Pseudorandom bit generators in stream-cipher cryptography

Progress in the design and analysis of pseudorandom bit generators over the last decade is surveyed. Background information is provided, and the linear feedback shift registers that serve as building blocks for constructing the generators are examined. Three methods for attacking keystream generators are reviewed, and three techniques for designing them are considered, focusing on how they fail or how their weakness is exposed under the attacks previously described. These techniques are nonlinear feedforward transformation, step control, and multiclocking.< >