SECP256K1 using SawTooth Swift

Question

I am trying to sign signature as well as verify using Sawtooth SDK from Sawtooth SDK . Looking at the documentation, i followed through but it didnt work.

import SawtoothSigning

public class Secp256k1 {

private var signer: Signer
private var privateKey: PrivateKey
private var context = Secp256k1Context() //Here it crashed with error Thread 1: EXC_BAD_ACCESS (code=2, address=0x7ffeeda61ff8)

 public func sign(message: [UInt8]) -> String {
    var result = ""
    do {
        result = try signer.sign(data: message)
    } catch {
        print("Error signing")
    }
    return result
}

public func getPrivateKey() -> PrivateKey {
    if let privateKey = UserDefaults.standard.string(forKey: "privateKey") {
        return Secp256k1PrivateKey.fromHex(hexPrivKey: privateKey)
    } else {
        let privateKey = context.newRandomPrivateKey()
        UserDefaults.standard.set(privateKey.hex(), forKey: "privateKey" )
        do {
            let pubKey = try context.getPublicKey(privateKey: privateKey)
            UserDefaults.standard.set(pubKey.hex(), forKey: "publicKey" )
        } catch {
            if #available(iOS 10.0, *) {
                print("Error creating public key")
            }
        }
        return privateKey
    }
}

public init() {
    self.privateKey = Secp256k1().getPrivateKey()
    self.signer = Signer(context: context, privateKey: self.privateKey)
}
}

Have anyone worked with this SDK and knows why is it crashing? Or is there any simpler SDK?

Answer 1

You've cycled Secp256k1 constructor (ie. calls Secp256k1() within own init ), that result in crash.

Here is possible variant of solution (tested & works with Xcode 11.4):

public class Secp256k1 {

    private var signer: Signer
    private var privateKey: PrivateKey
    private static var context = Secp256k1Context()          // << shared !!

    public func sign(message: [UInt8]) -> String {
        var result = ""
        do {
            result = try signer.sign(data: message)
        } catch {
            print("Error signing")
        }
        return result
    }

    public static func getPrivateKey() -> PrivateKey {        // << shared !!
        if let privateKey = UserDefaults.standard.string(forKey: "privateKey") {
            return Secp256k1PrivateKey.fromHex(hexPrivKey: privateKey)
        } else {
            let privateKey = context.newRandomPrivateKey()
            UserDefaults.standard.set(privateKey.hex(), forKey: "privateKey" )
            do {
                let pubKey = try context.getPublicKey(privateKey: privateKey)
                UserDefaults.standard.set(pubKey.hex(), forKey: "publicKey" )
            } catch {
                if #available(iOS 10.0, *) {
                    print("Error creating public key")
                }
            }
            return privateKey
        }
    }

    public init() {
        self.privateKey = Secp256k1.getPrivateKey()       // no cycle now !!
        self.signer = Signer(context: Secp256k1.context, privateKey: self.privateKey)
    }
}

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