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| import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.io.*;
import java.math.BigInteger;
public class RSAUtil {
/**
* * 生成密钥对
* * @return KeyPair
* * @throws EncryptException
*/
public static KeyPair generateKeyPair() throws EncryptException {
try {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",
new org.bouncycastle.jce.provider.BouncyCastleProvider());
final int KEY_SIZE = 1024;//没什么好说的了，这个值关系到块加密的大小，可以更改，但是不要太大，否则效率会低
keyPairGen.initialize(KEY_SIZE, new SecureRandom());
KeyPair keyPair = keyPairGen.genKeyPair();
return keyPair;
} catch (Exception e) {
throw new EncryptException(e.getMessage());
}
}
/**
* * 生成公钥
* * @param modulus
* * @param publicExponent
* * @return RSAPublicKey
* * @throws EncryptException
*/
public static RSAPublicKey generateRSAPublicKey(byte[] modulus, byte[] publicExponent) throws EncryptException {
KeyFactory keyFac = null;
try {
keyFac = KeyFactory.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new EncryptException(ex.getMessage());
}
RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(modulus), new BigInteger(publicExponent));
try {
return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);
} catch (InvalidKeySpecException ex) {
throw new EncryptException(ex.getMessage());
}
}
/**
* * 生成私钥
* * @param modulus
* * @param privateExponent
* * @return RSAPrivateKey
* * @throws EncryptException
*/
public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus, byte[] privateExponent) throws EncryptException {
KeyFactory keyFac = null;
try {
keyFac = KeyFactory.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new EncryptException(ex.getMessage());
}
RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(modulus), new BigInteger(privateExponent));
try {
return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);
} catch (InvalidKeySpecException ex) {
throw new EncryptException(ex.getMessage());
}
}
/**
* * 加密
* * @param key 加密的密钥
* * @param data 待加密的明文数据
* * @return 加密后的数据
* * @throws EncryptException
*/
public static byte[] encrypt(Key key, byte[] data) throws EncryptException {
try {
Cipher cipher = Cipher.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
cipher.init(Cipher.ENCRYPT_MODE, key);
int blockSize = cipher.getBlockSize();//获得加密块大小，如：加密前数据为128个byte，而key_size=1024 加密块大小为127 byte,加密后为128个byte;因此共有2个加密块，第一个127 byte第二个为1个byte
int outputSize = cipher.getOutputSize(data.length);//获得加密块加密后块大小
int leavedSize = data.length % blockSize;
int blocksSize = leavedSize != 0 ? data.length / blockSize + 1 : data.length / blockSize;
byte[] raw = new byte[outputSize * blocksSize];
int i = 0;
while (data.length - i * blockSize > 0) {
if (data.length - i * blockSize > blockSize)
cipher.doFinal(data, i * blockSize, blockSize, raw, i * outputSize);
else
cipher.doFinal(data, i * blockSize, data.length - i * blockSize, raw, i * outputSize);
//这里面doUpdate方法不可用，查看源代码后发现每次doUpdate后并没有什么实际动作除了把byte[]放到ByteArrayOutputStream中，而最后doFinal的时候才将所有的byte[]进行加密，可是到了此时加密块大小很可能已经超出了OutputSize所以只好用dofinal方法。
i++;
}
return raw;
} catch (Exception e) {
throw new EncryptException(e.getMessage());
}
}
/**
* * 解密
* * @param key 解密的密钥
* * @param raw 已经加密的数据
* * @return 解密后的明文
* * @throws EncryptException
*/
public static byte[] decrypt(Key key, byte[] raw) throws EncryptException {
try {
Cipher cipher = Cipher.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
cipher.init(cipher.DECRYPT_MODE, key);
int blockSize = cipher.getBlockSize();
ByteArrayOutputStream bout = new ByteArrayOutputStream(64);
int j = 0;
while (raw.length - j * blockSize > 0) {
bout.write(cipher.doFinal(raw, j * blockSize, blockSize));
j++;
}
return bout.toByteArray();
} catch (Exception e) {
throw new EncryptException(e.getMessage());
}
}
public static String byte2hex(byte[] b) {
String hs = "";
String stmp = "";
for (int i = 0; i < b.length; i++) {
stmp = Integer.toHexString(b[i] & 0xFF);
if (stmp.length() == 1) {
hs += "0" + stmp;
} else {
hs += stmp;
}
}
//return hs;
return hs.toUpperCase();
}
public static byte[] hex2byte(String hex) throws IllegalArgumentException {
if (hex.length() % 2 != 0) {
throw new IllegalArgumentException();
}
char[] arr = hex.toCharArray();
byte[] b = new byte[hex.length() / 2];
for (int i = 0, j = 0, l = hex.length(); i < l; i++, j++) {
String swap = "" + arr[i++] + arr[i];
int byteint = Integer.parseInt(swap, 16) & 0xFF;
b[j] = new Integer(byteint).byteValue();
}
return b;
}
/**
* *
* * @param args
* * @throws Exception
*/
public static void main(String[] args) throws Exception {
byte[] orgData = "test".getBytes();
KeyPair keyPair = RSAUtil.generateKeyPair();
RSAPublicKey pubKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey priKey = (RSAPrivateKey) keyPair.getPrivate();
byte[] pubModBytes = pubKey.getModulus().toByteArray();
System.out.println("PubKey Modulus:"+new BigInteger(pubModBytes).toString(16));
byte[] pubPubExpBytes = pubKey.getPublicExponent().toByteArray();
System.out.println("publicExponent:"+new BigInteger(pubPubExpBytes).toString(16));
byte[] priModBytes = priKey.getModulus().toByteArray();
byte[] priPriExpBytes = priKey.getPrivateExponent().toByteArray();
RSAPublicKey recoveryPubKey = RSAUtil.generateRSAPublicKey(pubModBytes, pubPubExpBytes);
RSAPrivateKey recoveryPriKey = RSAUtil.generateRSAPrivateKey(priModBytes, priPriExpBytes);
byte[] raw = RSAUtil.encrypt(priKey, orgData);
System.out.println("Encrypt:"+byte2hex(raw));
byte[] data = RSAUtil.decrypt(recoveryPubKey, raw);
System.out.println("Decrypt:"+new String(data));
}
} |