There are various file types for digital certificates and private keys depending on the issuer. The following types are common:
- *.pfx and *.p12: PKCS#12 files
- *.pem, *.cer and *.crt: BASE-64-coded certificates
- *.cer, *.crt and *.der: DER coded certificates
- *.key: BASE64 or DER coded keys
- *.pvk: Microsoft-specific key format
Apart from the straightforward certificates, there is another file type that is of significance in the world of certificate-secured VPN connections: The PCK#12 files which can contain multiple components such as a certificate and a private key. To process the PKCS#12 file, a password has to be entered which was set when the certificate was exported.
Note: BASE64-coded certificates have a header that typically features
the following lines: ----- BEGIN CERTIFICATE -----