Adding ECDSA (#71)

Author: csjones

Package.swift

@@ -39,19 +39,21 @@ let package = Package(
             cSettings: [
                 .headerSearchPath("secp256k1"),
                 // Basic config values that are universal and require no dependencies.
-                // https://github.com/bitcoin-core/secp256k1/blob/master/src/basic-config.h#L27-L31
+                // https://github.com/bitcoin-core/secp256k1/blob/master/src/basic-config.h#L26-L30
                 .define("ECMULT_WINDOW_SIZE", to: "15", nil),
+                .define("USE_NUM_NONE"),
+                .define("USE_FIELD_INV_BUILTIN"),
+                .define("USE_SCALAR_INV_BUILTIN"),
+                .define("USE_WIDEMUL_64"),
+                // Mirroring default value of `ECMULT_GEN_PREC_BITS` to 4 bits.
                 .define("ECMULT_GEN_PREC_BITS", to: "4", nil),
+                // Enabling additional secp256k1 modules.
                 .define("SECP256K1_ECDH_H"),
                 .define("SECP256K1_MODULE_ECDH_MAIN_H"),
                 .define("SECP256K1_EXTRAKEYS_H"),
                 .define("SECP256K1_MODULE_EXTRAKEYS_MAIN_H"),
                 .define("SECP256K1_SCHNORRSIG_H"),
                 .define("SECP256K1_MODULE_SCHNORRSIG_MAIN_H"),
-                .define("USE_NUM_NONE"),
-                .define("USE_FIELD_INV_BUILTIN"),
-                .define("USE_SCALAR_INV_BUILTIN"),
-                .define("USE_WIDEMUL_64")
             ]
         ),
         // Only include select utility extensions because most of Swift Crypto is not required
@@ -66,11 +68,19 @@ let package = Package(
                 "swift-crypto/Sources/Crypto/Util/SecureBytes.swift",
                 "swift-crypto/Sources/Crypto/Util/BoringSSL/RNG_boring.swift",
                 "swift-crypto/Sources/Crypto/Util/BoringSSL/SafeCompare_boring.swift",
+                "swift-crypto/Sources/Crypto/Signatures/Signature.swift",
+                "swift-crypto/Sources/Crypto/Digests/Digest.swift",
+                "swift-crypto/Sources/Crypto/CryptoKitErrors.swift",
                 "Zeroization.swift",
+                "SHA256.swift",
                 "String.swift",
                 "secp256k1.swift",
+                "ECDSA.swift",
                 "SafeCompare.swift",
-                "NISTCurvesKeys.swift"
+                "NISTCurvesKeys.swift",
+                "PrettyBytes.swift",
+                "EdDSA.swift",
+                "Digests.swift"
             ]
         ),
         .testTarget(

README.md

@@ -1,68 +1,47 @@
 [![Build Status](https://app.bitrise.io/app/ef44aebd8443b33b/status.svg?token=oDGzN3bMEwseXF_5MQUsTg&branch=main)](https://app.bitrise.io/app/ef44aebd8443b33b) [![](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2FGigaBitcoin%2Fsecp256k1.swift%2Fbadge%3Ftype%3Dswift-versions)](https://swiftpackageindex.com/GigaBitcoin/secp256k1.swift) [![](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2FGigaBitcoin%2Fsecp256k1.swift%2Fbadge%3Ftype%3Dplatforms)](https://swiftpackageindex.com/GigaBitcoin/secp256k1.swift)
 
 # 🔐 secp256k1.swift
-Swift library and bindings for ECDSA signatures and secret/public key operations using [libsecp256k1](https://github.com/bitcoin-core/secp256k1).
+Swift library plus bindings for ECDSA signatures and secret/public key operations using [libsecp256k1](https://github.com/bitcoin-core/secp256k1).
 
 
-# Objective
-This library aims to be a lightweight wrapper for clients to include ECDSA functionality in Swift. The package aims to stay up-to-date and uses a submodule set to the default git branch of secp256k1.
+# Objectives
 
+Long-term goals are:
+ - Lightweight ECDSA functionality
+ - APIs modeled after [Swift Crypto](https://github.com/apple/swift-crypto)
+ - Up-to-date with future versions of Swift and libsecp256k1
+ - Consistent across multiple platforms
 
-# Getting Started
 
-In your `Package.swift`:
-
-```swift
-dependencies: [
-    .package(
-        name: "secp256k1",
-        url: "https://github.com/GigaBitcoin/secp256k1.swift.git",
-        from: "0.2.0"
-    ),
-]
-```
-
-
-# Basic Usage
+# Usage
 
 ```swift
 import secp256k1
 
 let privateKeyBytes = try! "14E4A74438858920D8A35FB2D88677580B6A2EE9BE4E711AE34EC6B396D87B5C".byteArray()
 let privatekey = try! secp256k1.Signing.PrivateKey(rawRepresentation: privateKeyBytes)
 
-
 print(String(byteArray: privatekey.publicKey.rawRepresentation)) //  02734b3511150a60fc8cac329cd5ff804555728740f2f2e98bc4242135ef5d5e4e
-```
 
+let messageData = "Hello World!".data(using: .utf8)!
+let signature = try! privateKey.signature(for: messageData)
 
-# Advance Usage
-
-```swift
-import secp256k1
-
-// Initialize context
-let context = secp256k1_context_create(UInt32(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY))!
+print(try! signature.derRepresentation().base64EncodedString()) //  MEUCID8JELjY/ua6MSRKh/VtO7q2YAgpPOfqlwi05Lj/gC1jAiEAiJ1r82jIVc9G/2kooLnzIbg04ky/leocdLn9XE1LvwI=
+```
 
-// Setup private and public key variables
-var pubkeyLen = 33
-var cPubkey = secp256k1_pubkey()
-var pubkey = [UInt8](repeating: 0, count: pubkeyLen)
-let privkey = try! "14E4A74438858920D8A35FB2D88677580B6A2EE9BE4E711AE34EC6B396D87B5C".byteArray()
 
-// Verify the context and keys are setup correctly
-guard secp256k1_context_randomize(context, privkey) == 1,
-    secp256k1_ec_pubkey_create(context, &cPubkey, privkey) == 1,
-    secp256k1_ec_pubkey_serialize(context, &pubkey, &pubkeyLen, &cPubkey, UInt32(SECP256K1_EC_COMPRESSED)) == 1 else {
-    // Destory context after creation
-    secp256k1_context_destroy(context)
-    return
-}
+# Getting Started
 
-print(String(byteArray: pubKey)) //  02734b3511150a60fc8cac329cd5ff804555728740f2f2e98bc4242135ef5d5e4e
+In your `Package.swift`:
 
-// Destory context after creation
-secp256k1_context_destroy(context)
+```swift
+dependencies: [
+    .package(
+        name: "secp256k1",
+        url: "https://github.com/GigaBitcoin/secp256k1.swift.git",
+        from: "0.3.0"
+    ),
+]
 ```
 
