Configure invalid DSA public key size

UserNeeds changes for IntuneL_SelectDigitalSignatureInvalidDSABits

Supported on SUPPORTED_Windows7 (defined in the Windows templates)

5568.1000

What it does

This policy setting allows you to configure whether Office displays a digital signature as invalid because of the number of DSA public key bits used in the digital signature. If you enable this policy setting, you can specify the number of bits that Office treats as invalid in a digital signature. For example: 512, 768, etc. If you don’t configure this policy setting, Office won’t treat any digital signatures as invalid because of the number of bits in the public key. Enabling this policy causes the minimum DSA public key size to be the next largest option.

What it writes

Hive: HKEY_CURRENT_USER
Registry key: software\policies\microsoft\office\16.0\common\signatures

Why it needs changes for Intune

Policy references a Windows supportedOn definition.
ADMX-INTUNE-WINDOWS-SUPPORTEDON-REFERENCE

Options

Option	Type	Registry value	Allowed values
L_SelectDigitalSignatureHashingAlgorithmDropIDDefault: 0	Drop-down list	`invaliddsabits`	0`0` 512`512` 768`768` 1024`1024`

Configure and deploy

Choose a state and the option values; the output below is generated from the template for exactly that.

Enabled · User · template defaults

Registry file (.reg)

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\signatures]
"invaliddsabits"=dword:00000000

PowerShell

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Configure invalid DSA public key size
# Name: L_SelectDigitalSignatureInvalidDSABits
# Scope: User
# State: Enabled
# Source: office16.admx

Set-RegistryValue -Path 'Registry::HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\signatures' -Name 'invaliddsabits' -PropertyType 'DWord' -Value 0

The OMA-URI is an inferred ADMX-backed Policy CSP candidate derived from the source ADMX file name and policy name.
Some Microsoft policies use built-in Policy CSP pages whose area names don't match the ADMX file name, so verify the candidate against Microsoft Learn before deployment.

ADMX profile candidate (OMA-URI)

./User/Vendor/MSFT/Policy/Config/ADMX_office16/L_SelectDigitalSignatureInvalidDSABits

ADMX SyncML candidate

<SyncML xmlns="SYNCML:SYNCML1.2">
  <SyncBody>
    <Replace>
      <CmdID>1</CmdID>
      <Item>
        <Meta>
          <Format>chr</Format>
          <Type>text/plain</Type>
        </Meta>
        <Target>
          <LocURI>./User/Vendor/MSFT/Policy/Config/ADMX_office16/L_SelectDigitalSignatureInvalidDSABits</LocURI>
        </Target>
        <Data>&lt;enabled/&gt;
&lt;data id="L_SelectDigitalSignatureHashingAlgorithmDropID" value="0"/&gt;</Data>
      </Item>
    </Replace>
    <Final/>
  </SyncBody>
</SyncML>

Intune remediation scripts

Detection

$ErrorActionPreference = 'Stop'
$reasons = [System.Collections.Generic.List[string]]::new()

function Test-RegistryValueExists {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    return $null -ne (Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue)
}

function Test-RegistryValueEquals {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $Kind,
        [Parameter(Mandatory = $true)][object] $Expected
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    $valueObject = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue
    if ($null -eq $valueObject) {
        return $false
    }

    $actual = $valueObject.$Name
    switch ($Kind) {
        'String' { return [string]$actual -ceq [string]$Expected }
        'ExpandString' { return [string]$actual -ceq [string]$Expected }
        'DWord' { return [uint32]$actual -eq [uint32]$Expected }
        'QWord' { return [uint64]$actual -eq [uint64]$Expected }
        'MultiString' {
            $actualArray = @($actual)
            $expectedArray = @($Expected)
            if ($actualArray.Count -ne $expectedArray.Count) { return $false }
            for ($index = 0; $index -lt $actualArray.Count; $index++) {
                if ([string]$actualArray[$index] -cne [string]$expectedArray[$index]) { return $false }
            }
            return $true
        }
        'Binary' {
            $actualArray = [byte[]]$actual
            $expectedArray = [byte[]]$Expected
            if ($actualArray.Length -ne $expectedArray.Length) { return $false }
            for ($index = 0; $index -lt $actualArray.Length; $index++) {
                if ($actualArray[$index] -ne $expectedArray[$index]) { return $false }
            }
            return $true
        }
        default { return [string]$actual -ceq [string]$Expected }
    }
}

# Policy: Configure invalid DSA public key size
# Name: L_SelectDigitalSignatureInvalidDSABits
# Scope: User
# State: Enabled
# Source: office16.admx

