Pseudo random number generators?

Question

when we say something is pseudo random, that doesn't mean there is a pattern to it does it?

For example would it be safe to use pseudo random number generators for a credit card company to assign credit card numbers to different cards?

Answer 1

Pseudo random numbers are deterministic - they are predictable if you have enough knowledge of the algorithm and its current state (seed). The results are not safe to use for cryptography or other places where random numbers are required.



Computers can, however, create cryptographically strong random numbers. But, it requires something from outside the code itself - some sort of external source of entropy (randomness). This can be a result of timing external I/O events such as hard drive movements, mouse movements, or keystrokes. It can also be a result from dedicated hardware designed for the purpose of creating random data.



Computers have many types of specialized hardware beyond the processor and memory. Sound cards, video cards, hard drive controllers, fast timers, clocks, DMA controllers, ... This list may also include the random number generator.

Answer 2

Credit card numbers are not random, hence why you can determine if a credit card is valid using a bit of code:



http://www.beachnet.com/~hstiles/cardtype.html





But yes, professionally designed pseudo random number generators are safe to use. For example, if you were to try to make your own, it would be un-secure, and would have a lot of collision most likely.



The only way to make a 'real' random number generator would have to base the number on external sources, (ie nothing in the computer). An example might be a random number somewhat based on the current temperature and weather conditions outside, would be truly random.

Answer 3

It would be stupid to use random numbers for credit cards. You just assign them sequentially as they are approved.