 

Sources/bindings/include/SHA256.h

@@ -0,0 +1,18 @@
+//
+//  SHA256.h
+//  GigaBitcoin/secp256k1.swift
+//
+//  Copyright (c) 2021 GigaBitcoin LLC
+//  Distributed under the MIT software license
+//
+//  See the accompanying file LICENSE for information
+//
+
+#include "../secp256k1/src/hash.h"
+#include "../secp256k1/include/secp256k1.h"
+
+/// Exposes secp256k1 SHA256 implementation to the bindings target
+/// @param output  pointer to an array to be filled by the function
+/// @param input a pointer to the data to be hashed
+/// @param len the length of the data to be hashed
+void secp256k1_swift_sha256(unsigned char *output, const unsigned char *input, size_t len);

Sources/bindings/include/secp256k1.h

@@ -3,4 +3,4 @@
 #include "../secp256k1/include/secp256k1_preallocated.h"
 #include "../secp256k1/include/secp256k1_recovery.h"
 #include "../secp256k1/include/secp256k1_schnorrsig.h"
-#include "../secp256k1/include/secp256k1.h"
+#include "../secp256k1/include/secp256k1.h"

Sources/bindings/src/SHA256.c

@@ -0,0 +1,23 @@
+//
+//  SHA256.c
+//  GigaBitcoin/secp256k1.swift
+//
+//  Copyright (c) 2021 GigaBitcoin LLC
+//  Distributed under the MIT software license
+//
+//  See the accompanying file LICENSE for information
+//
+
+#include "SHA256.h"
+#include "../secp256k1/src/hash_impl.h"
+
+/// Exposes secp256k1 SHA256 implementation to the bindings target
+/// @param output  pointer to an array to be filled by the function
+/// @param input a pointer to the data to be hashed
+/// @param len the length of the data to be hashed
+void secp256k1_swift_sha256(unsigned char *output, const unsigned char *input, size_t len) {
+    secp256k1_sha256 hasher;
+    secp256k1_sha256_initialize(&hasher);
+    secp256k1_sha256_write(&hasher, input, len);
+    secp256k1_sha256_finalize(&hasher, output);
+}

Sources/implementation/Digests.swift

@@ -0,0 +1,69 @@
+//
+//  Digests.swift
+//  GigaBitcoin/secp256k1.swift
+//
+//  Modifications Copyright (c) 2021 GigaBitcoin LLC
+//  Distributed under the MIT software license
+//
+//  See the accompanying file LICENSE for information
+//
+//
+//  NOTICE: THIS FILE HAS BEEN MODIFIED BY GigaBitcoin LLC
+//  UNDER COMPLIANCE WITH THE APACHE 2.0 LICENSE FROM THE
+//  ORIGINAL WORK OF THE COMPANY Apple Inc.
+//
+//  THE FOLLOWING IS THE COPYRIGHT OF THE ORIGINAL DOCUMENT:
+//
+//
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftCrypto open source project
+//
+// Copyright (c) 2019-2020 Apple Inc. and the SwiftCrypto project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.md for the list of SwiftCrypto project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+// MARK: - SHA256Digest + DigestPrivate
+
+public struct SHA256Digest: Digest {
+    let bytes: (UInt64, UInt64, UInt64, UInt64)
+
+    public static var byteCount: Int {
+        get { return 32 }
+
+        set { fatalError("Cannot set SHA256.byteCount") }
+    }
+
+    public func withUnsafeBytes<R>(_ body: (UnsafeRawBufferPointer) throws -> R) rethrows -> R {
+        return try Swift.withUnsafeBytes(of: bytes) {
+            let boundsCheckedPtr = UnsafeRawBufferPointer(start: $0.baseAddress,
+                                                          count: Self.byteCount)
+            return try body(boundsCheckedPtr)
+        }
+    }
+
+    private func toArray() -> ArraySlice<UInt8> {
+        var array = [UInt8]()
+        array.appendByte(bytes.0)
+        array.appendByte(bytes.1)
+        array.appendByte(bytes.2)
+        array.appendByte(bytes.3)
+        return array.prefix(upTo: SHA256Digest.byteCount)
+    }
+
+    public var description: String {
+        return "\("SHA256") digest: \(toArray().hexString)"
+    }
+
+    public func hash(into hasher: inout Hasher) {
+        self.withUnsafeBytes { hasher.combine(bytes: $0) }
+    }
+}