compute x509 certificate thumbprint (#11717)

Co-authored-by: tienvn4 <tienvn4@ghtk.co>

core-java-modules/core-java-security-3/src/main/java/com/baeldung/certificate/Thumbprint.java

@@ -0,0 +1,38 @@
+package com.baeldung.certificate;
+
+import org.apache.commons.codec.digest.DigestUtils;
+
+import javax.xml.bind.DatatypeConverter;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.CertificateException;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+
+public class Thumbprint {
+
+    public static void main(String[] args) throws CertificateException, IOException, NoSuchAlgorithmException {
+        X509Certificate certObject = getCertObject("baeldung.pem");
+        System.out.println(getThumbprint(certObject));
+    }
+
+    public static X509Certificate getCertObject(String filePath) throws IOException, CertificateException {
+        try (FileInputStream is = new FileInputStream(filePath)) {
+            CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
+            return (X509Certificate) certificateFactory.generateCertificate(is);
+        }
+    }
+
+    private static String getThumbprint(X509Certificate cert) throws NoSuchAlgorithmException, CertificateEncodingException {
+        MessageDigest md = MessageDigest.getInstance("SHA-1");
+        md.update(cert.getEncoded());
+        return DatatypeConverter.printHexBinary(md.digest()).toLowerCase();
+    }
+
+    private static String getThumbprintWithApache(X509Certificate cert) throws CertificateEncodingException {
+        return DigestUtils.sha1Hex(cert.getEncoded());
+    }
+}