First Advisor

Thomas Shrimpton

Date of Publication

Summer 8-7-2015

Document Type


Degree Name

Doctor of Philosophy (Ph.D.) in Computer Science


Computer Science




Cryptography -- Mathematics, Computer security, Computer systems -- Access control, Data encryption (Computer science)



Physical Description

1 online resource (vi, 94 pages)


Tweakable ciphers are a building block used to construct a variety of cryptographic algorithms. Typically, one proves (via a reduction) that a tweakable-cipher-based algorithm is about as secure as the underlying tweakable cipher. Hence improving the security or performance of tweakable ciphers immediately provides corresponding benefits to the wide array of cryptographic algorithms that employ them. We introduce new tweakable ciphers, some of which have better security and others of which have better performance than previous designs. Moreover, we demonstrate that tweakable ciphers can be used directly (as opposed to as a building block) to provide authenticated encryption with associated data in a way that (1) is robust against common misuses and (2) can, in some cases, result in significantly shorter ciphertexts than other approaches.


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