40-bit MD5 Encryption

Now I want to talk about the 40-bit Decryption Method to everyone about the 40-bit encrypted data. In fact, it is still MD5 encryption, but some changes have been made:
Take admin as an example,
Admin's 16-bit and 32-bit ciphertext:
7a57a5a743894a0e
21232f297a57a5a743894a0e4a801fc3
When we encounter a ciphertext like 7a57a5a743894a0e4a801fc343894a0e4a801fc3, the decrypted ciphertext is admin.
If you look at it carefully, it is not difficult to find that the first 16 bits of the signature, 7a57a5a743894a0e, is the admin's 16-bit MD5 ciphertext; the last 24 bits are, please note, there is a 43894a0e between two 4a801f, 4a801fc3 is the last 8 bits of the 32-bit MD5 ciphertext, while 43894a0e is the last 8 bits of the 16-bit MD5 ciphertext.

This ciphertext can actually be seen as follows: First encrypt admin with 16-bit MD5, then add the last 8 digits of 32-bit MD5 ciphertext, and finally repeat the last 16-bit ciphertext (43894a0e4a801fc3, the 40-bit MD5 encrypted ciphertext was born.

After knowing the principle, we can see that the last 32-bit ciphertext is actually a 16-bit ciphertext repeat encrypted ciphertext, And we can simply take the first 16 digits out to crack it.

From: Kerry hacker