!!! Overview
[{$pagename}] is a [Symmetric Key] [cipher] where [plaintext] digits are combined with a [Pseudorandom] [Cipher] digit stream (keystream). 

[{$pagename}] is also known as [State Cipher]. 

[{$pagename}] has each [plaintext] digit is [encrypted|Encryption] one at a time with the corresponding digit of the keystream, to give a digit of the [ciphertext] stream. Since [encryption] of each digit is dependent on the current state of the cipher.

In practice, a digit is typically a [bit] and the combining operation an exclusive-or ([Bitwise XOR]).

The pseudorandom keystream is typically generated serially from a random seed value using digital shift registers. The seed value serves as the [cryptographic] key for decrypting the ciphertext stream. 

[{$pagename}] represent a different approach to symmetric encryption from [Block Ciphers]. 

[{$pagename}] typically execute at a higher speed than [Block Ciphers] and have lower hardware complexity. 

[{$pagename}] can be susceptible to serious security problems if used incorrectly, in particular, the same starting state (seed) must never be used twice.

!! More Information
There might be more information for this subject on one of the following:
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* [#1] - [Stream_cipher|Wikipedia:Stream_cipher|target='_blank'] - based on information obtained 2017-02-24-