在 C# 中给定一个键的 MD5 散列

MD5 Hashing Given a Key in C#

提问by Jared

I've been looking for a way to hash a given string in C# that uses a predetermined key.

我一直在寻找一种使用预定键在 C# 中散列给定字符串的方法。

On my adventures through the internet trying to find an example i have seen lots of MD5CryptoServiceProvider examples which seem to use a default key for the machine, but none of them that apply a specific key. I need to have a specific key to encode data as to synchronize it to someone else's server. I hand them a hashed string and an ID number and they use that analyze the data and return a similar set to me. So is there anyway to get md5 to hash via a specific key that would be consistent to both.

在我通过互联网尝试寻找示例的过程中，我看到了许多 MD5CryptoServiceProvider 示例，它们似乎使用机器的默认密钥，但没有一个应用特定密钥。我需要一个特定的密钥来编码数据以将其同步到其他人的服务器。我给他们一个散列字符串和一个 ID 号，他们使用它分析数据并返回一个类似的集合给我。那么无论如何要通过一个与两者一致的特定键来让 md5 散列。

I would prefer this to be done in C#, but if its not possible with the libraries can you do so with some web languages like php or asp?

我更喜欢用 C# 来完成这个，但是如果用库来做这件事是不可能的，你能用一些网络语言来做，比如 php 或 asp 吗？

Edit: Misunderstood the scenario I was thrown into and after a little sitting and thinking about why they would have me use a key it appears they want a key appended to the end of the string and hashed. That way the server can appended the key it has along with the data passed to ensure its a valid accessing computer. Anyways... thanks all ^_^

编辑：误解了我被扔进的场景，在坐了一会儿并思考为什么他们让我使用密钥之后，他们似乎想要将密钥附加到字符串的末尾并进行哈希处理。这样服务器就可以附加它所拥有的密钥以及传递的数据，以确保它是有效的访问计算机。无论如何...谢谢大家^_^

Edit2: As my comment below says, it was the term 'salting' I was oblivious to. Oh the joys of getting thrown into something new with no directions.

Edit2：正如我在下面的评论所说，这是我忘记的“盐渍”一词。哦，在没有方向的情况下投入新事物的乐趣。

采纳答案by Tom Ritter

MD5 is not encryption - it's a hash. It doesn't allow a string to be decrypted.

MD5 不是加密——它是一个散列。它不允许解密字符串。

You're looking for a symmetric encryption algorithm. It uses the same key to encrypt and decrypt. Trying to use encryption functions without understanding them is dangerous. Even if you think you understand them, you can make a mistake.

您正在寻找一种对称加密算法。它使用相同的密钥进行加密和解密。在不了解加密函数的情况下尝试使用它们是危险的。即使你认为你理解它们，你也可能犯错误。

If you're transferring data to another person's server, you may be better off using something like gpgto encrypt the file using a symmetric key you both agree on over the phone, orperhaps some public-key crypto. This way, you don't write any crypto code, and it's safer (not completely secure, mind you, but safer).

如果您要将数据传输到其他人的服务器，则最好使用gpg 之类的工具，使用双方通过电话达成一致的对称密钥或一些公钥加密来加密文件。这样，您无需编写任何加密代码，而且更安全（请注意，并非完全安全，但更安全）。

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Edit:I'm still trying to decipher your requirements.

编辑：我仍在尝试破译您的要求。

MD5 is an unkeyed hash function - there is not key in use at all. So let's say the server sends you a giant string, or a file, and a hash of it. You would then MD5 the string or file, and compare the hash you computed with the hash they sent. If they match - the data was not corrupted in transit. That doesn'tmean no one tampered with what they sent you in transit, because MD5 has no "secret sauce" to it. I can md5 anything I want and send it to you.

MD5 是一个未加密的哈希函数 - 根本没有使用密钥。因此，假设服务器向您发送一个巨大的字符串或文件，以及它的散列。然后，您将对字符串或文件进行 MD5，并将您计算的哈希值与它们发送的哈希值进行比较。如果它们匹配 - 数据在传输过程中没有损坏。这并不意味着没有人篡改他们在传输过程中发送给您的内容，因为 MD5 没有“秘诀”。我可以对任何我想要的东西进行 md5 并将其发送给您。

A HMAC is a keyed hash function. It has a secret ingredient that only you and the group you're communicating with should know - the secret key. If they send you a long string or file, and a HMAC, you can compute the HMAC yourself, compare your HMAC and theirs, and if they match, the data was not corrupted in transit, nor was the data tampered with.

HMAC 是一个键控散列函数。它有一个秘密成分，只有您和您与之通信的小组应该知道 - 密钥。如果他们向您发送一个长字符串或文件以及一个 HMAC，您可以自己计算 HMAC，将您的 HMAC 与他们的 HMAC 进行比较，如果它们匹配，则数据在传输过程中没有损坏，也没有被篡改。

回答by Naaff

MD5is a hash function and, strictly speaking, is not used to "encrypt" a string. It produces a 128-bit "Message Digest" (hence the MD in the name) that is used as a kind of fingerprint for the input string.

MD5是一个散列函数，严格来说，它不用于“加密”字符串。它产生一个 128 位的“消息摘要”（因此名称中的 MD）用作输入字符串的一种指纹。

回答by Chris Doggett

Tom's right: MD5 is just a one-way hash, you can't decrypt it. Try these links:

汤姆是对的：MD5 只是一种单向散列，您无法对其进行解密。试试这些链接：

• Symmetric Key Encryption in C#
• Public-Key RSA Encryption in C#

• C#中的对称密钥加密
• C# 中的公钥 RSA 加密

回答by JP Alioto

You can use AES from C# to do the type of encryption you are looking for. Here's an articleon how.

您可以使用 C# 中的 AES 来执行您正在寻找的加密类型。这是一篇关于如何操作的文章。

回答by Thomas Levesque

You should use one of the classes inherited from SymmetricAlgorithm, for instance :

您应该使用从 继承的类之一SymmetricAlgorithm，例如：

• AesCryptoServiceProvider
• DESCryptoServiceProvider
• RC2CryptoServiceProvider
• TripleDESCryptoServiceProvider

• AesCryptoServiceProvider
• DESCryptoServiceProvider
• RC2CryptoServiceProvider
• 三重DESCryptoServiceProvider

回答by tggagne

So, why does the following test fail if both input strings are identical?

那么，如果两个输入字符串相同，为什么下面的测试会失败？

    [TestMethod]
    public void MD5HashTest()
    {
        var hash1 = (new MD5CryptoServiceProvider()).ComputeHash(new System.Text.ASCIIEncoding().GetBytes("now is the time for all good men."));
        var hash2 = (new MD5CryptoServiceProvider()).ComputeHash(new System.Text.ASCIIEncoding().GetBytes("now is the time for all good men."));

        Assert.AreEqual(hash1, hash2);
    }