Java RSA加密&解密如下：
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import javax.crypto.Cipher;
import java.io.IOException;
import java.nio.charset.Charset;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
public class Sample {
public static final String RSA_ALGORITHM = "RSA";
public static final Charset UTF8 = Charset.forName("UTF-8");
public static void main(String [] args) throws Exception {
// generate public and private keys
KeyPair keyPair = buildKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
// encrypt the message
byte [] encrypted = encrypt(privateKey, "This is a secret message");
System.out.println(base64Encode(encrypted)); // <<encrypted message>>
// decrypt the message
byte[] secret = decrypt(publicKey, encrypted);
System.out.println(new String(secret, UTF8)); // This is a secret message
}
public static KeyPair buildKeyPair() throws NoSuchAlgorithmException {
final int keySize = 2048;
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA_ALGORITHM);
keyPairGenerator.initialize(keySize);
return keyPairGenerator.genKeyPair();
}
public static byte[] encrypt(PrivateKey privateKey, String message) throws Exception {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(message.getBytes(UTF8));
}
public static byte[] decrypt(PublicKey publicKey, byte [] encrypted) throws Exception {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, publicKey);
return cipher.doFinal(encrypted);
}
public static String base64Encode(byte[] data) {
return new BASE64Encoder().encode(data);
}
public static byte[] base64Decode(String data) throws IOException {
return new BASE64Decoder().decodeBuffer(data);
}
}
拿到RSA 公鑰和私鑰后我們可以保存到文件中褥蚯，代碼如下：
public void savePublicKey(PublicKey publicKey) throws IOException {
// 得到公鑰字符串
String publicKeyString = base64Encode(publicKey.getEncoded());
System.out.println("publicKeyString="+publicKeyString);
FileWriter fw = new FileWriter("publicKey.keystore");
BufferedWriter bw = new BufferedWriter(fw);
bw.write(publicKeyString);
bw.close();
}
public void savePrivateKey(PrivateKey privateKey) throws IOException {
// 得到私鑰字符串
String privateKeyString = base64Encode(privateKey.getEncoded());
System.out.println("privateKeyString="+privateKeyString);
FileWriter fw = new FileWriter("privateKey.keystore");
BufferedWriter bw = new BufferedWriter(fw);
bw.write(privateKeyString);
bw.close();
}
public static String base64Encode(byte[] data) {
return new BASE64Encoder().encode(data);
}
public static byte[] base64Decode(String data) throws IOException {
return new BASE64Decoder().decodeBuffer(data);
}
解析已有的公鑰和私鑰羡藐，代碼如下：
public static RSAPublicKey loadPublicKey(String publicKeyStr) throws Exception {
try {
byte[] buffer = base64Decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
}
}
public static RSAPrivateKey loadPrivateKey(String privateKeyStr) throws Exception {
try {
byte[] buffer = base64Decode(privateKeyStr);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
}
}
public static String base64Encode(byte[] data) {
return new BASE64Encoder().encode(data);
}
public static byte[] base64Decode(String data) throws IOException {
return new BASE64Decoder().decodeBuffer(data);
}
完整代碼如下：
package util;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import javax.crypto.Cipher;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.charset.Charset;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
public class Sample {
public static final String RSA_ALGORITHM = "RSA";
public static final Charset UTF8 = Charset.forName("UTF-8");
public static void main(String [] args) throws Exception {
// generate public and private keys
KeyPair keyPair = buildKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
// encrypt the message
byte [] encrypted = encrypt(privateKey, "This is a secret message");
System.out.println(base64Encode(encrypted)); // <<encrypted message>>
// decrypt the message
byte[] secret = decrypt(publicKey, encrypted);
System.out.println(new String(secret, UTF8)); // This is a secret message
}
public static KeyPair buildKeyPair() throws NoSuchAlgorithmException {
final int keySize = 2048;
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA_ALGORITHM);
keyPairGenerator.initialize(keySize);
return keyPairGenerator.genKeyPair();
}
public static byte[] encrypt(PrivateKey privateKey, String message) throws Exception {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(message.getBytes(UTF8));
}
public static byte[] decrypt(PublicKey publicKey, byte [] encrypted) throws Exception {
Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, publicKey);
return cipher.doFinal(encrypted);
}
/**
* 從字符串中加載公鑰
*
*/
public static RSAPublicKey loadPublicKey(String publicKeyStr) throws Exception {
try {
byte[] buffer = base64Decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
}
}
public static RSAPrivateKey loadPrivateKey(String privateKeyStr) throws Exception {
try {
byte[] buffer = base64Decode(privateKeyStr);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
}
}
public void savePublicKey(PublicKey publicKey) throws IOException {
// 得到公鑰字符串
String publicKeyString = base64Encode(publicKey.getEncoded());
System.out.println("publicKeyString="+publicKeyString);
FileWriter fw = new FileWriter("publicKey.keystore");
BufferedWriter bw = new BufferedWriter(fw);
bw.write(publicKeyString);
bw.close();
}
public void savePrivateKey(PrivateKey privateKey) throws IOException {
// 得到私鑰字符串
String privateKeyString = base64Encode(privateKey.getEncoded());
System.out.println("privateKeyString="+privateKeyString);
BufferedWriter bw = new BufferedWriter(new FileWriter("privateKey.keystore"));
bw.write(privateKeyString);
bw.close();
}
public static String base64Encode(byte[] data) {
return new BASE64Encoder().encode(data);
}
public static byte[] base64Decode(String data) throws IOException {
return new BASE64Decoder().decodeBuffer(data);
}
}
