Merge pull request #2 from starkbank/init

feature/init

.gitignore

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+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/
+DerivedData/
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+Package.resolved

.swiftpm/xcode/package.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+and this project adheres to the following versioning pattern:
+
+Given a version number MAJOR.MINOR.PATCH, increment:
+
+- MAJOR version when **breaking changes** are introduced;
+- MINOR version when **backwards compatible changes** are introduced;
+- PATCH version when backwards compatible bug **fixes** are implemented.
+
+
+## [Unreleased]
+### Added
+- first official version

Package.swift

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+// swift-tools-version:5.3
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "starkbank-ecdsa",
+    products: [
+        // Products define the executables and libraries a package produces, and make them visible to other packages.
+        .library(
+            name: "starkbank-ecdsa",
+            targets: ["starkbank-ecdsa"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+        .package(
+             url: "https://github.com/attaswift/BigInt.git",
+            from: "5.3.0")
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "starkbank-ecdsa",
+            dependencies: [
+                "BigInt"
+            ]),
+        .testTarget(
+            name: "starkbank-ecdsaTests",
+            dependencies: ["starkbank-ecdsa"]),
+    ]
+)

README.md

@@ -1 +1,125 @@
-# ecdsa-swift
+## A lightweight and fast pure Swift ECDSA
+
+### Overview
+
+This is a pure Swift implementation of the Elliptic Curve Digital Signature Algorithm. It is compatible with Swift 5.3. It is also compatible with OpenSSL. It uses some elegant math such as Jacobian Coordinates to speed up the ECDSA on pure Swift.
+
+### Curves
+
+We currently support `secp256k1`, but it's super easy to add more curves to the project. Just add them on `Curve.swift`
+
+### Speed
+
+We ran a test on a MAC Pro i5 2017. The libraries were run 100 times and the averages displayed bellow were obtained:
+
+| Library            | sign          | verify  |
+| ------------------ |:-------------:| -------:|
+| starkbank-ecdsa    |     0.3ms     |  1.1ms  |
+
+### Sample Code
+
+How to sign a json message for [Stark Bank]:
+
+```swift
+import starkbank
+
+// Generate privateKey from PEM string
+let privateKey = try PrivateKey.fromPem("""
+-----BEGIN EC PARAMETERS-----
+BgUrgQQACg==
+-----END EC PARAMETERS-----
+-----BEGIN EC PRIVATE KEY-----
+MHQCAQEEIODvZuS34wFbt0X53+P5EnSj6tMjfVK01dD1dgDH02RzoAcGBSuBBAAK
+oUQDQgAE/nvHu/SQQaos9TUljQsUuKI15Zr5SabPrbwtbfT/408rkVVzq8vAisbB
+RmpeRREXj5aog/Mq8RrdYy75W9q/Ig==
+-----END EC PRIVATE KEY-----
+""")
+
+// Create message from json
+let message = "This is a text message"
+
+let signature = Ecdsa.sign(message: message, privateKey: privateKey)
+
+// Generate Signature in base64. This result can be sent to Stark Bank in the request header as the Digital-Signature parameter.
+print(signature.toBase64())
+
+// To double check if the message matches the signature, do this:
+let publicKey = privateKey.publicKey()
+
+print(Ecdsa.verify(message: message, signature: signature, publicKey: publicKey))
+
+```
+
+Simple use:
+
+```swift
+import starkbank
+
+// Generate new Keys
+let privateKey = PrivateKey()
+let publicKey = privateKey.publicKey()
+
+let message = "My test message"
+
+// Generate Signature
+let signature = Ecdsa.sign(message: message, privateKey: privateKey)
+
+// To verify if the signature is valid
+print(Ecdsa.verify(message: message, signature: signature, publicKey: publicKey))
+```
+
+### OpenSSL
+
+This library is compatible with OpenSSL, so you can use it to generate keys:
+
+```
+openssl ecparam -name secp256k1 -genkey -out privateKey.pem
+openssl ec -in privateKey.pem -pubout -out publicKey.pem
+```
+
+Create a message.txt file and sign it:
+
+```
+openssl dgst -sha256 -sign privateKey.pem -out signatureDer.txt message.txt
+```
+
+To verify, do this:
+
+```swift
+import starkbank
+
+let publicKeyPem = try? NSString(contentsOfFile: NSString(string:"/path/to/your/public-key/publicKey.pem").expandingTildeInPath, encoding: String.Encoding.utf8.rawValue)
+let signatureDer = try? NSString(contentsOfFile: NSString(string:"/path/to/your/signature/signatureDer.txt").expandingTildeInPath, encoding: String.Encoding.utf8.rawValue)
+let message = try? NSString(contentsOfFile: NSString(string:"/path/to/your/message/message.txt").expandingTildeInPath, encoding: String.Encoding.utf8.rawValue)
+
+let publicKey = try PrivateKey.fromPem(privateKeyPem! as String)
+let signature = try Signature.fromDer(signatureDer)
+
+print(Ecdsa.verify(message: message! as String, signature: signature, publicKey: publicKey))
+```
+
+You can also verify it on terminal:
+
+```
+openssl dgst -sha256 -verify publicKey.pem -signature signatureDer.txt message.txt
+```
+
+NOTE: If you want to create a Digital Signature to use with [Stark Bank], you need to convert the binary signature to base64.
+
+```
+openssl base64 -in signatureDer.txt -out signatureBase64.txt
+```
+
+You can do the same with this library:
+
+```swift
+import starkbank
+
+let signatureDer = try? NSString(contentsOfFile: NSString(string:"/path/to/your/signature/signatureDer.txt").expandingTildeInPath, encoding: String.Encoding.utf8.rawValue)
+
+let signature = try Signature.fromDer(signatureDer)
+
+print(signature.toBase64())
+```
+
+[Stark Bank]: https://starkbank.com

