Hashing is a way to make sure that the file you downloaded is exactly the same as the one your friend downloaded. It's easy to test this by using MD5 hashing (which stands for Message Digest 5), which simply creates a unique string of letters and numbers based on the contents of your file.

What's an MD4 hash function?

MD4 message-digest algorithm is a cryptographic hash function with a digest length of 128 bits. MD4 hashi function is used to get the MD4 hash, which typically is represented as 32-digit hexadecimal numbers.

MD4 was the baseline authentication method for Windows going back all the way to Windows 2000 and many leagacy distributions of windows still use MD4 for NTLM and RC4 Kerberos for producing effectively MD4 (passwords).

A BRIEF INTRODUCTION

MD4 Hash Generator

MD4 is a message digest algorithm designed by Professor Ronald Rivest of MIT in 1990. It implements a cryptographic hash function for use in message integrity checks.

When data is hashed, it is run through a mathematical algorithm that produces a hash value. This value is typically a 32-character string of hexadecimal numbers (32-bit word). The same data will always produce the same hash value, but even a small change to the data will result in a completely different hash value.

MD4 was designed to be fast, which means a few security risks were overlooked in a trade-off for performance. However, It is still difficult to reverse the hashing process and determine the original data from a hash value.

The MD4 algorithm has influenced later designs, such as the MD5, SHA and RIPEMD algorithms. MD4 is still used to compute NT-hash password digests on certian distributions of Microsoft Windows NT, XP and Vista.

What can be hashed using MD4?

You can hash any type of file. Text, images, videos and even other types of files will all have the same hash value if they are identical. Even though a given file may be different in terms of length and other features like its filename or extension, it will always have the same MD4 hash value.

How does MD4 work?

To understand how MD4 hashing works, you should know what a hash function is. A hash function is a mathematical operation that takes an input message of any length and returns a fixed-length string called the hash value.

The main property of a good hash function is that it is impossible to find two different messages that produce the same hash value. This makes it easy to verify whether or not two messages are equivalent (i.e., if they contain the same information). In some ways, this is similar to how DNA fingerprinting works: there are billions of possible combinations for your DNA sequence but only one combination belongs uniquely to you!

The MD4 algorithm is as follows:

Append padding bits
Append length of message (in bits)
Initialize MD buffer
Process message in 16-word blocks
Output final state of MD buffer

You can understand the algorithm in depth though the original paper by Professor Ronald Rivest, here.

Is MD4 secure?

MD4 is not a secure hashing algorithm. By 1992 weaknesses had been found which led Rivest to produce a strengthened, but slower, version known as MD5. In 1998, H. Dobbertin (Cryptanalysis of MD4, Journal of Cryptology, Vol. 11, NO. 4, 1998, pp. 253-271) found the first MD4 collisions, and he gave an algorithm for generating such collisions, with a work factor that is approximately equal to the computation of 2^20 MD4 hashes.

Conclusion

MD4 is not a secure hashing algorithm and the MD4 hash should not be used for any cryptographic purposes. It was broken in 1992 and you can use MD4 to create a rainbow table for a target password, or even create your own colliding files that have identical hashes. This allows attackers to create brute force attacks against passwords with little difficulty on most systems, as long as they’re using MD4 for hashing.