Default SecurityProtocol in NET 4 5

Question

What is the default security protocol for communicating with servers that support up to TLS 1 2  Will  NET by default  choose the highest security protocol supported on the server side or do I have to explicitly add this line of code   System Net ServicePointManager SecurityProtocol    SecurityProtocolType Tls   SecurityProtocolType Tls11   SecurityProtocolType Tls12    Is there a way to change this default  besides a code change   Lastly  does  NET 4 0 only support up to TLS 1 0  i e  I have to upgrade client projects to 4 5 to support TLS 1 2   My motivation is to remove support for SSLv3 on the client side even if server supports it  I already have a powershell script to disable this in the machine registry  and to support the highest TLS protocol that the server supports   Update  Looking at the ServicePointManager class in  NET 4 0 I see no enumerated values for TLS 1 0 and 1 1  In both  NET 4 0 4 5  the default is SecurityProtocolType Tls SecurityProtocolType Ssl3  Hopefully this default won t break by disabling SSLv3 in the registry   However  I ve decided I have to upgrade all apps to  NET 4 5 and to explicitly add SecurityProtocolType Tls   SecurityProtocolType Tls11   SecurityProtocolType Tls12  anyway to all bootstrapping code of all applications   This will make outbound requests to various apis and services to not downgrade to SSLv3 and should select the highest level of TLS   Does this approach sound reasonable or overkill  I have many applications to update  and I want to future proof them since I hear even TLS 1 0 may be deprecated in the near future by some providers   As a client making outbound requests to APIs  does disabling SSL3 in the registry even have an effect in the  NET framework  I see by default  TLS 1 1 and 1 2 are not enabled  do we have to enable it via the registry  RE http   support microsoft com kb 245030    After a bit of investigation  I believe the registry settings will have no affect since they apply to IIS  server subkey  and browsers  client subkey    Sorry this post turned into multiple questions  followed up with  maybe  answers

User · Answer

There are two possible scenario   If you application run on  net framework 4 5 or less than that and you can easily deploy new code to the production then you can use of below solution  You can add below line of code before making api call  ServicePointManager SecurityProtocol   SecurityProtocolType Tls12      NET 4 5  If you cannot deploy new code and you want to resolve with the same code which is present in the production  then you have two options    Option 1    HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v4 0 30319   quot SchUseStrongCrypto quot  dword 00000001   HKEY LOCAL MACHINE SOFTWARE Wow6432Node Microsoft  NETFramework v4 0 30319   quot SchUseStrongCrypto quot  dword 00000001    then create a file with extension  reg and install  Note   This setting will apply at registry level and is applicable to all application present on that machine and if you want to restrict to only single application then you can use Option 2 Option 2   This can be done by changing some configuration setting in config file  You can add either of one in your config file   lt runtime gt       lt AppContextSwitchOverrides value  quot Switch System Net DontEnableSchUseStrongCrypto false quot   gt     lt  runtime gt   or  lt runtime gt     lt AppContextSwitchOverrides value  quot Switch System Net DontEnableSystemDefaultTlsVersions false quot   lt  runtime gt

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For completeness  here is a Powershell script that sets aforementioned registry keys   new-itemproperty -path  HKLM  SOFTWARE Microsoft  NETFramework v4 0 30319  -name  SchUseStrongCrypto  -Value 1 -PropertyType  DWord   new-itemproperty -path  HKLM  SOFTWARE Wow6432Node Microsoft  NETFramework v4 0 30319  -name  SchUseStrongCrypto  -Value 1 -PropertyType  DWord

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If you can use  NET 4 7 1 or newer  it will use TLS 1 2 as the minimum protocol based on the operating system capabilities  Per Microsoft recommendation    To ensure  NET Framework applications remain secure  the TLS version should not be hardcoded   NET Framework applications should use the TLS version the operating system  OS  supports

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For Key  HKEY LOCAL MACHINE SOFTWARE Microsoft NETFramework v4 0 30319  Value  SchUseStrongCrypto   You have to set the value to 1

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You can override the default behavior in following registry   Key    HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v4 0 30319  Value  SchUseStrongCrypto Type  REG DWORD Data   1   and  Key    HKEY LOCAL MACHINE SOFTWARE WOW6432Node Microsoft  NETFramework v4 0 30319 Value  SchUseStrongCrypto Type  REG DWORD Data   1   For details  please see the implementation of ServicePointManager

