- RNG (Random Number Generator) produces random bits
- non-deterministic
- uses external analog source
- DRBG (Deterministic Random Bit Generator) produces pseudorandom bits
- deterministic
- from a seed (taken from RNG)
- PRNG (Pseudo-Random Number Generator) produces pseudorandom bits
- non-deterministic
- from a seeds from an RNG to maintain entropy pool
- produces output bits using a DRBG
Analog Source + seed --> RNG --> 010..10 --> PRNG (DRBG is a component of PRNG) --> 0101011100..01
Deterministic Random Bit Generator, DRBGINPUT: short fixed-length seed (e.g. 256 bit)OUTPUT: arbitrarily long
| Bad, do not use | Good, do use |
|---|---|
| rand(3) | /dev/urandom |
| random(3) | Linux getrandom() |
| PHP rand() | Java SecureRandom |
| your own algorithm | Node.js crypto.randomBytes |
| &nbrp; | WINAPI BCryptGenRandom |
| &nbrp; | openssl rand |