Generate secure pseudorandom data either as a byte array or base64 string

Get-SecureRandom.ps1

<#
.SYNOPSIS
    Generate secure pseudorandom data either as a byte array or base64 string

.PARAMETER Bytes
    Number of bytes to generate. Defaults to 16.

.PARAMETER Base64
    Output bytes in base64-encoded string

.EXAMPLE
    .\Get-SecureRandom.ps1 -Bytes 32 -Base64

    Returns something like "cawixyAvJCwOsnqV58WbSurVXOb15zVkO6SQy+ZXlQk="
#>
[CmdletBinding()]
param(
    [Parameter()]
    [uint32]$Bytes = 16,

    [Parameter()]
    [switch]$Base64
)

$ErrorActionPreference = "Stop"
Set-StrictMode -Version 5.0

$buffer = [byte[]]::new($Bytes)
$rng = [Security.Cryptography.RandomNumberGenerator]::Create()
try {
    $rng.GetBytes($buffer)
} finally {
    $rng.Dispose()
}

if ($Base64) {
    [Convert]::ToBase64String($buffer)
} else {
    $buffer
}