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| * (Presented at . Requires about <math>2^{14}</math> MD4 computations. Demonstrates "Theoretical Pre-image Attack on MD4" and "Second Pre-Image Attack for Weak Messages".) | * (Presented at ]. Requires about <math>2^{14}</math> MD4 computations. Demonstrates "Theoretical ] on MD4" and "Second Pre-Image Attack for Weak Messages".) | ||
| * ("MD4 can be broken by ] ]s in real time. The attacks have been experimentally tested and run in milliseconds on a PC.") | * ("MD4 can be broken by ] ]s in real time. The attacks have been experimentally tested and run in milliseconds on a PC.") | ||
| * ("We were able to find collisions with probability almost 1, and the average complexity to find a collision is upper bounded by three times of MD4 hash operations.") | * ("We were able to find collisions with probability almost 1, and the average complexity to find a collision is upper bounded by three times of MD4 hash operations.") | ||
Revision as of 16:01, 4 November 2005
MD4 is a message digest algorithm (the fourth in a series) designed by Professor Ronald Rivest of MIT in 1990. It implements a cryptographic hash function for use in message integrity checks. The digest length is 128 bits. The algorithm has influenced later designs, such as the MD5, SHA and RIPEMD algorithms.
Weaknesses in MD4 were demonstrated by Den Boer and Bosselaers in a paper published in 1991. Many of the subsequent message digest designs based on it remain secure, in the sense that no effective attack has been published against them.
In August 2004, researchers reported generating collisions in MD4 using "hand calculation" .
MD4 hashes
The 128-bit (16-byte) MD4 hashes (also termed message digests) are typically represented as 32-digit hexadecimal numbers. The following demonstrates a 43-byte ASCII input and the corresponding MD4 hash:
MD4("The quick brown fox jumps over the lazy dog") = 1bee69a46ba811185c194762abaeae90
Even a small change in the message will (with overwhelming probability) result in a completely different hash, e.g. changing d to c:
MD4("The quick brown fox jumps over the lazy cog") = b86e130ce7028da59e672d56ad0113df
The hash of the zero-length string is:
MD4("") = 31d6cfe0d16ae931b73c59d7e0c089c0
See also
References
- Hans Dobbertin, 1998. Cryptanalysis of MD4. J. Cryptology 11(4): 253–271
- Hans Dobbertin: Cryptanalysis of MD4. Fast Software Encryption 1996: 53–69
External links
- Description of MD4 by Ron Rivest in RFC 1320
- An Attack on the Last Two Rounds of MD4
- A collision attack on MD4 (Presented at Eurocrypt 2005. Requires about MD4 computations. Demonstrates "Theoretical Pre-image Attack on MD4" and "Second Pre-Image Attack for Weak Messages".)
- On the Security of Encryption Modes of MD4, MD5 and HAVAL ("MD4 can be broken by related-key boomerang attacks in real time. The attacks have been experimentally tested and run in milliseconds on a PC.")
- Improved Collision Attack on MD4 ("We were able to find collisions with probability almost 1, and the average complexity to find a collision is upper bounded by three times of MD4 hash operations.")
- Paj's Home: Cryptography — by Paj in JavaScript. Also supports MD5, and SHA-1. Released under the BSD License. Contains links to several other implementations.
MD4 computations. Demonstrates "Theoretical | Cryptographic hash functions and message authentication codes | |
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| Common functions | |
| SHA-3 finalists | |
| Other functions | |
| Password hashing/ key stretching functions | |
| General purpose key derivation functions |
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| MAC functions | |
| Authenticated encryption modes | |
| Attacks | |
| Design | |
| Standardization | |
| Utilization | |