Fix nonce generation to url b64

Author: Marcus Arnett

Sources/SuiKit/Extensions/Data.swift

@@ -84,6 +84,14 @@ public extension Data {
         }
         return UInt16(s % 65535)
     }
+
+    func base64urlEncodedString() -> String {
+        var result = self.base64EncodedString()
+        result = result.replacingOccurrences(of: "+", with: "-")
+        result = result.replacingOccurrences(of: "/", with: "_")
+        result = result.replacingOccurrences(of: "=", with: "")
+        return result
+    }
 }
 
 public extension Data {

Sources/SuiKit/Utils/zkLogin/zkLoginNonce.swift

@@ -46,7 +46,7 @@ public struct zkLoginNonce {
         let ephPublicKey1 = publicKeyBytes % BigInt(2).power(128)
         let bigNum = try PoseidonUtilities.poseidonHash(inputs: [ephPublicKey0, ephPublicKey1, BigInt(maxEpoch), BigInt(randomness, radix: 10)!])
         let z = zkLoginUtilities.toBigEndianBytes(num: bigNum, width: 20)
-        let nonce = Data(z).base64EncodedString()
+        let nonce = Data(z).base64urlEncodedString()
         guard nonce.count == Self.nonceLength else { throw SuiError.notImplemented }
         return nonce
     }

Sources/SuiKit/Utils/zkLogin/zkLoginSignatureInputsClaim.swift

@@ -29,6 +29,11 @@ public struct zkLoginSignatureInputsClaim: KeyProtocol, Equatable, Codable {
     public var value: String
     public var indexMod4: UInt8
 
+    public init(value: String, indexMod4: UInt8) {
+        self.value = value
+        self.indexMod4 = indexMod4
+    }
+
     public func serialize(_ serializer: Serializer) throws {
         try Serializer.str(serializer, self.value)
         try Serializer.u8(serializer, self.indexMod4)

Sources/SuiKit/Utils/zkLogin/zkLoginSignatureInputsProofPoints.swift

@@ -30,6 +30,12 @@ public struct zkLoginSignatureInputsProofPoints: KeyProtocol, Equatable, Codable
     public var b: [[String]]
     public var c: [String]
 
+    public init(a: [String], b: [[String]], c: [String]) {
+        self.a = a
+        self.b = b
+        self.c = c
+    }
+
     public func serialize(_ serializer: Serializer) throws {
         try serializer.sequence(self.a, Serializer.str)
         try serializer.uleb128(UInt(self.b.count))

Sources/SuiKit/Utils/zkLogin/zkLoginUtilities.swift

@@ -59,22 +59,15 @@ public struct zkLoginUtilities {
     }
 
     public static func toPaddedBigEndianBytes(num: BigInt, width: Int) -> [UInt8] {
-        let hex = String(num, radix: 16, uppercase: false)
-
-        // Padding and Slicing
-        let paddedHex = String(hex).leftPad(toLength: width * 2, withPad: "0")
-
-        // Convert Hex String to Bytes
-        var bytes = [UInt8]()
-        for i in stride(from: 0, to: paddedHex.count, by: 2) {
-            let start = paddedHex.index(paddedHex.startIndex, offsetBy: i)
-            let end = paddedHex.index(paddedHex.startIndex, offsetBy: i + 2)
-            let byteString = paddedHex[start..<end]
-            if let byte = UInt8(byteString, radix: 16) {
-                bytes.append(byte)
-            }
+        let hex = String(num, radix: 16)
+        let paddedHex = String(repeating: "0", count: max(0, width * 2 - hex.count)) + hex
+        let finalHex = paddedHex.suffix(width * 2)
+        return stride(from: 0, to: width * 2, by: 2).map {
+            let startIndex = finalHex.index(finalHex.startIndex, offsetBy: $0)
+            let endIndex = finalHex.index(startIndex, offsetBy: 2)
+            let byteString = finalHex[startIndex..<endIndex]
+            return UInt8(byteString, radix: 16)!
         }
-        return bytes
     }
 
     public static func findFirstNonZeroIndex(bytes: [UInt8]) -> Int {

Tests/SuiKitTests/Unit/zkLogin/JWTUtilsTest.swift

@@ -38,4 +38,14 @@ final class JWTUtilsTest: XCTestCase {
         )
         XCTAssertEqual(extractedValue, "https://accounts.google.com")
     }
+    
+    func testThatGeneratingNonceWorksAsIntended() throws {
+        let pk = try ED25519PublicKey(value: "dkUcNsSSYV2cFz+L/WAlyxINuXHpah/MJnYZ57/GtKY=")
+        let nonce = try zkLoginNonce.generateNonce(
+            publicKey: pk,
+            maxEpoch: 954,
+            randomness: "176720613486626510701195520524108477720"
+        )
+        XCTAssertEqual("NN9BV-W7MlsscmY042AddYkO1N8", nonce)
+    }
 }