imclab / crypto-research

Eric & Mike, figuring stuff out

Plans:

• Implement CSS
• Break CSS
• Implement Knapsack algorithm
• Implement Blowfish?

Attacking DVD

• Each DVD has a Title Key (Tk) which decrypts the content (actually, it may have more than one, but this detail isn't necessary for this discussion).

  Dec(Ciphertext, Tk) = Plaintext
  

• The Title Key is not stored on the disc directly. Instead, it is encrypted with any number of Player Keys (Pk). Each encryption of the Title Key is stored on the disc.

  Enc(Tk, Pk1) = Tk1
  [ ... ]
  Enc(Tk, Pkn) = Tkn
  

  By controlling the Player Keys assigned to DVD manufacturers, DVDs may be region-locked.

• After finding the Title Key by breaking one encryption, all Player Keys can be deciphered with a chosen plaintext attack