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Some Notes About Various Certificate Operations Using OpenSSL

Our system support group delivered a signed certificate to be used in Apache SSL configuration. Its extension was *.pfx, which meant its contents were in PKCS12 format, and was containing both certificate and its private key in it. I needed to convert it into PEM format and to separate certificate from its private key.

The first command creates key file, and the second one converts certificate into PEM format;

openssl pkcs12 -in innova.pfx -nocerts -nodes -out innova.key
openssl pkcs12 -in innova.pfx -clcerts -nokeys -out innova.pem

I needed to create a CA cert list which will contain CA certificates appended to one another. CA certificates of our signed certificate were delivered in binary DER format. In order to create appended cert file in PEM format, I first needed to convert those binary CA certs into base64 encoded format. This is easy with “Certificate Export Wizard” in Win32 platform. You just need to open certificate and save it to file and select the format during this process. After that, I issued following command to create appended CA cert list in PEM format.

openssl x509 –in ca1.cer –text >> ca_cert_list.pem

I needed to repeat above command for each CA cert separately

In order to see CN (common name) specified in your certificate;

openssl x509 –text –in innova.pem

Above command will output cert info in textual form. If your certificate’s CN looks similar to “CN=\x00*\x00.\x00i\x00n\x00n\x00o\x00v\x00a\x00.\x00c\x00o\x00m\x00.\x00t\x00r”, don’t think that it is corrupted or so. If it is a wildcard certificate, that is issued for all *.innova.com.tr subdomains as in our example, outputing CN will be shown as above.

If your certificate’s format is PKCS12 then you must use;

openssl pkcs12 -info -in innova.pfx

Here, you will be prompted key passphrase, and asked a new PEM passphrase as well. Second passphrase is not important as we only display certificate structure in standard output.

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