I have a Windows service application that uses cpprestsdk and the http_client class. For troubleshooting purposes I need to decrypt the TLSv1.2 traffic (and the Encrypted Alert that leads to a RST-ACK) using Wireshark.

To accomplish this I am following the instructions at this Wireshark wikis link for TSL Decryption.

I cannot use the “RSA private key” method because our servers cipher suite is (EC)DHE.

So I am attempting to use the first method “Key log file using per-session secrets”. I do have the SSLKEYLOGFILE environment variable set. I have successfully decrypted traffic using Firefox, so I am confident I have that part setup correctly.

However, when I run our cpprestsdk application it writes nothing to the key log file. I know this because I have emptied the file then ran again and it is still empty. Then I run Firefox and it has session keys again.

I have looked around the cpprestsdk api and I do not see anything for enabling it. The Google machine and reference docs have not been very helpful so far.

How do I get cpprestsdk to output to the key log file? Is it even possible with cpprestsdk?