I am looking at integrating a public api in to an existing windows form application. The api requires openAuth authentication. All examples of this that I have seen are on web based applications.
How can openAUth be used on a client application?
thanks
Its not the easiest of things to explain, but I did this for a YouTube implementation:
I built a ShardOAuth Class that builds the messages:
#Region "Imports"
Imports System.Text
Imports System.Security.Cryptography
#End Region
Public NotInheritable Class SharedOAuth
#Region "Class Declarations"
Private Const unreservedChars As String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~"
Private Const OAuthVersion As String = "1.0"
Private Const OAuthParameterPrefix As String = "oauth_"
Private Const OAuthParameterExclusionPrefix As String = "xoauth_"
Private Const OAuthConsumerKeyKey As String = "oauth_consumer_key"
Private Const OAuthCallbackKey As String = "oauth_callback"
Private Const OAuthVersionKey As String = "oauth_version"
Private Const OAuthSignatureMethodKey As String = "oauth_signature_method"
Private Const OAuthSignatureKey As String = "oauth_signature"
Private Const OAuthTimestampKey As String = "oauth_timestamp"
Private Const OAuthNonceKey As String = "oauth_nonce"
Private Const OAuthTokenKey As String = "oauth_token"
Private Const OAuthTokenSecretKey As String = "oauth_token_secret"
#End Region
#Region "Constructor"
Private Sub New()
'prevent construction
End Sub
#End Region
#Region "Shared Functions"
Public Shared Function GetSignatureTypeNameFromType(ByVal signatureType As enumerations.OAuthEnumerations.SignatureTypes) As String
Select Case signatureType
Case enumerations.OAuthEnumerations.SignatureTypes.HmacSha1
Return "HMAC-SHA1"
Case Else
Return String.Empty
End Select
End Function
Public Shared Function GenerateTimeStamp() As String
'Implementation of UNIX current UTC time
Dim _ts As TimeSpan = DateTime.UtcNow - New DateTime(1970, 1, 1, 0, 0, 0, 0)
Return Convert.ToInt64(_ts.TotalSeconds).ToString(CultureInfo.InvariantCulture)
End Function
Public Shared Function GenerateNonce() As String
'Some random Number
Return New Random().Next(123400, 9999999).ToString
End Function
Public Shared Function UrlEncode(ByVal value As String) As String
Dim _result As New StringBuilder
If (String.IsNullOrEmpty(value)) Then
Return value
End If
For Each _symbol As Char In value
If unreservedChars.IndexOf(_symbol) <> -1 Then
_result.Append(_symbol)
Else
_result.Append(String.Format("%{0}", String.Format("{0:X2}", Asc(_symbol))))
End If
Next
Return _result.ToString
End Function
''' <summary>
'''Generates a signature using the specified signatureType
''' </summary>
''' <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
''' <param name="consumerKey">The consumer key</param>
''' <param name="consumerSecret">The consumer seceret</param>
''' <param name="token">The token, if available. If not available pass null or an empty string</param>
''' <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
''' <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
''' <param name="signatureType">The type of signature to use</param>
''' <returns>A base64 string of the hash value</returns>
Public Shared Function GenerateSignature(ByVal url As Uri, ByVal consumerKey As String, ByVal consumerSecret As String, ByVal token As String, ByVal tokenSecret As String, ByVal httpMethod As String, ByVal timeStamp As String, ByVal nonce As String, ByVal signatureType As enumerations.OAuthEnumerations.SignatureTypes, ByRef normalizedUrl As String, ByRef normalizedRequestParameters As String) As String
