Base64 Encode/Decode a string - Windows PowerShell Blog - Site Home

Today I came across http://scripts.readify.net/ . This sight is focused on Monad and MSH and is starting a collection of scripts at: http://scripts.readify.net/Scripts.aspx . You should visit their site and let them know what type of scripts would be useful to you.

I particularly liked their entry on how to Base64 encode a file. This is something that I need occassionally and I can never remember how to do it. I was about to include it as-is into my profile and decided that there was a better way to do this.

<IMPORTANT POINT>
Whenever you are adding some functions, you should make a conscious decision about whether those functions are best exposed as a "function" or as a "type extension".
</IMPORTANT POINT>

Both of these mechanisms are great and have their purpose but my observation is that people are not using type-extensions as much as they should. One of the huge benefits of type extensions is discoverability. Let me show you how to do this function as a type-extension and highlight the benefits of this approach.

When doing a type extension, you first need to decide what TYPE you are going to extend. In this case, I decided that I would extend SYSTEM.STRING as that was the most general purpose type for this function. I then encoded the following in a file called My.Types.Mshxml

</Types>
    <Type>
        <Name>System.String</Name>
        <Members>
            <ScriptProperty>
                <Name>ToBase64String</Name>
                <GetScriptBlock>
                 [System.Convert]::ToBase64String([System.Text.Encoding]::UNICODE.GetBytes($this))
  </GetScriptBlock>
            </ScriptProperty>
            <ScriptProperty>
                <Name>FromBase64String</Name>
                <GetScriptBlock>
                 [System.Text.Encoding]::UNICODE.GetString([System.Convert]::FromBase64String($this))
  </GetScriptBlock>
            </ScriptProperty>
        </Members>
    </Type>
</Types>

In my profile I load this file via the command:

Update-TypeData c:\msh\My.Types.mshxml

Once I do that, these properties are available to any STRING and can be discovered via Get-Member:

MSH> $x="Hello World"
MSH> $x |Get-Member

TypeName: System.String

Name             MemberType            Definition
----             ----------            ----------
Clone            Method                System.Object Clone()
CompareTo        Method                System.Int32 CompareTo(Object value), System.Int32 CompareTo(String strB)
Contains         Method                System.Boolean Contains(String value)
CopyTo           Method                System.Void CopyTo(Int32 sourceIndex, Char[] destination, Int32 destinationIndex, Int32 count)
EndsWith         Method                System.Boolean EndsWith(String value), System.Boolean EndsWith(String value, StringComparison comparisonType), System.Boolean EndsWith(String value, Boolean ignoreCase, CultureInfo culture)
...

Trim             Method                System.String Trim(Params Char[] trimChars), System.String Trim()
TrimEnd          Method                System.String TrimEnd(Params Char[] trimChars)
TrimStart        Method                System.String TrimStart(Params Char[] trimChars)
Chars            ParameterizedProperty System.Char Chars(Int32 index) {get;}
Length           Property              System.Int32 Length {get;}
FromBase64String ScriptProperty        System.Object FromBase64String {get=[System.Text.Encoding]::UNICODE.GetString([System.Convert]::FromBase64String($this));}
ToBase64String   ScriptProperty        System.Object ToBase64String {get=[System.Convert]::ToBase64String([System.Text.Encoding]::UNICODE.GetBytes($this));}

MSH> $x
Hello World
MSH> $x.ToBase64String
SABlAGwAbABvACAAVwBvAHIAbABkAA==
MSH> $x.ToBase64String.FromBase64String
Hello World
MSH>

Enjoy!

Jeffrey Snover
Monad Architect

[Edit: Monad has now been renamed to Windows PowerShell. This script or discussion may require slight adjustments before it applies directly to newer builds.]

PSMDTAG:CMDLET: Update-TypeData

PSMDTAG:FAQ: How do I base64 encode/decode a string?

PSMDTAG:PHILOSOPHY: Whenever you are adding some functions, you should make a conscious decision about whether those functions are best exposed as a "function" or as a "type extension".

PSMDTAG:DOTNET: System.Convert, System.Text.Encoding

PSMDTAG:TYPEEXTENSION: System.String