Verifiable Randomness Documentation

Verifiable Randomness Systems

View the Project on GitHub blockrand-api/blockrand-js

Determinism Is Not the Enemy of Fairness

One of the most common misconceptions developers have when thinking about randomness is this:

“If it’s deterministic, it can’t be fair.”

This belief is understandable—but incorrect. In fact, determinism is a prerequisite for verifiable fairness.

This document explains why.


The False Dichotomy: Random vs Deterministic

Many systems frame randomness like this:

This framing is flawed because it ignores when determinism happens and who controls it.

In real-world provably fair systems:

These are not opposites. They are complementary.


Why Verification Requires Determinism

Verification means:

  1. Given the same inputs
  2. Anyone can independently recompute the output
  3. And arrive at the exact same result

This is only possible if the algorithm is deterministic.

If the system produces different outputs for the same seed, then:

A non-deterministic system is, by definition, unverifiable.


Where Fairness Actually Comes From

Fairness does not come from unpredictability at reveal time.

Fairness comes from:

  1. The inability of any party to manipulate the seed before it is locked
  2. A public, fixed algorithm
  3. A verifiable reveal process

Once the seed is finalized, determinism is a feature, not a flaw.


Commit–Reveal Makes Determinism Safe

In a commit–reveal model:

  1. Parties commit to entropy without revealing it
  2. Commitments are locked (hashes published)
  3. Seeds are revealed later
  4. Outcomes are deterministically derived

At step 4:

Without determinism, commit–reveal collapses.


Casinos Already Use Deterministic Math

Ironically, most developers trust deterministic systems every day:

No one argues that blockchains are “unfair” because they’re deterministic.

They are trusted because they are deterministic.


Determinism vs Predictability

These are not the same thing.

Deterministic:

Predictable:

A system can be deterministic without being predictable.

Blockrand is designed exactly this way.


Why BlockRand Is Fully Deterministic by Design

Blockrand guarantees that:

This allows:

This is impossible without determinism.


The Real Enemy of Fairness

The real threats to fairness are:

None of these are solved by non-determinism.

They are solved by transparency.


Takeaway

Determinism does not weaken fairness.

Determinism enables fairness to be proven.

If a system cannot be deterministically verified, it is not provably fair—no matter how “random” it claims to be.