We investigate the spectrum for frames with block size four, and discuss several applications to the construction of other combinatorial designs. Our main result is that a frame of type hu, having blocks of size four, exists if and only if u ≥ 5, h ≡ 0 mod 3 and h(u − 1) ≡ 0 mod 4, except possibly where (i) h = 9 and u ∈ {13, 17, 29, 33, 93, 113, 133, 153, 173, 193}; (ii) h ≡ 0 mod 12 and u ∈ {...

Background. The class on complexity goes through how to design a fixed block size motion estimator. It is useful to have reviewed that class before proceeding with this document. Basically, often in video the only difference between much of the content in subsequent frames is motion (imagine panning a camera slowly over a fixed scene). If this is true the difference between subsequent frames ca...

In this paper, we present One-key CBC MAC (OMAC) and prove its security for arbitrary length messages. OMAC takes only one key, K (k bits) of a block cipher E. Previously, XCBC requires three keys, (k + 2n) bits in total, and TMAC requires two keys, (k + n) bits in total, where n denotes the block length of E. The saving of the key length makes the security proof of OMAC substantially harder th...