Programming Tutorials

Encrypting Passwords in Tomcat using Servlets

By: Sam Chen in JSP Tutorials on 2023-05-04  

Encrypting passwords is an essential aspect of web application security. Here are the steps to encrypt passwords in Tomcat using Servlets:

  1. Create a Java class that contains a method to encrypt a password. You can use any encryption algorithm like MD5, SHA-256, or BCrypt. Here is an example using BCrypt:

    import org.mindrot.jbcrypt.BCrypt;
    public class PasswordEncryptionUtil {
        public static String encryptPassword(String password) {
            return BCrypt.hashpw(password, BCrypt.gensalt());
        public static boolean checkPassword(String password, String hashedPassword) {
            return BCrypt.checkpw(password, hashedPassword);
  2. In your Servlet, get the plain password from the user and call the encryptPassword method to encrypt it.
    String plainPassword = request.getParameter("password");
    String encryptedPassword = PasswordEncryptionUtil.encryptPassword(plainPassword);
  3. Store the encrypted password in the database.
    Connection conn = DriverManager.getConnection(url, username, password);
    String sql = "INSERT INTO users (username, password) VALUES (?, ?)";
    PreparedStatement stmt = conn.prepareStatement(sql);
    stmt.setString(1, username);
    stmt.setString(2, encryptedPassword);
  4. When a user logs in, retrieve the encrypted password from the database and call the checkPassword method to verify the password.
    String plainPassword = request.getParameter("password");
    String hashedPassword = // retrieve hashed password from database using username
    boolean isValid = PasswordEncryptionUtil.checkPassword(plainPassword, hashedPassword);
    if (isValid) {
        // login successful
    } else {
        // login failed

By following these steps, you can encrypt passwords in Tomcat using Servlets and enhance the security of your web application.

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