“RNGs Exposed: Do They Really Generate Random Numbers?”
“RNGs Exposed: Do They Really Generate Random Numbers?”

“RNGs Exposed: Do They Really Generate Random Numbers?”

Introduction to RNGs

A random number generator (RNG) is a computational or physical device designed to generate numbers in an unpredictable way. The concept of random number generation dates back centuries, with early examples including dice rolls and shuffling cards. However, the modern form of RNGs emerged with the invention of computers.

At their core, RNGs work by using mathematical formulas or physical sources of randomness to produce sequences of random numbers. There are two main types of RNGs:

  • Pseudorandom number generators (PRNGs) – Algorithmic RNGs that use mathematical formulas to simulate randomness. PRNGs start with an initial seed value and apply formulas to generate a sequence of seemingly random numbers.
  • True random number generators (TRNGs) – RNGs that use unpredictable physical processes to generate randomness. Sources can include atmospheric noise, radioactive decay, and quantum mechanics.

Computer scientists John von Neumann and Stanislaw Ulam are credited with pioneering early PRNGs in the 1940s. Their “middle-square method” algorithm was an early attempt at using math to generate randomness. In the 1960s and 70s, scientists developed more sophisticated PRNGs based on linear congruential generators and linear feedback shift registers.

Modern applications rely on cryptographically secure PRNGs based on cryptographic hash functions. TRNGs have also been implemented in hardware like Intel’s RdRand instruction set. Overall, RNGs are now a fundamental component of many computer systems and serve crucial roles in cryptography, statistics, and other fields relying on randomness.

Types of RNGs

There are a few main types of random number generators (RNGs):

Pseudo RNGs

Pseudo RNGs, also known as deterministic RNGs, are algorithms that generate seemingly random numbers using mathematical formulas. The sequence of numbers is not truly random since it is determined by a set seed value. However, the sequence appears random and passes many statistical tests for randomness. Pseudo RNGs are commonly used in things like computer simulations and video games where speed and reproducibility are more important than true randomness. They are deterministic and will produce the exact same sequence when starting from the same seed value.

True RNGs

True RNGs, also known as hardware RNGs, generate randomness using physical processes. Some examples include measuring atmospheric noise, thermal noise from a semiconductor, or radioactive decay timings. The output of true RNGs is non-deterministic and cannot be predicted. They are considered to produce better quality random numbers than pseudo RNGs, but may be slower or require specialized hardware. True RNGs are necessary for applications like cryptography where unpredictability is critical.

Cryptographically Secure RNGs

Cryptographically secure pseudo RNGs (CSPRNGs) are a special type of pseudo RNG designed for use in cryptography. They generate randomness by repeatedly hashing a set of initial true random values. The hashing process introduces enough chaos to produce a sequence that is statistically random while still being deterministic. Seed values are regularly replenished with new true random numbers. CSPRNGs offer the speed of a PRNG with security approaching that of a true RNG. This makes them suitable for encryption, digital signatures, and authentication protocols which need high-quality randomness.

RNGs in Gambling

Random number generators (RNGs) play a critical role in gambling, powering everything from slot machines and keno drawings to scratch tickets and bingo cages. Casinos and lottery operators rely on RNGs to ensure game outcomes are random and fair.

For table games like roulette, weighted mechanical systems are often still used to pick random numbers. But for electronic games, RNGs built into the software decide each spin or hand. The algorithms generate long strings of random numbers, usually tens of thousands per second, then map portions of that sequence to game events and symbols. This aims to ensure results are really random and can’t be predicted.

Regulators typically audit and certify the RNGs gambling companies use. But some players still perceive electronic gambling as potentially rigged, less trustworthy than physical randomization methods. However, studies and field testing have not shown evidence of systematic RNG bias in major licensed casinos. Provably fair cryptography can also let players independently verify game randomness.

So properly implemented RNGs can offer verifiable randomness. But the rapid pace and lack of physicality may instinctively feel less fair to some gamblers. So addressing transparency and educating players on RNG testing may help build trust. Responsible gambling advocates also say focusing less on odds and more on entertainment value is wise when playing games that rely heavily on random chance.

RNGs in Video Games

Random number generators (RNGs) play a crucial role in many aspects of video games. Here are some of the key ways that RNGs affect gameplay:

Procedural Generation

Procedural generation refers to creating game content algorithmically rather than manually designing it. RNGs are commonly used in procedural generation to create randomized worlds, levels, characters, items, quests, and more.

