Powershell: How to grab base64 value from attribute of SearchResultEntry object? - powershell

Question

My goal is to fetch the published CRL of a CA from an LDAP connection.
I have a function to search the LDAP (not Active Directory!), which returns a System.DirectoryServices.Protocols.SearchResultEntryCollection as expected.
$results = LDAPsearch "$_LDAP_server`:$_LDAP_searchPort" "cn=$CA,$_LDAP_searchBase" '(&(certificateRevocationList=*))'
ForEach ($element in $results){
$element.Attributes['cn'].GetValues('string')
$element.Attributes['certificateRevocationList;binary'].GetValues('string')
}
The above properly reads the cn attribute value of each element returned, however the certificateRevocationList is returned in a strange format which does not correspond at all to the Base64 string I expect (e.g. the one that can be read if you export your data to an LDIF file or if you use the Linux ldapsearch command)...
How can I get the actual Base64 value ?
Unfortunately, you can only pass 'byte[]' or 'string' as parameter to the GetValues method (a 'Base64String' option here would be useful to me, but well...).
Current output below (where cn value is correctly written but not certificateRevocationList):

Answer 1

Retrieve the raw CRL as byte[], then convert to base64 yourself:
$crlBin = $element.Attributes['certificateRevocationList;binary'].GetValues('byte[]')
$crlB64 = [Convert]::ToBase64String($crlBin)

Answer 2

Just adding the option I ended up using, much easier since my end-goal was actually to save the CRL as a file (and be able to parse it):
$crlBin = $element.Attributes['certificateRevocationList;binary'].GetValues('byte[]')[0]
[IO.File]::WriteAllBytes("$_localDir\CRL_$CA.crl",$crlBin)
This writes the actual CRL file in DER format (can then easily be switched to PEM using certutil or openssl if needed). My initial idea was to construct a PEM-formatted CRL file from the Base64 value extracted, but I was looking way too far...
I'm leaving Mathias's response as the answer since he actually best answered my question ; I didn't specify that I wanted a CRL file in the end.