Contents
What is an entropy pool?
The entropy pool is used in two ways: random numbers are generated from it and it is replenished with entropy by the kernel. When random numbers are generated from the pool the entropy of the pool is diminished (because the person receiving the random number has some information about the pool itself).
What is kernel entropy pool?
The kernel maintains an entropy pool which is used to store random data generated from events like inter-keypress timings, inter-interrupt timings, etc. Randomness from these interfaces are fixed with the entropy pool using a sort of cyclic redundancy check-like function.
What is entropy source?
Definition(s): A physical source of information whose output either appears to be random in itself or by applying some filtering/distillation process. This output is used as input to either a RNG or PRNG.
Is entropy the same as randomness?
entropy, the measure of a system’s thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system.
How to create a random entropy pool in web server?
On a web-server you can combine server data (HW, SW, performance), client data (user-agent, request-time, cookie, URL variables, whatever you can gather), some external data (like random.org), mix everything with let say sha1 (mixed_data + time + some_secret_key) and you get fairly unpredictable bits of random data.
Why do we feed entropy into / dev / urandom?
Upon each reboot, the seed will be read, fed into /dev/urandom, and a new seed immediately generated (from /dev/urandom) to replace it. Thus, this guarantees that /dev/urandom will always have enough initial entropy to produce cryptographically strong alea, perfectly sufficient for any mundane cryptographic job, including password generation.
What’s the difference between urandom and / dev / random?
/dev/urandom will not block, while /dev/random may do so. /dev/random maintains a counter of “how much entropy it still has” under the assumption that any bits it has produced is a lost entropy bit.
How to generate random data in cryptography pool?
I use a combination of data sources and a good hashing algorithm to generate random data.