JAVAのRAS暗号化例
package com.gmail.crazier9527.util;
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;
/**
*
* RSA 。 ， ， 。
*
* http://www.bouncycastle.org bcprov-jdk16-143.jar。
*
* @author xiaoyusong
*
* mail: [email protected]
*
* msn:[email protected]
*
* @since 2004-5-20
*
*
*
*/
public class RSA {
/**
*
*
*
* @return KeyPair
*
* @throws Exception
*
*/
public static KeyPair generateKeyPair() throws Exception {
try {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",
new org.bouncycastle.jce.provider.BouncyCastleProvider());
final int KEY_SIZE = 1024;// ， ， ， ，
keyPairGen.initialize(KEY_SIZE, new SecureRandom());
KeyPair keyPair = keyPairGen.genKeyPair();
return keyPair;
} catch (Exception e) {
throw new Exception(e.getMessage());
}
}
/**
*
*
*
* @param modulus
*
* @param publicExponent
*
* @return RSAPublicKey
*
* @throws Exception
*
*/
public static RSAPublicKey generateRSAPublicKey(byte[] modulus,
byte[] publicExponent) throws Exception {
KeyFactory keyFac = null;
try {
keyFac = KeyFactory.getInstance("RSA",
new org.bouncycastle.jce.provider.BouncyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new Exception(ex.getMessage());
}
RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(
modulus), new BigInteger(publicExponent));
try {
return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);
} catch (InvalidKeySpecException ex) {
throw new Exception(ex.getMessage());
}
}
/**
*
*
*
* @param modulus
*
* @param privateExponent
*
* @return RSAPrivateKey
*
* @throws Exception
*
*/
public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus,
byte[] privateExponent) throws Exception {
KeyFactory keyFac = null;
try {
keyFac = KeyFactory.getInstance("RSA",
new org.bouncycastle.jce.provider.BouncyCastleProvider());
} catch (NoSuchAlgorithmException ex) {
throw new Exception(ex.getMessage());
}
RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(
modulus), new BigInteger(privateExponent));
try {
return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);
} catch (InvalidKeySpecException ex) {
throw new Exception(ex.getMessage());
}
}
/**
*
*
*
* @param key
*
*
* @param data
*
*
* @return
*
* @throws Exception
*
*/
public static byte[] encrypt(Key key, byte[] data) throws Exception {
try {
Cipher cipher = Cipher.getInstance("RSA",
new org.bouncycastle.jce.provider.BouncyCastleProvider());
cipher.init(Cipher.ENCRYPT_MODE, key);
int blockSize = cipher.getBlockSize();// ， ： 128 byte， key_size=1024
// 127
// byte, 128 byte; 2 ， 127
// byte 1 byte
int outputSize = cipher.getOutputSize(data.length);//
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);
// doUpdate ， doUpdate byte[] ByteArrayOutputStream ， doFinal byte[] ， OutputSize dofinal 。
i++;
}
return raw;
} catch (Exception e) {
throw new Exception(e.getMessage());
}
}
/**
*
*
*
* @param key
*
*
* @param raw
*
*
* @return
*
* @throws Exception
*
*/
public static byte[] decrypt(Key key, byte[] raw) throws Exception {
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 Exception(e.getMessage());
}
}
/**
*
*
*
* @param args
*
* @throws Exception
*
*/
public static void main(String[] args) throws Exception {
File file = new File("c:/test.html");
FileInputStream in = new FileInputStream(file);
ByteArrayOutputStream bout = new ByteArrayOutputStream();
byte[] tmpbuf = new byte[1024];
int count = 0;
while ((count = in.read(tmpbuf)) != -1) {
bout.write(tmpbuf, 0, count);
tmpbuf = new byte[1024];
}
in.close();
byte[] orgData = bout.toByteArray();
KeyPair keyPair = RSA.generateKeyPair();
RSAPublicKey pubKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey priKey = (RSAPrivateKey) keyPair.getPrivate();
byte[] pubModBytes = pubKey.getModulus().toByteArray();
byte[] pubPubExpBytes = pubKey.getPublicExponent().toByteArray();
byte[] priModBytes = priKey.getModulus().toByteArray();
byte[] priPriExpBytes = priKey.getPrivateExponent().toByteArray();
RSAPublicKey recoveryPubKey = RSA.generateRSAPublicKey(pubModBytes,
pubPubExpBytes);
RSAPrivateKey recoveryPriKey = RSA.generateRSAPrivateKey(priModBytes,
priPriExpBytes);
byte[] raw = RSA.encrypt(priKey, orgData);
file = new File("c:/encrypt_result.dat");
OutputStream out = new FileOutputStream(file);
out.write(raw);
out.close();
byte[] data = RSA.decrypt(recoveryPubKey, raw);
file = new File("c:/decrypt_result.html");
out = new FileOutputStream(file);
out.write(data);
out.flush();
out.close();
}
}必要なJARバッグを添付します.