BAMCIS.Base64.psm1
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Function Invoke-Base64UrlEscape { <# .SYNOPSIS Performs character escaping on a string that is already base64 encoded. .DESCRIPTION This cmdlet takes an input and escapes url characters, changing + to - and / to _. The specified padding character is also removed from the end. .PARAMETER InputObject The base64 string to escape. .PARAMETER Padding The trailing padding character to remove. This defaults to '='. .EXAMPLE $Base64Str = "SGVsbG8gV29y/bGQhIEhlbG+xvIQ==" $EscapedStr = $Base64Str | Invoke-Base64UrlEscape The escaped string will be "SGVsbG8gV29y_bGQhIEhlbG-xvIQ". .INPUTS System.String .OUTPUTS System.String .NOTES AUTHOR: Michael Haken LAST UPDATE: 1/27/2018 #> [CmdletBinding()] [OutputType([System.String])] Param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] [System.String]$InputObject, [Parameter()] [ValidateNotNull()] [System.Char]$Padding = '=' ) Begin { } Process { Write-Output -InputObject $InputObject.TrimEnd($Padding).Replace('+', '-').Replace('/', '_') } End { } } Function Invoke-Base64UrlUnescape { <# .SYNOPSIS Performs character unescaping on a string that is already base64 encoded and has already been escaped. .DESCRIPTION This cmdlet takes an input and unescapes url characters, changing - to + and _ to /. The appropriate amount of trailing padding is also added back. .PARAMETER InputObject The base64 string to unescape. .PARAMETER Padding The character that will be used for any necessary trailing padding. This defaults to '='. .EXAMPLE $EscapedStr = "SGVsbG8gV29y_bGQhIEhlbG-xvIQ" $Base64Str = $EscapedStr | Invoke-Base64UrlUnescape The escaped string will be "SGVsbG8gV29y/bGQhIEhlbG+xvIQ==". .INPUTS System.String .OUTPUTS System.String .NOTES AUTHOR: Michael Haken LAST UPDATE: 1/27/2018 #> [CmdletBinding()] [OutputType([System.String])] Param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] [System.String]$InputObject, [Parameter()] [ValidateNotNull()] [System.Char]$Padding = '=' ) Begin { } Process { $InputObject = $InputObject.Replace('-', '+').Replace('_', '/') switch ($InputObject.Length % 4) { 0 { # No padding should be added break } 2 { $InputObject += "$Padding$Padding" break } 3 { $InputObject += $Padding break } default { Write-Error -Exception (New-Object -TypeName System.ArgumentException("InputObject", "The input object is not a legal base64 string.")) -ErrorAction Stop } } Write-Output -InputObject $InputObject } End { } } Function ConvertTo-Base64UrlEncoding { <# .SYNOPSIS Converts a plain text string or bytes to a base64 url encoded string. .DESCRIPTION This cmdlet takes a string or a byte array and converts it to a base64 url encoded string. If a string is provided, you can specify the encoding to use to convert it to bytes, this defaults to UTF8. .PARAMETER InputObject The string to convert to a base64 url encoded string. .PARAMETER Bytes The bytes to convert to a base64 url encoded string. .PARAMETER Encoding The encoding to use to convert the InputObject parameter to a byte array. This defaults to UTF8. .PARAMETER Padding The character used as padding for the end of the base64 string before escaping, this defaults to '='. .EXAMPLE $Str = "Hello World!" $Base64UrlStr = $Str | ConvertTo-Base64UrlEncoding This converts the input string to a base64 url encoded string. .INPUTS System.String .OUTPUTS System.String .NOTES AUTHOR: Michael Haken LAST UPDATE: 1/27/2018 #> [CmdletBinding()] [OutputType([System.String])] Param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true, ParameterSetName = "Input")] [AllowEmptyString()] [System.String]$InputObject, [Parameter(Mandatory = $true, Position = 0, ParameterSetName = "Bytes")] [ValidateNotNull()] [System.Byte[]]$Bytes, [Parameter(ParameterSetName = "Input")] [ValidateNotNull()] [System.Text.Encoding]$Encoding = [System.Text.Encoding]::UTF8, [Parameter()] [ValidateNotNull()] [System.Char]$Padding = '=' ) Begin { } Process { if ($PSCmdlet.ParameterSetName -eq "Input") { $Bytes = $Encoding.GetBytes($InputObject) } $Temp = [System.Convert]::ToBase64String($Bytes) $Temp = Invoke-Base64UrlEscape -InputObject $Temp -Padding $Padding Write-Output -InputObject $Temp } End { } } Function ConvertFrom-Base64UrlEncoding { <# .SYNOPSIS Converts a base64 url encoded string back to a plain text string or bytes. .DESCRIPTION This cmdlet takes a base64 url encoded string and converts it back to a plain text string or a byte array. .PARAMETER InputObject The string to convert from a base64 url encoded string. .PARAMETER AsBytes Specifies that the output is returned as a byte array instead of a string. .PARAMETER Encoding The encoding to use to convert the base64 url encoded string back to a plain text string. This defaults to UTF8. .PARAMETER Padding The character used as padding for the end of the base64 string before escaping, this defaults to '='. .EXAMPLE $EscapedStr = "SGVsbG8gV29y_bGQhIEhlbG-xvIQ" $PlainText = $EscapedStr | ConvertFrom-Base64UrlEncoding This converts the input string back to a plain text string. .EXAMPLE $EscapedStr = "SGVsbG8gV29y_bGQhIEhlbG-xvIQ" $Bytes = $EscapedStr | ConvertFrom-Base64UrlEncoding -AsBytes This converts the input string back to a decoded byte array. .INPUTS System.String .OUTPUTS System.String .NOTES AUTHOR: Michael Haken LAST UPDATE: 1/27/2018 #> [CmdletBinding()] [OutputType([System.String])] Param( [Parameter(Mandatory = $true, Position = 0, ValueFromPipeline = $true)] [AllowEmptyString()] [System.String]$InputObject, [Parameter()] [Switch]$AsBytes, [Parameter()] [ValidateNotNull()] [System.Text.Encoding]$Encoding = [System.Text.Encoding]::UTF8, [Parameter()] [ValidateNotNull()] [System.Char]$Padding = '=' ) Begin { } Process { $InputObject = Invoke-Base64UrlUnescape -InputObject $InputObject -Padding $Padding [System.Byte[]]$Bytes = [System.Convert]::FromBase64String($InputObject) if ($AsBytes) { Write-Output -InputObject $Bytes } else { Write-Output -InputObject $Encoding.GetString($Bytes) } } End { } } |