Prefer specific encryption cipher algorithms for TLS

Computer and userIntune-readyPreferSlowCiphers

Supported on Microsoft Edge version 146, Windows 7 or later

155.0.4283.62

What it does

This policy configures Microsoft Edge to order its preferred encryption ciphers in TLS 1.3 based on algorithms approved by a specific compliance regime. Setting this policy does not guarantee that any specific algorithms will be negotiated. This policy allows server operators who support both compliant and non-compliant clients to differentiate between them, and use certain non-default algorithms with increased cryptographic strength only for clients explicitly configured to prefer them. Setting the policy to 'cnsa' configures Microsoft Edge to prefer ciphers required for compliance with the Commercial National Security Algorithm Suite versions 1.0 and 2.0 (CNSA 1.0 and 2.0). Not setting the policy, or setting it to 'default', configures Microsoft Edge to use its default ciphers. Setting this policy isn't required for security. The default cryptography used by Microsoft Edge is strong enough to withstand a brute-force attack using the entire power of the Sun. Setting this policy will cause Microsoft Edge to be slower when accessing websites. This policy only affects TLS 1.3 and QUIC. It doesn't affect earlier versions of TLS. Policy options mapping: * CNSA (cnsa) = Prefer ciphers satisfying the requirements of CNSA 1.0 and 2.0 * Default (default) = Use Microsoft Edge's default cipher order Use the preceding information when configuring this policy. Example value: cnsa

What it writes

Hive: HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER
Registry key: Software\Policies\Microsoft\Edge

Options

Option	Type	Registry value	Allowed values
Prefer specific encryption cipher algorithms for TLS	Drop-down list	`PreferSlowCiphers`	Prefer ciphers satisfying the requirements of CNSA 1.0 and 2.0`cnsa` Use Microsoft Edge's default cipher order`default`

Configure and deploy

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

Enabled · Computer · template defaults

Registry file (.reg)

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge]
"PreferSlowCiphers"="cnsa"

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: Prefer specific encryption cipher algorithms for TLS
# Name: PreferSlowCiphers
# Scope: Machine
# State: Enabled
# Source: msedge.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowCiphers' -PropertyType 'String' -Value 'cnsa'

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.
The generated payload is incomplete because one or more ADMX element values were not supplied: PreferSlowCiphers

ADMX profile candidate (OMA-URI)

./Device/Vendor/MSFT/Policy/Config/ADMX_msedge/PreferSlowCiphers

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: Prefer specific encryption cipher algorithms for TLS
# Name: PreferSlowCiphers
# Scope: Machine
# State: Enabled
# Source: msedge.admx

$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowCiphers' -Kind 'String' -Expected 'cnsa'
if (-not $isMatch) {
    $reasons.Add('Value mismatch: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge\PreferSlowCiphers') | 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: Prefer specific encryption cipher algorithms for TLS
# Name: PreferSlowCiphers
# Scope: Machine
# State: Enabled
# Source: msedge.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowCiphers' -PropertyType 'String' -Value 'cnsa'

History 37 retained releases

150.0.4078.8016 Jul 2026
- Already present in the first release ChangeIntel keeps.

36 later releases left it unchanged.

Template

Internal name: PreferSlowCiphers
Namespace: Microsoft.Policies.Edge
Template file: msedge.admx
Release: Microsoft Edge 155.0.4283.62 · file set 0a733b0040dbbf02…

Definition, editor controls and support

Definition

<policy class="Both" displayName="$(string.PreferSlowCiphers)" explainText="$(string.PreferSlowCiphers_Explain)" key="Software\Policies\Microsoft\Edge" name="PreferSlowCiphers" presentation="$(presentation.PreferSlowCiphers)" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Edge:CryptographyCompliance" />
      <supportedOn ref="Microsoft.Policies.Edge:SUPPORTED_WIN7_V146" />
      <elements>
        <enum id="PreferSlowCiphers" valueName="PreferSlowCiphers">
          <item displayName="$(string.PreferSlowCiphers_CNSA)">
            <value>
              <string>cnsa</string>
            </value>
          </item>
          <item displayName="$(string.PreferSlowCiphers_Default)">
            <value>
              <string>default</string>
            </value>
          </item>
        </enum>
      </elements>
    </policy>

Editor controls

<presentation id="PreferSlowCiphers" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions"><dropdownList refId="PreferSlowCiphers">Prefer specific encryption cipher algorithms for TLS</dropdownList></presentation>

Supported platforms and category

Microsoft.Policies.Edge:category:CryptographyCompliance
<category displayName="$(string.CryptographyCompliance_group)" name="CryptographyCompliance" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Edge:microsoft_edge" />
    </category>
Microsoft.Policies.Edge:category:microsoft_edge
<category displayName="$(string.microsoft_edge)" name="microsoft_edge" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Microsoft.Policies.Edge:definition:SUPPORTED_WIN7_V146
<definition displayName="$(string.SUPPORTED_WIN7_V146)" name="SUPPORTED_WIN7_V146" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Microsoft.Policies.Edge:category:CryptographyCompliance
<category displayName="$(string.CryptographyCompliance_group)" name="CryptographyCompliance" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Edge:microsoft_edge" />
    </category>
<strings><string id="Microsoft.Policies.Edge:CryptographyCompliance_group">Cryptography compliance policies</string></strings>
Microsoft.Policies.Edge:category:microsoft_edge
<category displayName="$(string.microsoft_edge)" name="microsoft_edge" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Microsoft.Policies.Edge:microsoft_edge">Microsoft Edge</string></strings>
Microsoft.Policies.Edge:definition:SUPPORTED_WIN7_V146
<definition displayName="$(string.SUPPORTED_WIN7_V146)" name="SUPPORTED_WIN7_V146" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Microsoft.Policies.Edge:SUPPORTED_WIN7_V146">Microsoft Edge version 146, Windows 7 or later</string></strings>