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Users have a choice to use CA-signed certificates and self-signed certificates:

• CA-signed certificates are issued by a know known and trusted Certificate Authority (CA).
• Self-signed certificates are created by the user and are not related to a known CA.

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The article explains how to create self-signed certificates by use of OpenSSL. This utility ships with Linux and most Unix environments and is available for Windows environments. The below examples are focused on Unix.

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root_ca_certificate root_ca_certificate

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Creating the Root CA Certificate

The first step includes to create the root-ca.key private key file and the root-ca.crt self-signed certificate file for the Root CA both in PEM format. This step is performed just once.

# step 1 Generate Certificate Authority (CA) Private Key
openssl ecparam -name prime256v1 -genkey -noout -out root-ca.key

# step 2: Generate Certificate Authority Certificate
openssl req -new -x509 -sha256 -key root-ca.key -out root-ca.crt

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server_certificate server_certificate

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Creating a Server Certificate

For a given server the second step next steps includes to create a private key and Certificate Signing Request (CSR). The resulting server certificate will be signed. 

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