normalizedUrl = String.Empty
normalizedRequestParameters = String.Empty
Dim _signatureBase As String
Dim _hash As HMACSHA1
Select Case signatureType
Case enumerations.OAuthEnumerations.SignatureTypes.HmacSha1
_signatureBase = GenerateSignatureBase(url, consumerKey, token, tokenSecret, httpMethod, timeStamp, nonce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, normalizedUrl, normalizedRequestParameters)
Dim _sb As New StringBuilder
With _sb
.Append(UrlEncode(consumerSecret))
.Append("&")
If (String.IsNullOrEmpty(tokenSecret)) Then
.Append("")
Else
.Append(UrlEncode(tokenSecret))
End If
End With
_hash = New HMACSHA1
_hash.Key = Encoding.ASCII.GetBytes(_sb.ToString)
Return GenerateSignatureUsingHash(_signatureBase, _hash)
Case Else
Throw New NotImplementedException
End Select
End Function
Public Shared Function GenerateSignatureUsingHash(ByVal signatureBase As String, ByVal hash As HashAlgorithm) As String
Return ComputeHash(hash, signatureBase)
End Function
Public Shared Function GenerateSignatureBase(ByVal url As Uri, ByVal consumerKey As String, ByVal token As String, ByVal tokenSecret As String, ByVal httpMethod As String, ByVal timeStamp As String, ByVal nonce As String, ByVal signatureType As enumerations.OAuthEnumerations.SignatureTypes, ByRef normalizedUrl As String, ByRef normalizedRequestParameters As String) As String
Dim _SignatureTypeName As String = GetSignatureTypeNameFromType(signatureType)
If String.IsNullOrEmpty(token) Then
token = String.Empty
End If
If String.IsNullOrEmpty(tokenSecret) Then
tokenSecret = String.Empty
End If
If String.IsNullOrEmpty(consumerKey) Then
Throw New ArgumentNullException("consumerKey")
End If
If String.IsNullOrEmpty(httpMethod) Then
Throw New ArgumentNullException("httpMethod")
End If
If String.IsNullOrEmpty(_SignatureTypeName) Then
Throw New ArgumentNullException("SignatureType")
End If
normalizedUrl = String.Empty
normalizedRequestParameters = String.Empty
Dim _params As List(Of QueryParameter) = getqueryparameters(url.Query)
With _params
.Add(New QueryParameter(OAuthVersionKey, OAuthVersion))
.Add(New QueryParameter(OAuthNonceKey, nonce))
.Add(New QueryParameter(OAuthTimestampKey, timeStamp))
.Add(New QueryParameter(OAuthSignatureMethodKey, _SignatureTypeName))
.Add(New QueryParameter(OAuthConsumerKeyKey, consumerKey))
If Not (String.IsNullOrEmpty(token)) Then
.Add(New QueryParameter(OAuthTokenKey, token))
End If
.Sort(New QueryParameterComparer)
End With
normalizedUrl = String.Format("{0}://{1}", url.Scheme, url.Host)
If Not ((url.Scheme = "http" AndAlso url.Port = 80) OrElse (url.Scheme = "https" AndAlso url.Port = 443)) Then
normalizedUrl = String.Format("{0}:{1}", normalizedUrl, url.Port)
End If
normalizedUrl = String.Format("{0}{1}", normalizedUrl, url.AbsolutePath)
normalizedRequestParameters = NormalizeRequestParameters(_params)
Dim _sb As New StringBuilder
With _sb
.AppendFormat(CultureInfo.InvariantCulture, "{0}&", httpMethod.ToUpper)
.AppendFormat(CultureInfo.InvariantCulture, "{0}&", UrlEncode(normalizedUrl))
.AppendFormat(CultureInfo.InvariantCulture, "{0}", UrlEncode(normalizedRequestParameters))
End With
Return _sb.ToString
End Function
#End Region
#Region "Private Methods"
Private Shared Function ComputeHash(ByVal hashAlgorithm As HashAlgorithm, ByVal data As String) As String
If hashAlgorithm Is Nothing Then
Throw New ArgumentNullException("hashAlgorithm")
End If
If String.IsNullOrEmpty(data) Then
Throw New ArgumentNullException("data")
End If
Dim _dataBuffer As Byte() = Encoding.ASCII.GetBytes(data)
