JAVA里面RSA加密算法的使用

打算写这个类用于spark插件加密对话消息用。
RSA的Java实现不能一次加密很大的字符，自己处理了一下，见下面的代码。
Base64编码类用的是一个Public domain Base64 for javahttp://iharder.sourceforge.net/current/java/base64/
其他的保存公钥到文件等简单的实现，就不详细说了，看代码吧。
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import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.*;
import java.io.*;
public class Encryptor {
private static final String KEY_FILENAME = "c:\\mykey.dat";
private static final String OTHERS_KEY_FILENAME = "c:\\Otherskey.dat";
// private static final int KEY_SIZE = 1024;
// private static final int BLOCK_SIZE = 117;
// private static final int OUTPUT_BLOCK_SIZE = 128;
private static final int KEY_SIZE = 2048; //RSA key 是多少位的
private static final int BLOCK_SIZE = 245;    //一次RSA加密操作所允许的最大长度
//这个值与 KEY_SIZE 已经padding方法有关。因为 1024的key的输出是128，2048key输出是256字节
//可能11个字节用于保存padding信息了，所以最多可用的就只有245字节了。
private static final int OUTPUT_BLOCK_SIZE = 256;
private SecureRandom secrand;
private Cipher rsaCipher;
private KeyPair keys;
private Map<String, Key> allUserKeys;
public Encryptor() throws Exception {
try {
allUserKeys = new HashMap<String, Key>();
secrand = new SecureRandom();
//SunJCE Provider 中只支持ECB mode，试了一下只有PKCS1PADDING可以直接还原原始数据，
//NOPadding导致解压出来的都是blocksize长度的数据，还要自己处理
//参见http://java.sun.com/javase/6/docs/technotes/guides/security/SunProviders.html#SunJCEProvider
//
//另外根据 Open-JDK-6.b17-src（http://www.docjar.com/html/api/com/sun/crypto/provider/RSACipher.java.html）
// 中代码的注释，使用RSA来加密大量数据不是一种标准的用法。所以现有实现一次doFinal调用之进行一个RSA操作，
//如果用doFinal来加密超过的一个操作所允许的长度数据将抛出异常。
//根据keysize的长度，典型的1024个长度的key和PKCS1PADDING一起使用时
//一次doFinal调用只能加密117个byte的数据。（NOPadding 和1024 keysize时128个字节长度）
//（2048长度的key和PKCS1PADDING 最多允许245字节一次）
//想用来加密大量数据的只能自己用其他办法实现了。可能RSA加密速度比较慢吧，要用AES才行
rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
throw e;
}
ObjectInputStream in;
try {
in = new ObjectInputStream(new FileInputStream(KEY_FILENAME));
} catch (FileNotFoundException e) {
if (false == GenerateKeys())
{
throw e;
}
LoadKeys();
return;
}
keys = (KeyPair) in.readObject();
in.close();
LoadKeys();
}
/*
* 生成自己的公钥和私钥
*/
private Boolean GenerateKeys() {
try {
KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA");
// secrand = new SecureRandom();
// sedSeed之后会造成 生成的密钥都是一样的
// secrand.setSeed("chatencrptor".getBytes()); // 初始化随机产生器
//key长度至少512长度，不过好像说现在用2048才算比较安全的了
keygen.initialize(KEY_SIZE, secrand); // 初始化密钥生成器
keys = keygen.generateKeyPair(); // 生成密钥组
AddKey("me", EncodeKey(keys.getPublic()));
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return false;
}
ObjectOutputStream out;
try {
out = new ObjectOutputStream(new FileOutputStream(KEY_FILENAME));
} catch (IOException e) {
e.printStackTrace();
return false;
}
try {
out.writeObject(keys);
} catch (IOException e) {
e.printStackTrace();
return false;
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
return true;
}

public String EncryptMessage(String toUser, String Message) throws IOException {
Key pubkey = allUserKeys.get(toUser);
if ( pubkey == null )
{
throw new IOException("NoKeyForThisUser") ;
}
try {
//PublicKey pubkey = keys.getPublic();
rsaCipher.init(Cipher.ENCRYPT_MODE, pubkey, secrand);
//System.out.println(rsaCipher.getBlockSize()); 返回0，非block 加密算法来的？
//System.out.println(Message.getBytes("utf-8").length);
//byte[] encryptedData = rsaCipher.doFinal(Message.getBytes("utf-8"));
byte[] data = Message.getBytes("utf-8");
