Here’s all you want to know about AES Encryption, the Advanced Encryption Standard which implements symmetric cryptography by means Rijndael algorithm in key lengths of 128, 192 and 256 bits.
AES, short for Advanced Encryption Standard, is a widely adopted symmetric encryption scheme used, for instance, to secure electronic communication and messages. AES – as its name implies – has been the outcome of standardization and evaluation process which took years to select from the best encryption algorithms. Finally, in 2001, the Rijndael algorithm has been chosen as winner by the US National Institute of Standards and Technology (NIST) to be implemented as underlying security algorithm of the AES standard which as of the these days has largely replaced its predecessor and derivates of DES (Data Encryption Standard) which is longer considered secure due to its small 56-bit key length for example.
The Rijndael algorithm, invented by two cryptographers Vincent Rijmen and Joan Daemen, implements the mathematical operations substitution, transposition, as well as permutation to plaintext, the term used to describe input in the cryptography domain. The AES Advanced Encryption Standard uses 10 rounds of these algebraic operations in a complex scheme to produce encrypted output, or cipher text as it is called in expert terms. AES-192 and AES-256 have 12 and 14 rounds, respectively.
In the AES implementation of Rijndael the algorithm operates on 128 bits block ciphers, and comprises key lengths of 128, 192 and 256 bits. It is common to refer to the symmetric key AES encryption standard as AES-128, AES-192 and AES-256 depending on the key strength. More about encryption can also be found in Bright Hub’s article Types of Encryption which explains the difference between asymmetric and symmetric encryption also shedding a light on stream and block ciphers.
Whereas cryptography aims at securing plain text does cryptanalysis try to break the key or underlying algorithm of an encryption scheme, Rijndael in the case of AES here. Cracking a 256-bit key is computationally infeasible but cryptanalysts who are aware of the inner working of Rijndael and who apply much more sophisticated methods than brute-force believe that the security margin is narrowing. Check out our article Can AES Encryption be Cracked? which takes into account the latest news about the security or strength of AES.
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