Java之加密演算法
阿新 • • 發佈：2018-11-04
加密演算法主要分為對稱加密、非對稱加密、Hash加密。
一、何為對稱加密？
對稱加密是指對稱密碼編碼技術，它的特點是檔案加密和解密使用相同的金鑰加密。
對稱機密的金鑰一般小於256bit。因為就金鑰而言，如果加密的金鑰越大，則其計算的複雜度越高，所需要的時間越長，而如果使用的金鑰較小，則很容易破解，所以金鑰的大小需根據業務需求去選擇。
通常，加密的演算法有：DES、3DES、Blowfish、IDEA、RC4、RC5、RC6和AES 。
程式碼段引用：https://blog.csdn.net/chengbinbbs/article/details/78640589
public class DESUtil {
private static final String KEY_ALGORITHM = "DES";
private static final String DEFAULT_CIPHER_ALGORITHM = "DES/ECB/PKCS5Padding";//預設的加密演算法
/**
* DES 加密操作
*
* @param content 待加密內容
* @param key 加密金鑰
* @return 返回Base64轉碼後的加密資料
*/
public static String encrypt(String content, String key) {
try {
Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 建立密碼器
byte[] byteContent = content.getBytes("utf-8");
cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(key));// 初始化為加密模式的密碼器
byte[] result = cipher.doFinal(byteContent);// 加密
return Base64.encodeBase64String(result);//通過Base64轉碼返回
} catch (Exception ex) {
Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
/**
* DES 解密操作
*
* @param content
* @param key
* @return
*/
public static String decrypt(String content, String key) {
try {
//例項化
Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
//使用金鑰初始化，設定為解密模式
cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key));
//執行操作
byte[] result = cipher.doFinal(Base64.decodeBase64(content));
return new String(result, "utf-8");
} catch (Exception ex) {
Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
/**
* 生成加密祕鑰
*
* @return
*/
private static SecretKeySpec getSecretKey(final String key) {
//返回生成指定演算法金鑰生成器的 KeyGenerator 物件
KeyGenerator kg = null;
try {
kg = KeyGenerator.getInstance(KEY_ALGORITHM);
//DES 要求金鑰長度為 56
kg.init(56, new SecureRandom(key.getBytes()));
//生成一個金鑰
SecretKey secretKey = kg.generateKey();
return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 轉換為DES專用金鑰
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(DESUtil.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
public static void main(String[] args) {
String content = "hello,您好";
String key = "
二、非對稱加密
何為非對稱加密？
非對稱加密是指加密和解密使用兩個不同的金鑰
通常，非對稱加密的演算法有：RSA、ECC（移動裝置用）、Diffie-Hellman、El Gamal、DSA（數字簽名用）
程式碼段引用：https://blog.csdn.net/chengbinbbs/article/details/78640589
public class RSAUtils {
/**
* 加密演算法RSA
*/
public static final String KEY_ALGORITHM = "RSA";
/**
* 簽名演算法
*/
public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
/**
* 獲取公鑰的key
*/
private static final String PUBLIC_KEY = "RSAPublicKey";
/**
* 獲取私鑰的key
*/
private static final String PRIVATE_KEY = "RSAPrivateKey";
/**
* RSA最大加密明文大小
*/
private static final int MAX_ENCRYPT_BLOCK = 117;
/**
* RSA最大解密密文大小
*/
private static final int MAX_DECRYPT_BLOCK = 128;
/**
* <p>
* 生成金鑰對(公鑰和私鑰)
* </p>
*
* @return
* @throws Exception
*/
public static Map<String, Object> genKeyPair() throws Exception {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<String, Object>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
/**
* <p>
* 用私鑰對資訊生成數字簽名
* </p>
*
* @param data 已加密資料
* @param privateKey 私鑰(BASE64編碼)
*
* @return
* @throws Exception
*/
public static String sign(byte[] data, String privateKey) throws Exception {
byte[] keyBytes = Base64Utils.decode(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(privateK);
signature.update(data);
return Base64Utils.encode(signature.sign());
}
/**
* <p>
* 校驗數字簽名
* </p>
*
* @param data 已加密資料
* @param publicKey 公鑰(BASE64編碼)
* @param sign 數字簽名
*
* @return
* @throws Exception
*
*/
public static boolean verify(byte[] data, String publicKey, String sign)
throws Exception {
byte[] keyBytes = Base64Utils.decode(publicKey);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PublicKey publicK = keyFactory.generatePublic(keySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(publicK);
