The client and server cannot communicate because they do not possess a common algorithm - ASP NET C IIS TLS 1 0 1 1 1 2 - Win32Exception

Question

I have an issue with a C  PayTrace Gateway  The below code was working fine until yesterday when I believe they turned off SSL3 due to the Poodle Exploit  When running the code below we got the following message  The remote server has forcefully closed the connection  After doing some research on the problem we determined that because our IIS Server 7 5 was configured to still use SSL3  C  defaulted to SSL3  which PayTrace would forcibly close the connection  We then removed SSL3 from the server  Which then lead to the following error    The client and server cannot communicate  because they do not possess a common algorithm    My guess is that there are additional SSL algorithm we need to install on the server now that SSL 3 is removed  Our IT staff claims that TLS 1 1 and TLS 1 2 are working and that ASP NET should be now defaulting to those  But I feel like there still must be something else we need to install on the server  I have no knowledge of SSL Algorithms so I have no idea where to begin    var postUrl   new StringBuilder       Initialize url with configuration and parameter values    postUrl AppendFormat  UN  0     this MerchantLoginID   postUrl AppendFormat  PSWD  0     this MerchantTransactionKey   postUrl Append  TERMS Y METHOD ProcessTranx TRANXTYPE Sale      postUrl AppendFormat  CC  0     cardNumber   postUrl AppendFormat  EXPMNTH  0     expirationMonth PadLeft 2   0     postUrl AppendFormat  EXPYR  0     expirationYear   postUrl AppendFormat  AMOUNT  0     transactionAmount   postUrl AppendFormat  BADDRESS  0     this AddressLine1   postUrl AppendFormat  BADDRESS2  0     this AddressLine2   postUrl AppendFormat  BCITY  0     this City   postUrl AppendFormat  BSTATE  0     this State   postUrl AppendFormat  BZIP  0     this Zip   postUrl AppendFormat  SADDRESS  0     this AddressLine1   postUrl AppendFormat  SADDRESS2  0     this AddressLine2   postUrl AppendFormat  SCITY  0     this City   postUrl AppendFormat  SSTATE  0     this State   postUrl AppendFormat  SZIP  0     this Zip   if   String IsNullOrEmpty this Country         postUrl AppendFormat  BCOUNTRY  0     this Country     if   String IsNullOrEmpty this Description         postUrl AppendFormat  DESCRIPTION  0     this Description     if   String IsNullOrEmpty this InvoiceNumber         postUrl AppendFormat  INVOICE  0     this InvoiceNumber     if  this IsTestMode        postUrl AppendFormat  TEST Y          postUrl Append     WebClient wClient   new WebClient    ServicePointManager SecurityProtocol   SecurityProtocolType Tls  String sRequest    PARMLIST     Url Encode postUrl ToString     wClient Headers Add  Content-Type    application x-www-form-urlencoded    string sResponse       sResponse   wClient UploadString PayTraceUrl  sRequest     Also  just an FYI  this issue is also happening when we connect to First Data E4 gateway so it s not just a PayTrace thing  My guess is that as more gateways turn off access to SSL3 we ll continue to run into issues with other gateways until this can be resolved on the server  Also  I did find a few suggestions online  some suggested placing the following code right before making the outbound request    ServicePointManager SecurityProtocol   SecurityProtocolType Tls    Unfortunately that did not work either  same error  Which is why I m thinking something additional needs to be installed on the IIS7 5 server  I m just not sure what

User · Answer

This was resolved  It turns out our IT Staff was correct  Both TLS 1 1 and TLS 1 2 were installed on the server  However  the issue was that our sites are running as ASP NET 4 0 and you have to have ASP NET 4 5 to run TLS 1 1 or TLS 1 2  So  to resolve the issue  our IT Staff had to re-enable TLS 1 0 to allow a connection with PayTrace    So in short  the error message   the client and server cannot communicate  because they do not possess a common algorithm   was caused because there was no SSL Protocol available on the server to communicate with PayTrace s servers    UPDATE   Please do not enable TLS 1 0 on your servers  this was a temporary fix and is not longer applicable since there are now better work-arounds that ensure strong security practices  Please see accepted answer for a solution  FYI  I m going to keep this answer on the site as it provides information on what the problem was  please do not down-vote

