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Thread: Help with Kraken API POST Method

  1. #1

    Thread Starter
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    Dec 2013
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    71

    Help with Kraken API POST Method

    I'm having trouble getting a POST code to work for the Kraken API. My issue is in the way the API-SIGN is encrypted/sent in the HTTP Header I think. Here is what the HTTP header is SUPPOSED to be sent as:

    API-Key = API key
    API-Sign = Message signature using HMAC-SHA512 of (URI path + SHA256(nonce + POST data)) and base64 decoded secret API key

    Also shown here https://www.kraken.com/help/api#general-usage

    And here are the three functions I've put together by working through other examples and POST programs I've built in the past:

    Code:
     Private Function QueryPrivate(a_sMethod As String, Optional props As String = Nothing) As String
            ' generate a 64 bit nonce using a timestamp at tick resolution
            _url = "https://api.kraken.com"
            _version = 0
            _key = "Key Here"
            _secret = "Secret Here"
    
            _rateGate = New RateGate(1, TimeSpan.FromSeconds(5))
            Dim nonce As Int64 = DateTime.Now.Ticks
            props = Convert.ToString("nonce=" + nonce.ToString()) & props
    
    
            Dim path As String = String.Format("/{0}/private/{1}", _version, a_sMethod)
            Dim address As String = _url & path
            Dim webRequest__1 As HttpWebRequest = DirectCast(WebRequest.Create(address), HttpWebRequest)
            webRequest__1.ContentType = "application/x-www-form-urlencoded"
            webRequest__1.Method = "POST"
            webRequest__1.Headers.Add("API-Key", _key)
    
    
            Dim base64DecodedSecred As Byte() = Convert.FromBase64String(_secret)
    
            Dim np = nonce.ToString() + Convert.ToChar(0) + props
    
            Dim pathBytes = Encoding.UTF8.GetBytes(path)
            Dim hash256Bytes = sha256_hash(np)
            Dim z = New Byte(pathBytes.Count() + (hash256Bytes.Count() - 1)) {}
            pathBytes.CopyTo(z, 0)
            hash256Bytes.CopyTo(z, pathBytes.Count())
    
            Dim signature = getHash(base64DecodedSecred, z)
    
            webRequest__1.Headers.Add("API-Sign", Convert.ToBase64String(signature))
    
            If props IsNot Nothing Then
    
                Using writer = New StreamWriter(webRequest__1.GetRequestStream())
                    writer.Write(props)
                End Using
            End If
    
            'Make the request
            Try
                'Wait for RateGate
                _rateGate.WaitToProceed()
    
                Using webResponse As WebResponse = webRequest__1.GetResponse()
                    Using str As Stream = webResponse.GetResponseStream()
                        Using sr As New StreamReader(str)
                            Dim responseContent3 As String = sr.ReadToEnd
                            Return responseContent3
                        End Using
                    End Using
                End Using
            Catch wex As WebException
                Using response As HttpWebResponse = DirectCast(wex.Response, HttpWebResponse)
                    Using str As Stream = response.GetResponseStream()
                        Using sr As New StreamReader(str)
                            Dim responseContent3 As String = sr.ReadToEnd
                            Return responseContent3
                        End Using
                    End Using
    
                End Using
            End Try
        End Function
        Private Function sha256_hash(value As [String]) As Byte()
            Using hash As SHA256 = SHA256Managed.Create()
                Dim enc As Encoding = Encoding.UTF8
    
                Dim result As [Byte]() = hash.ComputeHash(enc.GetBytes(value))
    
                Return result
            End Using
        End Function
    
        Private Function getHash(keyByte As Byte(), messageBytes As Byte()) As Byte()
            Using hmacsha512 = New HMACSHA512(keyByte)
    
                Dim result As [Byte]() = hmacsha512.ComputeHash(messageBytes)
    
    
                Return result
            End Using
        End Function
    Running the QueryPrivate function for say the account balances, gives me back an invalid key response. I'm not great with these encryptions. Hopefully someone else is better at them then me!

  2. #2
    New Member
    Join Date
    Jan 2018
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    2

    Exclamation Re: Help with Kraken API POST Method

    This message is from July, but since I have encountered exactly the same problem, I guess there are hundreds will run on the same brick wall. So I give what I found, to help the future reader of this message.

    This sub has been translated from C # (the example given on the kraken site).
    The C# compiled and referenced in my VB project works, the same sub translated in VB don't !

    After one day of mind-boggling, i logged each variable and i found this:

    np = 636529969190892278nonce=636529969190892278 (C#)
    np = 636529969355408169 nonce=636529969355408169 (VB)

    Apparently, VB and C# don't interpret tochar(0) in the same way.

    so i used:

    Code:
    Dim np = nonce & props
    instead of

    Code:
    Dim np = nonce & Convert.ToChar(0) & props

    and it's works ... enjoy



    I don't understand of course, anything in that, it would be nice that a specialist explain what happens with this ToChar(0). And why VB and C# don't understand this character in the same way.

  3. #3
    You don't want to know.
    Join Date
    Aug 2010
    Posts
    4,462

    Re: Help with Kraken API POST Method

    I just tested and that is not what I observed, but perhaps it matters how you output the string.

    The character with code '0' is generally "the null character", which shouldn't be printed at all. I don't see anything in that API documentation that says it should be there at all. I'm not sure why OP put it there.
    This answer is wrong. You should be using TableAdapter and Dictionaries instead.

  4. #4
    New Member
    Join Date
    Jan 2018
    Posts
    2

    Re: Help with Kraken API POST Method

    Quote Originally Posted by Sitten Spynne View Post
    I just tested and that is not what I observed, but perhaps it matters how you output the string.
    i wrote them in a txt file.

    I'm not sure why OP put it there.
    Me neither, after test, the C# function works well without this character

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