signature.update(data);
return signature.verify(Base64Utils.decode(sign));
}
/**
* <P>
* 私鑰解密
* </p>
*
* @param encryptedData 已加密資料
* @param privateKey 私鑰(BASE64編碼)
* @return
* @throws Exception
*/
public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
throws Exception {
byte[] keyBytes = Base64Utils.decode(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateK);
int inputLen = encryptedData.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 對資料分段解密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
}
/**
* <p>
* 公鑰解密
* </p>
*
* @param encryptedData 已加密資料
* @param publicKey 公鑰(BASE64編碼)
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
throws Exception {
byte[] keyBytes = Base64Utils.decode(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicK);
int inputLen = encryptedData.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 對資料分段解密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
} else {
cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_DECRYPT_BLOCK;
}
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
}
/**
* <p>
* 公鑰加密
* </p>
*
* @param data 源資料
* @param publicKey 公鑰(BASE64編碼)
* @return
* @throws Exception
*/
public static byte[] encryptByPublicKey(byte[] data, String publicKey)
throws Exception {
byte[] keyBytes = Base64Utils.decode(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
// 對資料加密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicK);
int inputLen = data.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 對資料分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(data, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
}
/**
* <p>
* 私鑰加密
* </p>
*
* @param data 源資料
* @param privateKey 私鑰(BASE64編碼)
* @return
* @throws Exception
*/
public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
throws Exception {
byte[] keyBytes = Base64Utils.decode(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateK);
int inputLen = data.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 對資料分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
} else {
cache = cipher.doFinal(data, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * MAX_ENCRYPT_BLOCK;
}
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
}
/**
* <p>
* 獲取私鑰
* </p>
*
* @param keyMap 金鑰對
* @return
* @throws Exception
*/
public static String getPrivateKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return Base64Utils.encode(key.getEncoded());
}
/**
* <p>
* 獲取公鑰
* </p>
*
* @param keyMap 金鑰對
* @return
* @throws Exception
*/
public static String getPublicKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return Base64Utils.encode(key.getEncoded());
}
}
三、Hash演算法
何為Hash演算法？
Hash演算法是一種單向的加密演算法，即無法解密(依目前的計算力，還是可以使用暴力破解，MD5聽說被破解過)。
通常，Hash演算法有：MD2、MD4、MD5、HAVAL、SHA
import java.security.MessageDigest;
import java.util.logging.Logger;
/**
* MD5加密演算法
*/
public class MD5 {
public static String MD5(String key) {
char hexDigits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
try {
byte[] btInput = key.getBytes();
// 獲得MD5摘要演算法的 MessageDigest 物件
MessageDigest mdInst = MessageDigest.getInstance("MD5");
// 使用指定的位元組更新摘要
mdInst.update(btInput);
// 獲得密文
byte[] md = mdInst.digest();
// 把密文轉換成十六進位制的字串形式
int j = md.length;
char str[] = new char[j * 2];
int k = 0;
for (int i = 0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 & 0xf];
str[k++] = hexDigits[byte0 & 0xf];
}
return new String(str);
} catch (Exception e) {
return null;
}
}
public static void main(String[] args){
String MD5_String;
MD5_String = MD5("weiqingde");
System.out.println(MD5_String);
}
}
注：如果需要使用這些加密演算法，可以去下載apache 下的commons包，該包擁有很多對稱加密、非對稱加密、Hash加密實現工具