User · Answer

My app is running in  net 4 7 2  Simplest solution was to add this to the config     lt system web gt       lt httpRuntime targetFramework  quot 4 7 2 quot   gt     lt  system web gt

User · Answer

There are two possible scenario  in my case I used 2nd point   If you are facing this issue in production environment 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 this issue can be done by changing some configuration setting 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

User · Answer

After messing with this for days  my final fix for our issues required two things   1  We added this line of code to all of our  Net libraries that make out bound api calls to other vendors that had also disabled their SSL v3   ServicePointManager SecurityProtocol   SecurityProtocolType Tls       Net 4 and below    2  This is the final and FULL registry changes you will need when you are running ASP Net 4 0 sites and will need to be slightly changed after you upgrade to ASP Net 4 5   After we rebooted the servers - all problems went away after this   Windows Registry Editor Version 5 00   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 Client   DisabledByDefault  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 Client   Enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 Server   DisabledByDefault  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 Server   Enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Client   DisabledByDefault  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Client   Enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Server   DisabledByDefault  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Server   Enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Server   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Server   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Server   DisabledByDefault  dword 00000000

User · Answer

In previous answers a few registry keys that might not exist are missed  They are SchUseStrongCrypto that must exist to allow to TLS protocols work properly   After the registry keys have been imported to registry it should not be required to make changes in code like       ServicePointManager SecurityProtocol   SecurityProtocolType Tls    Below there are all registry keys and values that are needed for x64 windows OS  If you have 32bit OS  x86  just remove the last 2 lines  TLS 1 0 will be disabled by the registry script  Restarting OS is required    Windows Registry Editor Version 5 00   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 Client   DisabledByDefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 2 0 server   disabledbydefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols ssl 3 0    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols ssl 3 0 client   disabledbydefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols ssl 3 0 server   disabledbydefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 0    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 0 client   disabledbydefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 0 server   disabledbydefault  dword 00000001  enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 1    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 1 client   disabledbydefault  dword 00000000  enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 1 server   disabledbydefault  dword 00000000  enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 2    HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 2 client   disabledbydefault  dword 00000000  enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols tls 1 2 server   disabledbydefault  dword 00000000  enabled  dword 00000001   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

User · Answer

There are several other posts about this now and they all point to enabling TLS 1 2   Anything less is unsafe   You can do this in  NET 3 5 with a patch  You can do this in  NET 4 0 and 4 5 with a single line of code  ServicePointManager SecurityProtocol   SecurityProtocolType Tls12      NET 4 5 ServicePointManager SecurityProtocol    SecurityProtocolType 3072      NET 4 0   In  NET 4 6  it automatically uses TLS 1 2   See here for more details   NET support for TLS

User · Answer

In my case  even though Target Framework of Project was 4 7 1  I was still getting same Error  Solution was to change httpRuntime in web config under system web to 4 7 1

User · Answer

Enabling TLS 1 0 solved our issues as well  after disabling SSL v3     Server 2012 R2 with ASP net 4 0 website processing against PPI pay services    This is the RegEdit script I used to set everything the way I wanted   We only disabled SSL v3 for the Client and not the server as doing that broke other things that we were not ready to deal with yet   After we upgrade the site to  Net 4 5 2 then we will disable TLS 1 0 again   This script enables all protocols  Server and Client except for SSL v3 for the Client      Be sure to backup your registry    Windows Registry Editor Version 5 00   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Client   Enabled  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols SSL 3 0 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 0 Server   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 1 Server   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Client   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Client   DisabledByDefault  dword 00000000   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Server   Enabled  dword 00000001   HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL Protocols TLS 1 2 Server   DisabledByDefault  dword 00000000

User · Answer

I fixed this error by upgrading the app from  Net Framework 4 5 to 4 6 2   TLS-1 2 was correctly installed on the server  and older versions like TLS-1 1 were disabled  However   Net 4 5 does not support TLS-1 2