Sources/starkbank-ecdsa/Curve.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Rafael Stark on 2/14/21.
+//
+
+import BigInt
+import Foundation
+
+
+public class CurveFp {
+
+    public var A: BigInt
+    public var B: BigInt
+    public var P: BigInt
+    public var N: BigInt
+    public var G: Point
+    public var name: String
+    public var oid: [Int]
+
+    init(name: String, A: BigInt, B: BigInt, P: BigInt, N: BigInt, Gx: BigInt, Gy: BigInt, oid: [Int]) {
+        self.A = A
+        self.B = B
+        self.P = P
+        self.N = N
+        self.G = Point(Gx, Gy)
+        self.name = name
+        self.oid = oid
+    }
+
+    /**
+    Verify if the point `p` is on the curve
+    - Parameter p: Point p = Point(x, y)
+    - Returns: boolean
+    */
+    func contains(p: Point) -> Bool {
+        if (p.x < 0 || p.x >= self.P) {
+            return false
+        }
+        if (p.y < 0 || p.y >= self.P) {
+            return false
+        }
+        if ((p.y.power(2) - (p.x.power(3) + self.A * p.x + self.B)) % self.P != 0) {
+            return false
+        }
+        return true
+    }
+
+    func length() -> Int {
+        return (1 + String(N, radix: 16).count) / 2
+    }
+}
+
+public let secp256k1 = CurveFp(
+    name: "secp256k1",
+    A: BigInt("0000000000000000000000000000000000000000000000000000000000000000", radix: 16)!,
+    B: BigInt("0000000000000000000000000000000000000000000000000000000000000007", radix: 16)!,
+    P: BigInt("fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f", radix: 16)!,
+    N: BigInt("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141", radix: 16)!,
+    Gx: BigInt("79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798", radix: 16)!,
+    Gy: BigInt("483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8", radix: 16)!,
+    oid: [1, 3, 132, 0, 10]
+)
+
+public let prime256v1 = CurveFp(
+    name: "prime256v1",
+    A: BigInt("ffffffff00000001000000000000000000000000fffffffffffffffffffffffc", radix: 16)!,
+    B: BigInt("5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b", radix: 16)!,
+    P: BigInt("ffffffff00000001000000000000000000000000ffffffffffffffffffffffff", radix: 16)!,
+    N: BigInt("ffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551", radix: 16)!,
+    Gx: BigInt("6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296", radix: 16)!,
+    Gy: BigInt("4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5", radix: 16)!,
+    oid: [1, 2, 840, 10045, 3, 1, 7]
+)
+
+let supportedCurves = [
+    secp256k1,
+    prime256v1
+]
+
+let curvesByOid = supportedCurves.reduce([Array<Int>: CurveFp]()) { (dict, curve) -> [Array<Int>: CurveFp] in
+    var dict = dict
+    dict[curve.oid] = curve
+    return dict
+}
+
+public func getCurveByOid(_ oid: Array<Int>) throws -> CurveFp {
+    if (curvesByOid[oid] == nil) {
+        throw Error.invalidOidError("Unknown curve with oid {receivedOid}; The following are registered: {registeredOids}"
+                                        .replacingOccurrences(of: "{receivedOid}", with: oid.description)
+                                        .replacingOccurrences(of: "{registeredOids}", with: supportedCurves.description))
+    }
+    return curvesByOid[oid]!
+}

