functions/converters/ConvertFrom-Base64.ps1

function ConvertFrom-Base64 {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)]
        [string]$Data
    )

    process {
        [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($Data))
    }
}