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I'm attempting to authenticate to MyScript using the REST API but I seem to have a malformed request or i'm computing the HMAC incorrectly in Swift. I'm not exactly sure what the issue is. Here is the error:

["code": access.not.granted, "message": Access not granted]

"""swift

import Foundation

import CryptoSwift

import CommonCrypto

struct RecognitionService {

    let apiKey: String

    let hmacKey: String

    let exampleRequest: [String: Any] = [

 "contentType": "Math",

 "configuration": [],

 "strokeGroups": [

 [

                "strokes": []

 ]

 ]

 ]

    init(apiKey: String, hmacKey: String, header: [String: String]? = nil) {

        self.apiKey = apiKey

        self.hmacKey = hmacKey

 }

    func computeHmacSha512(requestBody: String) -> String {

        let userKey = apiKey + hmacKey

        let hmacResult: String = requestBody.hmac(algorithm: HMACAlgorithm.SHA512, key: userKey)

        return hmacResult

 }

    func post() {

        let session = URLSession.shared

        let hmac = self.computeHmacSha512(requestBody: asString(jsonDictionary: exampleRequest))

 let url = URL(string: "https://cloud.myscript.com/api/v4.0/iink/batch")

        var request = URLRequest(url: url!)

 request.setValue("application/vnd.myscript.latex,application/json", forHTTPHeaderField: "Accept")

        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        request.setValue(apiKey, forHTTPHeaderField: "applicationKey")

        request.setValue(hmac, forHTTPHeaderField: "hmacKey")

        request.httpMethod = "POST"

        request.httpBody = asJson(jsonDict: exampleRequest)

        let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in

            guard error == nil else {

                return

 }

            guard let data = data else {

                return

 }

            do {

                if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {

                    print(json)

 }

            } catch let error {

                print(error.localizedDescription)

 }

 })

        task.resume()

 }

}

func asString(jsonDictionary: [String: Any]) -> String {

    do {

        if let json = asJson(jsonDict: jsonDictionary) {

            return String(data: json, encoding: String.Encoding.utf8) ?? ""

        } else {

            return ""

 }

    } catch {

        return ""

 }

}

func asJson(jsonDict: [String: Any]) -> Data? {

    do {

        let data = try JSONSerialization.data(withJSONObject: jsonDict, options: .prettyPrinted)

        return data

    } catch {

        return nil

 }

}

enum HMACAlgorithm {

    case MD5, SHA1, SHA224, SHA256, SHA384, SHA512

    func toCCHmacAlgorithm() -> CCHmacAlgorithm {

        var result: Int = 0

        switch self {

        case .MD5:

            result = kCCHmacAlgMD5

        case .SHA1:

            result = kCCHmacAlgSHA1

        case .SHA224:

            result = kCCHmacAlgSHA224

        case .SHA256:

            result = kCCHmacAlgSHA256

        case .SHA384:

            result = kCCHmacAlgSHA384

        case .SHA512:

            result = kCCHmacAlgSHA512

 }

        return CCHmacAlgorithm(result)

 }

    func digestLength() -> Int {

        var result: CInt = 0

        switch self {

        case .MD5:

            result = CC_MD5_DIGEST_LENGTH

        case .SHA1:

            result = CC_SHA1_DIGEST_LENGTH

        case .SHA224:

 result = CC_SHA224_DIGEST_LENGTH

        case .SHA256:

 result = CC_SHA256_DIGEST_LENGTH

        case .SHA384:

 result = CC_SHA384_DIGEST_LENGTH

        case .SHA512:

 result = CC_SHA512_DIGEST_LENGTH

 }

        return Int(result)

 }

}

extension String {

    func hmac(algorithm: HMACAlgorithm, key: String) -> String {

        let cKey = key.cString(using: String.Encoding.utf8)

        let cData = self.cString(using: String.Encoding.utf8)

        var result = [CUnsignedChar](repeating: 0, count: Int(algorithm.digestLength()))

        CCHmac(algorithm.toCCHmacAlgorithm(), cKey!, strlen(cKey!), cData!, strlen(cData!), &result)

        let hmacData:NSData = NSData(bytes: result, length: (Int(algorithm.digestLength())))

 let hmacBase64 = hmacData.base64EncodedString(options: NSData.Base64EncodingOptions.lineLength76Characters)

        return String(hmacBase64)

 }

}

"""

Hi,

Yes, I also tried it with just hmac; however, that does not work either.

Thank you.

Hi Olivier,

Yes the same error is being thrown. Here is the request in cURL:

curl -X POST -H "Content-Type: application/json" -H "Accept: application/vnd.myscript.latex,application/json" -H "applicationKey: *******" -H "hmac: ******" -d "{\"contentType\": \"Math\", \"strokeGroups\": []}" https://cloud.myscript.com/api/v4.0/iink/batch

Thank you for the response. Unfortunately, I'm still getting access not granted. Do you believe it is an error in the generation of the hmac?