Prefer specific key exchange algorithms for TLS

Computer and userIntune-readyPreferSlowKexAlgorithms

Supported on Microsoft Edge version 146, Windows 7 or later

155.0.4283.62

What it does

This policy configures Microsoft Edge to prioritize certain key agreement algorithms (supported groups) in TLS 1.3 based on compliance requirements. If you set this policy to 'cnsa2', Microsoft Edge prefers the algorithms required for the Commercial National Security Algorithm Suite 2.0 (CNSA 2.0). If you leave this policy unset or set it to 'default', the browser uses its standard key exchange order. This policy does not guarantee negotiation of a specific algorithm. It is designed to help server operators distinguish clients with compliance requirements and apply higher-strength, non-default algorithms only when appropriate. This policy applies only to TLS 1.3 and QUIC. The default cryptography used by Microsoft Edge already provides strong security, but enabling this policy may reduce performance when accessing websites. Policy options mapping: * CNSA2.0 (cnsa2) = Prefer key exchange methods satisfying the requirements of CNSA 2.0 * Default (default) = Use Microsoft Edge's default supported groups Use the preceding information when configuring this policy. Example value: cnsa2

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 key exchange algorithms for TLS	Drop-down list	`PreferSlowKexAlgorithms`	Prefer key exchange methods satisfying the requirements of CNSA 2.0`cnsa2` Use Microsoft Edge's default supported groups`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]
"PreferSlowKexAlgorithms"="cnsa2"

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 key exchange algorithms for TLS
# Name: PreferSlowKexAlgorithms
# Scope: Machine
# State: Enabled
# Source: msedge.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowKexAlgorithms' -PropertyType 'String' -Value 'cnsa2'

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: PreferSlowKexAlgorithms

ADMX profile candidate (OMA-URI)

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

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 key exchange algorithms for TLS
# Name: PreferSlowKexAlgorithms
# Scope: Machine
# State: Enabled
# Source: msedge.admx

$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowKexAlgorithms' -Kind 'String' -Expected 'cnsa2'
if (-not $isMatch) {
    $reasons.Add('Value mismatch: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge\PreferSlowKexAlgorithms') | 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 key exchange algorithms for TLS
# Name: PreferSlowKexAlgorithms
# Scope: Machine
# State: Enabled
# Source: msedge.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge' -Name 'PreferSlowKexAlgorithms' -PropertyType 'String' -Value 'cnsa2'

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: PreferSlowKexAlgorithms
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="$(string.PreferSlowKexAlgorithms)" explainText="$(string.PreferSlowKexAlgorithms_Explain)" key="Software\Policies\Microsoft\Edge" name="PreferSlowKexAlgorithms" presentation="$(presentation.PreferSlowKexAlgorithms)" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Edge:CryptographyCompliance" />
      <supportedOn ref="Microsoft.Policies.Edge:SUPPORTED_WIN7_V146" />
      <elements>
        <enum id="PreferSlowKexAlgorithms" valueName="PreferSlowKexAlgorithms">
          <item displayName="$(string.PreferSlowKexAlgorithms_CNSA2_0)">
            <value>
              <string>cnsa2</string>
            </value>
          </item>
          <item displayName="$(string.PreferSlowKexAlgorithms_Default)">
            <value>
              <string>default</string>
            </value>
          </item>
        </enum>
      </elements>
    </policy>

Editor controls

<presentation id="PreferSlowKexAlgorithms" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions"><dropdownList refId="PreferSlowKexAlgorithms">Prefer specific key exchange 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>