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Can AES Encryption be Cracked?

Apart from social engineering exist two ways to break an encryption key like AES, brute force and cryptanalysis. Find out here whether AES encryption can be cracked any time soon, along with the latest AES development and recommendations from IT security evangelist Bruce Schneier.

Besides social engineering exist two ways to break any encryption key, brute force and cryptanalysis. After the introduction we look at why AES and similar encryption schemes are secure against brute-force attacks using computer power to crack a key. Then you will find the latest development from the studies of AES by means of cryptanalysis. If you are not familiar with encryption it is recommended reading Bright Hub’s article What is AES Encryption? and Types of Encryption.

Brute Force

Mathematicians have discovered that any positive integer greater than one can be expressed as the product of its prime factors; the prime decomposition of the number 22 for instance is 2 x 11. There are a number of algorithms for integer factorization, but the difficulty and complexity to find the prime factor increases at the last sub-exponentially with the size of the integer.

This essentially means that the prime decomposition of large numbers is computationally infeasible with traditional computers. As the strongest encryption algorithms in use today, such as, for instance, Rijndael, which has become the Advanced Encryption Standard (AES), employ large integer factorization, AES in unbreakable – again with the premise of traditional computers in mind.

A quantum computer operating on qubits instead of bits offer polynomial speed for some computing problems including Integer factorization, so that taking into account Cobham’s thesis we know that the traditional encryption algorithm keys can be feasibly computed. Therefore, when quantum computing gets out of the lab will ciphertext produced by traditional cryptography no longer be secure.

Cryptanalysis

The Advanced Encryption Standard can be used with 256-bit keys, immune against Moore’s Law for the years to come. However, cryptanalysts studying the inner working of an algorithm are constantly trying to find a weakness in the encryptions algorithms or to break it. Most “vulnerabilities” are usually of rather theoretical nature, so there is nothing to worry about for an ordinary computer user as the subject is being watched and followed by the IT security community which has been trying to crack publicly documented encryption schemes including AES for years.

Yet, it was only recently when Bruce Schneier, the inventor of Twofish and Blowfish AES competitors stipulated “that the safety margin of AES is much less than previously believed [1].” Schneier demands that AES implements more round of Rijndael for any key length “and for new applications I suggest that people don’t use AES-256. AES-128 provides more than enough security margin for the foreseeable future


The Blowfish Encryption Algorithm

DES is the workhorse of cryptography algorithms, and it’s long past time to replace the 19-year-old standard. The recent design of a $1M machine that could recover a DES key in 3.5 hours only confirmed what everybody knew: DES’s key size is far too small for today.

The world only partly trusted DES because it survived the scrutiny of the NSA. Experts trusted DES because it was a published standard, and because it survived 20 years of intensive cryptanalysis by cryptographers around the world. Cryptography is like that: confidence in an algorithm grows as group after group tries to break it and fails.

Candidates for a replacement are emerging, but none has taken widespread hold. Triple-DES is the conservative approach; IDEA (used in PGP) is the most promising new algorithm. And there is a bevy of unpatented also-rans: RC4 (once a trade secret of RSA Data Security, Inc. but now publicly available on the Internet), SAFER, and my own Blowfish.

I first presented Blowfish at the Cambridge Algorithms Workshop (“Description of a New Variable-Length Key, 64-bit Block Cipher (Blowfish),” Fast Software Encryption, R. Anderson, ed., Lecture Notes in Computer Science #809, Springer-Verlag, 1994) and in Dr. Dobb’s Journal (April 1994). From the start Blowfish was intended to be a completely free–unpatented, unlicensed, and uncopyrighted–alternative to DES. Since then it has been analyzed by some people and has started to see use in some systems, both public and private. This article presents new Blowfish code, as well as updates on the algorithm’s security.