# Why does the SRP6 calculation of B included a multiplier k = 3?

In SRP6 $B$ is calculated as $B=kv+ g^b, k=3$. What is the purpose of $k$, and why was it fixed as $3$?

(In SRP 6b, this value $3$ is replaced by $k = H(N,g)$, but this question is about SRP 6.)

-

## migrated from security.stackexchange.comFeb 12 '13 at 9:23

This question came from our site for Information security professionals.

–  CodesInChaos Feb 12 '13 at 9:48
Are you talking about SRP-6 or SRP-6a? It seems like 6a doesn't use k=3 like you claim. –  CodesInChaos Feb 12 '13 at 9:59
Sorry my mistake SRP6 using k = 3, in SRP6a using k –  user236501 Feb 12 '13 at 11:02
I edited the question to be more clear – please check that it still fits to your actual question. For SRP 6a, please refer to the question linked by ChodesInChaos. –  Paŭlo Ebermann Feb 12 '13 at 20:03
Yes, I did went through the post already, but still don't quite get the answer. –  user236501 Feb 13 '13 at 4:47