int blocks = data.length / BLOCK_SIZE ;
int lastBlockSize = data.length % BLOCK_SIZE ;
byte [] encryptedData = new byte[ (lastBlockSize == 0 ? blocks : blocks + 1)* OUTPUT_BLOCK_SIZE];
for (int i=0; i < blocks; i++)
{
//int thisBlockSize = ( i + 1 ) * BLOCK_SIZE > data.length ? data.length - i * BLOCK_SIZE : BLOCK_SIZE ;
rsaCipher.doFinal(data,i * BLOCK_SIZE, BLOCK_SIZE, encryptedData ,i * OUTPUT_BLOCK_SIZE);
}
if (lastBlockSize != 0 ){
rsaCipher.doFinal(data, blocks * BLOCK_SIZE, lastBlockSize,encryptedData ,blocks * OUTPUT_BLOCK_SIZE);
}
//System.out.println(encrypted.length); 如果要机密的数据不足128/256字节，加密后补全成为变为256长度的。
//数量比较小时，Base64.GZIP产生的长度更长，没什么优势
//System.out.println(Base64.encodeBytes(encrypted,Base64.GZIP).length());
//System.out.println(Base64.encodeBytes(encrypted).length());
//System.out.println (rsaCipher.getOutputSize(30));
//这个getOutputSize 只对 输入小于最大的block时才能得到正确的结果。其实就是补全 数据为128/256 字节
return Base64.encodeBytes(encryptedData);
} catch (InvalidKeyException e) {
e.printStackTrace();
throw new IOException("InvalidKey") ;
}catch (ShortBufferException e) {
e.printStackTrace();
throw new IOException("ShortBuffer") ;
}
catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new IOException("UnsupportedEncoding") ;
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
throw new IOException("IllegalBlockSize") ;
} catch (BadPaddingException e) {
e.printStackTrace();
throw new IOException("BadPadding") ;
}finally {
//catch 中 return 或者throw之前都会先调用一下这里
}
}
public String DecryptMessage(String Message) throws IOException {
byte[] decoded = Base64.decode(Message);
PrivateKey prikey = keys.getPrivate();
try {
rsaCipher.init(Cipher.DECRYPT_MODE, prikey, secrand);
int blocks = decoded.length / OUTPUT_BLOCK_SIZE;
ByteArrayOutputStream decodedStream = new ByteArrayOutputStream(decoded.length);
for (int i =0 ;i < blocks ; i ++ )
{
decodedStream.write (rsaCipher.doFinal(decoded,i * OUTPUT_BLOCK_SIZE, OUTPUT_BLOCK_SIZE));
}
return new String(decodedStream.toByteArray(), "UTF-8");
} catch (InvalidKeyException e) {
e.printStackTrace();
throw new IOException("InvalidKey");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new IOException("UnsupportedEncoding");
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
throw new IOException("IllegalBlockSize");
} catch (BadPaddingException e) {
e.printStackTrace();
throw new IOException("BadPadding");
} finally {
// catch 中 return 或者throw之前都会先调用一下这里。
}
}
public boolean AddKey(String user, String key) {
PublicKey publickey;
try {
publickey = DecodePublicKey(key);
} catch (Exception e) {
return false;
}
allUserKeys.put(user, publickey);
SaveKeys();
return true;
}

private boolean LoadKeys() {
BufferedReader input;
try {
input = new BufferedReader(new InputStreamReader(
new FileInputStream(OTHERS_KEY_FILENAME)));
} catch (FileNotFoundException e1) {
// e1.printStackTrace();
return false;
}
try {
allUserKeys.clear();
String line;
while ((line = input.readLine()) != null) {
String[] temp = line.split("\\|");
String user = temp[0];
PublicKey key = DecodePublicKey(temp[1]);
allUserKeys.put(user, key);
}
} catch (Exception e) {
return false;
} finally {
try {
input.close();
} catch (Exception e) {
return false;
}
}
return true;
}
private boolean SaveKeys() {
FileWriter output;
try {
output = new FileWriter(OTHERS_KEY_FILENAME);
} catch (IOException e1) {