Dim _hashBytes As Byte() = hashAlgorithm.ComputeHash(_dataBuffer)
Return Convert.ToBase64String(_hashBytes)
End Function
Private Shared Function NormalizeRequestParameters(ByVal parameters As IList(Of QueryParameter)) As String
Dim _p As QueryParameter
Dim _sb As New StringBuilder
For i As Integer = 0 To parameters.count - 1
_p = parameters(i)
_sb.AppendFormat(CultureInfo.InvariantCulture, "{0}={1}", _p.Name, _p.Value)
If i < parameters.count - 1 Then
_sb.Append("&")
End If
Next
Return _sb.ToString
End Function
Private Shared Function GetQueryParameters(ByVal parameters As String) As List(Of QueryParameter)
If (parameters.StartsWith("?")) Then
parameters = parameters.Remove(0, 1)
End If
Dim _result As New List(Of QueryParameter)
Dim _p As String() = parameters.Split("&"c)
Dim _temp As String()
If Not (String.IsNullOrEmpty(parameters)) Then
For Each s As String In _p
If Not (String.IsNullOrEmpty(s)) AndAlso Not (s.StartsWith(OAuthParameterExclusionPrefix)) Then 'AndAlso (s.StartsWith(OAuthParameterPrefix)) Then
If s.IndexOf("=") > -1 Then
_temp = s.Split("="c)
_result.Add(New QueryParameter(_temp(0), _temp(1)))
Else
_result.Add(New QueryParameter(s, String.Empty))
End If
End If
Next
End If
Return _result
End Function
#End Region
End Class
And then a Class to use these lower level functions to build and Parse the OAuth Messages
Public MustInherit Class BaseOAuth
Inherits BaseAccess
#Region "Class Declarations"
Protected Const CONSUMER_KEY As String = "anonymous"
Protected Const CONSUMER_SECRET As String = "anonymous"
Protected Const SCOPEURL As String = "http://gdata.youtube.com" '
Protected m_FeedCollection As ArrayList
#End Region
#Region "Constructor"
Public Sub New()
MyBase.new()
End Sub
Public Sub New(ByVal context As Common.Statefulogic.Context)
MyBase.new(context)
End Sub
#End Region
#Region "Public Properties"
#End Region
#Region "Private Functions"
#End Region
#Region "Public Methods"
Public Function SignCommandUrl(ByVal commandUrl As String) As String
Return SignCommandUrl(commandUrl, Nothing, Nothing)
End Function
Public Function SignCommandUrl(ByVal commandUrl As String, ByVal overrideToken As String, ByVal overrideTokenSecret As String) As String
Dim _commandUri = New Uri(commandUrl)
Dim _oAuthSignature As String
Dim _oAuthTimeStamp As String = SharedOAuth.GenerateTimeStamp
Dim _oAuthNOnce As String = SharedOAuth.GenerateNonce
Dim _oAuth_normalized_url As String = String.Empty
Dim _oAuth_normalized_params As String = String.Empty
If Not (String.IsNullOrEmpty(overrideToken)) OrElse Not (String.IsNullOrEmpty(overrideTokenSecret)) Then
_oAuthSignature = SharedOAuth.GenerateSignature(_commandUri, CONSUMER_KEY, CONSUMER_SECRET, overrideToken, overrideTokenSecret, "GET", _oAuthTimeStamp, _oAuthNOnce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, _oAuth_normalized_url, _oAuth_normalized_params)
Else
If MasterAccessToken Is Nothing Then
_oAuthSignature = SharedOAuth.GenerateSignature(_commandUri, CONSUMER_KEY, CONSUMER_SECRET, String.Empty, String.Empty, "GET", _oAuthTimeStamp, _oAuthNOnce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, _oAuth_normalized_url, _oAuth_normalized_params)
Else
_oAuthSignature = SharedOAuth.GenerateSignature(_commandUri, CONSUMER_KEY, CONSUMER_SECRET, SharedOAuth.UrlEncode(MasterAccessToken.Token), MasterAccessToken.TokenSecret, "GET", _oAuthTimeStamp, _oAuthNOnce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, _oAuth_normalized_url, _oAuth_normalized_params)
End If
End If
'Get a token
Dim _sb As New System.Text.StringBuilder
With _sb
.Append(_oAuth_normalized_url)
.Append("?")