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I m running under  NET 4 5 2  and I wasn t happy with any of these answers  As I m talking to a system which supports TLS 1 2  and seeing as SSL3  TLS 1 0  and TLS 1 1 are all broken and unsafe for use  I don t want to enable these protocols  Under  NET 4 5 2  the SSL3 and TLS 1 0 protocols are both enabled by default  which I can see in code by inspecting ServicePointManager SecurityProtocol  Under  NET 4 7  there s the new SystemDefault protocol mode which explicitly hands over selection of the protocol to the OS  where I believe relying on registry or other system configuration settings would be appropriate  That doesn t seem to be supported under  NET 4 5 2 however  In the interests of writing forwards-compatible code  that will keep making the right decisions even when TLS 1 2 is inevitably broken in the future  or when I upgrade to  NET 4 7  and hand over more responsibility for selecting an appropriate protocol to the OS  I adopted the following code   SecurityProtocolType securityProtocols   ServicePointManager SecurityProtocol  if  securityProtocols HasFlag SecurityProtocolType Ssl3     securityProtocols HasFlag SecurityProtocolType Tls     securityProtocols HasFlag SecurityProtocolType Tls11         securityProtocols  amp     SecurityProtocolType Ssl3   SecurityProtocolType Tls   SecurityProtocolType Tls11       if  securityProtocols    0                securityProtocols    SecurityProtocolType Tls12            ServicePointManager SecurityProtocol   securityProtocols      This code will detect when a known insecure protocol is enabled  and in this case  we ll remove these insecure protocols  If no other explicit protocols remain  we ll then force enable TLS 1 2  as the only known secure protocol supported by  NET at this point in time  This code is forwards compatible  as it will take into consideration new protocol types it doesn t know about being added in the future  and it will also play nice with the new SystemDefault state in  NET 4 7  meaning I won t have to re-visit this code in the future  I d strongly recommend adopting an approach like this  rather than hard-coding any particular security protocol states unconditionally  otherwise you ll have to recompile and replace your client with a new version in order to upgrade to a new security protocol when TLS 1 2 is inevitably broken  or more likely you ll have to leave the existing insecure protocols turned on for years on your server  making your organisation a target for attacks

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I have found that when I specify only TLS 1 2 that it will still down negotiate to 1 1  System Net ServicePointManager SecurityProtocol    SecurityProtocolType Tls12   I have specified this in the Global asax startup method for my  net 4 5 web app

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An alternative to hard-coding ServicePointManager SecurityProtocol or the explicit SchUseStrongCrypto key as mentioned above  You can tell  NET to use the default SCHANNEL settings with the SystemDefaultTlsVersions key  e g     HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v4 0 30319   SystemDefaultTlsVersions  dword 00000001  HKEY LOCAL MACHINE SOFTWARE Wow6432Node Microsoft  NETFramework v4 0 30319   SystemDefaultTlsVersions  dword 00000001

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Following code will    print enabled protocols print available protocols enable TLS1 2 if platform supports it and if it is not enabled to begin with disable SSL3 if it is enabled print end result   Constants    48 is SSL3 192 is TLS1 768 is TLS1 1 3072 is TLS1 2   Other protocols will not be affected  This makes this compatible with future protocols  Tls1 3  etc     Code     print initial status     Console WriteLine  Runtime      System Diagnostics FileVersionInfo GetVersionInfo typeof int  Assembly Location  ProductVersion       Console WriteLine  Enabled protocols        ServicePointManager SecurityProtocol       Console WriteLine  Available protocols          Boolean platformSupportsTls12   false      foreach  SecurityProtocolType protocol in Enum GetValues typeof SecurityProtocolType                              Console WriteLine protocol GetHashCode             if  protocol GetHashCode      3072               platformSupportsTls12   true                      Console WriteLine  Is Tls12 enabled      ServicePointManager SecurityProtocol HasFlag  SecurityProtocolType 3072             enable Tls12  if possible     if   ServicePointManager SecurityProtocol HasFlag  SecurityProtocolType 3072            if  platformSupportsTls12               Console WriteLine  Platform supports Tls12  but it is not enabled  Enabling it now                 ServicePointManager SecurityProtocol     SecurityProtocolType 3072            else               Console WriteLine  Platform does not supports Tls12                         disable ssl3    if  ServicePointManager SecurityProtocol HasFlag SecurityProtocolType Ssl3            Console WriteLine  Ssl3SSL3 is enabled  Disabling it now              disable SSL3  Has no negative impact if SSL3 is already disabled  The enclosing  if  if just for illustration        System Net ServicePointManager SecurityProtocol  amp    SecurityProtocolType Ssl3                                 Console WriteLine  Enabled protocols        ServicePointManager SecurityProtocol     Output  Runtime  4 7 2114 0 Enabled protocols    Ssl3  Tls Available protocols   0 48 192 768 3072 Is Tls12 enabled  False Platform supports Tls12  but it is not enabled  Enabling it now  Ssl3 is enabled  Disabling it now  Enabled protocols    Tls  Tls12

