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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>公钥密码术代码示例</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr> 第 4 页(共5 页)</nobr></font></td>
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<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
import java.security.*;
import javax.crypto.*;
//
// Public Key cryptography using the RSA algorithm.
public class PublicExample {
public static void main (String[] args) throws Exception {
//
// check args and get plaintext
if (args.length !=1) {
System.err.println("Usage: java PublicExample text");
System.exit(1);
}
byte[] plainText = args[0].getBytes("UTF8");
//
// generate an RSA key
System.out.println( "\nStart generating RSA key" );
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(1024);
KeyPair key = keyGen.generateKeyPair();
System.out.println( "Finish generating RSA key" );
//
// get an RSA cipher object and print the provider
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
System.out.println( "\n" + cipher.getProvider().getInfo() );
//
// encrypt the plaintext using the public key
System.out.println( "\nStart encryption" );
cipher.init(Cipher.ENCRYPT_MODE, key.getPublic());
byte[] cipherText = cipher.doFinal(plainText);
System.out.println( "Finish encryption: " );
System.out.println( new String(cipherText, "UTF8") );
//
// decrypt the ciphertext using the private key
System.out.println( "\nStart decryption" );
cipher.init(Cipher.DECRYPT_MODE, key.getPrivate());
byte[] newPlainText = cipher.doFinal(cipherText);
System.out.println( "Finish decryption: " );
System.out.println( new String(newPlainText, "UTF8") );
}
}
</code>
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