What is MD4 and How Does It Work?
MD4 (Message Digest Algorithm 4) is a cryptographic hash function that produces a 128-bit hash value, typically expressed as a 32-character hexadecimal number. Created by Ronald Rivest in 1990, MD4 processes any amount of input data and generates a fixed-length hash. Even the tiniest change in the input produces a completely different hash.
Common MD4 Applications
- Legacy System Support: Maintain compatibility with older systems requiring MD4
- Data Deduplication: Identify duplicate content by comparing hashes
- Archive Verification: Verify integrity of historical backup files
- Database Checksums: Detect data corruption or changes in legacy databases
- Cache Keys: Generate unique identifiers for caching mechanisms
MD4 Characteristics
- Hash Length: Always produces 128-bit (32 hexadecimal character) hash
- Deterministic: Same input always produces same hash
- One-Way Function: Cannot reverse hash to original input
- Fast Computation: Rapid hashing of large files or text
- Avalanche Effect: Tiny input change produces completely different hash
MD4 vs Other Hash Algorithms
MD4 produces a 32-character hash, similar to MD5, while SHA-1 produces 40 characters, and SHA-256 produces 64 characters. MD4 is faster than MD5 but both are considered cryptographically broken. For new projects, use SHA-256, SHA-3, or bcrypt. MD4 remains useful only for legacy systems that specifically require it.
Security Considerations
MD4 has known cryptographic weaknesses and should NOT be used for password storage or security-critical applications. Collision attacks are possible. For security purposes, use stronger algorithms like SHA-256, SHA-3, or purpose-built password hashing functions like bcrypt, scrypt, or Argon2. MD4 should only be used when required for legacy system compatibility.