add drand precompile

contract-tests/src/contracts/drand.ts

@@ -0,0 +1,37 @@
+// Drand precompile address: 0x80e = 2062
+export const IDRAND_ADDRESS = "0x000000000000000000000000000000000000080e";
+
+export const IDrandABI = [
+    {
+        inputs: [
+            {
+                internalType: "uint64",
+                name: "round",
+                type: "uint64",
+            },
+        ],
+        name: "getRandomness",
+        outputs: [
+            {
+                internalType: "bytes32",
+                name: "",
+                type: "bytes32",
+            },
+        ],
+        stateMutability: "view",
+        type: "function",
+    },
+    {
+        inputs: [],
+        name: "getLastStoredRound",
+        outputs: [
+            {
+                internalType: "uint64",
+                name: "",
+                type: "uint64",
+            },
+        ],
+        stateMutability: "view",
+        type: "function",
+    },
+] as const;

contract-tests/test/drand.precompile.test.ts

@@ -0,0 +1,98 @@
+import * as assert from "assert";
+
+import { getDevnetApi } from "../src/substrate";
+import { getPublicClient } from "../src/utils";
+import { ETH_LOCAL_URL } from "../src/config";
+import { devnet } from "@polkadot-api/descriptors";
+import { PublicClient } from "viem";
+import { TypedApi } from "polkadot-api";
+import { toViemAddress } from "../src/address-utils";
+import { IDrandABI, IDRAND_ADDRESS } from "../src/contracts/drand";
+
+describe("Test Drand Precompile", () => {
+    let publicClient: PublicClient;
+    let api: TypedApi<typeof devnet>;
+
+    before(async () => {
+        publicClient = await getPublicClient(ETH_LOCAL_URL);
+        api = await getDevnetApi();
+    });
+
+    describe("Drand Randomness Functions", () => {
+        it("getLastStoredRound returns a value", async () => {
+            const lastRound = await publicClient.readContract({
+                abi: IDrandABI,
+                address: toViemAddress(IDRAND_ADDRESS),
+                functionName: "getLastStoredRound",
+                args: [],
+            });
+
+            const lastRoundFromApi = await api.query.Drand.LastStoredRound.getValue({ at: "best" });
+
+            assert.ok(lastRound !== undefined, "getLastStoredRound should return a value");
+            assert.strictEqual(
+                typeof lastRound,
+                "bigint",
+                "getLastStoredRound should return a bigint"
+            );
+            assert.ok(lastRound === lastRoundFromApi, "Last stored round should match the value from the API");
+        });
+
+        it("getRandomness returns bytes32 for a round", async () => {
+            const lastRound = await publicClient.readContract({
+                abi: IDrandABI,
+                address: toViemAddress(IDRAND_ADDRESS),
+                functionName: "getLastStoredRound",
+                args: [],
+            });
+
+            const randomness = await publicClient.readContract({
+                abi: IDrandABI,
+                address: toViemAddress(IDRAND_ADDRESS),
+                functionName: "getRandomness",
+                args: [lastRound],
+            });
+
+            const pulseFromApi = await api.query.Drand.Pulses.getValue(lastRound, { at: "best" });
+            const randomnessFromApi = pulseFromApi?.randomness.asHex();
+
+            assert.ok(randomness !== undefined, "getRandomness should return a value");
+            assert.strictEqual(
+                typeof randomness,
+                "string",
+                "getRandomness should return a hex string (bytes32)"
+            );
+            assert.strictEqual(
+                randomness.length,
+                66,
+                "bytes32 should be 0x + 64 hex chars"
+            );
+            assert.strictEqual(
+                randomness,
+                randomnessFromApi,
+                "Randomness should match the value from the API"
+            );
+        });
+
+        it("getRandomness for non-existent round returns zero bytes", async () => {
+            // Use a very high round number that will not have a stored pulse
+            const nonExistentRound = BigInt(999999999);
+            const randomness = await publicClient.readContract({
+                abi: IDrandABI,
+                address: toViemAddress(IDRAND_ADDRESS),
+                functionName: "getRandomness",
+                args: [nonExistentRound],
+            });
+
+            console.log("randomness", randomness);
+
+            assert.ok(randomness !== undefined, "getRandomness should return a value");
+            const zeroBytes32 = "0x" + "0".repeat(64);
+            assert.strictEqual(
+                randomness.toLowerCase(),
+                zeroBytes32,
+                "getRandomness for non-existent round should return zero bytes32"
+            );
+        });
+    });
+});

pallets/admin-utils/src/lib.rs

@@ -147,6 +147,8 @@ pub mod pallet {
         AddressMapping,
         /// Voting power precompile
         VotingPower,
+        /// Drand randomness precompile
+        Drand,
     }
 
     #[pallet::type_value]

precompiles/Cargo.toml

@@ -39,6 +39,7 @@ pallet-admin-utils.workspace = true
 subtensor-swap-interface.workspace = true
 pallet-crowdloan.workspace = true
 pallet-shield.workspace = true
+pallet-drand.workspace = true
 
