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Can someone please provide a description of TCB algorithm?

+1  A: 

My cryptographic skills are a little bit rusty - but IMHO, Tweaked Codebook = Tweakable Block Cipher.

It's basically ECB with a Tweak, that "patches" ECB's biggests flaws: identical plaintext blocks result in identical ciphertext (exposing your ciphertext to malicious substitution and showing data patterns).

With a plaintext message P, cut in n-bits blocks X1, X2, X3... Xi... Xn

  1. Xi (XOR) Tweak(i) -> CC
  2. Encrypt_function(CC) -> Ci

Depending on your implementation, your Tweak is generated using a function of your choice (taking your block number as a parameter). A very simple (unsecure?) one could be:

  • Tweak(i) = i

I'm not 100% OK with my answer; at least that's what I remember and that's what I get when looking at an extract of IEEE 1619-2007. I'd really like to read more on this!

Brian Clozel
I got one doc on implementation from the link you provided to WikiPedia: http://axelkenzo.ru/index.php?downloads=1619-2007-NIST-Submission.pdfIt looks like it has some clues ;)
FractalizeR
Yep. I didn't put this link in my answer - it seems like there's a copyright issue with this document (see page 1). Keep us updated!
Brian Clozel