Prefer specific key exchange algorithms for TLS

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. This policy can be set for the machine and for the user. If set for the user, this policy only affects network requests initiated by the user profile, and may not affect network requests made by Microsoft Edge to carry out browser-wide background tasks; those are controlled by the machine-level value. If this policy is set at both the machine level and the user level, the machine-level value applies, unless the policy precedence order has been changed by the CloudUserPolicyOverridesCloudMachinePolicy policy. For versions 155 and below, this policy is machine-wide only. 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

Configure and deploy

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

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Edge]
"PreferSlowKexAlgorithms"="cnsa2"

$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'

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

$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' {
            $actualBits = if ($actual -is [uint64]) { $actual } else { [BitConverter]::ToUInt64([BitConverter]::GetBytes([int64]$actual), 0) }
            $expectedBits = if ($Expected -is [uint64]) { $Expected } else { [BitConverter]::ToUInt64([BitConverter]::GetBytes([int64]$Expected), 0) }
            return $actualBits -eq $expectedBits
        }
        '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

$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 48 retained releases

1. 156.0.4314.4222 Oct 2026
   Registry key: Software\Policies\Microsoft\Edge · Value name: Not specified
   • Description … strong security, but enabling this policy may reduce performance when accessing websites. [added: This policy can be set for the machine and for the user. If set for the user, this policy only affects network requests initiated by the user profile, and may not affect network requests made by Microsoft Edge to carry out browser-wide background tasks; those are controll…]Policy options mapping: * CNSA2.0 (cnsa2) = Prefer key exchange methods satisfying …
     Whole description, marked

     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. [added: This policy can be set for the machine and for the user. If set for the user, this policy only affects network requests initiated by the user profile, and may not affect network requests made by Microsoft Edge to carry out browser-wide background tasks; those are controlled by the machine-level value. If this policy is set at both the machine level and the user level, the machine-level value applies, unless the policy precedence order has been changed by the CloudUserPolicyOverridesCloudMachinePolicy policy. For versions 155 and below, this policy is machine-wide only. ]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

2. 150.0.4078.8016 Jul 2026
   • Already present in the first release ChangeIntel keeps.

46 later releases left it unchanged.

Template

Internal name

PreferSlowKexAlgorithms

Namespace

Microsoft.Policies.Edge

Template file

msedge.admx

Release

Microsoft Edge 156.0.4314.56 · file set be6514e922522376…

<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>

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

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>