest has to do with analysis. We call intuition here the sympathy by which one is transported into the interior of an object in order to coincide with what there is unique and consequently inexpressible in it. Analysis, on the contrary, is the operation which reduces the object to elements already known.”
—Henri Bergson (1859–1941)