Java 加密算法
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2024-03-16 18:46:22
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1. 散列算法
MD5和SHA主要通过采集文件的信息摘要，以此进行计算并加密。常被用来一致性验证、数字证书和安全访问认证。
MD5加密
MD5加密后的位数一般为两种，16位与32位。16位实际上是从32位字符串中，取中间的第9位到第24位的部分。
public class MD5 {
public static void encrypt(String value) {
try {
MessageDigest md = MessageDigest.getInstance("md5");
md.update(value.getBytes());
System.out.println("MD5:" + ByteTool.byte2hex(md.digest()));
} catch (NoSuchAlgorithmException e) {
}
}
}
ByteTool.java文件
public class ByteTool {
private static String HexStr = "0123456789abcdef";
public static String byte2hex(byte[] bytes) {
String result = new String();
for (byte b : bytes) {
result = result + HexStr.charAt((b >> 4) & 0xF);
result = result + HexStr.charAt(b& 0xF);
}
return result;
}
}
"Hello World, This is a Test String!"输出
MD5:c1af26fa2188af7991b84a8db1e37c0d
SHA加密
SHA家族有五个算法，分别是SHA-1、SHA-224、SHA-256、SHA-384、SHA-512。
public class SHA {
public static void encrypt(String algorithm, String value) {
try {
MessageDigest md = MessageDigest.getInstance(algorithm);
md.update(value.getBytes());
System.out.println(algorithm + ":" + ByteTool.byte2hex(md.digest()));
} catch (NoSuchAlgorithmException e) {
}
}
}
SHA-1输出
SHA-1:ae4f2fc085b7e1dea58da3de3f7d5418ff6e59ff
SHA-256输出
SHA-256:e90d80449a1aa8aab9509403b924d420fc8df9b2ff9d2285938875d872ae3eb4
2. 对称加密
对称加密指加密和解密使用相同**的加密算法。
DES加密
DES是美国国家标准研究所提出的算法，加解密的数据安全性和**长度成正比。
public class DES {
private static final String Algorithm = "DES";
private static final byte[] Password = "13578642".getBytes();
public static void encrypt(String value, byte[] password) {
try {
DESKeySpec desKey = new DESKeySpec(password);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(Algorithm);
SecretKey securekey = keyFactory.generateSecret(desKey);
SecureRandom random = new SecureRandom();
Cipher cipher = Cipher.getInstance(Algorithm);
cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
System.out.println(Algorithm + ":" + ByteTool.byte2hex(cipher.doFinal(value.getBytes())));
} catch (Exception e) {
}
}
public static void decrypt(byte[] value, byte[] password) {
try {
DESKeySpec desKey = new DESKeySpec(password);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(Algorithm);
SecretKey securekey = keyFactory.generateSecret(desKey);
SecureRandom random = new SecureRandom();
Cipher cipher = Cipher.getInstance(Algorithm);
cipher.init(Cipher.DECRYPT_MODE, securekey, random);
System.out.println(Algorithm + ":" + new String(cipher.doFinal(value)));
} catch (Exception e) {
}
}
}
输出
DES:4bf8e50bb824399876b476d415017c8656e89652550bcb2ffdd42d36edd7de2072a7ed4cc5cbfbde
ByteTool把输出转化成byte数组，并进行解密
public class ByteTool {
private static String HexStr = "0123456789abcdef";
public static byte[] hex2byte(String value) {
byte[] result = new byte[value.length() / 2];
for (int i = 0; i < result.length; i++) {
result[i] = (byte) Integer.parseInt(value.substring(i*2, i*2 + 2), 16);
}
return result;
}
}
解密结果为
DES:Hello World, This is a Test String!
