不，你不能解密/反向md5，因为它是一个单向哈希函数，直到你不能在md5中发现广泛的漏洞。 另一种方法是有一些网站有大量的密码集数据库，所以你可以尝试在线解码你的MD5或SHA1哈希字符串。 我尝试了http://www.mycodemyway.com/encrypt-and-decrypt/md5这样的网站，它对我来说工作得很好，但这完全取决于你的哈希，如果哈希存储在数据库中，那么你可以得到实际的字符串。

理论上，你不能。哈希的意义在于它是单向的。这意味着如果有人设法获得哈希列表，他们仍然无法获得您的密码。此外，这意味着即使有人在多个网站上使用相同的密码(是的，我们都知道我们不应该这样做，但是……)任何访问站点A的数据库的人都不能在站点B上使用该用户的密码。

The fact that MD5 is a hash also means it loses information. For any given MD5 hash, if you allow passwords of arbitrary length there could be multiple passwords which produce the same hash. For a good hash it would be computationally infeasible to find them beyond a pretty trivial maximum length, but it means there's no guarantee that if you find a password which has the target hash, it's definitely the original password. It's astronomically unlikely that you'd see two ASCII-only, reasonable-length passwords that have the same MD5 hash, but it's not impossible.

MD5是一个不好的哈希密码:

它的速度很快，这意味着如果你有一个“目标”散列，尝试很多密码，看看你是否能找到一个散列到目标的密码是很便宜的。盐析对这种情况没有帮助，但它有助于增加寻找与使用不同盐析的多个哈希中的任何一个匹配的密码的代价。 我相信它有已知的缺陷，这使得它更容易发现冲突，尽管在可打印文本(而不是任意二进制数据)中发现冲突至少会更困难。

我不是安全专家，所以除了“不要使用自己的身份验证系统”之外，我不会给出具体的建议。从信誉良好的供应商那里找一个，然后使用它。安全系统的设计和实现都是一项棘手的工作。

MD5哈希算法是不可逆的，所以MD5解码在不可能，但一些网站有批量设置密码匹配，所以你可以尝试在线解码MD5哈希。

在网上试试:

MD5解密

md5online

md5decrypter

不可能，至少在合理的时间内是不可能的。

通常的处理方式是密码“重置”。也就是说，你给他们一个新的(随机的)密码，并在电子邮件中发送给他们。

不。MD5不是加密(尽管它可能被用作一些加密算法的一部分)，它是一个单向哈希函数。作为转换的一部分，大部分原始数据实际上“丢失”了。

Think about this: An MD5 is always 128 bits long. That means that there are 2128 possible MD5 hashes. That is a reasonably large number, and yet it is most definitely finite. And yet, there are an infinite number of possible inputs to a given hash function (and most of them contain more than 128 bits, or a measly 16 bytes). So there are actually an infinite number of possibilities for data that would hash to the same value. The thing that makes hashes interesting is that it is incredibly difficult to find two pieces of data that hash to the same value, and the chances of it happening by accident are almost 0.

A simple example for a (very insecure) hash function (and this illustrates the general idea of it being one-way) would be to take all of the bits of a piece of data, and treat it as a large number. Next, perform integer division using some large (probably prime) number n and take the remainder (see: Modulus). You will be left with some number between 0 and n. If you were to perform the same calculation again (any time, on any computer, anywhere), using the exact same string, it will come up with the same value. And yet, there is no way to find out what the original value was, since there are an infinite number of numbers that have that exact remainder, when divided by n.

That said, MD5 has been found to have some weaknesses, such that with some complex mathematics, it may be possible to find a collision without trying out 2128 possible input strings. And the fact that most passwords are short, and people often use common values (like "password" or "secret") means that in some cases, you can make a reasonably good guess at someone's password by Googling for the hash or using a Rainbow table. That is one reason why you should always "salt" hashed passwords, so that two identical values, when hashed, will not hash to the same value.

一旦一段数据通过哈希函数运行，就没有回头路了。

唯一可以工作的是(如果我们提到密码只是散列，没有添加任何类型的盐来防止重放攻击，如果是这样，你必须知道盐)顺便说一句，得到一个字典攻击工具，许多单词，数字等文件，然后创建两行，一行是单词，数字(在字典中)，另一个是单词的散列，并比较散列，如果匹配你得到它…

这是唯一的方法，不用进行密码分析。