For example, Minecraft uses RNGs to procedurally generate new terrain and dungeons every time you explore. Rogue-like games like Binding of Isaac have randomly generated floors and items each playthrough. Even non-procedurally generated games use RNGs to randomly place some items and details to add variety.

Procedural generation powered by RNGs provides near-infinite content while minimizing human design efforts. It also increases replayability since players encounter new situations each time.

Loot Drops

The loot that enemies drop when defeated is often determined by RNGs. Games will have loot tables with certain items and their drop chances. When an enemy dies, the game rolls an RNG to see what item(s) they will drop based on the probabilities.

This creates an exciting variability in rewards. Getting a rare powerful weapon feels more special when the RNG aligns. It also incentivizes players to replay content and “farm” enemies to get desired loot.

Some games like Borderlands display the actual percentage chances for different rarity item drops. Others keep the systems hidden. But RNGs are almost always used under the hood to govern loot drops.

Damage Calculation

RNGs frequently factor into damage calculation in video games. When a player attacks an enemy, the game will:

  • Take the player’s base damage value
  • Apply random variance with a RNG (often +/- 10-20%)
  • Calculate defenses and resistances
  • Roll another RNG for “critical hit” chance
  • Determine the final damage dealt

The RNG variance creates unpredictability in damage outputs. A weapon won’t do the exact same damage every single attack. This makes combat feel more dynamic and less robotic.

RNGs are thus integral to major aspects of video games like procedural content, rewarding players, and combat mechanics. Their ability to inject randomness enhances gameplay variety and replayability.

RNGs for Security

Random number generators play a critical role in many aspects of computer security and cryptography. Two key uses of RNGs for security include:

Generating Encryption Keys

Most modern encryption algorithms rely on randomly generated encryption keys to secure data. The keys are generated through cryptographically secure pseudo-random number generators (CSPRNGs). These CSPRNGs are designed to generate a sequence of random numbers that are unpredictable enough to make brute force attacks infeasible.

To generate a cryptographic key, the CSPRNG produces a random byte string of sufficient length for the algorithm. For example, AES-256 encryption uses 256-bit keys, so the RNG would output 256 random bits to use as the key. Proper randomization of keys is essential to prevent attackers from guessing or determining the keys through analysis.

Creating Salts for Password Hashing

When storing user passwords, the passwords should not be stored in plain text. Instead, they are passed through a cryptographic hash function after being combined with a random salt value.

The salt is generated using a CSPRNG each time a user creates an account or changes their password. This salt is then appended or prepended to the password before hashing. Using a random salt value protects against rainbow table attacks, makes it difficult for attackers to determine passwords through hash collisions, and prevents the same password from having the same hash.

By utilizing cryptographically strong random number generators, system security can be enhanced significantly. Proper use of RNGs protects the confidentiality and integrity of sensitive data and user accounts.

Potential Biases

All RNGs have potential sources of bias that can influence the randomness of the numbers generated. Two key areas that can introduce bias are seeding practices and algorithm limitations.

Seeding Practices

Most RNGs require a starting number or “seed” to begin generating outputs. How this seed is selected can impact the randomness of the sequence. If the seed is not sufficiently random itself, it can skew the results. For example, using the system time as the seed could introduce periodicity based on how often new seeds are generated. Cryptographically secure methods are preferred for seed generation.

Algorithm Limitations

The algorithms at the heart of RNGs have inherent limitations that bound how random they can be. Because computers operate deterministically, RNG algorithms use various tricks to emulate randomness within those constraints. Simple linear congruential generators are notorious for their observable patterns. More complex cryptographic algorithms do better, but may have subtle correlations across long sequences. Proper statistical testing is required to identify and mitigate these biases.

Overall, RNGs require careful implementation and testing to account for sources of bias and ensure sufficient randomness for the intended application. While improvements continue to be made, true randomness may not be possible computationally. Understanding the limitations helps set proper expectations when relying on RNGs for critical tasks.

Testing RNGs

RNGs are crucial components in many applications, so verifying their randomness is important. There are several methods used to test the quality of RNGs.

Statistical Tests

Statistical tests analyze the output of RNGs to detect patterns and biases. Common statistical tests include:

  • Frequency test – Checks if certain values occur more often than expected. All outcomes should occur roughly equally.
  • Runs test – Looks for unexpected sequences or runs of the same outcome. The oscillations between outcomes should be random.
  • Serial correlation test – Checks if each new random number depends on the previous one. Each outcome should be independent.
  • Poker test – Determines if a 5-card poker hand from the RNG has the expected distribution of hands.
  • Chi-squared test – Compares the observed distribution to the expected uniform distribution. Used to detect biases.

