Tweakable Block Ciphers

作者：Moses Liskov, Ronald L. Rivest, David Wagner · 发表于：Journal of Cryptology · 年份：2010 · DOI：10.1007/s00145-010-9073-y · 被引用次数：196 · 研究领域：Cryptographic Implementations and Security、Coding theory and cryptography、Chaos-based Image/Signal Encryption

A common trend in applications of block ciphers over the past decades has been to employ block ciphers as one piece of a “mode of operation”—possibly, a way to make a secure symmetric-key cryptosystem, but more generally, any cryptographic application. Most of the time, these modes of operation use a wide variety of techniques to achieve a subgoal necessary for their main goal: instantiation of “essentially different” instances of the block cipher. We formalize a cryptographic primitive, the “ tweakable block cipher .” Such a cipher has not only the usual inputs—message and cryptographic key—but also a third input, the “tweak.” The tweak serves much the same purpose that an initialization vector does for CBC mode or that a nonce does for OCB mode. Our abstraction brings this feature down to the primitive block-cipher level, instead of incorporating it only at the higher modes-of-operation levels. We suggest that (1) tweakable block ciphers are easy to design, (2) the extra cost of making a block cipher “tweakable” is small, and (3) it is easier to design and prove the security of applications of block ciphers that need this variability using tweakable block ciphers.