TNT: How to Tweak a Block Cipher
theory and application of cryptographic techniques(2020)
摘要
In this paper, we propose Tweak-aNd-Tweak (\\(\\mathsf {TNT}\\) for short) mode, which builds a tweakable block cipher from three independent block ciphers. \\(\\mathsf {TNT}\\) handles the tweak input by simply XOR-ing the unmodified tweak into the internal state of block ciphers twice. Due to its simplicity, \\(\\mathsf {TNT}\\) can also be viewed as a way of turning a block cipher into a tweakable block cipher by dividing the block cipher into three chunks, and adding the tweak at the two cutting points only. \\(\\mathsf {TNT}\\) is proven to be of beyond-birthday-bound \\(2^{2n/3}\\) security, under the assumption that the three chunks are independent secure n-bit SPRPs. It clearly brings minimum possible overhead to both software and hardware implementations. To demonstrate this, an instantiation named TNT-AES with \\(6 \\), \\(6 \\), \\(6 \\) rounds of AES as the underlying block ciphers is proposed. Besides the inherent proven security bound and tweak-independent rekeying feature of the \\(\\mathsf {TNT}\\) mode, the performance of TNT-AES is comparable with all existing TBCs designed through modular methods.
更多查看译文
关键词
AES, Tweakable block cipher, chi(2) method, Proof
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络