use JIP5 secret key seed derivation (#343)

Author: qiweiii

Blockchain/Sources/Blockchain/Validator/DevKeyStore.swift

@@ -32,31 +32,20 @@ public final class DevKeyStore: KeyStore {
     }
 
     public static func getDevKey(seed: UInt32) throws -> KeySet {
-        var seedData = Data(repeating: 0, count: 32)
-        let seedByte = seed.encode()
-        for i in 0 ..< 8 {
-            seedData[i * 4 ..< (i + 1) * 4] = seedByte
-        }
-        let seedData32 = Data32(seedData)!
-        let bandersnatch = try Bandersnatch.SecretKey(from: seedData32)
-        let ed25519 = try Ed25519.SecretKey(from: seedData32)
-        let bls = try BLS.SecretKey(from: seedData32)
+        let trivialSeed = JIP5SeedDerive.trivialSeed(seed)
+        let derivedSeeds = JIP5SeedDerive.deriveKeySeeds(from: trivialSeed)
+
+        let bandersnatch = try Bandersnatch.SecretKey(from: derivedSeeds.bandersnatch)
+        let ed25519 = try Ed25519.SecretKey(from: derivedSeeds.ed25519)
+        let bls = try BLS.SecretKey(from: trivialSeed)
         return KeySet(bandersnatch: bandersnatch.publicKey, ed25519: ed25519.publicKey, bls: bls.publicKey)
     }
 }
 
 extension KeyStore {
     @discardableResult
     public func addDevKeys(seed: UInt32) async throws -> KeySet {
-        var seedData = Data(repeating: 0, count: 32)
-        let seedByte = seed.encode()
-        for i in 0 ..< 8 {
-            seedData[i * 4 ..< (i + 1) * 4] = seedByte
-        }
-        let seedData32 = Data32(seedData)!
-        let bandersnatch = try await add(Bandersnatch.self, seed: seedData32)
-        let ed25519 = try await add(Ed25519.self, seed: seedData32)
-        let bls = try await add(BLS.self, seed: seedData32)
-        return KeySet(bandersnatch: bandersnatch.publicKey, ed25519: ed25519.publicKey, bls: bls.publicKey)
+        let trivialSeed = JIP5SeedDerive.trivialSeed(seed)
+        return try await generateKeys(from: trivialSeed)
     }
 }

Blockchain/Sources/Blockchain/Validator/KeySet.swift

@@ -14,10 +14,13 @@ public struct KeySet: Codable, Sendable {
 }
 
 extension KeyStore {
-    public func generateKeys() async throws -> KeySet {
-        let bandersnatch = try await generate(Bandersnatch.self)
-        let ed25519 = try await generate(Ed25519.self)
-        let bls = try await generate(BLS.self)
+    public func generateKeys(from seed: Data32) async throws -> KeySet {
+        let derivedSeeds = JIP5SeedDerive.deriveKeySeeds(from: seed)
+
+        let bandersnatch = try await add(Bandersnatch.self, seed: derivedSeeds.bandersnatch)
+        let ed25519 = try await add(Ed25519.self, seed: derivedSeeds.ed25519)
+        let bls = try await add(BLS.self, seed: seed)
+
         return KeySet(bandersnatch: bandersnatch.publicKey, ed25519: ed25519.publicKey, bls: bls.publicKey)
     }
 

Utils/Sources/Utils/Crypto/JIP5SeedDerive.swift

@@ -0,0 +1,38 @@
+import Foundation
+
+/// This module implements the standard method for deriving validator secret key seeds
+public enum JIP5SeedDerive {
+    /// Derives Ed25519 and Bandersnatch secret key seeds from a master seed
+    ///
+    /// - Parameter seed: The 32-byte master seed
+    /// - Returns: A tuple containing (ed25519SecretSeed, bandersnatchSecretSeed)
+    public static func deriveKeySeeds(from seed: Data32) -> (ed25519: Data32, bandersnatch: Data32) {
+        let ed25519Prefix = "jam_val_key_ed25519"
+        let bandersnatchPrefix = "jam_val_key_bandersnatch"
+
+        let ed25519Input = Data(ed25519Prefix.utf8) + seed.data
+        let ed25519SecretSeed = ed25519Input.blake2b256hash()
+
+        let bandersnatchInput = Data(bandersnatchPrefix.utf8) + seed.data
+        let bandersnatchSecretSeed = bandersnatchInput.blake2b256hash()
+
+        return (ed25519: ed25519SecretSeed, bandersnatch: bandersnatchSecretSeed)
+    }
+
+    /// Creates a trivial seed from a 32-bit unsigned integer for testing purposes
+    ///
+    /// Implements: trivial_seed(i) = repeat_8_times(encode_as_32bit_le(i))
+    ///
+    /// - Parameter i: The 32-bit unsigned integer
+    /// - Returns: A 32-byte seed with the integer repeated 8 times in little-endian format
+    public static func trivialSeed(_ i: UInt32) -> Data32 {
+        var seedData = Data(capacity: 32)
+        let littleEndianBytes = i.littleEndian.encode()
+
+        for _ in 0 ..< 8 {
+            seedData.append(contentsOf: littleEndianBytes)
+        }
+
+        return Data32(seedData)!
+    }
+}

