I read about the AEZ encryption scheme as presented at the CAESAR competition. To me it seems like a construction of an arbitrary length block cipher from a smaller one. The key component is the mixing function. (See the figure… Left: without cipher text stealing, Right: with cipher text stealing.)
Image source: http://www.cs.ucdavis.edu/~rogaway/aez/aez.pdf
In my opinion the properties of a mixing function would be:
- keyable with good avalanche effect
- no need to be cryptographically secure
- arbitrary length
- fast (at least faster than encryption cipher)
AEZ uses reduced round AES as the core of its mixing function. Overall operation time is about 1.8 AES (as mentioned in the document). This algorithm will be bound to the AES cipher.
I wonder, is there an alternative mix function with these properties floating around?