A PowerShell function to duplicated the Unix base64 util.

Convert-Base64.ps1

function Convert-Base64 {
    [CmdletBinding()]
    [Alias("base64")]
    param (
        [Parameter(Mandatory, Position = 0, ValueFromPipeline)]
        [string]
        $InputObject,

        [Parameter()]
        [switch]
        $Decode
    )

    process {
        switch ($true) {
            $Decode {
                [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($InputObject))
                break;
            }
            Default {
                [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($InputObject))
            }
        }
    }
}

Example

You can copy Linux sample code and run in PowerShell without any changes.

kubectl get secret keptn-api-token -n keptn -ojsonpath='{.data.keptn-api-token}' | base64 -d