/* Athena/Aegis Encrypted Chat Platform
* RSACrypto.java: Provides access to RSA cryptography libraries
*
* Copyright (C) 2010 OlympuSoft
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import javax.crypto.Cipher;
/**
* RSA Cryptography library methods
* @author OlympuSoft
*/
public class RSACrypto {
// The public and private keys that are used throughout the program
private static RSAPublicKeySpec pub;
private static RSAPrivateKeySpec priv;
/**
* Retrieve the publickeyspec
* @return Public key spec
*/
public static RSAPublicKeySpec getPublicKey() {
return pub;
}
/**
* Retrieve the privatekeyspec
* @return The private key spec
*/
public static RSAPrivateKeySpec getPrivateKey() {
return priv;
}
/**
* This method will generate the users RSA key files, one public and one private
*/
public static void generateRSAKeyPair() {
try {
// Define type of encryption for which these keys are made
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
// Define key size
kpg.initialize(2048);
// Generate the key pairs
KeyPair kp = kpg.genKeyPair();
Key publicKey = kp.getPublic();
Key privateKey = kp.getPrivate();
KeyFactory fact = KeyFactory.getInstance("RSA");
// Define public key
pub = fact.getKeySpec(kp.getPublic(), RSAPublicKeySpec.class);
//Define private key
priv = fact.getKeySpec(kp.getPrivate(), RSAPrivateKeySpec.class);
} catch (Exception e) {
System.out.println("An error has occured in 'generateRSAKeyPair'");
}
}
/**
* Encrypt a message using a provided public key
* @param plainText Plaintext message
* @param mod Modulus of the public key
* @param exp Exponent of the public key
* @return Byte[] of the encrypted message
*/
public static byte[] rsaEncryptPublic(String plainText, BigInteger mod, BigInteger exp) {
try {
//Grab the key from this file
PublicKey pubKey = makePublicKey(mod, exp);
//Define the cipher style
//RSA OF COURSE
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
//That's right, cipherData, you wish you knew what the message was.
byte[] cipherData = cipher.doFinal(plainText.getBytes());
return cipherData;
} catch (Exception e) {
System.out.println("An error has occured in 'rsaEncryptPublic'");
}
return null;
}
/**
* Decrypt a message using a provided public key
* @param cipherText The encrypted message byte[]
* @param mod Modulus of the public key
* @param exp Exponent of the public key
* @return The decrypted message as a string
*/
public static String rsaDecryptPublic(byte[] cipherText, BigInteger mod, BigInteger exp) {
try {
//Grab the key from this file
PublicKey pubKey = makePublicKey(mod, exp);
//Define the cipher style
//RSA OF COURSE
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, pubKey);
//That's right, cipherData, you wish you knew what the message was.
byte[] cipherData = cipher.doFinal(cipherText);
String plainText = new String(cipherData);
return plainText;
} catch (Exception e) {
e.printStackTrace();
return "SYSTEM ERROR: There was an issue decrypting the message. Please check that you have the public keyfile for the user.";
//System.out.println("An error has occured in 'rsaDecryptPublic'");
}//return null;
}
/**
* Encrypt a message using a provided private key
* @param plainText The plaintext message to be encrypted
* @param mod The modulus part of the private key
* @param exp The exponent part of the private key
* @return The encrypted message as a byte[]
*/
public static byte[] rsaEncryptPrivate(String plainText, BigInteger mod, BigInteger exp) {
try {
//Grab the key from this file
PrivateKey privKey = makePrivateKey(mod, exp);
//Define the cipher style
//RSA OF COURSE
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privKey);
//That's right, cipherData, you wish you knew what the message was.
