March 5, 2002
Practical Aspects of Modern Cryptography
30
RNGs in Kerberos v4 (continued)
nThe seed is a 32-bit value, so while the session key is used for DES (64 bits long, normally 56 bits of entropy), it has only 32 bits of entropy
nWhat’s worse, the five values have predictable portions
nTime is completely predictable
nProcessID is mostly predictable
nEven hostID has 12 predictable bits (of 32 total)