Key Schedule for RC6

Input: User-supplied b byte key preloaded into the c - word array L[0,…,c-1]

Number r of rounds

Output: w-bit round keys S[0,…,2r + 3]

Procedure: S[0]=Pw

for i=1 to 2r+3 do

S[i]=S[i-1]+Qw

A=B=i=j=0

v=3 ? max{c, 2r+4}

for s=1 to v do

{

A=S[i]=(S[i]+A+B)<<ɛ

B=L[j]=(L[j]+A+B)<<<(A+B)

i=(i+1) mod (2r+4)

j=(j+1) mod c

}

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