RegistryPolicyFile: MultiString with multiple items not formatted correctly in policy file

[General-Fault]

Details of the scenario you tried and the problem that is occurring

When setting a registry policy file value that is a MultiString with multiple entries, all items end up in the same entry separated by spaces.

For example, when setting the group policy "ComputerConfiguration\Administrative Templates\Network\SSL ConfigurationSettings\ECC Curve Order" (registry key "HKLM:\SOFTWARE\Policies\Microsoft\Cryptography\Configuration\SSL\00010002:EccCurves" to @('curve25519', 'NistP384', NistP256'), the three values are saved in one string as 'curve25519 NistP384 NistP256'.

The fault can be found in New-GPRegistrySettingsEntry (

GPRegistryPolicyDsc/source/Modules/GPRegistryPolicyFileParser/GPRegistryPolicyFileParser.psm1

Line 310 in 3f0c234

$dataBytes = [System.Text.Encoding]::Unicode.GetBytes($RegistryPolicy.ValueData + "`0")

) where the ValueData array is implicitly cast to a string before being passed to Unicode.GetBytes. The array string separates the values with a space, not a null character as is needed.

Verbose logs showing the problem

N/A

Suggested solution to the issue

New-GPRegistrySettingsEntry should join the values with a null character before passing to Unicode.GetBytes

as in

[System.Text.Encoding]::Unicode.GetBytes(($RegistryPolicy.ValueData -join "`0") + "`0")

Similarly Format-MultiStringValue should not split on a space.

The DSC configuration that is used to reproduce the issue (as detailed as possible)

This can be reproduced using Invoke-DscResource

invoke-dscresource -ModuleName GPRegistryPolicyDsc -Name RegistryPolicyFile -Method Set -Property @{
    TargetType = 'ComputerConfiguration'
    Key = 'SOFTWARE\Policies\Microsoft\Cryptography\Configuration\SSL\00010002'
    ValueName = 'EccCurves'
    ValueData = @('curve25519', 'NistP384', 'NistP256')
    ValueType = 'MultiString'
    Ensure = 'Present'
} -verbose

The operating system the target node is running

Name	Value
OsName	Microsoft Windows 10 Enterprise LTSC
OsOperatingSystemSKU	125
OsArchitecture	64-bit
WindowsVersion	1809
WindowsBuildLabEx	17763.1.amd64fre.rs5_release.180914-1434
OsLanguage	en-US
OsMuiLanguages	{en-US}

Version and build of PowerShell the target node is running

Name	Value
PSVersion	5.1.17763.1852
PSEdition	Desktop
PSCompatibleVersions	{1.0, 2.0, 3.0, 4.0...}
BuildVersion	10.0.17763.1852
CLRVersion	4.0.30319.42000
WSManStackVersion	3.0
PSRemotingProtocolVersion	2.3
SerializationVersion	1.1.0.1

Version of the DSC module that was used

Name	Version	Path
GPRegistryPolicyDsc	1.2.0	C:\Program Files\WindowsPowerShell\Modules\GPRegistryPolicyDsc\1.2.0\GPRegistryPolicyDsc.psd1

[bcwilhite]

@erjenkin and I are able to reproduce this issue. We'll have a fix PR submitted this afternoon with additional detail/findings.