Random number generator

Random number generator

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About random numbers

Random numbers are values ​​drawn with equal probability within a certain range and are widely used in computer science, statistics, cryptography and other fields.

Random number quality assessment

Excellent: True random number
Good: Cryptographically secure pseudo-random number
General: Statistical pseudo-random number
Poor: Simple linear pseudo-random number

Influencing factors: random number generation algorithm, entropy source quality, random seed selection, etc.

The scientific background of random numbers

Random number generation involves multiple scientific fields, including mathematics, physics, and computer science:

  • Pseudo-random number generator (PRNG): Generate seemingly random sequences based on deterministic algorithms, such as linear congruence method, Mason rotation algorithm, etc.
  • True Random Number Generator (TRNG): Use the randomness of physical processes to generate true random numbers, such as thermal noise, quantum phenomena, etc.
  • Cryptographic Secure Pseudo-Random Number Generator (CSPRNG): High-quality pseudo-random number generator designed for cryptography applications

In computers, most random numbers are actually "pseudo-random numbers", which are generated by deterministic algorithms but exhibit statistically randomness. True random numbers need to take advantage of uncertainties in physical processes, such as radioactive decay or atmospheric noise.

The quality of random numbers is often evaluated by a variety of statistical tests, such as the NIST Random Number Test Suite, which detects patterns and deviations in a sequence.

FAQ

What is a true random number?

True random numbers are generated based on uncertainty in physical processes, such as quantum phenomena or thermal noise. They are unpredictable and unreproducible, unlike pseudo-random numbers generated based on algorithms.

How random are there in the browser?

The Math.random() function used by the browser generates pseudo-random numbers, which are suitable for general purposes but are not suitable for cryptography applications. For higher security needs, modern browsers provide the getRandomValues() method in the Web Crypto API.

How to test the quality of random numbers?

The quality of random numbers can be evaluated through a variety of statistical tests, such as frequency tests, run tests, and entropy tests. Professional tools include NIST Random Number Test Suite and Diehard Testing.

Why do you need to set a random seed?

Random seeds are the initial value of the pseudo-random number generator, which determines the entire random sequence that is subsequently generated. Setting up fixed seeds can make random sequences reproducible, which is useful in scientific experiments and debugging.

Random number usage tips

Choose the right range

Set a suitable range of random numbers according to specific needs to avoid excessive or too small range affecting the use effect.

Precautions for safe application

For security-sensitive scenarios, use a cryptographically secure random number generator to avoid simple pseudo-random numbers.

Save important results

For important random results, save or export them in time to avoid data loss due to refreshing pages or clearing caches.

Analyze randomness

Use data visualization tools to analyze the random number distribution to ensure that the generated results meet the expected randomness requirements.

Random Number Knowledge Encyclopedia

What are pseudo-random numbers?

Pseudo-random numbers are seemingly random but actually predictable sequences of numbers generated by deterministic algorithms. Most "random numbers" in computers are actually pseudo-random numbers, which are based on an initial seed value and can generate sequences with good statistical characteristics.

Entropy of random numbers

Entropy is an important indicator for measuring stochasticity. High entropy values ​​indicate higher uncertainty and randomness. The true random number generator captures entropy from physical phenomena, while the pseudo-random number generator relies on algorithmic design to simulate high entropy characteristics.

Periodicity of random numbers

All pseudo-random number generators have a "cycle", after which the sequence will start to repeat. Good random number generators have very long periods, such as the Mason rotation algorithm (MT19937) has a period of 2^19937-1, which is huge enough to avoid duplication in practical applications.

Uniform distribution and non-uniform distribution

Basic random numbers are usually evenly distributed, with the probability of occurrence of each number equal. In some applications, non-uniformly distributed random numbers are needed, such as normal distribution (Gaussian distribution), exponential distribution, etc., which can be obtained from uniformly distributed random numbers through specific algorithms.