This is a bit of a super duper specific question, but who knows there's someone out there that can help me.
I happen to have Philips Hue Bridge and I would love to know what personal information it is sharing with the outside world. Using tcpdump on my router I figured the Hue Bridge has a rather talkative personality. But because it talks over SSL tunnels, I have no idea what it says. So what I did is I setup a SonicWall with SSL-DPI with a CA, got root access to the Hue Bridge and found the application that does the talking to wws://ws.meethue.com (its called websocketcd). I then replaced the root certificate on the Hue Bridge, adjusted the cipher to match the Sonicwall and now I am stuck due to boost.asio trowing an validation error of my certificate:
error:14090086:lib(20):func(144):reason(134)
For those not too familiar with the error codes, this is what they mean:
lib(20) is ERR_LIB_SSL
func(144) is SSL_F_SSL3_GET_SERVER_CERTIFICATE
reason(134) is SSL_R_CERTIFICATE_VERIFY_FAILED
To verify it's not my SonicWall or certificate that is causing the problem, I executed openssl s_client -connect ws.meethue.com:443 -CAfile ca.pem from the Hue Bridge and that validates the chain perfectly fine, the same way as the original certificate. I also verified that the application is loading my root certificate and cipher correctly (because if change the cipher, I get a cipher error error). Also in my browser, I can visit https://ws.meethue.com without certificate errors. Here's my self made certificate chain, in case someone wants to check it: https://gofile.io/d/5msjoJ (password for download/key 1020304050, it's a temporary key that only exists in my local test env. so it's safe to share ;-)
If websocketcd wasn't a binary file, the problem was super easy to solve using set_verify_mode, but unfortunately it is a binary and that makes life significantly more complicated.
Is there anyone who can give me advice how to make this blob called websocketcd with boost.asio in it accept my root certificate? What I tried too: letting it communicate without ssl and with ssl without encryption (eNULL:aNULL ciphers). I am a bit hesitant to share the blob but for those who have a Hue Bridge too, it's located at /usr/bin/websocketcd.
For those interested: after some 20hrs, I figured that websocketcd requires a certificate revocation list for each CA in the chain (which do not have to have any revoked serials). These CLRs need to be included in the root CA file that is loaded using the ca-filename argument. I was not aware that Boost Asio could demand that a CLR is present for each CA, but apparently, they (Signify) managed to do so.