Client certificate authentication not working

[numericOverflow]

I'm on a (rooted) Samsung Note10+ running Android 10, trying to connect to a personal mosquitto broker I'm running. Authentication is via certificates only, and that works fine using the same certificates on my windows machine via MQTT-Explorer (v0.3.5). Given that, I don't think the issue is with the certs themselves.

I've copied the 3 certs (CA/Cert/Key) over from my linux based PKI, but it appears as though they are not being used when connecting to my mosquitto broker. I get the error shown below in my mosquitto logs saying "peer did not return a certificate"

I can provide more detail of you need it, just let me know how I can help.

I'm running MQTTClient version 4.5.1

2020-12-25_16:49:41: New connection from 192.168.1.1:40940 on port 8883.
2020-12-25_16:49:41: OpenSSL Error[0]: error:1417C0C7:SSL routines:tls_process_client_certificate:peer did not return a certificate
2020-12-25_16:49:41: Bad socket read/write on client <unknown>, disconnecting.

[numericOverflow]

FYI - I also tried with a PKCS12 file container of the certificates, and I get the same error from mosquitto: "tls_process_client_certificate:peer did not return a certificate"

[andreapx]

I've got a problem too with the SSL connection.
On the server log I see:
OpenSSL Error[0]: error:14035416:SSL routines:ACCEPT_SR_CERT:sslv3 alert certificate unknown OpenSSL Error[1]: error:140350E5:SSL routines:ACCEPT_SR_CERT:ssl handshake failure Client <unknown> disconnected: Protocol error.

The certificate is working on a linux client.
@numericOverflow did you manage to solve this problem?

[numericOverflow]

@andreapx - I never did get it working. I messed around with it for quite a while but could never get it to work correctly. The project I needed it for hit some other issues and stalled, so I kind of abandoned this issue.

Just curiously, what broker are you using?

[andreapx]

Just curiously, what broker are you using?

I'm using Mosqitto and I don't have any problem using it with Node Red.