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Cipher Update

Cipher Update

Information about the upcoming update of supported TLS cipher suites


We will soon update our Bambora Epay domains to only support the four (4) following TLS1.2 cipher suites:


1)

IANA name: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256

OpenSSL name: ECDHE-ECDSA-AES128-GCM-SHA256

Cipher information: https://ciphersuite.info/cs/TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256/


2)

IANA name: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256

OpenSSL name: ECDHE-RSA-AES128-GCM-SHA256

Cipher information: https://ciphersuite.info/cs/TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256/


3)

IANA name: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384

OpenSSL name: ECDHE-ECDSA-AES256-GCM-SHA384

Cipher information: https://ciphersuite.info/cs/TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384/


4)

IANA name: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

OpenSSL name: ECDHE-RSA-AES256-GCM-SHA384

Cipher information: https://ciphersuite.info/cs/TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384/


This means that older operating systems, applications and other software that acts as a client to perform requests to our public domains might fail to negotiate a cipher suite and the requests will fail.


The error message might for example be something like:

"Could not create SSL/TLS secure channel"

"Algorithm/Cipher negotiation failed"

"TLS/SSL Handshake Failure"



It is only required that a single of the listed cipher suites is supported by the client application.

Please note that we will not be able to identify which clients that does not support our cipher suites. This change only affects traffic to our domains, and not requests to your domains (callbacks).



The timeline for the update is as follows:

September 14, 12.00-12.30 CET: Temporary switch to the new cipher suites

September 21, 12.00-13.00 CET: Temporary switch to the new cipher suites

September 28, 12.00 CET: Permanent switch to the new cipher suites


Complete list of affected domains:


ssl.ditonlinebetalingssystem.dk

admin.ditonlinebetalingssystem.dk

relay.ditonlinebetalingssystem.dk



How to verify if your client supports the cipher suites:


Important:

If you are using a hosting provider, then they should be able to confirm if the cipher suites are supported by them.


We have created the following new temporary Bambora Epay API endpoint that will redirect to the original endpoint (redirects only works with GET requests for most clients):


https://cipher-test-ssl.ditonlinebetalingssystem.dk (redirects to https://ssl.ditonlinebetalingssystem.dk)


If you can update your client config or code to point to the "cipher-test-"-prefixed domain name and the client gets any kind of HTTP response from the server (even errors), then you can be certain that your client supports the new cipher suites. If the client does not get any server response, then it probably does not support the new cipher suites. Try to log and debug to find out if you get a response from the server. Remember to change back to original domain and settings after finishing the tests.



In case you are unable change the client config or code, try to use the same runtime as your client application to perform requests to the "cipher-test-"-prefixed domain. If you get a HTTP response then the runtime and OS support the cipher suites.




When you are running a C-based interpreter/language like Python, Ruby, PHP, Bash, etc., then the OpenSSL version that it was built with will decide the supported ciphers. In case you are running .NET or Powershell on Windows, then the supported ciphers are decided by the Windows version and installed patches.



What can I do if I suspect that a client does not support any of the cipher suites:


In most cases an update to a sufficiently new version of the client application's interpreter/framework/platform/runtime will provide support for at least one of our supported cipher suites. For example, if you are running a PHP script, then upgrading PHP should be sufficient.


Please note that if you are running .NET applications or Powershell on "Windows 8"/"Windows Server 2012 R2" or earlier, then it will unfortunately not work to upgrade .NET or Powershell, but you will most likely need to upgrade to a newer OS that support our ciphers. On the other hand, running software that uses OpenSSL on Windows should always work if the OpenSSL version supports the listed ciphers and the application is configured accordingly.


Another option to support our ciphers on legacy systems is to set up a TLS-terminating proxy in your network to perform the requests to us. It's important that the proxy is hosted in your network, else the transmitted data will be less protected than when using a strong cipher end-to-end. Please note that we cannot provide support on how to set up a proxy.