Functions/ConvertTo-Base64UrlEncodedString.ps1
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function ConvertTo-Base64UrlEncodedString { <# .SYNOPSIS Base 64 URL encodes an input string. .DESCRIPTION Base 64 URL encodes an input string required for the payload or header of a JSON Web Token (JWT). .PARAMETER InputString The string to be base64 URL encoded. .PARAMETER Bytes The byte array derived from a string to be base64 URL encoded. .EXAMPLE $jwtPayload = '{"role":"Administrator","sub":"first.last@company.com","jti":"545a310d890F47B9b1F5dc104f782ABD","iat":1551286711,"nbf":1551286711,"exp":1551287011}' ConvertTo-Base64UrlEncodedString -InputString $jwtPayload Base 64 URL encodes a JSON value. .INPUTS System.String A string is received by the InputString parameter. .OUTPUTS System.String Returns a base 64 URL encoded string for the given input. .LINK https://tools.ietf.org/html/rfc4648#section-5 #> [CmdletBinding()] [Alias('b64e', 'Encode')] [OutputType([System.String])] param ( [Parameter(Position=0,ParameterSetName="String",Mandatory=$true,ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)] [string]$InputString, [Parameter(Position=1,ParameterSetName="Byte Array",Mandatory=$false,ValueFromPipeline=$false,ValueFromPipelineByPropertyName=$false)] [byte[]]$Bytes ) PROCESS { [string]$base64UrlEncodedString = "" if ($PSBoundParameters.ContainsKey("Bytes")) { try { $output = [Convert]::ToBase64String($Bytes) $output = $output.Split('=')[0] # Remove any trailing '='s $output = $output.Replace('+', '-') # 62nd char of encoding $output = $output.Replace('/', '_') # 63rd char of encoding $base64UrlEncodedString = $output } catch { $ArgumentException = New-Object -TypeName System.ArgumentException -ArgumentList $_.Exception.Message Write-Error -Exception $ArgumentException -Category InvalidArgument -ErrorAction Stop } } else { try { $encoder = [System.Text.UTF8Encoding]::new() [byte[]]$inputBytes = $encoder.GetBytes($InputString) $base64String = [Convert]::ToBase64String($inputBytes) [string]$base64UrlEncodedString = "" $base64UrlEncodedString = $base64String.Split('=')[0] # Remove any trailing '='s $base64UrlEncodedString = $base64UrlEncodedString.Replace('+', '-'); # 62nd char of encoding $base64UrlEncodedString = $base64UrlEncodedString.Replace('/', '_'); # 63rd char of encoding } catch { $ArgumentException = New-Object -TypeName System.ArgumentException -ArgumentList $_.Exception.Message Write-Error -Exception $ArgumentException -Category InvalidArgument -ErrorAction Stop } } return $base64UrlEncodedString } } |