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Here all you want to know symmetric encryption and asymmetric encryption, the fundamental types of encryption schemes. This article also features stream ciphers, blocks ciphers and, for instance, sheds a light on Public Key Cryptography.

An encryption algorithm is mathematical operation where plaintext is transformed to so called ciphertext, unintelligible to anyone who doesn’t know the secret key to decrypt it. Encryption algorithms have their roots in the Greek history, and until the advent of computing have encrypted messages been the domain of the military and erudites. These days encryption is also used for secure online banking, digital rights management, protecting health data and email exchange such as by PGP for example.

Encryption algorithms are called symmetric when the same secret, password or key is used to encrypt and to decrypt. Shared secret algorithms either operate on a bit bases (stream ciphers) or encrypt chunk of bites (block ciphers). Encryption algorithms which use a different key for decryption and encryption are called asymmetric and have some functional advantages over symmetric encryption which if fast, and can be secured by on-the-fly key generation and frequent key changes.

The downside of symmetric encryption is that anyone who knows the secret key or password can transform the secret cipher text to plaintext. This makes symmetric encryption vulnerable to leaking, and spying out passwords. A famous example of symmetric encryption used to be DES (Data Encryption Standard) which is no longer in wide use. DES and its variants have now largely been replaced with Advanced Encryption Standard (AES) which uses a 128, 192, or 256 bit key. The longer the key the more secure the message is in general (“theoretically stronger”).

Asymmetric encryption on the other hand employs a different key for decryption and encryptions by so called public key encryption in which anyone can get the public key of the recipient to encrypt files or messages so that only the holder of the private key of the public-private key pair can open the item. In a similar operation can the holder of the private key sign messages so that anyone can check message authenticity. RSA ( Rivest, Shamir and Adleman) is the de-facto standard algorithm public key encryption algorithm. The downside of public key encryption is that asymmetric encryption usually is much slower and needs more computing power than shared secret encryption.

When have been discussing types of encryption in terms of symmetry, which is common. Another way to classify encryption algorithms is differentiating in secure and non-secure encryption. Secure encryption algorithms are those whose inner workings have been made known to the public such as, for example AES whilst until recently perhaps no-one has discovered a flaw in the algorithm or was able to break it (In contrast are secret encryption schemes usually considered not to be secure. Rather, people speak of security through obscurity). save money at fast cash

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.