Overview of the Crypto Kit updates in Citrix Workspace for Windows and Mac

Applicable Products

Citrix Workspace App 1904 for Windows and later. Also for Citrix Workspace App 1910 and later.

Note: Citrix has deprecated weak cryptography across the board. If the configurations on the backend is not updated to support one of the 3 supported strong cipher suites, you will not be able to connect.

At least one of these is required:
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030)
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (0xc028)
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013)

Objective

This feature is an important change to the secure communication protocol. Cipher suites with the prefix TLS_RSA_ do not offer forward secrecy and are considered weak. These cipher suites were deprecated in Citrix Receiver version 13.10 with an option for backward compatibility.

In this release, the TLS_RSA_ cipher suites have been removed entirely. Instead, this release supports the advanced TLS_ECDHE_RSA_ cipher suites. If your environment is not configured with the TLS_ECDHE_RSA_ cipher suites, client launches are not supported due to weak ciphers.

This document aims to detail the changes to the cipher suites.

What’s New?

The following advanced cipher suites are supported:

• TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030)

• TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (0xc028)
• TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013)

In earlier releases, the GPO configuration that was available under the below Computer Configuration node which allowed to enable the deprecated cipher suites has been removed now.

Administrative Template>Citrix Component>Citrix Workspace>Network Routing>Deprecated Cipher Suites


The following cipher matrix provides the ciphers supported by the latest SSL SDK:

Expected failure scenarios and edge cases

• TCP

  • OPEN mode: Session launch is not supported when the client is configured forGOVand the VDA forCOM. This happens because a common cipher suite is absent.

  • FIPS/NIST(SP800-52) compliance mode: Session launch is not supported when the VDA is configured for COM the client for COM, GOV, or ANY, or the other way around. This happens because a common cipher suite is absent.

• DTLS v1.0supports the following cipher suites:

• TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
• TLS_EMPTY_RENEGOTIATION_INFO_SCSV

• DTLS v1.2supports the following cipher suites:
  • TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
  • TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
  • TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
  • TLS_EMPTY_RENEGOTIATION_INFO_SCSV

• Therefore, session launch is not supported from a client configured for GOV to a VDA configured for COM. Also, fallback to TCP is not supported. When you use DTLS v1.0, session launch is not supported for clients configured for GOV because a common cipher suite is absent.

.

• 迪泰不支持FIPS / NIST合规模式。
• DTLS v1.2 is supported by Windows 10 (1607 and later) and Windows 2016 VDAs. For more information, see Knowledge Center articlehttps://support.citrix.com/article/CTX230010.
• DTLS v1.2 is not supported by Citrix Gateway. This scenario can be tested only with DTLS v1.0. For Citrix Gateway ciphers troubleshooting, see Knowledge Center articlehttps://support.citrix.com/article/CTX235509.

The following matrices provide details of internal and external network connections:

• Matrix for internal network connections (Citrix Gateway scenario)

• Matrix for external network connections (Citrix Gateway scenario)

Note: When NetScaler Gateway is used

1. For the EDT to work, NetScaler Gateway must be of version 12.1 or higher since the older versions doesn't support ECDHE cipher suites in DTLS mode.
2. NetScaler Gateway doesn't support DTLS 1.2 so TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 and TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 are not supported and NetScaler Gateway must be configured to use TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA for it to work in DTLS 1.0

For more information, see the Citrix Workspace app forWindowsandMacdocumentation.