Attribute to and addapted from https://github.com/ghost1face/base62/blob/master/Base62/Base62Converter.cs

Base62EncodeDecode.psm1

function Base62Encode([string] $inputStr = [Guid]::NewGuid().ToString()) 
{
    [byte[]] $byteArr = [system.Text.Encoding]::UTF8.GetBytes($inputStr)
    $converted = BaseConvert $byteArr 256 62

    $sb = [System.Text.StringBuilder]::new()
    for ($i = 0; $i -lt $converted.Length; $i++) {
        $sb.Append($CharacterSet[$converted[$i]]) | Out-Null
    }
    
    return $sb.ToString()
}

function Base62Decode([string] $inputStr)
{
    [byte[]] $byteArr = [System.Byte[]]::CreateInstance([System.Byte], $inputStr.Length)
    for ($i = 0; $i -lt $byteArr.Length; $i++) {
        $byteArr[$i] = $CharacterSet.IndexOf($inputStr[$i]) -as [byte]
    }

    $converted = BaseConvert $byteArr 62 256
    return [system.Text.Encoding]::UTF8.GetString($converted, 0, $converted.Length)
}


function BaseConvert([byte[]] $source, [int] $sourceBase, [int] $targetBase)
{
    $result = New-Object Collections.Generic.List[Int]
    [int] $count = 0

    while (($count = $source.Length) -gt 0) {
        $quotient =  New-Object Collections.Generic.List[byte]
        [int] $remainder = 0

        for ($i = 0; $i -lt $count; $i++) {
            [int] $accumalator = $source[$i] + $remainder * $sourceBase
            [byte] $digit = [System.Convert]::ToByte(($accumalator - ($accumalator % $targetBase)) / $targetBase)
            $remainder = $accumalator % $targetBase
            if ($quotient.Count -gt 0 -OR $digit -ne 0) {
                $quotient.Add($digit)
            }
        }


        $result.Insert(0, $remainder)
        $source = $quotient.ToArray()
    }

    [byte[]] $output = [System.Byte[]]::CreateInstance([System.Byte], $result.Count) 
    for ($i = 0; $i -lt $result.Count; $i++) {
        $output[$i] = $result[$i] -as [byte]
    }

    return $output
}

Export-ModuleMember -Function * -Alias *