QUOTE(jack_herer @ Nov 18 2009, 12:19 PM)
this is not true, as it is a 16 bit key, not a 256 bit. and verifing the key is not so hard and doesn't need to flash, because YOU give the fw the data to encrypt,
fw encrypt this data, than you can verify the key bruteforcing this data as you sent the "unencrypted data"
All wrong. -- The DVD KEY is 16byte key, all bytes have 8 bits, so that is 128bit key.
Here is a section on 128bit keys taken from the Wikipedia on "Brute Force Attack":
There is a physical argument that a 128-bit symmetric key is secure against brute force attack. The so-called Von Neumann-Landauer Limit implied by the laws of physics sets a lower limit on the energy required to perform a computation of ln(2)kT per bit erased in a computation, where T is the temperature of the computing device in kelvins, k is the Boltzmann constant, and the natural logarithm of 2 is about 0.693. No irreversible computing device can use less energy than this, even in principle.
Thus, in order to simply flip through the possible values for a 128-bit symmetric key (ignoring doing the actual computing to check it) would require 2128 − 1 bit flips. If we assume that the calculation occurs near room temperature (~300 K) we can apply the Von Neumann-Landauer Limit to estimate the energy required as ~1018 joules, which is equivalent to consuming 30 gigawatts of power for one year (30◊109 W◊365◊24◊3600 s = 9.46◊1017 J). The full actual computationóchecking each key to see if you have found a solutionówould consume many times this amount.
However, this argument assumes that the register values are changed using conventional set and clear operations which inevitably generate entropy. It has been shown that computational hardware can be designed not to encounter this theoretical obstruction (see reversible computing), though no such computers are known to have been constructed.
The amount of time required to break a 128-bit key is also daunting. Each of the 2128 (340,282,366,920,938,463,463,374,607,431,768,211,456) possibilities must be checked. A device that could check a billion billion keys (1018) per second would still require about 1013 years to exhaust the key space. This is a thousand times longer than the age of the universe, which is about 13,000,000,000 (1.3◊1010) years.
So I come back check back with you in 13 billion years, too see if you have found your DVD key by then.