Pseudo-random number

A pseudo-random number is a number belonging to a sequence which appears to be random, but is in fact generated by a deterministic algorithm. They are used extensively in computer science in places where "randomness" is essential to some application, but the use of hardware random number generators is impractical or not desirable. See Random number for more on the history of random and pseudorandom numbers.

The qualities which are required of a pseudo-random sequence of (binary) digits -- if it is to be used in any application where apparent randomness is important -- are as follows:

• the 2ⁿ different patterns of n successive digits should each occur about as often as each other
• sequences of n(>1) 0s should occur about half as often as sequences of n-1 0s, and about as often as n 1s

Various examples of pseudorandom number generators exist, such as linear congruential generators, inversive generators PN Sequences etc.

See also

• Pseudo-random binary sequence

• Pseudorandom number generator

• PN Sequences

External links

• Using and Creating Cryptographic-Quality Random Numbers