User · Answer

There are a couple of things that you need to check related to this  Whenever there is an error like this thrown related to making a secure connection  try running a script like the one below in Powershell with the name of the machine or the uri  like  quot www google com quot   to get results back for each of the different protocol types   function Test-SocketSslProtocols             CmdletBinding         param           Parameter Mandatory  true   string  ComputerName           int  Port   443           string    ProtocolNames    null                 set results list          ProtocolStatusObjArr    System Collections ArrayList           if  ProtocolNames -eq  null             if parameter  ProtocolNames empty get system list          ProtocolNames    System Security Authentication SslProtocols    Get-Member -Static -MemberType Property   Where-Object      Name -notin    quot Default quot    quot None quot       ForEach-Object      Name                foreach  ProtocolName in  ProtocolNames             create and connect socket          use default port 443 unless defined otherwise          if the port specified is not listening it will throw in error          ensure listening port is a tls exposed port          Socket   New-Object System Net Sockets Socket  System Net Sockets SocketType   Stream   System Net Sockets ProtocolType   Tcp           Socket Connect  ComputerName   Port            initialize default obj          ProtocolStatusObj    PSCustomObject                Computer    ComputerName             Port    Port              ProtocolName    ProtocolName             IsActive    false             KeySize    null             SignatureAlgorithm    null             Certificate    null                    try                 create netstream              NetStream   New-Object System Net Sockets NetworkStream  Socket   true                wrap stream in security sslstream              SslStream   New-Object System Net Security SslStream  NetStream   true               SslStream AuthenticateAsClient  ComputerName   null   ProtocolName   false                         RemoteCertificate    System Security Cryptography X509Certificates X509Certificate2  SslStream RemoteCertificate              ProtocolStatusObj IsActive    true              ProtocolStatusObj KeySize    RemoteCertificate PublicKey Key KeySize              ProtocolStatusObj SignatureAlgorithm    RemoteCertificate SignatureAlgorithm FriendlyName              ProtocolStatusObj Certificate    RemoteCertificate                     catch                  ProtocolStatusObj IsActive    false             Write-Error  quot Failure to connect to machine  ComputerName using protocol   ProtocolName  quot              Write-Error                          finally                             SslStream Close                                void  ProtocolStatusObjArr Add  ProtocolStatusObj              Write-Output  ProtocolStatusObjArr     Test-SocketSslProtocols -ComputerName  quot www google com quot   It will try to establish socket connections and return complete objects for each attempt and successful connection  After seeing what returns  check your computer registry via regedit  put  quot regedit quot  in run or look up  quot Registry Editor quot    place Computer HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control SecurityProviders SCHANNEL  in the filepath and ensure that you have the appropriate TLS Protocol enabled for whatever server you re trying to connect to  from the results you had returned from the scripts   Adjust as necessary and then reset your computer  this is required   Try connecting with the powershell script again and see what results you get back  If still unsuccessful  ensure that the algorithms  hashes  and ciphers that need to be enabled are narrowing down what needs to be enabled  IISCrypto is a good application for this and is available for free  It will give you a real time view of what is enabled or disabled in your SChannel registry where all these things are located   Also keep in mind the Windows version  DotNet version  and updates you have currently installed because despite a lot of TLS options being enabled by default in Windows 10  previous versions required patches to enable the option  One last thing  TLS is a TWO-WAY street  keep this in mind  with the idea being that the server s having things available is just as important as the client  If the server only offers to connect via TLS 1 2 using certain algorithms then no client will be able to connect with anything else  Also  if the client won t connect with anything else other than a certain protocol or ciphersuite the connection won t work  Browsers are also something that need to be taken into account with this because of their forcing errors on HTTP2 for anything done with less than TLS 1 2 DESPITE there NOT actually being an error  they throw it to try and get people to upgrade but the registry settings do exist to modify this behavior

User · Answer

In a previous answer  it was suggested to use this line of code for  Net 4 5   ServicePointManager SecurityProtocol   SecurityProtocolType Tls12      NET 4 5   I would encourage you to OR that value in to whatever the existing values are like this   ServicePointManager SecurityProtocol    SecurityProtocolType Tls12      NET 4 5   If you look at the list of values  you notice that they are a power of two   This way  in the future when things shift to TLS 2 0 for example  your code will still work

[c#] The client and server cannot communicate, because they do not possess a common algorithm - ASP.NET C# IIS TLS 1.0 / 1.1 / 1.2 - Win32Exception

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