[zk-token-sdk] Potential for a malicious prover to generate proofs over MAX_COMMITEMNTS (ottersec #7)

[samkim-crypto]

Problem

In Batched range proofs u64/u128/u256 the MaxCommitments are checked using if statement while creating a proof but not included in proof, which leads dishonest prover to prove a crafted proof which has over or greater than MaxCommitments by a verifier. The verifier needs to ensure the length of bit_lengths is less than MaxCommitments.

Proposed Solution

Add a check to verify bit_lengths in range proof verification.