Stream of Ciphers

Question

Name some of the Other Stream of Ciphers which is existed.

Answer 1

There are the huge numbers of alternative stream ciphers which have been proposed in cryptographic literature as well as an evenly huge number which appear in implementations and products universally. Many are based on the employ of LFSRs since such ciphers tend to be more amenable to analysis and it is easier to assess the security that they offer.

Rueppel recommends that there are fundamentally four distinct approaches to the stream cipher design. The first is termed the information-theoretic approach as described by Shannon's analysis of one-time pad. The second approach is that of system-theoretic design. In essence, the cryptographer designs the cipher along established guidelines which make sure that cipher is resistant to all recognized attacks. While there is, evidently, no substantial guarantee which future cryptanalysis will be unsuccessful, it is this design approach which is conceivably the most common in cipher design. The third approach is to attempt to relate the complexity of breaking the stream cipher (where "breaking" means being capable to expect the unnoticed keystream with a success rate better than can be accomplished by guessing) to solving some tricky problem. This complexity-theoretic approach is extremely appealing, however in practice the ciphers that have been developed tend to be rather slow and impractical. The final approach highlighted through Rueppel is that of designing the randomized cipher. Here the aim is to make sure that the cipher is resistant to any practical amount.