My task is the following:
- Retrieve my public and private key from the keystore I created.
- Use these keys to encrypt a paragraph using my RSA 2048-bit public key.
- Digitally sign the result using the DSA-SHA-1 signature algorithm.
- Save the digital signature output on a file called
output.dat.
The program below is throwing error : "java.security.InvalidKeyException: No installed provider supports this key: sun.security.provider.DSAPublicKeyImpl".
import java.security.*;
import java.security.KeyStore.*;
import java.io.*;
import java.security.PublicKey;
import java.security.PrivateKey;
import javax.crypto.Cipher;
import java.nio.charset.*;
import sun.security.provider.*;
import javax.crypto.*;
public class Code {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
try {
/* getting data for keystore */
File file = new File(System.getProperty("user.home") + File.separatorChar + ".keystore");
FileInputStream is = new FileInputStream(file);
KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
/*Information for certificate to be generated */
String password = "abcde";
String alias = "mykeys";
String alias1 = "skeys";
String filepath ="C:\\email.txt";
/* getting the key*/
keystore.load(is, password.toCharArray());
PrivateKey key = (PrivateKey)keystore.getKey(alias, "bemylife".toCharArray());
//PrivateKey key = cert1.getPrivateKey();
//PublicKey key1= (PrivateKey)key;
/* Get certificate of public key */
java.security.cert.Certificate cert = keystore.getCertificate(alias);
/* Here it prints the public key*/
System.out.println("Public Key:");
System.out.println(cert.getPublicKey());
/* Here it prints the private key*/
System.out.println("\nPrivate Key:");
System.out.println(key);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE,cert.getPublicKey());
String cleartextFile = "C:\\email.txt";
String ciphertextFile = "D:\\ciphertextRSA.png";
FileInputStream fis = new FileInputStream(cleartextFile);
FileOutputStream fos = new FileOutputStream(ciphertextFile);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
byte[] block = new byte[32];
int i;
while ((i = fis.read(block)) != -1) {
cos.write(block, 0, i);
}
cos.close();
/* computing the signature*/
Signature dsa = Signature.getInstance("SHA1withDSA", "SUN");
dsa.initSign(key);
FileInputStream f = new FileInputStream(ciphertextFile);
BufferedInputStream in = new BufferedInputStream(f);
byte[] buffer = new byte[1024];
int len;
while ((len = in.read(buffer)) >= 0) {
dsa.update(buffer, 0, len);
};
in.close();
/* Here it prints the signature*/
System.out.println("Digital Signature :");
System.out.println( dsa.sign());
/* Now Exporting Certificate */
System.out.println("Exporting Certificate. ");
byte[] buffer_out = cert.getEncoded();
FileOutputStream os = new FileOutputStream(new File("d:\\signedcetificate.cer"));
os.write(buffer_out);
os.close();
/* writing signature to output.dat file */
byte[] buffer_out1 = dsa.sign();
FileOutputStream os1 = new FileOutputStream(new File("d:\\output.dat"));
os1.write(buffer_out1);
os1.close();
} catch (Exception e) {System.out.println(e);}
}
}
