---
title: Avoid hardcoded seeds in random number generators
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > Avoid hardcoded seeds in random number generators
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Avoid hardcoded seeds in random number generators

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## Metadata{% #metadata %}

**ID:** `dart-security/insecure-random-seed`

**Language:** Dart

**Severity:** Warning

**Category:** Security

**CWE**: [335](https://cwe.mitre.org/data/definitions/335.html)

## Description{% #description %}

Constructing `Random` with a hardcoded integer seed makes the entire sequence of generated values fully predictable and reproducible by anyone who reads the source code.

Never seed a PRNG with a constant. Use `Random()` for non-security contexts or `Random.secure()` for cryptographic purposes, both of which use unpredictable seed sources.

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```dart
import 'dart:math';

void main() {
  final r1 = Random(0);
  final r2 = Random(42);
}
```

```dart
import 'dart:math';

void main() {
  final r = Random(0xFF);
}
```

## Compliant Code Examples{% #compliant-code-examples %}

```dart
import 'dart:math';

void main() {
  final r = Random();
  print(r.nextInt(100));
}
```

```dart
import 'dart:math';

void main() {
  final r = Random.secure();
  print(r.nextInt(100));
}
```

```dart
import 'dart:math';

void main(int seed) {
  final r = Random(seed);
  print(r.nextInt(100));
}
```
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