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Some of the those leaving comments have noted that setting System Net ServicePointManager SecurityProtocol to specific values means that your app won t be able to take advantage of future TLS versions that may become the default values in future updates to  NET   Instead of specifying a fixed list of protocols  you can instead turn on or off protocols you know and care about  leaving any others as they are   To turn on TLS 1 1 and 1 2 without affecting other protocols   System Net ServicePointManager SecurityProtocol         SecurityProtocolType Tls11   SecurityProtocolType Tls12    Notice the use of    to turn on these flags without turning others off   To turn off SSL3 without affecting other protocols   System Net ServicePointManager SecurityProtocol  amp    SecurityProtocolType Ssl3

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According to Transport Layer Security  TLS  best practices with the  NET Framework  To ensure  NET Framework applications remain secure  the TLS version should not be hardcoded  Instead set the registry keys  SystemDefaultTlsVersions and SchUseStrongCrypto   Windows Registry Editor Version 5 00   HKEY LOCAL MACHINE SOFTWARE WOW6432Node Microsoft  NETFramework v2 0 50727   SystemDefaultTlsVersions  dword 00000001  SchUseStrongCrypto  dword 00000001   HKEY LOCAL MACHINE SOFTWARE WOW6432Node Microsoft  NETFramework v4 0 30319   SystemDefaultTlsVersions  dword 00000001  SchUseStrongCrypto  dword 00000001   HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v2 0 50727   SystemDefaultTlsVersions  dword 00000001  SchUseStrongCrypto  dword 00000001   HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v4 0 30319   SystemDefaultTlsVersions  dword 00000001  SchUseStrongCrypto  dword 00000001

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I got the problem when my customer upgraded TLS from 1 0 to 1 2  My application is using  net framework 3 5 and run on server  So i fixed it by this way    Fix the program   Before call HttpWebRequest GetResponse   add this command   ServicePointManager SecurityProtocol   SecurityProtocolType Ssl3   SecurityProtocolType Tls   SecurityProtocolTypeExtensions Tls11   SecurityProtocolTypeExtensions Tls12    Extensions 2 DLLs by adding 2 new classes  System Net and System Security Authentication      namespace System Net               using System Security Authentication          public static class SecurityProtocolTypeExtensions                       public const SecurityProtocolType Tls12    SecurityProtocolType SslProtocolsExtensions Tls12              public const SecurityProtocolType Tls11    SecurityProtocolType SslProtocolsExtensions Tls11              public const SecurityProtocolType SystemDefault    SecurityProtocolType 0                        namespace System Security Authentication               public static class SslProtocolsExtensions                       public const SslProtocols Tls12    SslProtocols 0x00000C00              public const SslProtocols Tls11    SslProtocols 0x00000300                      Update Microsoft batch   Download batch     For windows 2008 R2  windows6 1-kb3154518-x64 msu For windows 2012 R2  windows8 1-kb3154520-x64 msu   For download batch and more details you can see here   https   support microsoft com en-us help 3154518 support-for-tls-system-default-versions-included-in-the- net-framework-3 5 1-on-windows-7-sp1-and-server-2008-r2-sp1

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Create a text file with a  reg extension and the following contents   Windows Registry Editor Version 5 00   HKEY LOCAL MACHINE SOFTWARE Microsoft  NETFramework v4 0 30319   SchUseStrongCrypto  dword 00000001   HKEY LOCAL MACHINE SOFTWARE Wow6432Node Microsoft  NETFramework v4 0 30319   SchUseStrongCrypto  dword 00000001   Or download it from the following source   https   tls1test salesforce com s NET40-Enable-TLS-1 2 reg  Double-click to install

