Java offers a comprehensive and pluggable security framework as part of the standard JDK. It covers key areas such as authentication, authorization, cryptography, secure communication, and bytecode-level sandboxing.

• java.security – Core security architecture (permissions, policies, secure random)
• javax.crypto – Cryptographic operations like encryption/decryption
• java.security.cert – Certificate management (X.509)
• javax.net.ssl – Secure Sockets Layer (SSL/TLS)
• javax.security.auth – Java Authentication and Authorization Service (JAAS)

Java applications can be run with a security manager that enforces permissions via policy files.

grant {
    permission java.io.FilePermission "/tmp/*", "read,write";
};

Used to compute checksums or validate content.

MessageDigest md = MessageDigest.getInstance("SHA-256");
byte[] hash = md.digest("data".getBytes());
System.out.println(Base64.getEncoder().encodeToString(hash));

To verify the authenticity of data.

Signature sign = Signature.getInstance("SHA256withRSA");
sign.initSign(privateKey);
sign.update(data.getBytes());
byte[] signature = sign.sign();

AES Example:

KeyGenerator keyGen = KeyGenerator.getInstance("AES");
SecretKey key = keyGen.generateKey();

Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] encrypted = cipher.doFinal("SecretMessage".getBytes());

Java supports secure socket communication via SSLSocket, SSLServerSocket, and HttpsURLConnection.

• Securely storing and transmitting sensitive data
• Authenticating users or systems
• Ensuring code runs in controlled environments (sandboxing)
• SSL-based encrypted communication (web servers/clients)
• Implementing secure APIs or payment systems

Security in Java is built to be extensible and robust. It enables developers to plug in third-party providers, enforce fine-grained permissions, and implement cryptographic workflows without relying on external libraries.