.NET Framework 3.5 and TLS 1.2

Question

I currently have a web application that uses the .NET 3.5 framework and I am wondering if it will be compatible with TLS 1.2. No where in our code are we dictating TLS version. This is a legacy application and recompiling is not on the table right now. I am not finding much info on whether you can or cannot, but I was under the impression that compatibility is more dependent on the OS version. It looks like the minimum is 2008 R2. The goal is to get paypal to communicate properly come July 1st.

Answer 1

As was mentioned .net 3.5.1 DOES now support TLS 1.2; but you don't need the registry changes mentioned by @Paulina's answer.

I'm using VS 2008 with .net 3.5.30729.4926. All I had to do was:

Add imports:

Imports System.Security.Authentication Imports System.Net 

Add this to my code (C#):

public const SslProtocols _Tls12 = (SslProtocols)0x00000C00; public const SecurityProtocolType Tls12 = (SecurityProtocolType)_Tls12; ServicePointManager.SecurityProtocol = Tls12 

VB.net version:

Const _Tls12 As SslProtocols = DirectCast(&HC00, SslProtocols) Const Tls12 As SecurityProtocolType = DirectCast(_Tls12, SecurityProtocolType) ServicePointManager.SecurityProtocol = Tls12 

Culled from: https://support.microsoft.com/en-us/help/3154518/support-for-tls-system-default-versions-included-in-the-.net-framework Note: by defining the const in my code I could ignore everything else in the article including the registry edits and cs files.

Answer 2

As you can see from the docs, TLS 1.2 is not in the enumeration for SslProtocols, it was added to the enum in .NET 4.5 (thanks @orhun).

There is no workaround for TLS 1.2 compatibility on .NET 3.5.

Unfortunately you will have to upgrade to .NET 4.5 or later to get TLS 1.2 compatibility.

EDIT 10/11/17

My above answer is no longer accurate. In May of 2017, Microsoft released a package to allow TLS 1.2 in .NET 3.5.1.