Convert GUID string to octetBytes using PowerShell

I have a powershell script which outputs all Exchange 2003 mailboxes by size.

$computers = "vexch01","vexch02"
foreach ($computer in $computers) {
  Get-Wmiobject -namespace root\MicrosoftExchangeV2 -class Exchange_Mailbox -computer $computer | sort-object -desc Size | select-object MailboxDisplayName,StoreName,@{Name="Size/Mb";Expression={[math]::round(($_.Size / 1024),2)}}, MailboxGUID | Export-Csv -notype -Path $computer.csv 
}

Currently this outputs the MailboxGUID as a string type GUID (e.g. {21EC2020-3AEA-1069-A2DD-08002B30309D}). I want to look up users in AD by this, but AD stores them in octetBytes format.

I have found some powershell functions which will do the conversion but only when the curly braces are removed. The Guid.ToString method should supply this, but I can't get it to work in the above.

However, if I could figure out how to do that, the Guid.ToByteArray method might get me even closer.

Has anyone cracked this?

Update: the answers so far helped me write a function that converts the mailboxguid into the correct format for searching via LDAP. However, I now开发者_开发技巧 cannot get this working in the script. This is my updated script:

function ConvertGuidToLdapSearchString(
    [parameter(mandatory=$true, position=0)]$Guid
)
{
    $guid_object = [System.Guid]$Guid
    ($guid_object.ToByteArray() | foreach { '\' + $_.ToString('x2') }) -join ''
}

# Gets data through WMI from specified Exchange mailbox servers
$servers = "vexch01","vexch02"
foreach ($server in $servers) {
  Get-Wmiobject -namespace root\MicrosoftExchangeV2 -class Exchange_Mailbox -computer $computer | sort-object -desc Size | select-object MailboxDisplayName,StoreName,@{Name="Size/Mb";Expression={[math]::round(($_.Size / 1024),2)}}, @{Name="LDAP Guid";Expression={ConvertGuidToLdapSearchString(MailboxGUID)}} | Export-Csv -notype -Path $server.csv 
}

I'm not sure why using the function in the select-object with @{Name="LDAP Guid";Expression={ConvertGuidToLdapSearchString(MailboxGUID)}} doesn't work.

Is there another way of using this function in select-object that will give the string?

In conjunction with Andy Schneider's answer, you may find this function useful:

function Convert-GuidToLdapSearchString(
    [parameter(mandatory=$true, position=0)][guid]$Guid
)
{
    ($Guid.ToByteArray() | foreach { '\' + $_.ToString('x2') }) -join ''
}

(I thought I had a more clever way to do this by adding a ScriptProperty to System.Guid, but I seem to have learned that you can't effectively add members to structs.)

I'm not sure I understand what you are trying to accomplish based on your comment, but I think you may have just left out a $_. Here is a somewhat contrived example that creates an object with a property that is a GUID, then uses select and Convert-GuidToLdapSearchString to convert the format. I hope it helps.

$o = New-Object PSObject -Property @{ GUID = $([Guid]::NewGuid()) }
$o
$o | select @{ Name='SearchString'; Expression={ Convert-GuidToLdapSearchString $_.GUID } }

This is not at all how I had imagined the function being used. I expected you would use it to create an LDAP search clause such as:

$searchString = Convert-GuidToLdapSearchString '{9e76c48b-e764-4f0c-8857-77659108a41e}'
$searcher = [adsisearcher]"(msExchMailboxGuid=$searchString)"
$searcher.FindAll()

Are you casting the string to a GUID ?

$guid = [System.Guid]"{21EC2020-3AEA-1069-A2DD-08002B30309D}"
$guid.ToString()
$guid.ToByteArray()