md5的碰撞率是多少? [英] What is the clash rate for md5?

问题描述

md5 算法发生冲突的概率是多少?我相信它非常低.

What's the probability for the clash for the md5 algorithm? I believe it is extremely low.

推荐答案

平均而言，如果您不尝试故意创建冲突，您需要散列大约 2^64 个值才能在它们之间获得单个冲突.哈希冲突与生日问题非常相似.

You need to hash about 2^64 values to get a single collision among them, on average, if you don't try to deliberately create collisions. Hash collisions are very similar to the Birthday problem.

如果看两个任意值，碰撞概率只有2^-128.

If you look at two arbitrary values, the collision probability is only 2^-128.

md5 的问题在于，制作散列为相同值的两个不同文本相对容易.但这需要蓄意攻击，而且不会意外发生.即使是故意攻击，目前也无法获得与给定哈希匹配的纯文本.

The problem with md5 is that it's relatively easy to craft two different texts that hash to the same value. But this requires a deliberate attack, and doesn't happen accidentally. And even with a deliberate attack it's currently not feasible to get a plain text matching a given hash.

简而言之，md5 对于非安全目的是安全的，但在许多安全应用程序中都被破坏了.

In short md5 is safe for non security purposes, but broken in many security applications.

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