.Net Framework 4.6.1 not defaulting to TLS 1.2

Question

I had a similar problem and this is what worked for me.

1. open Powershell and check for supported protocols by using [Net.ServicePointManager]::SecurityProtocol

2. Run the following 2 cmdlets to set .NET Framework strong cryptography registry keys:

   set strong cryptography on 64 bit .Net Framework (version 4 and above)

   Set-ItemProperty -Path 'HKLM:\SOFTWARE\Wow6432Node\Microsoft\.NetFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Value '1' -Type DWord

   set strong cryptography on 32 bit .Net Framework (version 4 and above)

   Set-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\.NetFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Value '1' -Type DWord

3. Restart Powershell and check again for supported protocol by using [Net.ServicePointManager]::SecurityProtocol

It should now display Tls12 as well.

Hope this helps

As others have mentioned there are a number of Windows Registry keys that must be set to enable TLS 1.2 in existing .NET applications without explicitly setting the protocol version in application code.

In order to make .NET 4.x code select the strongest available protocol by default (i.e. when a protocol is not explicitly specified in code), the following registry keys are needed:

On 32-bit and 64-bit versions of Windows: HKLM\SOFTWARE\Microsoft\.NETFramework\v4.0.30319\SchUseStrongCrypto: 0X00000001

On 64-bit versions of Windows: HKLM\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319\SchUseStrongCrypto: 0X00000001

The WOW6432Node value is needed to enable TLS 1.2 in 32-bit applications when run on 64-bit systems.

But here's the quick and easy solution: https://github.com/TheLevelUp/pos-tls-patcher

Update:

If you're targetting .NET 4.6 or 4.7 you'll be interested in Transport Layer Security (TLS) best practices with the .NET Framework.

Note that TLS Patcher linked above very much follows the Microsoft recommendation for existing .NET 4.0 and 4.5 apps that cannot target .NET 4.6 or higher.

The reason why the security protocol did not default to TLS 1.2 is because there is no default value for this in .NET Framework 4.6.1. Sorry if this is reiterating what's already been said but I wanted to elaborate and I don't have enough reputation to comment.

There is no default value in 4.6.2 either, however like one of the commenters mentioned above, a console application does seem to default to TLS 1.2. I tried the exact same code in a website project targeting 4.6.2 and it did NOT default to TLS 1.2.

4.7 and above does have a default value of SecurityProtocolType.SystemDefault.

"This allows .NET Framework networking APIs based on SslStream (such as FTP, HTTP, and SMTP) to inherit the default security protocols from the operating system or from any custom configurations performed by a system administrator"

https://docs.microsoft.com/en-us/dotnet/api/system.net.servicepointmanager.securityprotocol?view=netframework-4.7#System_Net_ServicePointManager_SecurityProtocol

We experienced a similar problem while hosting our .NET 4.6.2 application in IIS.

We could solve the problem by adding the httpRuntime element to the web.config. Without it our service did not default to TLS 1.2.

<httpRuntime targetFramework="4.6.2" />

For more info see https://docs.microsoft.com/en-us/dotnet/api/system.web.configuration.httpruntimesection?view=netframework-4.7.2

MSDN: ServicePointManager.SecurityProtocol Property

This property selects the version of the Secure Sockets Layer (SSL) or Transport Layer Security (TLS) protocol to use for new connections that use the Secure Hypertext Transfer Protocol (HTTPS) scheme only; existing connections are not changed. Note that no default value is listed for this property, on purpose.

The security landscape changes constantly, and default protocols and protection levels are changed over time in order to avoid known weaknesses. Defaults will vary depending on individual machine configuration, and on which software is installed, and on which patches have been applied.

Taken from here