OpenSSL "req -x509 -newkey" - Generate Private Key and Certificate


How to generate a new private key with a public key and generate a self-signed certificate using a single OpenSSL "req" command?



If you do not have a pair of private key and public key, and you want to generate self-signed certificate to represent your personal identity or server identity, you can use the OpenSSL "req -x509 -newkey" command as shown below. The same command will generate a pair of RSA private key and public key for you too.


OpenSSL> req -x509 -newkey rsa:512 -keyout rsa_test.key -out rsa_test.crt
Generating a 512 bit RSA private key
writing new private key to 'rsa_test.key'
Enter PEM pass phrase: fyicenter
Verifying - Enter PEM pass phrase: fyicenter
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [AU]:us
State or Province Name (full name) [Some-State]:NY
Locality Name (eg, city) []:New York
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Donald Inc.
Organizational Unit Name (eg, section) []:IT
Common Name (e.g. server FQDN or YOUR name) []
Email Address []

Options used in this "req" command are:

  • "-x509" - Generate self-signed certificate.
  • "-newkey rsa:512" - Generate a pair of 512-bit RSA private key with public key, and generate a new CSR.
  • "-keyout rsa_test.key" - Save the pair of RSA private key with public key to the given file.
  • "-out rsa_test.crt" - Save output, self-signed certificate, to the given file.
  • "fyicenter" - Password to protect the RSA private key file.


OpenSSL Self-Signed Certificate Components

OpenSSL "verify" - Validate Self-Signed Certificate

OpenSSL "req" Command

⇑⇑ OpenSSL Tutorials

2016-11-15, 797👍, 0💬