Block Cipher Modes of Operation

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:

    Only he who can view his own past as an abortion sprung from compulsion and need can use it to full advantage in the present. For what one has lived is at best comparable to a beautiful statue which has had all its limbs knocked off in transit, and now yields nothing but the precious block out of which the image of one’s future must be hewn.
    Walter Benjamin (1892–1940)

    The eye is the first circle; the horizon which it forms is the second; and throughout nature this primary figure is repeated without end. It is the highest emblem in the cipher of the world.
    Ralph Waldo Emerson (1803–1882)

    The essence of belief is the establishment of a habit; and different beliefs are distinguished by the different modes of action to which they give rise.
    Charles Sanders Peirce (1839–1914)

    Human knowledge and human power meet in one; for where the cause is not known the effect cannot be produced. Nature to be commanded must be obeyed; and that which in contemplation is as the cause is in operation as the rule.
    Francis Bacon (1560–1626)