Matrox Extio 3 Series User Manual page 24

Certificates and private keys
Supported certificate formats are X.509 and PKCS#12. PKCS#12 containers must be protected by a
single password (i.e. PKCS#12 generated by "openssl pkcs12 -twopass" are not supported).
Certificates in the X.509 format and private keys format must all be PEM or DER encoded.
Supported private key formats are RSA, ECDSA, and PKCS#8.
24 Matrox Extio 3 Series – User Guide