加密参数transformation
可以指定不同的transformation来进行加密算法。这个参数分为三段，加解密算法/工作模式/填充方式。 常采用的是NoPadding（不填充）、Zeros填充（0填充）、PKCS5Padding填充。
工作模式，详情可参考Java 块加密
- ECB模式，又称电子密码本模式(Electronic codebook)，是最简单的块密码加密模式。
- CBC模式，密码分组链接（Cipher-block chaining）模式。
- PCBC，填充密码块链接（Propagating cipher-block chaining）或称为明文密码块链接（Plaintext cipher-block chaining）
- CFB，密文反馈（CFB，Cipher feedback）模式
- OFB，OFB模式（输出反馈：Output feedback）
- CTR，CTR模式（Counter mode，CM）也被称为ICM模式（Integer Counter Mode，整数计数模式）和SIC模式（Segmented Integer Counter）
指定
public class DES {
private static final String Algorithm = "DES";
private static final String Transformation = "DES/CBC/PKCS5Padding";
private static final byte[] Password = "13578642".getBytes();
private static final byte[] IvParameter = "12345678".getBytes();
public static void encryptTransformation(String value, byte[] password) {
try {
DESKeySpec desKey = new DESKeySpec(password);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(Algorithm);
SecretKey securekey = keyFactory.generateSecret(desKey);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.ENCRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + ByteTool.byte2hex(cipher.doFinal(value.getBytes())));
} catch (Exception e) {
}
}
public static void decryptTransformation(byte[] value, byte[] password) {
try {
DESKeySpec desKey = new DESKeySpec(password);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(Algorithm);
SecretKey securekey = keyFactory.generateSecret(desKey);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.DECRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + new String(cipher.doFinal(value)));
} catch (Exception e) {
}
}
}
输出
DES:7eb90b79d6d43b006add77fe406d8727ab01e09aa506618ea995319216e6ead632fdfced012ed865
3DES加密
3DES是DES加密算法的一种模式，它使用3条64位的**对数据进行三次加密，提高了安全强度。不过desede算法处理速度较慢，**计算时间较长，加密效率不高。
修改相关算法为DESede，其中password必须为24位。
public class DESede {
private static final String Algorithm = "DESede";
private static final String Transformation = "DESede/CBC/PKCS5Padding";
private static final byte[] Password = "123456781234567812345678".getBytes();
private static final byte[] IvParameter = "12345678".getBytes();;
public static void encryptTransformation(String value, byte[] password) {
try {
SecretKey securekey = new SecretKeySpec(password, Algorithm);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.ENCRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + ByteTool.byte2hex(cipher.doFinal(value.getBytes())));
} catch (Exception e) {
}
}
public static void decryptTransformation(byte[] value, byte[] password) {
try {
SecretKey securekey = new SecretKeySpec(password, Algorithm);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.DECRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + new String(cipher.doFinal(value)));
} catch (Exception e) {
}
}
}
输出
DESede:c37551bb77f741d0b00f2f4e819bbdbcfac4e0c0095b9b9e231bf4e19a1d904bffafd60765749948
AES加密
AES是一个迭代的、对称**分组的密码，它可以使用128、192和256位**，并且用128位（16字节）分组加密和解密数据。
下面例子使用128位**加密，如果**大于128, 会抛出java.security.InvalidKeyException: Illegal key size异常，可参考这里。
public class AES {
private static final String Algorithm = "AES";
private static final String Transformation = "AES/CBC/PKCS5Padding";
private static final byte[] Password = "1234567812345678".getBytes();
private static final byte[] IvParameter = "1234567887654321".getBytes();
public static void encryptTransformation(String value, byte[] password) {
try {
SecretKey securekey = new SecretKeySpec(password, Algorithm);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.ENCRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + ByteTool.byte2hex(cipher.doFinal(value.getBytes())));
} catch (Exception e) {
}
}
public static void decryptTransformation(byte[] value, byte[] password) {
try {
SecretKey securekey = new SecretKeySpec(password, Algorithm);
IvParameterSpec iv = new IvParameterSpec(IvParameter);
Cipher cipher = Cipher.getInstance(Transformation);
cipher.init(Cipher.DECRYPT_MODE, securekey, iv);
System.out.println(Algorithm + ":" + new String(cipher.doFinal(value)));
} catch (Exception e) {
}
}
}
输出
AES:8642be6ffca8e366e01c06478a23906e531131079ab0e6da7ff5888a033fb5221a26d2161f66e60bcee53b2ee1314cc2