MD4 (Message-Digest Algorithm 4) is a cryptographic hash function designed by Ronald Rivest in 1990. It produces a 128-bit (16-byte) hash value, typically expressed as a 32-character hexadecimal number. MD4 was the predecessor to MD5 and while it's considered cryptographically broken, it's still used in some legacy systems and protocols like NTLM authentication.
What is MD4?
MD4 is a cryptographic hash function designed by Ronald Rivest in 1990. It was designed to be faster than MD2 while still providing a 128-bit hash. MD4 became the basis for later hash functions including MD5, SHA-1, and RIPEMD.
Key Features
- 128-bit Output: Produces a 32-character hexadecimal hash
- Fast Processing: Optimized for 32-bit processors
- Three Rounds: Uses three rounds of 16 operations each
- HMAC Support: Can be used with a secret key for message authentication
Security Note
MD4 is considered cryptographically broken and should not be used for security-critical applications. Collision attacks against MD4 can be performed in fractions of a second. For secure hashing, consider using SHA-256 or SHA-3. MD4 is still used in some legacy protocols like NTLM.