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The BEST solution to this problem appears to be to upgrade to at least  NET 4 6 or later  which will automatically choose strong protocols as well as strong ciphers   If you can t upgrade to  NET 4 6  the advice of setting   System Net ServicePointManager SecurityProtocol    SecurityProtocolType Tls11   SecurityProtocolType Tls12   And using the registry settings   HKEY LOCAL MACHINE SOFTWARE Microsoft NETFramework v4 0 30319     SchUseStrongCrypto   DWORD of 1 HKEY LOCAL MACHINE SOFTWARE Wow6432Node Microsoft NETFramework v4 0 30319     SchUseStrongCrypto   DWORD of 1  Results in using something other than TLS 1 0 and a strong cipher   In my testing  only the setting in the Wow6432Node made any difference  even though my test application was built for Any CPU

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Microsoft recently published best practices around this   https   docs microsoft com en-us dotnet framework network-programming tls Summary Target  Net Framework 4 7  remove any code setting the SecurityProtocol  thus the OS will ensure you use the most secure solution  NB  You will also need to ensure that the latest version of TLS is supported  amp  enabled on your OS  OS                          TLS 1 2 support  Windows 10                     Supported  and enabled by default  Windows Server 2016              Windows 8 1                    Supported  and enabled by default  Windows Server 2012 R2        Windows 8 0                    Supported  and enabled by default  Windows Server 2012           Windows 7 SP1                  Supported  but not enabled by default   Windows Server 2008 R2 SP1    Windows Server 2008         -  Support for TLS 1 2 and TLS 1 1 requires an update  See Update to add support for TLS 1 1 and TLS 1 2 in Windows Server 2008 SP2  Windows Vista               -  Not supported     To enable TLS1 2 via the registry see https   docs microsoft com en-us windows-server security tls tls-registry-settings tls-12       Path  HKLM  SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS1 2 Server          Property  Enabled         Type  REG DWORD         Value  1          Property  DisabledByDefault          Type  REG DWORD         Value  0      Path  HKLM  SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS1 2 Client          Property  Enabled         Type  REG DWORD         Value  1          Property  DisabledByDefault          Type  REG DWORD         Value  0  For more information and older frameworks  please refer to the MS link

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The registry change mechanism worked for me after a struggle  Actually my application was running as 32bit  So I had to change the value under path   HKEY LOCAL MACHINE SOFTWARE Wow6432Node Microsoft NETFramework v4 0 30319   The value type needs to be DWORD and value above 0  Better use 1

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The default System Net ServicePointManager SecurityProtocol in both  NET 4 0 4 5 is SecurityProtocolType Tls SecurityProtocolType Ssl3    NET 4 0 supports up to TLS 1 0 while  NET 4 5 supports up to TLS 1 2  However  an application targeting  NET 4 0 can still support up to TLS 1 2 if  NET 4 5 is installed in the same environment   NET 4 5 installs on top of  NET 4 0  replacing System dll    I ve verified this by observing the correct security protocol set in traffic with fiddler4 and by manually setting the enumerated values in a  NET 4 0 project   ServicePointManager SecurityProtocol    SecurityProtocolType 192    SecurityProtocolType 768    SecurityProtocolType 3072    Reference   namespace System Net        System Flags      public enum SecurityProtocolType              Ssl3   48         Tls   192         Tls11   768         Tls12   3072            If you attempt the hack on an environment with ONLY  NET 4 0 installed  you will get the exception      Unhandled Exception  System NotSupportedException  The requested security protocol is not supported       at System Net ServicePointManager set SecurityProtocol SecurityProtocolType v   alue    However  I wouldn t recommend this  hack  since a future patch  etc  may break it    Therefore  I ve decided the best route to remove support for SSLv3 is to    Upgrade all applications to  NET 4 5 Add the following to boostrapping code to override the default and future proof it   System Net ServicePointManager SecurityProtocol    SecurityProtocolType Tls   SecurityProtocolType Tls11   SecurityProtocolType Tls12     Someone correct me if this hack is wrong  but initial tests I see it works

[.net] Default SecurityProtocol in .NET 4.5

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