Appendix: Create SSL Certificate

Prerequisites

• Create the root pair (rootCA key & rootCA cert).
• Prepare the mkdir /root/ca directory.
• Create the directory structure:

  # cd /root/ca
  # mkdir certs crl newcerts private
  # chmod 700 private
  # touch index.txt
  # echo 1000 > serial

• Copy the root CA configuration (openssl.cnf) to /root/ca/openssl.cnf
• Create the root key:

  # cd /root/ca
  # openssl genrsa -aes256 -out private/<rootCA>.key.pem 4096

• Enter pass phrase for <rootCA>.key.pem: <Enter password>
• Verifying - Enter pass phrase for <rootCA>.key.pem: <Enter password>

# chmod 400 private/<rootCA>.key.pem

Create Root Certificate

• Use the <rootCA>.key.pem root key to create the <rootCA>.cert.pem root certificate.

  # cd /root/ca
  # openssl req -config openssl.cnf -key private/<rootCA>.key.pem -new -x509 -days 7300 -sha256 -extensions v3_ca -out certs/<rootCA>.cert.pem

• Enter the pass phrase for <rootCA>.key.pem: <password for “rootCA.key.pem”>

  You are about to be asked to enter information that will be incorporated
  into your certificate request.
  -----
  Country Name (2 letter code) [XX]: <Enter country code>
  State or Province Name []: <Enter state or province>
  Locality Name []: <Enter city>
  Organization Name []: <Enter company name>
  Organizational Unit Name []: <Enter company OU>
  Common Name []: <Enter some value>
  Email Address []: <Enter admin mail account>

# chmod 444 certs/<rootCA>.cert.pem

Verify Root Certificate

# cd /<rootCA>.cert.pem

The output shows:

• The Signature Algorithm used
• The dates of certificate Validity
• The Public-Key bit length
• The Issuer, which is the entity that signed the certificate
• The Subject, which refers to the certificate itself

The Issuer and Subject are identical as the certificate is self-signed. Note that all root certificates are self-signed.

Signature Algorithm: sha256WithRSAEncryption
    Issuer: C=GB, ST=England,
            O=Alice Ltd, OU=Alice Ltd Certificate Authority,
            CN=Alice Ltd Root CA
    Validity
        Not Before: Apr 11 12:22:58 2015 GMT
        Not After : Apr  6 12:22:58 2035 GMT
    Subject: C=GB, ST=England,
             O=Alice Ltd, OU=Alice Ltd Certificate Authority,
             CN=Alice Ltd Root CA
    Subject Public Key Info:
        Public Key Algorithm: rsaEncryption
            Public-Key: (4096 bit)

The output also shows the X509v3 extensions. We applied the v3_ca extension, so the options from [ v3_ca ] should be reflected in the output.

X509v3 extensions:
    X509v3 Subject Key Identifier:
        38:58:29:2F:6B:57:79:4F:39:FD:32:35:60:74:92:60:6E:E8:2A:31
    X509v3 Authority Key Identifier:
        keyid:38:58:29:2F:6B:57:79:4F:39:FD:32:35:60:74:92:60:6E:E8:2A:31

    X509v3 Basic Constraints: critical
        CA:TRUE
    X509v3 Key Usage: critical
        Digital Signature, Certificate Sign, CRL Sign