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如何将md5哈希组合到字节数组以获得相等的md5哈希组合数组

[英]How to combine md5 hashes to of byte array to get equalent md5 hash of combined array

原文 2014-09-14 12:15:52 6 2 c#/ .net/ md5

I have two byte arrays lets say A and B. And I computed MD5 Hash AH and BH for them respectively. 我有两个字节数组，可以说A和B。分别为它们计算了MD5哈希值AH和BH。 Now if I Combine these arrays A and B to AB, and compute MD5 hash as ABH what whould be the way to combine AH and BH to equate ABH? 现在，如果我将这些数组A和B组合为AB，并将MD5哈希计算为ABH，那么将AH和BH组合为ABH的方法是什么？

2 个解决方案

Based on your comments that you don't need a cryptographic hash, but just some kind of "fingerprint" to give a certain degree of hash = data assurance, then here's one possibility: 根据您的评论，您不需要加密哈希，而只需某种“指纹”即可提供一定程度的哈希=数据保证，那么就有一种可能性：

The simplest hash of all is to just XOR (exclusive-or) the data against itself. 最简单的哈希是将数据与自身进行XOR（异或）运算。 So for an 8-byte hash, you just walk over the data and XOR every 8 bytes together, producing an 8-byte hash. 因此，对于8字节的哈希，您只需遍历数据并每8个字节进行XOR运算，即可产生8字节的哈希。 This provides a very high degree of certainty, unless the "bad guys" know how you do the hashing, then it is easy to fake. 这提供了很高的确定性，除非“坏蛋”知道您如何进行哈希处理，否则很容易伪造。

If you concatenate two data arrays, A and B, then as long as A is a multiple of 8 in length, or if it's acceptable to place zeros padding between A and B so A + padding is a multiple of 8, then the combined hash will be (hash of A) XOR (hash of B). 如果连接两个数据数组A和B，则只要A的长度是8的倍数，或者如果在A和B之间放置零填充是可接受的，那么A +填充是8的倍数，则合并的哈希将为（A的哈希）XOR（B的哈希）。 (At least, that's what I learned 50 years ago, if I remember right.) （如果我没记错的话，至少这是我50年前学到的。）

Edit: 编辑：

Just found this: Why is XOR the default way to combine hashes? 刚刚发现：为什么XOR是组合哈希的默认方法？

密码学专家可能有能力使用值的部分MD5哈希值来获取有关完整值的MD5哈希值的一些信息，但出于实际目的，获取值的MD5哈希值的唯一方法是计算MD5从该值散列。