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<TITLE>Signing a Java Object (Java Developers Almanac Example)
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<h1>The Java Developers Almanac 1.4</h1>
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<A HREF="../java.security/pkg.html">java.security</A><font color="#666666" class="xsmall-font">
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<B><A HREF="../java.security/pkg.html#Signatures">Signatures</A></B><font color="#666666" class="xsmall-font">
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<h3>e205. Signing a Java Object</h3>
A signed object makes a copy of a serializable object and signs it
with a private key. Since the signed object makes a copy of the
original object, any further modifications to the original object do
not affect the signed object.
<pre> // Create a public and private key
PublicKey publicKey = null;
PrivateKey privateKey = null;
try {
// Generate a 1024-bit Digital Signature Algorithm (DSA) key pair
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
keyGen.initialize(1024);
KeyPair keypair = keyGen.genKeyPair();
privateKey = keypair.getPrivate();
publicKey = keypair.getPublic();
} catch (NoSuchAlgorithmException e) {
}
// Create the signed object
SignedObject so = null;
try {
Serializable o = new <font color="#0066ff"><i>MyClass</i></font>();
Signature sig = Signature.getInstance(privateKey.getAlgorithm());
so = new SignedObject(o, privateKey, sig);
} catch (NoSuchAlgorithmException e) {
} catch (SignatureException e) {
} catch (InvalidKeyException e) {
} catch (IOException e) {
}
// Verify the signed object
try {
Signature sig = Signature.getInstance(publicKey.getAlgorithm());
// Verify the signed object
boolean b = so.verify(publicKey, sig);
// Retrieve the object
<font color="#0066ff"><i>MyClass</i></font> o = (<font color="#0066ff"><i>MyClass</i></font>)so.getObject();
} catch (SignatureException e) {
} catch (InvalidKeyException e) {
} catch (NoSuchAlgorithmException e) {
} catch (ClassNotFoundException e) {
} catch (IOException e) {
}
public class <font color="#0066ff"><i>MyClass</i></font> implements Serializable {
String s = <font color="#0066ff"><i>"my string"</i></font>;
int i = <font color="#0066ff"><i>123</i></font>;
}
</pre>
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<b>Related Examples</b></font></td>
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e202. <a class="eglink" href="ListSig.html?l=rel">
Listing All Available Signature Algorithms
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e203. <a class="eglink" href="CreateSig.html?l=rel">
Creating a Signature
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e204. <a class="eglink" href="VerifySig.html?l=rel">
Verifying a Signature
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See also:
<a class="eglink" href="/egs/java.security/pkg.html?l=rel#Key%20Store">
Key Store
</a>
<a class="eglink" href="/egs/java.security/pkg.html?l=rel#Message%20Digests">
Message Digests
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<a class="eglink" href="/egs/java.security/pkg.html?l=rel#Permissions">
Permissions
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<a class="eglink" href="/egs/java.security/pkg.html?l=rel#Policy%20Files">
Policy Files
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<a class="eglink" href="/egs/java.security/pkg.html?l=rel#Public%20and%20Private%20Keys">
Public and Private Keys
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