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);

}

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