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admin_Renewing a CA-Signed Certificate in a Keystore

A digital certificate has a validity period, after which the certificate expires. Once a certificate expires, it is no longer valid, and it can cause the client-server communication to fail at the SSL handshake level. Therefore, it is important to plan certificate renewal ahead of time. Neglecting certificate renewal can eventually lead to a catastrophic situation such as major service outage.

Following are the high level steps you need to follow to renew an expired certificate in a keystore.

Tip

Following are a few important points to keep in mind when you are renewing an expired certificate:

  • Use the same certificate authority that you used when you first got the public certificate. If you use a different certificate authority for certificate renewal, you will have to import the new CA-certificate as well as the intermediate certificates to the keystore and the client’s trust store.
  • If the certificate authority’s certificate is not in the keystore, you will get the following error when you try to import the CA-signed certificate to the keystore:

        keytool error: java.lang.Exception: Failed to establish chain from reply

    To overcome the above error, be sure to first import the CA-signed certificate as well as the intermediate certificates to the keystore in the correct order.

Now let's take a look at each high level step in detail .

Step 1: Check the validity period of the certificate

Follow one of the steps below to view the validity period of a certificate:

  • If you have a public hostname, go to https://www.sslshopper.com/ssl-checker.html and specify the hostname of your server. SSL hopper lists all the information about the server certificate.
  • If you have a java keystore, execute the following keytool command to view the certificate information:

        keytool -list -keystore <keystore_name.jks> -alias <cert_alias> -v

    This prompts for the keystore password. Once you specify the password, you can view the certificate information in a human readable format where the validity period is displayed as follows:

            Valid from: Sun Jun 18 19:26:25 IST 2017 until: Sat Jun 19 19:26:25 IST 2027
  • If you have the certificate file, execute the following openssl command:

            x509 -in <certname.cer> -text -noout

    This displays the validity as follows:

            Validity
                        Not Before: Jun 18 13:56:25 2017 GMT
                        Not After : Jun 19 13:56:25 2027 GMT
  • If it is a website, you can view the certificate information via the browser. All major browsers provide the capability to view certificate information.

Once you view the validity period of a certificate and if it says that the certificate is about to expire or has already expired, the next step you should generate a Certificate Signing Request (CSR) and get a new certificate generated from the CA.

Step 2: Generate a certificate signing request

Depending on the type of keystore you have, follow one of the steps below to generate a CSR:

  • If you have a java keystore, execute the following command:

            keytool -certreq -alias <cert_alias> -file <CSR.csr> -keystore <keystore_name.jks>
    !!! note

    Note

    If you want generate a CSR with a subject alternative name (SAN), be sure to use the -ext attribute in the keytool command to specify required SAN.

    Following is a sample keytool command that includes a SAN:

        keytool -certreq -alias test -file test.csr -keystore test.jks -ext SAN=dns:test.example.com
  • If you have the private key and public key, execute the following command:

        openssl x509 -x509toreq -in <cert_name.crt> -out <CSR.csr> -signkey <private_key.key>

Once you generate the CSR, you need to submit the CSR to your certificate authority to get a new CA-signed certificate. For testing purposes you can go to http://www.getacert.com/signacert.html and submit your CSR to obtain a new CA-signed certificate for free.

After you obtain a new certificate, you have to import the new certificate to a keystore if you are using a java keystore.

Step 3: Import the new certificate to a keystore

  • Execute the following command to import a new certificate to a keystore:

            keytool -import -v -trustcacerts -alias <current_alias> -file <ca_signed_cert.cer> -keystore <keystore_name.jks>
    !!! tip

    If you want to view information related to the renewed certificate, execute the following keytool command:

        keytool -list -keystore <keystore_name.jks> -alias <cert_alias> -v
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