Utils/Tests/UtilsTests/Crypto/JIP5SeedDeriveTests.swift

@@ -0,0 +1,81 @@
+import Foundation
+import Testing
+@testable import Utils
+
+struct Vector {
+    let index: UInt32
+    let seedHex: String
+    let ed25519SeedHex: String
+    let ed25519PubHex: String
+    let bandersnatchSeedHex: String
+    let bandersnatchPubHex: String
+}
+
+// test vectors from JIP-5 spec
+let vectors: [Vector] = [
+    Vector(
+        index: 0,
+        seedHex: "0000000000000000000000000000000000000000000000000000000000000000",
+        ed25519SeedHex: "996542becdf1e78278dc795679c825faca2e9ed2bf101bf3c4a236d3ed79cf59",
+        ed25519PubHex: "4418fb8c85bb3985394a8c2756d3643457ce614546202a2f50b093d762499ace",
+        bandersnatchSeedHex: "007596986419e027e65499cc87027a236bf4a78b5e8bd7f675759d73e7a9c799",
+        bandersnatchPubHex: "ff71c6c03ff88adb5ed52c9681de1629a54e702fc14729f6b50d2f0a76f185b3"
+    ),
+    Vector(
+        index: 1,
+        seedHex: "0100000001000000010000000100000001000000010000000100000001000000",
+        ed25519SeedHex: "b81e308145d97464d2bc92d35d227a9e62241a16451af6da5053e309be4f91d7",
+        ed25519PubHex: "ad93247bd01307550ec7acd757ce6fb805fcf73db364063265b30a949e90d933",
+        bandersnatchSeedHex: "12ca375c9242101c99ad5fafe8997411f112ae10e0e5b7c4589e107c433700ac",
+        bandersnatchPubHex: "dee6d555b82024f1ccf8a1e37e60fa60fd40b1958c4bb3006af78647950e1b91"
+    ),
+    Vector(
+        index: 2,
+        seedHex: "0200000002000000020000000200000002000000020000000200000002000000",
+        ed25519SeedHex: "0093c8c10a88ebbc99b35b72897a26d259313ee9bad97436a437d2e43aaafa0f",
+        ed25519PubHex: "cab2b9ff25c2410fbe9b8a717abb298c716a03983c98ceb4def2087500b8e341",
+        bandersnatchSeedHex: "3d71dc0ffd02d90524fda3e4a220e7ec514a258c59457d3077ce4d4f003fd98a",
+        bandersnatchPubHex: "9326edb21e5541717fde24ec085000b28709847b8aab1ac51f84e94b37ca1b66"
+    ),
+    Vector(
+        index: 3,
+        seedHex: "0300000003000000030000000300000003000000030000000300000003000000",
+        ed25519SeedHex: "69b3a7031787e12bfbdcac1b7a737b3e5a9f9450c37e215f6d3b57730e21001a",
+        ed25519PubHex: "f30aa5444688b3cab47697b37d5cac5707bb3289e986b19b17db437206931a8d",
+        bandersnatchSeedHex: "107a9148b39a1099eeaee13ac0e3c6b9c256258b51c967747af0f8749398a276",
+        bandersnatchPubHex: "0746846d17469fb2f95ef365efcab9f4e22fa1feb53111c995376be8019981cc"
+    ),
+    Vector(
+        index: 4,
+        seedHex: "0400000004000000040000000400000004000000040000000400000004000000",
+        ed25519SeedHex: "b4de9ebf8db5428930baa5a98d26679ab2a03eae7c791d582e6b75b7f018d0d4",
+        ed25519PubHex: "8b8c5d436f92ecf605421e873a99ec528761eb52a88a2f9a057b3b3003e6f32a",
+        bandersnatchSeedHex: "0bb36f5ba8e3ba602781bb714e67182410440ce18aa800c4cb4dd22525b70409",
+        bandersnatchPubHex: "151e5c8fe2b9d8a606966a79edd2f9e5db47e83947ce368ccba53bf6ba20a40b"
+    ),
+    Vector(
+        index: 5,
+        seedHex: "0500000005000000050000000500000005000000050000000500000005000000",
+        ed25519SeedHex: "4a6482f8f479e3ba2b845f8cef284f4b3208ba3241ed82caa1b5ce9fc6281730",
+        ed25519PubHex: "ab0084d01534b31c1dd87c81645fd762482a90027754041ca1b56133d0466c06",
+        bandersnatchSeedHex: "75e73b8364bf4753c5802021c6aa6548cddb63fe668e3cacf7b48cdb6824bb09",
+        bandersnatchPubHex: "2105650944fcd101621fd5bb3124c9fd191d114b7ad936c1d79d734f9f21392e"
+    ),
+]
+
+struct JIP5SeedDeriveTests {
+    @Test(arguments: vectors)
+    func testJIP5SeedDerivationAndPublicKeys(vector: Vector) throws {
+        let seed = JIP5SeedDerive.trivialSeed(vector.index)
+        #expect(seed.toHexString() == vector.seedHex)
+
+        let derived = JIP5SeedDerive.deriveKeySeeds(from: seed)
+        #expect(derived.ed25519.toHexString() == vector.ed25519SeedHex)
+        #expect(derived.bandersnatch.toHexString() == vector.bandersnatchSeedHex)
+
+        let ed25519Pub = try Ed25519.SecretKey(from: derived.ed25519).publicKey
+        let bandersnatchPub = try Bandersnatch.SecretKey(from: derived.bandersnatch).publicKey
+        #expect(ed25519Pub.data.toHexString() == vector.ed25519PubHex)
+        #expect(bandersnatchPub.data.toHexString() == vector.bandersnatchPubHex)
+    }
+}