http://www.webcitation.org/5rocpRxhN

 

Quote - Ah, but what about the dreaded massively distributed cracking brute force method for attacking something like 128 bit RC5 encryption?  There are massive zombie farms of infected computers throughout the world and some may have gotten as big as 1 million infected computers.  What if that entire army was unleashed upon the commonly used 128 bit RC5 encryption?  Surprisingly, the answer is not much.  For the sake of argument, let’s say we unleash 4.3 billion computers for the purpose of distributed cracking.  This means that it would be 4.3 billion or 2 to the 32 times faster than a single computer.  This means we could simply take 2 to the 128 combinations for 128-bit encryption and divide it by 2 to the 32 which means that 2 to the 96 bits are left.  With 96 bits left, it’s still 4.3 billion times stronger than 64 bit encryption.  64 bit encryption happens to be the world record for the biggest RC5 bit key cracked in 2002 which took nearly 5 years to achieve for a massive distributed attack. Now that we know that the distributed attacks will only shave off a few bits, what about Moore’s law which historically meant that computers roughly doubled in speed every 18 months?  That means in 48 years we can shave another 32 bits off the encryption armor which means 5 trillion future computers might get lucky in 5 years to find the key for RC5 128-bit encryption.  But with 256-bit AES encryption, that moves the date out another 192 years before computers are predicted to be fast enough to even attempt a massively distributed attack.  To give you an idea how big 256 bits is, it’s roughly equal to the number of atoms in the universe!