byte[] cipherData = cipher.doFinal(plainText.getBytes());
return cipherData;
} catch (Exception e) {
//return "SYSTEM ERROR: There was an issue encrypting the message. Please check your private key";
System.out.println("An error has occured in 'rsaEncryptPrivate'");
}
return null;
}
/**
* Decrypt a message using a provided private key
* @param cipherText Byte[] of the encrypted message
* @param mod Modulus part of the private key
* @param exp Exponent part of the private key
* @return The decrypted message as a string
*/
public static String rsaDecryptPrivate(byte[] cipherText, BigInteger mod, BigInteger exp) {
try {
//Grab the key from this file
PrivateKey privKey = makePrivateKey(mod, exp);
//Define the cipher style
//RSA OF COURSE
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privKey);
//That's right, cipherData, you wish you knew what the message was.
byte[] cipherData = cipher.doFinal(cipherText);
String plainText = new String(cipherData);
return plainText;
} catch (Exception e) {
return "SYSTEM ERROR: There was an issue decrypting the message. Please check your private key";
}
}
/**
* Puts a public key together using a modulus and exponent
* @param mod Modulus piece of the public key
* @param exp Exponent piece of the public key
* @return The public key constructed
*/
public static PublicKey makePublicKey(BigInteger mod, BigInteger exp) {
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(mod, exp);
KeyFactory fact = null;
PublicKey pubKey = null;
try {
fact = KeyFactory.getInstance("RSA");
} catch (Exception e) {
System.out.println("KeyFactory issue in makePublicKey");
}
try {
pubKey = fact.generatePublic(keySpec);
} catch (Exception e) {
System.out.println("KeyFactory issue in makePublicKey");
}
return pubKey;
}
/**
* Creates a private key using a modulus and exponent
* @param mod The modulus piece of the private key
* @param exp The exponent piece of the private key
* @return The private key constructed
*/
public static PrivateKey makePrivateKey(BigInteger mod, BigInteger exp) {
RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(mod, exp);
KeyFactory fact = null;
PrivateKey privKey = null;
try {
fact = KeyFactory.getInstance("RSA");
} catch (Exception e) {
System.out.println("KeyFactory issue in makePublicKey");
}
try {
privKey = fact.generatePrivate(keySpec);
} catch (Exception e) {
System.out.println("KeyFactory issue in makePublicKey");
}
return privKey;
}
/**
* Load a public key from a file
* @param The filename of the public key
* @return The public key read in from the file
* @throws IOException
*/
static RSAPublicKeySpec readPubKeyFromFile(String keyFileName) throws IOException {
//Define the name of the file
//MAKE sure it's the same as the one we're looking for!
ObjectInputStream oin = new ObjectInputStream(new FileInputStream(keyFileName));
try {
BigInteger m = (BigInteger) oin.readObject();
BigInteger e = (BigInteger) oin.readObject();
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(m, e);
return keySpec;
} catch (Exception e) {
throw new RuntimeException("An error has occured in 'readKeyFromFile'", e);
} finally {
//Close the file stream
oin.close();
}
}
/**
* Grab the private key from a file
* @param keyFileName The filename
* @return The private key
* @throws IOException
*/
static RSAPrivateKeySpec readPrivKeyFromFile(String keyFileName) throws IOException {
//This is how we'll get the file
ObjectInputStream oin = null;
try {
//Make sure this selects the correct file!
oin = new ObjectInputStream(new FileInputStream(keyFileName));
//Grab the m and e values for the RSA key file process
BigInteger m = (BigInteger) oin.readObject();
BigInteger e = (BigInteger) oin.readObject();
//Run RSA Private Key input
RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(m, e);
//Return the private key
return keySpec;
} catch (Exception e) {
System.out.println("An error has occured in readPrivKeyFromFile");
} finally {
oin.close();
}
return null;
}
/**
* Save a key to a file
* @param fileName File to write to
* @param mod Modulus
* @param exp Exponent
* @throws IOException
*/
public static void saveToFile(String fileName, BigInteger mod, BigInteger exp) throws IOException {
//Define the new file
ObjectOutputStream oout = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(fileName)));
try {
//Write the files
oout.writeObject(mod);
oout.writeObject(exp);
} catch (Exception e) {
throw new IOException("Unexpected error", e);
} finally {
oout.close();
}
}
}