Certificate Format Conversion

Sometimes there is a need to convert a SSL certificate from one format to another for example a load balancer & Windows IIS will probably require different formats. You can use openssl to do this conversion by using the following commands.

Convert from PEM to PFX (e.g. from F5 to Windows IIS)

openssl pkcs12 -export -out output.pfx -inkey input.key -in input.crt -certfile input.ca-bundle -passout pass:<PASSWORD>

Where
output.pfx      - this is the output file
input.key       - this is the original key file used to create the csr
input.crt       - this is the signed certifiate file received back from the certificate authority
input.ca-bundle - this is the cert chain file
<PASSWORD>      - this is the password to protect the private key on the pfx bundle

Convert from PFX to PEM with no output private key password (e.g. from Windows IIS / Verisign to DenyAll WAF)

openssl pkcs12 -in input.pfx -out output.pem -nodes

If the private key in the pfx input is protected by a password, you will be prompted.

Check a chainfile is valid for a certificate

openssl verify -CAfile certchain.pem -verbose cert.pem