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# MD5¶

## Basic description¶

The input and output of MD5 are as follows

• Input: Any long message, 512-bit long packet.
• Output: 128-bit message digest.

For a detailed introduction, please search for yourself.

In addition, sometimes the md5 we get is 16-bit. In fact, the 16-bit is the length of the 32-bit md5, which is derived from the 32-bit md5 value. It is to remove the first eight bits of 32-bit md5 and get the last eight bits.

In general, we can determine whether it is an MD5 function by initializing the function. In general, if a function has the following four initialized variables, you can guess that the function is an MD5 function, because this is the initialization IV of the MD5 function.

0x67452301，0xEFCDAB89，0x98BADCFE，0x10325476


## Crack¶

At present, it can be said that md5 has been basically broken. The general MD5 collision can be obtained on the following online.

## topic¶

• CFF 2016 a lot of salt
• JarvisOJ a lot of salt