nReally good random numbers are hard to acquire
nBest bits come from physical systems
nRadioactive decay (http://www.fourmilab.ch/hotbits/)
nNoise diodes
nLava Lamps
nGetting many truly random bits is slow
nGetting many shared truly random bits is more
awkward
nGetting “good randomness” is important for many crypto algorithms
nPicking private key components & secret keys
nSome algorithms (e.g. DSA) require random input!