YoSin Tools

MD4 Hash Generator

Generate MD4 hash values online. Supports UTF-8, UTF-16, Hex, and Base64 input encodings, plus HMAC-MD4 with a secret key.

Input
Output
Share Link
Settings
Hash

Related Hash Tools

MD4 FileHash from file MD2128-bit hash MD5128-bit hash SHA1160-bit hash CRCCyclic checksum

Frequently Asked Questions

What is MD4?
MD4 (Message Digest 4) is a cryptographic hash function designed by Ronald Rivest in 1990 and published as RFC 1320. It produces a 128-bit digest and served as the direct predecessor to MD5. MD4 is faster than MD5 but significantly weaker — practical collision attacks exist.
Where is MD4 used today?
MD4 is used in Microsoft's NTLM authentication protocol for Windows password hashing, in rsync's rolling checksum algorithm, and in some legacy systems. Outside of these specific use cases it is rarely encountered.
Is MD4 secure?
No. MD4 was broken in 1995 and practical collision attacks were demonstrated shortly after. It must not be used for digital signatures, password storage, or any application requiring collision resistance. Use SHA-256 or SHA-3 instead.
How does MD4 differ from MD5?
MD4 uses three rounds of processing while MD5 uses four, making MD4 faster but less secure. MD5 also introduced additional non-linear functions and added a unique additive constant to each operation to address MD4's weaknesses.

About MD4 Hash

MD4 (Message Digest 4) was designed by Ronald Rivest in 1990 as a fast hash function for 32-bit processor architectures. It produces a 128-bit (16-byte) digest and processes the input in 512-bit (64-byte) blocks through three distinct rounds of bitwise operations. While it represented a significant performance improvement over MD2, weaknesses in its design were discovered quickly.

MD4 in NTLM Authentication

The most notable modern use of MD4 is in Microsoft's NT LAN Manager (NTLM) authentication protocol. Windows stores the NT hash of a user's password as the MD4 hash of the UTF-16LE-encoded password. This is why MD4 remains relevant in penetration testing and Windows security research contexts.

MD4 vs MD5

MD4 operates in three rounds and is faster than MD5, which uses four rounds. Ronald Rivest himself designed MD5 as a more conservative and secure replacement after potential weaknesses in MD4 were identified. Despite being faster, MD4 is much weaker — Dobbertin published a full collision attack in 1995. MD5 also has known collisions, but they are harder to produce.

Practical Uses Today

Despite its cryptographic weakness, MD4 can still be used for non-security purposes such as fast checksums, hash tables, and content-based deduplication where collision resistance is not critical. The YoSin Tools MD4 calculator provides an accurate, browser-based implementation suitable for learning, legacy compatibility testing, and data verification tasks.