Add generator in G1 in BlindSign

[alessandroguggino]

From the BlindSign function:

bbs-signature/draft-blind-bbs-signatures.md

Line 175 in 506d70c

6. b = commitment + h0 \* s'' + h\[j1\] \* msg\[1\] + ... + h\[jK\] \* msg\[K\]

We should add P1, the generator point in G1, in order to make a valid signature after the unblinding:
b = commitment + P1 + h0 * s'' + h[j1] * msg[1] + ... + h[jK] * msg[K]

If you agree with me I will open a pull request where I will change b as proposed and add P1's definition into the Terminology section.

[BasileiosKal]

Yeap! That makes sense to me.

[alessandroguggino]

I have seen that in the main draft P1 is defined in Notation instead of Terminology. But there is no Notation section. May I add it and modify the structure of the document following the one of the main draft?
This is related to issue #90.
Otherwise, I just change the calculation of b for now.

[tplooker]

Yes @alessandroguggino as documented in #90 feel free to update it for consistency. I would suggest instead of duplicating the terminology you could just reference the core draft?