需求：
实现RSA非对称加密算法
实现：
public static class RSACoder {
public static final String KEY_ALGORITHM = "RSA";
private static final int KEY_SIZE = 512;
private static final String PUBLIC_KEY = "RSAPublicKey";
private static final String PRIVATE_KEY = "RSAPrivateKey";
public static Map<String, Object> initKey() throws Exception {
KeyPairGenerator keyPairGenerator = KeyPairGenerator
.getInstance(KEY_ALGORITHM);
keyPairGenerator.initialize(KEY_SIZE);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<String, Object>();
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
public static byte[] encryptByPrivateKey(byte[] data, byte[] key)
throws Exception {
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(data);
}
public static byte[] encryptByPublicKey(byte[] data, byte[] key)
throws Exception {
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
return cipher.doFinal(data);
}
public static byte[] decryptByPrivateKey(byte[] data, byte[] key)
throws Exception {
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(data);
}
public static byte[] decryptByPublicKey(byte[] data, byte[] key)
throws Exception {
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, pubKey);
return cipher.doFinal(data);
}
public static byte[] getPrivateKey(Map<String, Object> keyMap) {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return key.getEncoded();
}
public static byte[] getPublicKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return key.getEncoded();
}
}