Sources/starkbank-ecdsa/Ecdsa.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Rafael Stark on 2/15/21.
+//
+
+import BigInt
+import Foundation
+
+
+public class Ecdsa {
+
+    public static func sign(message: String, privateKey: PrivateKey, hashfunc: Hash = Sha256()) -> Signature {
+        let hashMessage = hashfunc.digest(message)
+        let numberMessage = BinaryAscii.intFromHex(BinaryAscii.hexFromData(hashMessage as Data))
+        let curve = privateKey.curve
+        let randNum = RandomInteger.between(min: BigInt(1), max: curve.N)
+        let randomSignPoint = Math.multiply(curve.G, randNum, curve.N, curve.A, curve.P)
+        let r = randomSignPoint.x.modulus(curve.N)
+        let s = ((numberMessage + r * privateKey.secret) * (Math.inv(randNum, curve.N))).modulus(curve.N)
+        return Signature(r, s)
+    }
+
+    public static func verify(message: String, signature: Signature, publicKey: PublicKey, hashfunc: Hash = Sha256()) -> Bool {
+        let hashMessage = hashfunc.digest(message)
+        let numberMessage = BinaryAscii.intFromHex(BinaryAscii.hexFromData(hashMessage as Data))
+        let curve = publicKey.curve
+        let r = signature.r
+        let s = signature.s
+
+        if (r < 1 || r >= curve.N) {
+            return false
+        }
+        if (s < 1 || s >= curve.N) {
+            return false
+        }
+
+        let inv = Math.inv(s, curve.N)
+        let u1 = Math.multiply(curve.G, (numberMessage * inv).modulus(curve.N), curve.N, curve.A, curve.P)
+        let u2 = Math.multiply(publicKey.point, (r * inv).modulus(curve.N), curve.N, curve.A, curve.P)
+        let v = Math.add(u1, u2, curve.A, curve.P)
+        if (v.isAtInfinity()) {
+            return false
+        }
+        return v.x.modulus(curve.N) == r
+    }
+}

Sources/starkbank-ecdsa/Hash.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Rafael Stark on 2/15/21.
+//
+
+import Foundation
+import CommonCrypto
+
+
+public protocol Hash {
+    func digest(_ string: String) -> NSData
+    func digest(_ data: NSData) -> NSData
+}
+
+public class Sha256: Hash {
+
+    public init() {}
+
+    public func digest(_ string: String) -> NSData {
+        let data = string.data(using: String.Encoding.utf8)!
+        return digest(data as NSData)
+    }
+
+    public func digest(_ data : NSData) -> NSData {
+        let digestLength = Int(CC_SHA256_DIGEST_LENGTH)
+        var hash = [UInt8](repeating: 0, count: digestLength)
+        CC_SHA256(data.bytes, UInt32(data.length), &hash)
+        return NSData(bytes: hash, length: digestLength)
+    }
+}