App Control: CDC Connectivity Error "The Client and Server Cannot Communicate Because They Do Not Possess a Common Algorithm"

[#1]

Environment

• App Control Server: 7.x - 8.x
• Microsoft Windows Server: All Supported Versions
• TLS 1.0 disabled

Symptoms

Error in console

• "Collective Defense Cloud / Bit9 Software Reputation Service Unavailable"

Error in C:\Program Files (x86)\Bit9\Parity Server\Reporter\ParityReporter.txt

• "An unexpected error occurred on a receive. ---> System.ComponentModel.Win32Exception: The client and server cannot communicate, because they do not possess a common algorithm"

Cause

.Net not using the latest TLS version

Resolution

1. Add DWORD entries to the registry of the App Control application server:
   • [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
2. Restart the App Control Server

Additional Notes

Adding the registry keys will force .Net to use the latest version of TLS

Related Content

App Control: Requirements for Disabling TLS 1.0/1.1 and Enable TLS 1.2 on the App Control Server and...
Enable Transport Layer Security (TLS) 1.2 overview - Configuration Manager
App Control: How To Check CDC/SRS Status and Connectivity