Practical Internet of Things Security - Second Edition

Random number generation

Randomness of numbers is a keystone of cryptography given their use in generating a number of different cryptographic variables, such as keys. Large, random numbers are difficult to guess or iterate through (brute force), whereas highly deterministic numbers are not. Random Number Generators (RNGs) come in two basic flavors, deterministic and nondeterministic. Deterministic simply means they are algorithm-based, and for a single set of inputs they will always produce the same output. Non-deterministic means the RNG is generating random data in some other fashion, typically from very random physical events, such as circuit noise and other low bias sources (even semi-random interrupts occurring in operating systems). ...