Private/ConvertFrom-Base64Url.ps1
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function ConvertFrom-Base64Url { <# .SYNOPSIS Converts a Base64 URL safe string to a decoded string. .DESCRIPTION This function takes a Base64 URL safe string, replaces URL safe characters with Base64 characters, handles padding, and decodes it to a UTF-8 string. .PARAMETER Base64UrlSafeString The Base64 URL safe string to be decoded. .EXAMPLE PS> ConvertFrom-Base64Url -Base64UrlSafeString "SGVsbG8td29ybGQ_" Hello-world .INPUTS [string] The Base64 URL safe string to be decoded. .OUTPUTS [string] The decoded string. #> [cmdletbinding()] param ( [Parameter(Mandatory)] [string]$Base64UrlSafeString ) # replace - and _ with + and / $base64 = $Base64UrlSafeString.Replace('-', '+').Replace('_', '/') # handle padding $padding = $base64.Length % 4 if ($padding -eq 2) { $base64 += "==" } elseif ($padding -eq 3) { $base64 += "=" } # decode the base64 string $bytes = [Convert]::FromBase64String($base64) $decodedString = [System.Text.Encoding]::UTF8.GetString($bytes) return $decodedString } |