PowerShell:
Generating random numbers

How to:

PowerShell offers a straightforward approach to generate random numbers using the Get-Random cmdlet. This cmdlet can produce random numbers within a default range or a specified range.

# Generate a random number between 0 and Int32.MaxValue
$randomNumber = Get-Random
Write-Output $randomNumber

To specify a range, use the -Minimum and -Maximum parameters:

# Generate a random number between 1 and 100
$randomNumber = Get-Random -Minimum 1 -Maximum 101
Write-Output $randomNumber

For more control, you can instantiate an object of the System.Random class:

# Using System.Random for a sequence of numbers
$rand = New-Object System.Random
foreach ($i in 1..5) {
    $randomNumber = $rand.Next(1, 101)
    Write-Output $randomNumber
}

If you need a random selection from an array or collection, Get-Random can directly pick an item:

# Random selection from an array
$array = 1..10
$randomItem = Get-Random -InputObject $array
Write-Output $randomItem

Deep Dive

The Get-Random cmdlet in PowerShell leverages the .NET class System.Random under the hood to generate pseudorandom numbers. These are “pseudo” because they use algorithms to produce sequences of numbers that only appear random. For most applications, this level of randomness is sufficient. However, for use cases requiring cryptographic security, System.Random is not suitable due to its predictable nature.

PowerShell and .NET offer System.Security.Cryptography.RNGCryptoServiceProvider for cryptographic randomness, which is more appropriate for generating encryption keys or other security-sensitive operations:

# Cryptographically secure random numbers
$rng = [System.Security.Cryptography.RNGCryptoServiceProvider]::new()
$bytes = New-Object byte[] 4
$rng.GetBytes($bytes)
$randomNumber = [BitConverter]::ToInt32($bytes, 0)
Write-Output $randomNumber

While Get-Random and System.Random satisfy a broad set of needs for randomness in scripting and application logic, it’s essential to select the right tool for the job, especially in security-centric applications where predictability can present a vulnerability.