Random Number Generator

How this works ???

A random sequence is generated by the computer using a generators called Random Number Generator

What is Random Number Generator ?

A generator which can generate numbers that couldn't be able to predict. But how can we say a sequence is predictable or not and hence comes the classification in Random Number GeneratorS. Random Number Generator was classified into two types, non-deterministic random bit generator (NRBG) and Deterministic Random Bit Generators (DRBG). Random Bits produced by involving some physical process which are unpredictable, fall into class of NRBG’s. The rest of the random bit generators which were developed using some strong mathematical logic and algorithms, fall into the class of DRBGs

A physical process is unpredictable by nature but what about mathematical logic or algorithms they are always predictable if we know the logic or the algorithm. To understand this lets look at an implementation in here.

Documentation

Please look at the paper by clicking the button "Read Paper", for detailed information about Random Number Generators
Read Paper »

Implementation

Linear Congruential Generator

A most important Random Number Generator which could be easily understandable is a Linear Congruential Generator. The following Script would help you understand the formula as well as the pros and cons of this kind.

Multiplyer   * Seed  + offset  % Modulus  = RNG Sequence Period Length =

In the given example here we could see that the modulus is 90 so this means we can have numbers generated would be less than or equal to 90 but this cannot happen in all the cases unless they met the following conditions.

1. m and the offset c are relatively prime,
2. a - 1 is divisible by all prime factors of m,
3. a - 1 is divisible by 4 if m is divisible by 4.

i.e if the generator's values follow these rules then we can obtain a generator with maximum period length.

If you would like to try a bad generator put in values as mentioned below

1. multyplier=30
2. Seed=11
3. offset=11
4. modulus=90

RC4 PRNG

These RNG's are used in many places like games ,cryptography,gambling etc. The following RNG is one of the mostly used cryptographically secure pseudo-random number generator(CSPRNG). This kind is difficult to crack the logic but not impossible, the time it takes to crack these ciphers would be soo long and hence can be considered that these are practically secure random sequence than a perfect random sequence.

More Information

The following videos could be a helpful to understand the concept more clearly

1. Random vs. Pseudorandom Number Generators
2. Random Numbers (2 of 2: Linear Congruential Generator)