Hi Felipe,

I don't think that's possible with Mbed TLS 3.0, but it was possible with Mbed TLS 2.x and will be possible again in Mbed TLS 3.1: you can access the DER representation of the certificate from the raw​ field of the mbedtls_x509_crt​ structure. A simple call to memcpy()​ should to the trick.

If you want to ouput it as PEM, I think you'll have to call `mbedtls_pem_write_buffer()` manually with appropriate values for header​ and footer​.

Regards,
Manuel.
From: mbed-tls <mbed-tls-bounces@lists.trustedfirmware.org> on behalf of Felipe Gasper via mbed-tls <mbed-tls@lists.trustedfirmware.org>
Sent: 01 December 2021 21:02
To: mbed-tls@lists.trustedfirmware.org <mbed-tls@lists.trustedfirmware.org>
Subject: [mbed-tls] Output a mbedtls_x509_crt?
 
Hello,

        Is it possible to output a mbedtls_x509_crt as PEM or DER? I’ve been combing the API docs but don’t see how I can do this export. I see controls for exporting a newly-built cert, but not one that comes from, e.g., mbedtls_ssl_get_peer_cert().

        Thank you!

Cheers,
-Felipe Gasper
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