.Append(_oAuth_normalized_params)
.Append("&")
.Append("oauth_signature")
.Append("=")
.Append(SharedOAuth.UrlEncode(_oAuthSignature))
End With
Return _sb.ToString
End Function
Public Function BuildPostHeader(ByVal commandUrl As String) As String
Dim _commandUri = New Uri(commandUrl)
Dim _oAuthTimeStamp As String = SharedOAuth.GenerateTimeStamp
Dim _oAuthNOnce As String = SharedOAuth.GenerateNonce
Dim _oAuth_normalized_url As String = String.Empty
Dim _oAuth_normalized_params As String = String.Empty
Dim _oAuthSignature As String
If MasterAccessToken Is Nothing Then
_oAuthSignature = SharedOAuth.GenerateSignature(_commandUri, CONSUMER_KEY, CONSUMER_SECRET, String.Empty, String.Empty, "POST", _oAuthTimeStamp, _oAuthNOnce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, _oAuth_normalized_url, _oAuth_normalized_params)
Else
_oAuthSignature = SharedOAuth.GenerateSignature(_commandUri, CONSUMER_KEY, CONSUMER_SECRET, SharedOAuth.UrlEncode(MasterAccessToken.Token), MasterAccessToken.TokenSecret, "POST", _oAuthTimeStamp, _oAuthNOnce, enumerations.OAuthEnumerations.SignatureTypes.HmacSha1, _oAuth_normalized_url, _oAuth_normalized_params)
End If
Dim _sb As New System.Text.StringBuilder
With _sb
.Append("Authorization: OAuth oauth_version=""1.0"", ")
.AppendFormat("oauth_nonce=""{0}"", ", _oAuthNOnce)
.AppendFormat("oauth_timestamp=""{0}"", ", _oAuthTimeStamp)
.AppendFormat("oauth_consumer_key=""{0}"", ", CONSUMER_KEY)
.AppendFormat("oauth_token=""{0}"", ", MasterAccessToken.Token)
.Append("oauth_signature_method=""HMAC-SHA1"", ")
.AppendFormat("oauth_signature=""{0}""", _oAuthSignature)
End With
Return _sb.ToString
End Function
Public Shared Function PostRequestReturnCollection(ByVal commandUrl As String) As NameValueCollection
Dim _nameValCollection As NameValueCollection
Dim _request As HttpWebRequest = CType(WebRequest.Create(commandUrl), HttpWebRequest)
Using _response As HttpWebResponse = CType(_request.GetResponse, HttpWebResponse)
Using _reader As TextReader = New StreamReader(_response.GetResponseStream)
_nameValCollection = HttpUtility.ParseQueryString(_reader.ReadToEnd)
End Using
End Using
Return _nameValCollection
End Function
#End Region
End Class
And Finally a Call to Get the OAuth Tokens..
