Drand voting dapp

src/contracts/voting/Scarb.toml

@@ -0,0 +1,15 @@
+[package]
+name = "voting"
+version = "0.1.0"
+edition = "2024_07"
+
+[dependencies]
+garaga = { path = "../.." }
+starknet = "2.8.2"
+
+[cairo]
+sierra-replace-ids = false
+
+[[target.starknet-contract]]
+casm = true
+casm-add-pythonic-hints = true

src/contracts/voting/src/drand_verifier.cairo

@@ -0,0 +1,60 @@
+use super::drand_verifier_constants::{G2_GEN, precomputed_lines};
+
+#[starknet::interface]
+trait IDrandQuicknet<TContractState> {
+    fn verify_round_and_get_randomness(
+        ref self: TContractState, full_proof_with_hints: Span<felt252>,
+    ) -> Option<felt252>;
+}
+
+#[starknet::contract]
+mod DrandQuicknet {
+    // use starknet::SyscallResultTrait;
+    use garaga::definitions::{G1Point, G1G2Pair};
+    use garaga::pairing_check::{multi_pairing_check_bls12_381_2P_2F, MPCheckHintBLS12_381};
+    // use garaga::ec_ops::{G1PointTrait, G2PointTrait};
+    use garaga::utils::drand::{
+        round_to_curve_bls12_381, DRAND_QUICKNET_PUBLIC_KEY, HashToCurveHint
+    };
+    use super::{precomputed_lines, G2_GEN};
+    use garaga::utils::hashing::hash_G1Point;
+
+    // const ECIP_OPS_CLASS_HASH: felt252 =
+    //     0x7918f484291eb154e13d0e43ba6403e62dc1f5fbb3a191d868e2e37359f8713;
+    // use starknet::ContractAddress;
+
+    #[storage]
+    struct Storage {}
+
+    #[derive(Drop, Serde)]
+    struct DrandHint {
+        round_number: u64,
+        signature: G1Point,
+        hash_to_curve_hint: HashToCurveHint,
+        mpcheck_hint: MPCheckHintBLS12_381,
+    }
+    #[abi(embed_v0)]
+    impl IDrandQuicknet of super::IDrandQuicknet<ContractState> {
+        fn verify_round_and_get_randomness(
+            ref self: ContractState, mut full_proof_with_hints: Span<felt252>,
+        ) -> Option<felt252> {
+            let drand_hint: DrandHint = Serde::deserialize(ref full_proof_with_hints).unwrap();
+            let message = round_to_curve_bls12_381(
+                drand_hint.round_number, drand_hint.hash_to_curve_hint
+            );
+
+            let check = multi_pairing_check_bls12_381_2P_2F(
+                pair0: G1G2Pair { p: drand_hint.signature, q: G2_GEN },
+                pair1: G1G2Pair { p: message, q: DRAND_QUICKNET_PUBLIC_KEY },
+                lines: precomputed_lines.span(),
+                hint: drand_hint.mpcheck_hint,
+            );
+
+            match check {
+                true => Option::Some(hash_G1Point(message)),
+                false => Option::None,
+            }
+        }
+    }
+}
+