$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\signatures' -Name 'invaliddsabits' -Kind 'DWord' -Expected 0
if (-not $isMatch) {
    $reasons.Add('Value mismatch: HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\signatures\invaliddsabits') | Out-Null
}

if ($reasons.Count -eq 0) {
    Write-Output 'Compliant'
    exit 0
}

$reasons | ForEach-Object { Write-Output $_ }
exit 1

Remediation

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Configure invalid DSA public key size
# Name: L_SelectDigitalSignatureInvalidDSABits
# Scope: User
# State: Enabled
# Source: office16.admx

Set-RegistryValue -Path 'Registry::HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\common\signatures' -Name 'invaliddsabits' -PropertyType 'DWord' -Value 0

History 1 retained release

5568.100010 Aug 2026
- Already present in the first release ChangeIntel keeps.

Template

Internal name: L_SelectDigitalSignatureInvalidDSABits
Namespace: office16.Office.Microsoft.Policies.Windows
Template file: office16.admx
Release: Microsoft 365 Apps 5568.1000 · file set 8be05d876aae137d…

Definition, editor controls and support

Definition

<policy class="User" displayName="$(string.L_SelectDigitalSignatureInvalidDSABits)" explainText="$(string.L_SelectDigitalSignatureInvalidDSABitsExplain)" key="software\policies\microsoft\office\16.0\common\signatures" name="L_SelectDigitalSignatureInvalidDSABits" presentation="$(presentation.L_SelectDigitalSignatureHashingAlgorithm)" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="office16.Office.Microsoft.Policies.Windows:L_DigSig" />
      <supportedOn ref="Microsoft.Policies.Windows:SUPPORTED_Windows7" />
      <elements>
        <enum id="L_SelectDigitalSignatureHashingAlgorithmDropID" valueName="invaliddsabits">
          <item displayName="$(string.L_SelectDigitalSignatureAlgorithmBitsStr0)">
            <value>
              <decimal value="0" />
            </value>
          </item>
          <item displayName="$(string.L_SelectDigitalSignatureAlgorithmBitsStr1)">
            <value>
              <decimal value="512" />
            </value>
          </item>
          <item displayName="$(string.L_SelectDigitalSignatureAlgorithmBitsStr2)">
            <value>
              <decimal value="768" />
            </value>
          </item>
          <item displayName="$(string.L_SelectDigitalSignatureAlgorithmBitsStr3)">
            <value>
              <decimal value="1024" />
            </value>
          </item>
        </enum>
      </elements>
    </policy>

Editor controls

<presentation id="L_SelectDigitalSignatureHashingAlgorithm" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
        <dropdownList defaultItem="0" noSort="true" refId="L_SelectDigitalSignatureHashingAlgorithmDropID">
        </dropdownList>
      </presentation>

Supported platforms and category

office16.Office.Microsoft.Policies.Windows:category:L_DigSig
<category displayName="$(string.L_DigSig)" name="L_DigSig" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="office16.Office.Microsoft.Policies.Windows:L_SecuritySettings" />
    </category>
office16.Office.Microsoft.Policies.Windows:category:L_MicrosoftOfficeSystem
<category displayName="$(string.L_MicrosoftOfficeSystem)" name="L_MicrosoftOfficeSystem" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
office16.Office.Microsoft.Policies.Windows:category:L_SecuritySettings
<category displayName="$(string.L_SecuritySettings)" name="L_SecuritySettings" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="office16.Office.Microsoft.Policies.Windows:L_MicrosoftOfficeSystem" />
    </category>
office16.Office.Microsoft.Policies.Windows:unresolved:Microsoft.Policies.Windows:SUPPORTED_Windows7
<unresolved reference="Microsoft.Policies.Windows:SUPPORTED_Windows7" />
office16.Office.Microsoft.Policies.Windows:category:L_DigSig
<category displayName="$(string.L_DigSig)" name="L_DigSig" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="office16.Office.Microsoft.Policies.Windows:L_SecuritySettings" />
    </category>
<strings><string id="office16.Office.Microsoft.Policies.Windows:L_DigSig">Digital Signatures</string></strings>
office16.Office.Microsoft.Policies.Windows:category:L_MicrosoftOfficeSystem
<category displayName="$(string.L_MicrosoftOfficeSystem)" name="L_MicrosoftOfficeSystem" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="office16.Office.Microsoft.Policies.Windows:L_MicrosoftOfficeSystem">Microsoft Office 2016</string></strings>
office16.Office.Microsoft.Policies.Windows:category:L_SecuritySettings
<category displayName="$(string.L_SecuritySettings)" name="L_SecuritySettings" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="office16.Office.Microsoft.Policies.Windows:L_MicrosoftOfficeSystem" />
    </category>
<strings><string id="office16.Office.Microsoft.Policies.Windows:L_SecuritySettings">Security Settings</string></strings>