Editing RC4 (section)

===Key-scheduling algorithm (KSA)===
The [[Key schedule|key-scheduling]] algorithm is used to initialize the permutation in the array "S". "keylength" is defined as the number of bytes in the key and can be in the range 1 ≤ keylength ≤ 256, typically between 5 and 16, corresponding to a [[key length]] of 40–128&nbsp;bits. First, the array "S" is initialized to the [[identity permutation]]. S is then processed for 256 iterations in a similar way to the main PRGA, but also mixes in bytes of the key at the same time.

 '''for''' i '''from''' 0 '''to''' 255
     S[i] := i
 '''endfor'''
 j := 0
 '''for''' i '''from''' 0 '''to''' 255
     j := (j + S[i] + key[i [[modulo operation|mod]] keylength]) mod 256
     swap values of S[i] and S[j]
 '''endfor'''