import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
//下載地址： http://commons.apache.org/codec/download_codec.cgi
public static class MyRsa {
/**
* String to hold name of the encryption algorithm.
*/
public static final String ALGORITHM = "RSA";
/**
* String to hold the name of the private key file.
*/
public static final String PRIVATE_KEY_FILE = "D:/rsa/pkcs8_priv.pem";
/**
* String to hold name of the public key file.
*/
public static final String PUBLIC_KEY_FILE = "D:/rsa/public.key";
/**
* Encrypt the plain text using public key.
*
* @param text
* : original plain text
* @param key
* :The public key
* @return Encrypted text
* @throws java.lang.Exception
*/
public static byte[] encrypt(String text, PublicKey key) {
byte[] cipherText = null;
try {
// get an RSA cipher object and print the provider
final Cipher cipher = Cipher.getInstance(ALGORITHM);
// encrypt the plain text using the public key
cipher.init(Cipher.ENCRYPT_MODE, key);
cipherText = cipher.doFinal(text.getBytes());
} catch (Exception e) {
e.printStackTrace();
}
return cipherText;
}
/**
* Decrypt text using private key.
*
* @param text
* :encrypted text
* @param key
* :The private key
* @return plain text
* @throws java.lang.Exception
*/
public static String decrypt(byte[] text, PrivateKey key) {
byte[] dectyptedText = null;
try {
// get an RSA cipher object and print the provider
final Cipher cipher = Cipher.getInstance(ALGORITHM);
// decrypt the text using the private key
cipher.init(Cipher.DECRYPT_MODE, key);
dectyptedText = cipher.doFinal(text);
} catch (Exception ex) {
ex.printStackTrace();
}
return new String(dectyptedText);
}
public static void test() {
String s = "Hello world";
try {
BufferedReader privateKey = new BufferedReader(new FileReader(
PRIVATE_KEY_FILE));
BufferedReader publicKey = new BufferedReader(new FileReader(
PUBLIC_KEY_FILE));
String strPrivateKey = "";
String strPublicKey = "";
String line = "";
while((line = privateKey.readLine()) != null){
strPrivateKey += line;
}
while((line = publicKey.readLine()) != null){
strPublicKey += line;
}
privateKey.close();
publicKey.close();
// 私鑰需要使用pkcs8格式的，公鑰使用x509格式的
String strPrivKey = strPrivateKey.replace("-----BEGIN PRIVATE KEY-----", "")
.replace("-----END PRIVATE KEY-----", "");
String strPubKey = strPublicKey.replace("-----BEGIN PUBLIC KEY-----", "")
.replace("-----END PUBLIC KEY-----", "");
//System.out.print(strPrivKey);
//System.out.println(strPubKey);
byte [] privKeyByte = Base64.decodeBase64(strPrivKey);
byte [] pubKeyByte = Base64.decodeBase64(strPubKey);
PKCS8EncodedKeySpec privKeySpec = new PKCS8EncodedKeySpec(privKeyByte);
//PKCS8EncodedKeySpec pubKeySpec = new PKCS8EncodedKeySpec(pubKeyByte);
//X509EncodedKeySpec privKeySpec = new X509EncodedKeySpec(privKeyByte);
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(pubKeyByte);
KeyFactory kf = KeyFactory.getInstance("RSA");
PrivateKey privKey = kf.generatePrivate(privKeySpec);
PublicKey pubKey = kf.generatePublic(pubKeySpec);
byte [] encryptByte = encrypt(s, pubKey);
System.out.println(decrypt(encryptByte, privKey));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvalidKeySpecException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
