Java實現MD5加密與解密
阿新 • • 發佈：2019-01-06
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class TestMD5 {
public static void Md5(String plainText){
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(plainText.getBytes());
byte b[] = md.digest();
int i;
StringBuffer buf = new StringBuffer("");
for (int offset = 0; offset < b.length; offset++) {
i = b[offset];
if(i<0) i+= 256;
if(i<16)
buf.append("0");
buf.append(Integer.toHexString(i));
}
System.out.println("result: " + buf.toString());//32位的加密
System.out.println("result: " + buf.toString().substring(8,24));//16位的加密
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
// MD5加碼。32位
public static String MD5(String inStr) {
MessageDigest md5 = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
System.out.println(e.toString());
e.printStackTrace();
return "";
}
char[] charArray = inStr.toCharArray();
byte[] byteArray = new byte[charArray.length];
for (int i = 0; i < charArray.length; i++)
byteArray[i] = (byte) charArray[i];
byte[] md5Bytes = md5.digest(byteArray);
StringBuffer hexValue = new StringBuffer();
for (int i = 0; i < md5Bytes.length; i++) {
int val = ((int) md5Bytes[i]) & 0xff;
if (val < 16)
hexValue.append("0");
hexValue.append(Integer.toHexString(val));
}
return hexValue.toString();
}
// 可逆的加密演算法
public static String KL(String inStr) {
// String s = new String(inStr);
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
a[i] = (char) (a[i] ^ 't');
}
String s = new String(a);
return s;
}
// 加密後解密
public static String JM(String inStr) {
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
a[i] = (char) (a[i] ^ 't');
}
String k = new String(a);
return k;
}
public static void main(String[] args) {
Md5("123456");
System.out.println();
String s = new String("123456");
System.out.println("原始：" + s);
System.out.println("MD5後：" + MD5(s));
System.out.println("MD5後再加密：" + KL(MD5(s)));
System.out.println("解密為MD5後的：" + JM(KL(MD5(s))));
}
}