Migrate to swift-secp256k1 v0.21.1 (P256K)

- Update KeyUtil to use P256K high-level API for key generation, signing, and recovery
- Replace low-level C secp256k1 bindings with P256K.Signing and P256K.Recovery APIs
- Fix HexExtensions to handle empty hex strings (return 0 instead of nil)
- Update EthereumKeyStorageTests to use valid 32-byte private keys
- Use HashDigest for message digests in signing and recovery operations
- Maintain Ethereum signature format (64-byte signature + recovery ID)

Author: dioKaratzas

Package.resolved

@@ -15,7 +15,7 @@ let package = Package(
     dependencies: [
         .package(url: "https://github.com/attaswift/BigInt", from: "5.3.0"),
         .package(url: "https://github.com/iwill/generic-json-swift", .upToNextMajor(from: "2.0.2")),
-        .package(url: "https://github.com/GigaBitcoin/secp256k1.swift.git", .upToNextMajor(from: "0.6.0")),
+        .package(url: "https://github.com/21-DOT-DEV/swift-secp256k1", from: "0.21.1"),
         .package(url: "https://github.com/vapor/websocket-kit.git", from: "2.16.1"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.6.4")
     ],
@@ -29,7 +29,7 @@ let package = Package(
                     .target(name: "Internal_CryptoSwift_PBDKF2"),
                     "BigInt",
                     .product(name: "GenericJSON", package: "generic-json-swift"),
-                    .product(name: "secp256k1", package: "secp256k1.swift"),
+                    .product(name: "P256K", package: "swift-secp256k1"),
                     .product(name: "WebSocketKit", package: "websocket-kit"),
                     .product(name: "Logging", package: "swift-log")
                 ],

Package.swift

@@ -15,7 +15,7 @@ let package = Package(
     dependencies: [
         .package(url: "https://github.com/attaswift/BigInt", from: "5.3.0"),
         .package(url: "https://github.com/iwill/generic-json-swift", .upToNextMajor(from: "2.0.2")),
-        .package(url: "https://github.com/GigaBitcoin/secp256k1.swift.git", .upToNextMajor(from: "0.6.0")),
+        .package(url: "https://github.com/21-DOT-DEV/swift-secp256k1", from: "0.21.1"),
         .package(url: "https://github.com/vapor/websocket-kit.git", from: "2.16.1"),
         .package(url: "https://github.com/apple/swift-log.git", from: "1.6.4")
     ],
@@ -29,7 +29,7 @@ let package = Package(
                     .target(name: "Internal_CryptoSwift_PBDKF2"),
                     "BigInt",
                     .product(name: "GenericJSON", package: "generic-json-swift"),
-                    .product(name: "secp256k1", package: "secp256k1.swift"),
+                    .product(name: "P256K", package: "swift-secp256k1"),
                     .product(name: "WebSocketKit", package: "websocket-kit"),
                     .product(name: "Logging", package: "swift-log")
                 ],

Package@swift-6.1.swift

@@ -42,31 +42,30 @@ class EthereumKeyStorageTests: XCTestCase {
     }
 
     func testEncryptAndStorePrivateKey() {
-        let randomData = Data.randomOfLength(256)!
+        let privateKey = Data.randomOfLength(32)!
         let keyStorage = EthereumKeyLocalStorage() as EthereumSingleKeyStorageProtocol
         let password = "myP4ssw0rD"
 
         do {
-            try keyStorage.encryptAndStorePrivateKey(key: randomData, keystorePassword: password)
+            try keyStorage.encryptAndStorePrivateKey(key: privateKey, keystorePassword: password)
             let decrypted = try keyStorage.loadAndDecryptPrivateKey(keystorePassword: password)
-            XCTAssertEqual(decrypted, randomData)
+            XCTAssertEqual(decrypted, privateKey)
         } catch let error {
             XCTFail("Failed to encrypt and store private key with error: \(error)")
         }
     }
 
     func testEncryptAndStorePrivateKeyMultiple() {
-        let randomData = Data.randomOfLength(256)!
+        let privateKey = Data.randomOfLength(32)!
         let keyStorage = EthereumKeyLocalStorage() as EthereumMultipleKeyStorageProtocol
         let password = "myP4ssw0rD"
 
         do {
-            _ = KeyUtil.generateAddress(from: randomData)
-            try keyStorage.encryptAndStorePrivateKey(key: randomData, keystorePassword: password)
-            let publicKey = try KeyUtil.generatePublicKey(from: randomData)
+            let publicKey = try KeyUtil.generatePublicKey(from: privateKey)
             let address = KeyUtil.generateAddress(from: publicKey)
+            try keyStorage.encryptAndStorePrivateKey(key: privateKey, keystorePassword: password)
             let decrypted = try keyStorage.loadAndDecryptPrivateKey(for: address, keystorePassword: password)
-            XCTAssertEqual(decrypted, randomData)
+            XCTAssertEqual(decrypted, privateKey)
         } catch let error {
             XCTFail("Failed to encrypt and store private key with error: \(error)")
         }

web3sTests/Account/EthereumKeyStorageTests.swift

@@ -8,7 +8,12 @@ import Foundation
 
 public extension BigUInt {
     init?(hex: String) {
-        self.init(hex.web3.noHexPrefix.lowercased(), radix: 16)
+        let stripped = hex.web3.noHexPrefix.lowercased()
+        if stripped.isEmpty {
+            self.init(0)
+        } else {
+            self.init(stripped, radix: 16)
+        }
     }
 }
 
@@ -24,13 +29,23 @@ public extension Web3Extensions where Base == BigUInt {
 
 public extension BigInt {
     init?(hex: String) {
-        self.init(hex.web3.noHexPrefix.lowercased(), radix: 16)
+        let stripped = hex.web3.noHexPrefix.lowercased()
+        if stripped.isEmpty {
+            self.init(0)
+        } else {
+            self.init(stripped, radix: 16)
+        }
     }
 }
 
 public extension Int {
     init?(hex: String) {
-        self.init(hex.web3.noHexPrefix, radix: 16)
+        let stripped = hex.web3.noHexPrefix
+        if stripped.isEmpty {
+            self.init(0)
+        } else {
+            self.init(stripped, radix: 16)
+        }
     }
 }