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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

Blowfish is symmetric block cipher encryption algorithm designed by the famous IT security technologist, BT Chief Security Technology Officer, and author Bruce ‘Almighty’ Schneier in 1993. The Blowfish encryption algorithm operates on 64-bit bit blocks of plaintext and supports variable key lengths ranging from 32 up to 448 bits; the default key length is 128 bits.

The technicalities of the Blowfish algorithm are quite complex and involve Feistel ciphers using large key-dependent S-boxes. As there is no successful cryptanalysis attacks known a Blowfish secured message can only be cracked using brute-force. This, in turn, can be prevented by using 256-bit keys for example.

Please find in Bright Hub’s article Can AES Encryption be Cracked? why attempts of cracking Blowfish used in conjunction with a reasonable lenght key by means of brute force can be ruled out (The underlying maths principles have been translated in easy-to-understand language).

The benefits of Blowfish include that the algorithm is unpatented and royalty-free, without any licensing requirements. The same is true for Twofish, an AES finalists designed by Schneier et al’s Counterpane Labs, gradually replacing Blowfish encryption. Twofish, first published in 1998, is a symmetric key block cipher algorithm using a block size of 128 bits .

Twofish uses key lengths of 128 bit, 192 bit or 256-bit. The Twofish algorithm is similar to the Blowfish algorithm and applies 16 rounds of encryption to 64-bit bit blocks plaintext input. More about block ciphers and stream ciphers can be found in Bright Hub’s article Types of Encryption.

Depending on on the key length as well as whether Twofish is used for hardware based or software based encryption Twofish may outperform AES in terms of speed. Many people believe Rijndael has just become more popular than Twofish because it received more attention since it was chosen for Advanced Encryption Standard (AES) by NIST in 2001.