AEZ definition
Examples of AEZ in a sentence
Even if a more complicated key scheduling is used (as was done, for instance, in AEZ v2 and v3), it is still straightforward to see that a certain fraction of the keys allows for collisions in the tweakable blockcipher.
In other words, while the issues with the external key padding could be mitigated using a stronger key scheduling, the issues with the tweakable blockcipher in AEZ are more structural.
In this work we focus on AEZ v4, the latest version that has been submitted to CAESAR [17].
From this point of view, our attacks violate the robustness claims on AEZ.
We discuss the AEZ tweakable blockcipher primitive, as well as its weak key issues, in Sect.
AEZ is an authenticated encryption scheme by Hoang, Krovetz, and Rogaway [18].
The four sub-algorithms of AEZ internally use a tweakable blockcipher ˜ I J L ∈ { , } j, i ∈ T {− , }× E : {0, 1}3·128 ×T × {0, 1}128 → {0, 1}128, (2) that gets as input a key 0 1 3·128, a tweak ( ) := 1 0 [0..7] ∪ N+ × N , and bijectively transforms a plaintext X into a ciphertext ˜E (X).
The application of AEZ on Africa leads to one regional agro-ecological zone (RAEZ) for North Africa and four RAEZs for Sub-Saharan Africa (FAO 1994 et al).
We will show how these weak keys can be used to attack the AEZ mode and to distinguish it from a random primitive in constant time.
AEZ uses the two blockciphers AES4 and AES10, where for r ∈ {4, 10}, AESrK0 ,K1 ,...,Kr (X) = aesr(··· aesr(X ⊕ K0) ··· ⊕ Kr−1) ⊕ Kr. The tweakable blockcipher in AEZ is furthermore built of multiplications.