Can't establish TLS-PSK connection to MQTT broker

[Grzegorz Blach]

Hello,

I'm writing software for my own board with nrf52840 and SIM800C modem.

I try to connect to MQTT broker. It works when I have TLS disabled or have TLS with certificate enabled. But fails when I try to connect to broker with TLS-PSK enabled.

In Zephyr logs I see: "net_sock_tls: TLS handshake error: -7600" or sometimes "net_sock_tls: TLS handshake error: -7280"

And in MQTT broker logs I see: "OpenSSL Error[0]: error:14201076:SSL routines:tls_choose_sigalg:no suitable signature algorithm"

I can connect to broker using mosquitto_pub command, so it looks that broker is configured correctly.

Could you point me out what might be wrong?

[Heidi]

Hi!

I'll need some more information about your application. For instance, are you running the TLS stack on the nRF52840 or the modem? 

Best regards,

Heidi

[Grzegorz Blach]

I'm running TLS stack on the nRF52840. Generally the network part of my application is based on these samples:

https://github.com/nrfconnect/sdk-zephyr/tree/master/samples/net/gsm_modem

https://github.com/nrfconnect/sdk-zephyr/tree/master/samples/net/dns_resolve

https://github.com/nrfconnect/sdk-zephyr/tree/master/samples/net/mqtt_publisher