Java 如何解码我的 md5 加密以及如何正确调用该函数？
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How do I decode my md5 encryption and how do I call the function properly?
提问by user2030485
I have two questions 1 I have the following code and I don't know how to use it from another part of my code, i.e when the user registers to encrypt my string password
我有两个问题 1 我有以下代码，但我不知道如何从代码的另一部分使用它，即当用户注册以加密我的字符串密码时
public static final String md5(final String toEncrypt) {
try {
final MessageDigest digest = MessageDigest.getInstance("md5");
digest.update(toEncrypt.getBytes());
final byte[] bytes = digest.digest();
final StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
sb.append(String.format("%02X", bytes[i]));
}
return sb.toString().toLowerCase();
}
catch (Exception exc) { return ""; // Impossibru! }
}
Second question is how would I decrypt that string when I pull it from my database to match what a user types in a editbox.
第二个问题是，当我从数据库中提取该字符串以匹配用户在编辑框中键入的内容时，我将如何解密该字符串。
回答by Doorknob
- You're not supposed to "decrypt" MD5. The whole point of a hashing function is to make it very hard to unhash it. (of course, hackers try and sometimes succeed, but that's a different topic.)You hash the user's input, and thencompare it with the hashed password in the database.
- To call it, simply use
String hashedPassword = md5("some person's password");. Just like a normal method. - You should probably actually do some exception handling, rather than just ignoring them. At leastlog them, at the very minimum. Or return
null, or use athrowsclause. Just don't completely ignore them. I don't even know what's going on on line 3... you should probably make those separate lines. Also, your indentation is
a bitextremely strange. You will spend muchmore time reading your code than writing it, so make it readable now, and you'll thank your past self later. In fact, I already see a bug:catch (Exception exc) { return ""; // Impossibru! }The close bracket is commented out.
- 你不应该“解密”MD5。散列函数的全部意义在于使其很难解散。（当然，黑客会尝试，有时会成功，但这是一个不同的话题。）您对用户的输入进行散列，然后将其与数据库中的散列密码进行比较。
- 要调用它，只需使用
String hashedPassword = md5("some person's password");. 就像正常的方法一样。 - 您实际上应该进行一些异常处理，而不是仅仅忽略它们。在至少记录他们，在最起码。或 return
null，或使用throws子句。只是不要完全忽略它们。 我什至不知道第 3 行发生了什么……您可能应该单独制作这些行。另外，你的缩进是
有点怪异之极。你会花很多更多的时间阅读你的代码比编写，所以让它现在可读的，以后你会感谢你的过去的自己。事实上，我已经看到了一个错误：catch (Exception exc) { return ""; // Impossibru! }右括号被注释掉。
回答by Seth McClaine
md5 is a one way encryption method. The only way to find what the encrypted version is, is to md5 hash combinations of characters until the results match
md5 是一种单向加密方法。找到加密版本的唯一方法是对字符进行 md5 哈希组合，直到结果匹配
