What are the popular examples of Block Cipher?

There are some popular examples of Block Cipher which are as follows −

The CAST Block Cipher − The CAST Block Cipher is an advancement of the DES block cipher, introduced in Canada by Carlisle Adams and Stafford Tavares. The name of the cipher appear to be after the initials of the inventors. The CAST algorithm has 64 bit block size and has a key of size 64 bits.

CAST is based on the Feistel structure to perform the substitution permutation network. The authors defines that they need the Feistel mechanism, as it is well considered and free of basic structural weaknesses.

Blowfish − Blowfish is a 64-bit block cipher introduced by Bruce Schneier. Blowfish was designed for quick ciphering on 32-bit microprocessors. Blowfish is also solid and has a variable key length which can be enhanced to 448 bits.

Blowfish is accessible for applications where the key does not modify generally like communication links or file encryptor. However for software like packet switching or as a one-way hash function, it is not proper.

Blowfish is not perfect for smart cards, which needed even more compact ciphers. Blowfish is quicker than DES when performed on 32-bit microprocessors.

IDEA − IDEA stands for International Data Encryption Algorithm. It is another block cipher. It works on 64 bit data blocks and the key is 128 bit long. It was introduced by Xuejia Lai and James Massey, and named IDEA in 1990, after changing and enhancing the original proposal of the cipher based on the seminal work on Differential cryptanalysis by Biham and Shamir.

The design principle behind IDEA is the combining of arithmetical operations from different algebraic sets. These arithmetical operations are simply performed both in hardware and software.

IDEA has a very simple key scheduling. It creates the 128 bit key and divides it into eight 16 bit blocks. The first six blocks are utilized for the first round, while the remaining two are to be utilized for the second round. Thus the whole 128 bit key is given a rotation for 25 steps to the left and again divided into eight blocks.

The first four blocks are utilized as the remaining subkeys for the second round, while the last four blocks are to be utilized for the third round. The key is given a left shift by 25 bits, and the another subkeys are acquired. The procedure is continued till the end of the algorithm.

RC5 − RC5 was invented by Ron Rivest. It is a block encryption algorithm depends on the symmetric key. The main feature of this it is quite fast as it needs only primitive computer operations. It enables a variable number of rounds and variable bit size key to insert flexibility.

Another benefit of using RC5 is that it needed less memory for implementation. This feature allows RC 5 to be used for several purposes such as desktop operation, smart cards, etc.