Adding Zero Knowledge Proof Semaphore contract

[iam-dev]

What is Semaphore:
The privacy in Semaphore is created by introducing a larger set of identities called “identity commitments,” which are hashes of a secret string, and comparable to a traditional public key. This set is represented as a Merkle tree in order to allow anyone in the set to efficiently prove membership. However, because this Merkle proof would leak an individual member’s identity, the proof needs to be verified in zero knowledge. This zero knowledge proof (ZKP) can then be transmitted to prove membership without leaking the identity, and be verified by anyone.

Semaphore fundamentally has two main parts to it: a set of identities and a mechanism to prove membership. Users can create a zero knowledge proof that simultaneously proves three important claims:

Membership “I am a member of the set.”
One-shot “I have not made a claim before in this context.”
Signal “I want to say this ....”

Semaphore docs
Example code