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When you have a tweakable block cipher such as Threefish and your objective is full disk encryption:

Is XTS mode unnecessary? Do you just use the block-length data address (sector + offset, etc) as the tweak to the block cipher?

user2684562
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1 Answers1

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The purpose of XTS is to apply a tweak (and also to handle the last block with ciphertext stealing). If the block-cipher is tweakable then obviously that element is handled.

Would still need to figure something out for the last block.

The solution will most likely involve modifying XTS in-place where the tweak schedule is eliminated in favor of supplying the tweakable block-cipher with the proper address/index as the tweak.

Lamira Ya
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