For more info on a specific newsletter, click the title. Details will be displayed in a new window.
Subscribe to
Computerworld 40 years of the most authoritative source of news and information for IT leaders.
Opinion: Cryptanalysis of MD5 and SHA: Time for a new standard
or
Other Security Stories
|
|
|
|
August 19, 2004 (Computerworld) -- At the Crypto 2004 conference in Santa Barbara, Calif., this week, researchers announced several weaknesses in common hash functions. These results, while mathematically significant, aren't cause for alarm. But even so, it's probably time for the cryptography community to get together and create a new hash standard.
One-way hash functions are a cryptographic construct used in many applications. They are used with public-key algorithms for both encryption and digital signatures. They are used in integrity checking. They are used in authentication. They have all sorts of applications in a great many different protocols. Much more than encryption algorithms, one-way hash functions are the workhorses of modern cryptography.
In 1990, Ron Rivest invented the hash function MD4. In 1992, he improved on MD4 and developed another hash function: MD5. In 1993, the National Security Agency published a hash function very similar to MD5, called the Secure Hash Algorithm (SHA). Then in 1995, citing a newly discovered weakness that it refused to elaborate on, the NSA made a change to SHA. The new algorithm was called SHA-1. Today, the most popular hash function is SHA-1, with MD5 still being used in older applications.
One-way hash functions are supposed to have two properties. One, they're one-way. This means that it's easy to take a message and compute the hash value, but it's impossible to take a hash value and re-create the original message. (By "impossible," I mean "can't be done in any reasonable amount of time.") Two, they're collision-free. This means that it's impossible to find two messages that hash to the same hash value. The cryptographic reasoning behind these two properties is subtle, and I invite curious readers to learn more in my book Applied Cryptography.
Breaking a hash function means showing that either -- or both -- of those properties aren't true. Cryptanalysis of the MD4 family of hash functions has proceeded in fits and starts over the past decade or so, with results against simplified versions of the algorithms and partial results against the whole algorithms.
This year, Eli Biham and Rafi Chen, and separately Antoine Joux, announced some pretty impressive cryptographic results against MD5 and SHA. Collisions have been demonstrated in SHA. And there are rumors, unconfirmed at this writing, of results against SHA-1.
The magnitude of these results depends on who you are. If you're a cryptographer, this is a huge deal.
|
Print this Story |
|
Send Us Feedback |
|
E-mail this Story |
|
Digg this Story |
|
Slashdot this Story |
|
|
|
|
|
 |
|
All Zones Application Performance Zone Business Continuity Zone Data Center Management Zone Enterprise-Class Security Zone The File Data Management Zone Grid Computing on Windows Zone Security Management Zone ITIL Best Practices Zone The SAS Zone Storage Virtualization Zone Business Intelligence and Analytics Zone |
 See your link here
|
 |
||||||||
| ||||||||
| ||||||||
| ||||||||
|
Why SaaS is Vital to Email and Web Security
Download this Executive Bulletin (a $49.95 value) for free, compliments of MessageLabs.
Get this white paper now!
Read up on the latest ideas and technologies from companies that sell hardware, software and services.
- Google gives away home-cooked Web application security scanner
- Microsoft trumpets security additions in upcoming IE8
- Apple cuts price of high-end SSD MacBook Air by $500
- More top stories
Security Management ZoneSecurity management is the process of developing a comprehensive data protection plan. It takes into account all potential threats, the existing network environment, the future needs of the organization, and lays out a multi-tiered blueprint to integrate the security technology needed to combat these threats. CDW can help keep your network and data secure. Visit the CDW Security Management Zone now See All Zones
|
 Fired up about IT? Join Sharkbait and share your true tales of IT. SharkBait is the place for you to sound off about everything IT – the good, the bad, and the rest of the weird stuff you deal with every day.New baits 
|
"Security Directions" virtual trade show2008's Code-Red Security Issues for Protecting the EnterpriseWebcasts, white papers, demos, and more. Presented in a unique 3-d environment. Enter our show right now! Click here to enter
|
 In SecuritySecurity's important, and risk must be addressed, right? Sure, but watch for four signs your policies go a bit overboard. Click here to read the latest column by Jon Espenschied |
|
|