// 1.printStackTrace();
return false;
}
try {
for (String user : allUserKeys.keySet()) {
Key key = allUserKeys.get(user);
output.write(user + "|" + EncodeKey(key) + "\n");
}
} catch (IOException e1) {
// 1.printStackTrace();
return false;
} finally {
try {
output.close();
} catch (Exception e) {
return false;
}
}
return true;
}
/**
* 解密base64编码得到公钥
*
* @param key
*            密钥字符串（经过base64编码）
* @throws Exception
*/
public static PublicKey DecodePublicKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = Base64.decode(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}
/**
* 解密base64编码得到私钥
*
* @param key
*            密钥字符串（经过base64编码）
* @throws Exception
*/
public static PrivateKey DecodePrivateKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = Base64.decode(key);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}
/**
* 编码key为base64字符串
*
* @return
*/
public static String EncodeKey(Key key) {
byte[] keyBytes = key.getEncoded();
// System.out.print(key.getFormat()) ;
String s = Base64.encodeBytes(keyBytes);
return s;
}
}
===============测试类============================
import java.util.Iterator ;
import java.security.Security ;
import java.security.Provider ;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
//   Provider [ ] providers = Security.getProviders () ;
//   for ( int i = 0 ; i < providers.length ; i++ )
//   {
//   String name = providers[i].getName () ;
//   String info = providers[i].getInfo () ;
//   double version = providers[i].getVersion () ;
//   System.out.println ("-------------------------------------" ) ;
//   System.out.println ( "name: " + name ) ;
//   System.out.println ( "info: " + info ) ;
//   System.out.println ( "version: " + version ) ;
//
//   for ( Iterator iter = providers[i].keySet().iterator () ; iter.hasNext () ; )
//   {
//   String key = (String) iter.next () ;
//   System.out.println ( "\t" + key +
//   "\t" +
//   providers[i].getProperty ( key ) ) ;
//   }
//
//   System.out.println (
//
//   "-------------------------------------" );
//   }
//
//   int i = 123/ 256;
//   System.out.println(i);
//   i = 257/ 256;
//   System.out.println(i);
//   i = 512/ 256;
//   System.out.println(i);
//   i = 513/ 256;
//   System.out.println(i);
//String str = "widebriht的测试，哈哈^_^";
//String str = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4dYTv3xxgsu2SmgqJzPWzSOziMDnOV+tAxQGumNAJKcBxOlD5hQlqTGRnUoqIp8z3brioFJBtMs8wAeA+pfpJhFyqodI9frr0I3Y4PUgwRlL7ozGA9hu9CBOADQNKE7g7UgOTQ/joE26YoYPCHKx/vYQncOe45axOCqcXBWViw20WgPr1g0qj9CarQLM7e4dUNMCYcX0ZGvqIy7Js2FjuLsNaK249k9y2fjIqqu8FzhjvIEDCtrMNyTvV5coV5rDGTEC5KfJft0oeCTXrhcgzMBdaG9DXFQezQIepMdPAT+kga/qJ69b95I02LMwyCDhwPmH873UNQAmdMpJ7bZTTwIDAQAB";
String str = "MIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0BMIIBIjANBgkqhkiG9w0Bddddd";
try {
Encryptor ddd = new Encryptor();
str = ddd.EncryptMessage("me", str);
// System.out.println(str.length());
String str2 = "jhahahh my god ";
str2 = ddd.EncryptMessage("me", str2);
str2 = ddd.DecryptMessage(str2);
str = ddd.DecryptMessage(str);
} catch (Exception e) {
if (e.getMessage() == "NoKeyForThisUser") {
System.out.println("NoKeyForThisUser");
}
}
// str = ddd.DecryptMessage(
// "inI5y3PfFXt0oNWXuYLBbTkIaaxZFzgWuMfYTqpT91b51UUQN0T8iK6l8XnS+WShC/ZGL9noX6vO8sDmiJ+z1I7/WTgvOOW5XE+G7+edGzh6bfRGPxhG16MJpl2y/FsIErsKgZmybERE8F0IP551/b0xGmrZhyj09/NwZln3qUg=");
//System.out.println(str);
}
}