 [lints]
 workspace = true
@@ -65,6 +66,7 @@ std = [
 	"pallet-subtensor-swap/std",
 	"pallet-subtensor/std",
 	"pallet-shield/std",
+	"pallet-drand/std",
 	"precompile-utils/std",
 	"scale-info/std",
 	"sp-core/std",

precompiles/src/drand.rs

@@ -0,0 +1,57 @@
+use core::marker::PhantomData;
+
+use fp_evm::PrecompileHandle;
+use precompile_utils::EvmResult;
+use sp_core::H256;
+
+use crate::PrecompileExt;
+
+/// Drand precompile for smart contract access to Drand beacon randomness.
+///
+/// This precompile allows smart contracts to read verifiable randomness from the
+/// Drand Quicknet beacon that is bridged on-chain by the Drand pallet.
+pub struct DrandPrecompile<R>(PhantomData<R>);
+
+impl<R> PrecompileExt<R::AccountId> for DrandPrecompile<R>
+where
+    R: frame_system::Config + pallet_drand::Config,
+    R::AccountId: From<[u8; 32]>,
+{
+    const INDEX: u64 = 2062;
+}
+
+#[precompile_utils::precompile]
+impl<R> DrandPrecompile<R>
+where
+    R: frame_system::Config + pallet_drand::Config,
+    R::AccountId: From<[u8; 32]>,
+{
+    /// Get the 32-byte randomness for a specific Drand round.
+    ///
+    /// Returns the SHA256 hash of the BLS signature for the given round.
+    /// Returns 32 zero bytes if no pulse exists for the round.
+    ///
+    /// # Arguments
+    /// * `round` - The Drand round number (u64)
+    ///
+    /// # Returns
+    /// * `bytes32` - The 32-byte randomness, or zeros if round not stored
+    #[precompile::public("getRandomness(uint64)")]
+    #[precompile::view]
+    fn get_randomness(_: &mut impl PrecompileHandle, round: u64) -> EvmResult<H256> {
+        let randomness = pallet_drand::Pallet::<R>::random_at(round);
+        Ok(H256::from(randomness))
+    }
+
+    /// Get the last Drand round that has been stored on-chain.
+    ///
+    /// Returns 0 if no pulses have been stored yet.
+    ///
+    /// # Returns
+    /// * `uint64` - The last stored round number
+    #[precompile::public("getLastStoredRound()")]
+    #[precompile::view]
+    fn get_last_stored_round(_: &mut impl PrecompileHandle) -> EvmResult<u64> {
+        Ok(pallet_drand::LastStoredRound::<R>::get())
+    }
+}

precompiles/src/lib.rs

@@ -31,6 +31,7 @@ pub use address_mapping::AddressMappingPrecompile;
 pub use alpha::AlphaPrecompile;
 pub use balance_transfer::BalanceTransferPrecompile;
 pub use crowdloan::CrowdloanPrecompile;
+pub use drand::DrandPrecompile;
 pub use ed25519::Ed25519Verify;
 pub use extensions::PrecompileExt;
 pub use leasing::LeasingPrecompile;
@@ -48,6 +49,7 @@ mod address_mapping;
 mod alpha;
 mod balance_transfer;
 mod crowdloan;
+mod drand;
 mod ed25519;
 mod extensions;
 mod leasing;
@@ -75,6 +77,7 @@ where
         + pallet_crowdloan::Config
         + pallet_shield::Config
         + pallet_subtensor_proxy::Config
+        + pallet_drand::Config
         + Send
         + Sync
         + scale_info::TypeInfo,
@@ -112,6 +115,7 @@ where
         + pallet_crowdloan::Config
         + pallet_shield::Config
         + pallet_subtensor_proxy::Config
+        + pallet_drand::Config
         + Send
         + Sync
         + scale_info::TypeInfo,
@@ -136,7 +140,7 @@ where
         Self(Default::default())
     }
 
-    pub fn used_addresses() -> [H160; 27] {
+    pub fn used_addresses() -> [H160; 28] {
         [
             hash(1),
             hash(2),
@@ -165,6 +169,7 @@ where
             hash(VotingPowerPrecompile::<R>::INDEX),
             hash(ProxyPrecompile::<R>::INDEX),
             hash(AddressMappingPrecompile::<R>::INDEX),
+            hash(DrandPrecompile::<R>::INDEX),
         ]
     }
 }
@@ -180,6 +185,7 @@ where
         + pallet_crowdloan::Config
         + pallet_shield::Config
         + pallet_subtensor_proxy::Config
+        + pallet_drand::Config
         + Send
         + Sync
         + scale_info::TypeInfo,
@@ -273,6 +279,9 @@ where
                     PrecompileEnum::AddressMapping,
                 )
             }
+            a if a == hash(DrandPrecompile::<R>::INDEX) => {
+                DrandPrecompile::<R>::try_execute::<R>(handle, PrecompileEnum::Drand)
+            }
             _ => None,
         }
     }

runtime/src/lib.rs

@@ -243,7 +243,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
     //   `spec_version`, and `authoring_version` are the same between Wasm and native.
     // This value is set to 100 to notify Polkadot-JS App (https://polkadot.js.org/apps) to use
     //   the compatible custom types.
-    spec_version: 380,
+    spec_version: 381,
     impl_version: 1,
     apis: RUNTIME_API_VERSIONS,
     transaction_version: 1,