Cryptography & Algorithms
Theory and implementation of cryptographic algorithms...
56 files
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Tweakable Block Ciphers
By Teddy Rogers
We propose a new cryptographic primitive, the “tweakable block cipher.” Such a cipher has not only the usual inputs—message and cryptographickey—butal so a third input, the “tweak.” The tweak serves much the same purpose that an initialization vector does for CBC mode or that an once does for OCB mode. Our proposal thus 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 modes of operation based on tweakable block ciphers.
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Verifying Curve25519 Software
By Teddy Rogers
This paper presents results on formal verification of high-speed cryptographic software. We consider speed-record-setting hand-optimized assembly software for Curve25519 elliptic-curve key exchange presented by Bernstein et al. at CHES 2011. Two versions for different micro-architectures are available. We successfully verify the core part of the computation, and reproduce detection of a bug in a previously published edition. An SMT solver supporting array and bit-vector theories is used to establish almost all properties. Remaining properties are verified in a proof assistant with simple rewrite tactics. We also exploit the compositional of Hoare logic to address the scalability issue. Essential differences between both versions of the software are discussed from a formal-verification perspective.
75 downloads
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White-Box Attack Resistant Cryptography
By Teddy Rogers
This thesis is focused on a study of security issues related to an execution of cryptographic algorithms in an untrusted environment. It mainly studies whitebox cryptography methods of transforming algorithms in such a way they resist attacks like key-extraction and inverting in some extent. Particularly it examines whitebox transformations of AES cipher and attacks on these transformations. Transformations construction and implementation is described. In the thesis was discovered the known attack works also on AES transformation using dual ciphers by Karroumi that was supposed to resist the attack. The new improvements for increasing a resistance of transformations to known attacks were proposed.
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White-Box Cryptography and SPN Ciphers. LRC Method
By Teddy Rogers
The method of concealing a linear relationship between elements of a finite field (LRC method) is described. An LRC method based approach to the secure white-box implementations creating problem is considered. SPN cipher characteristics to create its secure White-Box implementation are revealed.
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XOR Encrypting
By Teddy Rogers
This article will explain how to encrypt a section or specified number of bytes in a executable file using XOR method.
97 downloads
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Algorithm Descriptions
By Teddy Rogers
Short and quick descriptions of; SHA-1, MD5, SHA-256, CRC32, Adler32.
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