KeyStore getCertificateAlias() method in Java with Examples

The getCertificateAlias() method of java.security.KeyStore class is used to get name of the first KeyStore entry which has the specified Certificate.
Syntax:

public final String getCertificateAlias(Certificate cert)
    throws KeyStoreException

Parameter: This method accepts the certificate name a parameter which is to be matched with Keystore entry.
Return Value: This method returns the name of the first KeyStore entry which has the specified Certificate.
Exception: This method throws KeyStoreException if you don’t initialize this keystore.
Note: All the programs in this article won’t run on online IDE as no ‘privatekey’ Keystore exists. You can check this code on Java compiler on your system. To check this code, create a Keystore ‘privatekey’ on your system and set your own keystore password to access that keystore.
Below are the examples to illustrate the getCertificateAlias() method:
Example 1:

Java

// Java program to demonstrate getCertificateAlias() method

import java.security.*;
import java.security.cert.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {

            // creating the object of KeyStore
            // and getting instance
            // By using getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");

            // keystore password is required to access keystore
            char[] pass = ("123456").toCharArray();

            // creating and initializing object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/private Key.store");

            // initializing keystore object
            sr.load(is, pass);

            // getting the certificate
            X509Certificate cert
                = (X509Certificate)sr
                      .getCertificate("ftpkey");

            // getting alias name for the keyentry
            // using getCertificateAlias() method
            String alias = sr.getCertificateAlias(cert);

            // display the result
            System.out.println("alias name for the particular entry : "
                               + alias);
        }

        catch (NoSuchAlgorithmException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (FileNotFoundException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (IOException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (CertificateException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Example 2: For KeyStoreException

Java

// Java program to demonstrate getCertificateAlias() method

import java.security.*;
import java.security.cert.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {

            // creating the object of KeyStore
            // and getting instance
            // By using getInstance() method
            KeyStore sr = KeyStore.getInstance("JKS");

            // keystore password is required to access keystore
            char[] pass = ("123456").toCharArray();

            // creating and initializing object of InputStream
            InputStream is
                = new FileInputStream(
                    "f:/java/private Key.store");

            // initializing keystore object
            // sr.load(is, pass);

            // getting the certificate
            X509Certificate cert
                = (X509Certificate)sr
                      .getCertificate("ftpkey");

            // getting alias name for the keyentry
            // using getCertificateAlias() method
            String alias = sr.getCertificateAlias(cert);

            // display the result
            System.out.println("alias name for the particular entry : "
                               + alias);
        }
        catch (FileNotFoundException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (NullPointerException e) {

            System.out.println("Exception thrown : " + e);
        }
        catch (KeyStoreException e) {

            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

Reference: https://docs.oracle.com/javase/9/docs/api/java/security/KeyStore.html#getCertificateAlias-java.security.cert.Certificate-