Auditing Procedures

In addition to statistical tests, auditing the design and source code of RNGs can verify their integrity:

  • Review the algorithm – Flawed formulas can undermine randomness despite passing stats tests.
  • Examine the seeding process – A weak or predictable seed can lead to non-random patterns. Seeds should have sufficient entropy.
  • Check for hidden constants – Hardcoded constants for any purpose could introduce biases.
  • Assess the programming – Coding mistakes could affect the RNG implementation. Rigorous code review is necessary.
  • Monitor updates – Changes to the software could modify the RNG behavior over time.

Together, statistical testing and auditing procedures help ensure RNGs produce sufficiently random and unbiased results for the intended application. Ongoing verification is essential for RNGs used in critical systems.

RNGs in Machine Learning

Random number generators play an important role in machine learning algorithms. They are commonly used for:

Weight Initialization

When training neural networks and other machine learning models, the initial weights given to the model are often randomly initialized. Using an RNG allows the model to start with a unique set of weights each time training begins. This introduces some noise and diversity into the training process, helping the model avoid local optima and converge on a robust set of weights. Different RNG seeds will produce different starting weights, which can impact the end performance.

Data Shuffling

Most machine learning datasets are shuffled prior to training, splitting the data into train/validation/test sets, and batching. Shuffling the data helps ensure the model sees a broad mix of examples during training and avoids any biases that may exist in the order of the original dataset. Pseudorandom number generators are used to randomly permute the data points while keeping the distribution intact. The RNG seed controls the shuffling, allowing repeatable experiments. Poor shuffling can skew the distribution across batches and reduce model accuracy.

RNGs are a fundamental part of the training process for many machine learning algorithms. Care must be taken to ensure the RNGs provide sufficient randomness and avoid introducing biases during weight initialization, data shuffling, and other steps. Proper use of RNGs can enhance model generalization and robustness.

Philosophical Implications

The prevalence of random number generators (RNGs) in our digital world has prompted debates around determinism, free will, and the fundamental nature of randomness.

On one hand, the outputs of a well-designed RNG should be truly unpredictable and non-deterministic. Each number should have equal probability of occurring, unbound by causal links. This aligns with indeterminist philosophical views, which argue that some events are not predetermined and that true randomness exists. The uncertainty introduced by RNGs seems to support notions of free will – that our choices and actions are not set in stone.

However, a counterargument is that RNG algorithms are fully determined and predictable, in that their outputs depend wholly on the initial seed. Given the same starting point, an RNG will produce the exact same sequence every time. This aligns more with a deterministic worldview – that everything proceeds from past states in a predictable way, leaving no room for true randomness. From this lens, RNGs may provide the illusion of randomness and freedom while still behaving in a mechanical, prescribed manner.

These debates reflect deeper divisions around whether fundamental randomness exists in the world, or whether uncertainty is merely a consequence of our limited knowledge. RNGs force us to confront philosophical questions around the source and nature of unpredictability. Their role in sensitive domains like gambling and encryption also surfaces issues of fairness, control, and transparency. Though RNGs may not settle these debates, understanding their mechanisms and implications provides insight into our conceptions of randomness.


Random number generators play an important role in many aspects of our lives, from gambling and video games to computer security and machine learning algorithms. In this article, we explored the different types of RNGs and how they work to produce sequences of random numbers.

We looked at how RNGs affect the odds in games of chance, introducing unpredictability but also the potential for bias. Testing and verifying the randomness of an RNG is crucial for fairness and security. While true randomness may not exist, cryptographically secure pseudo-random number generators get us quite close.

As RNGs continue improving, they will likely play an even bigger part in emerging technologies like AI and blockchain. Security experts and statisticians are working to develop ever more sophisticated algorithms resistant to prediction or manipulation.

Philosophically, the randomness in our lives highlights how little control we have over certain events. But properly implemented RNGs provide the appearance of chance while ensuring mathematical fairness behind the scenes.

In summary, random number generation requires complex math and computing power to approximate true randomness. RNGs impact many aspects of the digital world, both visibly through games and invisibly in secure systems. Understanding how they work helps us use them judiciously and improve them for the future.

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