DevTut

# Secure objects

# SealedObject (javax.crypto.SealedObject)

This class enables a programmer to create an object and protect its confidentiality with a cryptographic algorithm.

Given any Serializable object, one can create a SealedObject that encapsulates the original object, in serialized format (i.e., a "deep copy"), and seals (encrypts) its serialized contents, using a cryptographic algorithm such as AES, DES, to protect its confidentiality. The encrypted content can later be decrypted (with the corresponding algorithm using the correct decryption key) and de-serialized, yielding the original object.

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Serializable obj = new String("John");
// Generate key
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(128);
SecretKey aesKey = kgen.generateKey();
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, aesKey);
SealedObject sealedObject = new SealedObject(obj, cipher);
System.out.println("sealedObject-" + sealedObject);
System.out.println("sealedObject Data-" + sealedObject.getObject(aesKey));

# SignedObject (java.security.SignedObject)

SignedObject is a class for the purpose of creating authentic runtime objects whose integrity cannot be compromised without being detected.

More specifically, a SignedObject contains another Serializable object, the (to-be-)signed object and its signature.

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//Create a key
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA", "SUN");
SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
keyGen.initialize(1024, random);
// create a private key
PrivateKey signingKey = keyGen.generateKeyPair().getPrivate();
// create a Signature
Signature signingEngine = Signature.getInstance("DSA");
signingEngine.initSign(signingKey);
// create a simple object 
Serializable obj = new String("John");
// sign our object
SignedObject signedObject = new SignedObject(obj, signingKey, signingEngine);

System.out.println("signedObject-" + signedObject);
System.out.println("signedObject Data-" + signedObject.getObject());

# Syntax

  • SealedObject sealedObject = new SealedObject(obj, cipher);
  • SignedObject signedObject = new SignedObject(obj, signingKey, signingEngine);

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