MD5¶

Basic Description¶

The input and output of MD5 are as follows:

• Input: A message of arbitrary length, processed in 512-bit blocks.
• Output: A 128-bit message digest.

For a detailed introduction, please search on your own.

Additionally, sometimes the MD5 we obtain is 16 characters long. In fact, those 16 characters are derived from the 32-character MD5 value. It is obtained by removing the first eight characters and the last eight characters from the 32-character MD5.

Generally, we can determine whether a function is an MD5 function by its initialization. If a function has the following four initialization variables, we can guess that it is an MD5 function, as these are the initialization IVs of the MD5 function.

0x67452301，0xEFCDAB89，0x98BADCFE，0x10325476

Cracking¶

Currently, MD5 can be considered basically broken. Common MD5 collisions can be obtained from the following websites:

• http://www.cmd5.com/
• http://www.ttmd5.com/
• http://pmd5.com/
• https://www.win.tue.nl/hashclash/fastcoll_v1.0.0.5.exe.zip (generates MD5 collisions with a specified prefix)

Challenges¶

• CFF 2016 Many Salts
• JarvisOJ Many Salts