Openssl seems to inspects application data?

[Kreissl, Jochen]

Hi,

I am using openssl (3.2) in an application.
Handshake works just fine but I get a very weird behavior when I receive a big certificate chain inside application data (TLS 1.3 but NOT using Post-Handshake Auth, this is some level-7 auth protocol on top of tls).
The openssl error I get is error:0308010C:digital envelope routines::unsupported
Which ... seems to indicate that openssl is trying (and failing) to interpret the certificate chain...?

I really don't understand what is going on.
I thought openssl would treat any application data sent using SSL_write following a completed handshake would be opaque for openssl - because why would it look inside and try to parse something?

Does anyone have an explanation or have encountered something similar?


Regards
Jochen

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