Public Function RequestApplicationAccess() As TokenParams
Dim _oAuthCallbackConfirmed As Boolean
Dim _oAuthTokenUrl As String
Dim _oauth_Authenticate_Page As String
Dim _oAuthtokendataCollection As NameValueCollection
Dim _request As HttpWebRequest
Dim _oauth_token As String = String.Empty
Dim _oauth_token_secret As String = String.Empty
Dim _oauth_verifier As String = String.Empty
m_CallbackSite = "http://www.previewthebestof.co.uk/_services/googleauth.aspx"
'Generate a signature
Dim _RequestUrl As String = "https://www.google.com/accounts/OAuthGetRequestToken"
_oAuthTokenUrl = SignCommandUrl(String.Format("{0}?scope={1}&oauth_callback={2}&xoauth_displayname={3}", _RequestUrl, SharedOAuth.UrlEncode(SCOPEURL), SharedOAuth.UrlEncode(m_CallbackSite), SharedOAuth.UrlEncode(APPDISPLAYNAME)))
_oAuthtokendataCollection = PostRequestReturnCollection(_oAuthTokenUrl)
_oauth_token = _oAuthtokendataCollection.Item("oauth_token")
_oauth_token_secret = _oAuthtokendataCollection.Item("oauth_token_secret")
If _oAuthtokendataCollection.Count = 3 Then
_oAuthCallbackConfirmed = CType(_oAuthtokendataCollection.Item("oauth_callback_confirmed"), Boolean)
End If
If String.IsNullOrEmpty(_oauth_token) OrElse String.IsNullOrEmpty(_oauth_token_secret) Then
Throw New N5.Common.ExceptionManager.N5Exception("Cannot get an authentication token (_oauth_token or _oauth_token_secret is blank)")
End If
'----------------------------------------------------
'Write the token to the users profile
m_Context.UserObject.SetUserAuthenticationTokens(_oauth_token, String.Empty, String.Empty, String.Empty)
'-----------------------------------------------------
'Authorize the token
_RequestUrl = "https://www.google.com/accounts/OAuthAuthorizeToken"
_oAuthTokenUrl = String.Format("{0}?oauth_token={1}", _RequestUrl, SharedOAuth.UrlEncode(_oauth_token))
_request = CType(WebRequest.Create(_oAuthTokenUrl), HttpWebRequest)
Using _response = CType(_request.GetResponse, HttpWebResponse)
Using _reader As TextReader = New StreamReader(_response.GetResponseStream)
_oauth_Authenticate_Page = _reader.ReadToEnd
End Using
End Using
If Not (_oauth_Authenticate_Page.ToLower.Contains("<html>")) Then
Throw New N5.Common.ExceptionManager.N5Exception("AuthToken Respose does not contain a webpage")
End If
'Response contains html, which is the youtube authentication page - need to show this to the user
'write to temp file
Dim _tempFileName As String = IO.Path.Combine(My.Computer.FileSystem.SpecialDirectories.Temp, String.Concat(FilenameUtilities.GetRandomFilename, ".htm"))
Using _tempFile As New StreamWriter(_tempFileName)
_tempFile.Write(_oauth_Authenticate_Page)
End Using
'Load a browser form and navigate to the file just created.
Using _browser As New BasePopupBrowser
With _browser
.WindowState = FormWindowState.Maximized
.AutoCloseText = "<H1>OAuth Token Authorised</H1>"
.CheckForAutoCloseText = True
.NavigateTo(New System.Uri(_tempFileName))
End With
End Using
'Clean up the tempfile
My.Computer.FileSystem.DeleteFile(_tempFileName)
'------------------------------------------------------
'Check the db for a request_token - did the user press authorise?
m_Context.UserObject.RefreshUserAuthenticationTokens()
Dim _dv As DataView = m_Context.UserObject.AuthenticationTokensDataView
_dv.RowFilter = "TokenName='YouTubeAuthVerifier'"
If _dv.Count > 0 Then
_oauth_verifier = _dv(0)("Value").ToString
End If
If String.IsNullOrEmpty(_oauth_verifier) Then
'We didnt get a verification token back, chances are the user pressed reject, Doh!
Return Nothing
End If
'---------------------------------------------------------
'Now we need to exchange the request token for an access token
_RequestUrl = String.Format("https://www.google.com/accounts/OAuthGetAccessToken?oauth_verifier={0}", SharedOAuth.UrlEncode(_oauth_verifier))
_oAuthTokenUrl = SignCommandUrl(_RequestUrl, _oauth_token, _oauth_token_secret)
_oAuthtokendataCollection = PostRequestReturnCollection(_oAuthTokenUrl)
_oauth_token = _oAuthtokendataCollection.Item("oauth_token")
_oauth_token_secret = _oAuthtokendataCollection.Item("oauth_token_secret")
m_Context.UserObject.SetUserAuthenticationTokens(String.Empty, String.Empty, _oauth_token, _oauth_token_secret)
Return New TokenParams(_oauth_token, _oauth_token_secret)
End Function
The Wrox book Professional Twitter Development: With Examples in .NET 3.5 has a walkthrough of doing OAuth from a C# client, and the code is available as a free download from their website.