Allow cryptography algorithms compatible with Windows NT 4.0
Verified with Windows 11 25H2 — updated on July 30, 2026
Supported on: At least Windows Vista
Path in the GPO console
Computer Configuration\Administrative Templates\System\Net Logon Description
This policy setting controls whether the Net Logon service will allow the use of older cryptography algorithms that are used in Windows NT 4.0. The cryptography algorithms used in Windows NT 4.0 and earlier are not as secure as newer algorithms used in Windows 2000 or later, including this version of Windows. By default, Net Logon will not allow the older cryptography algorithms to be used and will not include them in the negotiation of cryptography algorithms. Therefore, computers running Windows NT 4.0 will not be able to establish a connection to this domain controller. If you enable this policy setting, Net Logon will allow the negotiation and use of older cryptography algorithms compatible with Windows NT 4.0. However, using the older algorithms represents a potential security risk. If you disable this policy setting, Net Logon will not allow the negotiation and use of older cryptography algorithms. If you do not configure this policy setting, Net Logon will not allow the negotiation and use of older cryptography algorithms.
Registry
Software\Policies\Microsoft\Netlogon\Parameters Value name: AllowNT4Crypto
Enabled: AllowNT4Crypto = 1
Disabled: AllowNT4Crypto = 0
MDM / Intune (CSP)
./Device/Vendor/MSFT/Policy/Config/ADMX_Netlogon/Netlogon_AllowNT4Crypto Microsoft Learn documentation Mapping data: Microsoft Learn (CC BY 4.0)
Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Allow cryptography algorithms compatible with Windows NT 4.0
; State: Enabled
; Supported on: At least Windows Vista
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Netlogon\Parameters]
"AllowNT4Crypto"=dword:00000001More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AllowNT4Crypto' -Value 1 -Type DWordIntune XML
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/ADMX_Netlogon/Netlogon_AllowNT4Crypto
Data type: String
Value:
<enabled/>Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters' -Name 'AllowNT4Crypto' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AllowNT4Crypto' -Value 1 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters' -Name 'AllowNT4Crypto' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Allow cryptography algorithms compatible with Windows NT 4.0
# State: Enabled
# Supported on: At least Windows Vista
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AllowNT4Crypto' -Value 1 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.