Secret key Algorithms in Cryptography
Secret key algorithms are also known as symmetric key as well as shared-key algorithms. A secret key is shared between sender and receiver and the usual key size is 80–256 bits. DES, 3DES, AES, IDEA, RC2/4/5/6, and Blowfish are some of the symmetric key algorithms. These types of algorithms are much faster because it contains simple mathematical operations. Key is used to encrypt and decrypt data. This pre-shared key is known prior to the data transfers between sender and receiver when the key is shorter it executes faster. Symmetric ciphers can be divided as block and stream ciphers where block type encrypts data blockwise and stream ciphers encrypts in a pace data is transmitted. DES, AES, RSA are some block ciphers and A5, RC4 can be considered as stream ciphers.
DES (Data Encryption Standard) symmetric encryption
DES key length is 56bits and has a medium speed to encrypt and decrypt data which also has medium resource consumption. When DES is in ECB mode if the same block is encrypted twice the ciphertext is also the same. It’s a disadvantage because similar texts can be identified easily. But when in CBC mode it uses the previously encrypted block to encrypt new one, so it does not give out the same ciphertext for the same text. DES includes stream cipher modes as CFB (Cipher Feedback) and OFB (Output feedback).
3DES
Among DES type ciphers 3DES is the strongest algorithm because it has a higher security strength where data is encrypted in a sequence manner, for example, Encrypts, Decrypts, Encrypts which can use same or different keys for each step. Key size is also as big as 168 bits, but speed is low.
AES (Advanced Encryption Standard)
This encryption algorithm is developed based on the Rijndael algorithm which uses key length up to 256 bits. In addition, it is faster, more efficient and also suitable for high-throughput low latency environments but its very young algorithm comparing to DES.
RC Algorithms
RC algorithms are widely used in networking applications because of its speed and variable key length capabilities. RC has many types like RC2, RC4, RC5, and RC6. RC4 is a stream cipher while all others are block ciphers which have different kinds of key lengths.
