How to: Create a Custom Token

This topic shows how to create a custom security token using the SecurityToken class, and how to integrate it with a custom security token provider and authenticator. For a complete code example see the Custom Token sample.

A security token is essentially an XML element that is used by the Windows Communication Foundation (WCF) security framework to represent claims about a sender inside the SOAP message. WCF security provides various tokens for system-provided authentication modes. Examples include an X.509 certificate security token represented by the X509SecurityToken class or a Username security token represented by the UserNameSecurityToken class.

Sometimes an authentication mode or credential is not supported by the provided types. In that case, it is necessary to create a custom security token to provide an XML representation of the custom credential inside the SOAP message.

The following procedures show how to create a custom security token and how to integrate it with the WCF security infrastructure. This topic creates a credit card token that is used to pass information about the client's credit card to the server.

For more information about custom credentials and security token manager, see Walkthrough: Creating Custom Client and Service Credentials.

See the System.IdentityModel.Tokens namespace for more classes that represent security tokens.

For more information about credentials, security token manager, and provider and authenticator classes, see Security Architecture.

Procedures

A client application must be provided with a way to specify credit card information for the security infrastructure. This information is made available to the application by a custom client credentials class. The first step is to create a class to represent the credit card information for custom client credentials.

To create a class that represents credit card information inside client credentials

  1. Define a new class that represents the credit card information for the application. The following example names the class CreditCardInfo.

  2. Add appropriate properties to the class to allow an application set the necessary information required for the custom token. In this example, the class has three properties: CardNumber, CardIssuer, and ExpirationDate.

    public class CreditCardInfo
    {
        string cardNumber;
        string cardIssuer;
        DateTime expirationDate;
    
        public CreditCardInfo(string cardNumber, string cardIssuer, DateTime expirationDate)
        {
            this.cardNumber = cardNumber;
            this.cardIssuer = cardIssuer;
            this.expirationDate = expirationDate;
        }
    
        public string CardNumber
        {
            get { return this.cardNumber; }
        }
    
        public string CardIssuer
        {
            get { return this.cardIssuer; }
        }
    
        public DateTime ExpirationDate
        {
            get { return this.expirationDate; }
        }
    }
    
    Public Class CreditCardInfo
    
        Private _cardNumber As String
        Private _cardIssuer As String
        Private _expirationDate As DateTime
    
        Public Sub New(ByVal cardNumber As String, ByVal cardIssuer As String, _
                       ByVal expirationDate As DateTime)
            Me._cardNumber = cardNumber
            Me._cardIssuer = cardIssuer
            Me._expirationDate = expirationDate
        End Sub
    
        Public ReadOnly Property CardNumber() As String
            Get
                Return Me._cardNumber
            End Get
        End Property
    
        Public ReadOnly Property CardIssuer() As String
            Get
                Return Me._cardIssuer
            End Get
        End Property
    
        Public ReadOnly Property ExpirationDate() As DateTime
            Get
                Return Me._expirationDate
            End Get
        End Property
    
    End Class
    

Next, a class that represents the custom security token must be created. This class is used by the security token provider, authenticator, and serializer classes to pass information about the security token to and from the WCF security infrastructure.

To create a custom security token class

  1. Define a new class derived from the SecurityToken class. This example creates a class named CreditCardToken.

  2. Override the Id property. This property is used to get the local identifier of the security token that is used to point to the security token XML representation from other elements inside the SOAP message. In this example, a token identifier can be either passed to it as a constructor parameter or a new random one is generated every time a security token instance is created.

  3. Implement the SecurityKeys property. This property returns a collection of security keys that the security token instance represents. Such keys can be used by WCF to sign or encrypt parts of the SOAP message. In this example, the credit card security token cannot contain any security keys; therefore, the implementation always returns an empty collection.

  4. Override the ValidFrom and ValidTo properties. These properties are used by WCF to determine the validity of the security token instance. In this example, the credit card security token has only an expiration date, so the ValidFrom property returns a DateTime that represents the date and time of the instance creation.

    class CreditCardToken : SecurityToken
    {
        CreditCardInfo cardInfo;
        DateTime effectiveTime = DateTime.UtcNow;
        string id;
        ReadOnlyCollection<SecurityKey> securityKeys;
    
        public CreditCardToken(CreditCardInfo cardInfo) : this(cardInfo, Guid.NewGuid().ToString()) { }
    
        public CreditCardToken(CreditCardInfo cardInfo, string id)
        {
            if (cardInfo == null)
            {
                throw new ArgumentNullException("cardInfo");
            }
            if (id == null)
            {
                throw new ArgumentNullException("id");
            }
    
            this.cardInfo = cardInfo;
            this.id = id;
            // The credit card token is not capable of any cryptography.
            this.securityKeys = new ReadOnlyCollection<SecurityKey>(new List<SecurityKey>());
        }
    
        public CreditCardInfo CardInfo 
        { 
            get { return this.cardInfo; } 
        }
    
        public override ReadOnlyCollection<SecurityKey> SecurityKeys 
        { 
            get { return this.securityKeys; } 
        }
    
        public override DateTime ValidFrom 
        { 
            get { return this.effectiveTime; } 
        }
    
        public override DateTime ValidTo 
        { 
            get { return this.cardInfo.ExpirationDate; } 
        }
        
        public override string Id 
        { 
            get { return this.id; } 
        }
    }
    
    Friend Class CreditCardToken
        Inherits SecurityToken
    
        Private _cardInfo As CreditCardInfo
        Private _effectiveTime As DateTime = DateTime.UtcNow
        Private _id As String
        Private _securityKeys As ReadOnlyCollection(Of SecurityKey)
    
        Public Sub New(ByVal cardInfo As CreditCardInfo)
            Me.New(cardInfo, Guid.NewGuid().ToString())
        End Sub
    
        Public Sub New(ByVal cardInfo As CreditCardInfo, _
                       ByVal id As String)
            If cardInfo Is Nothing Then
                Throw New ArgumentNullException("cardInfo")
            End If
            If id Is Nothing Then
                Throw New ArgumentNullException("id")
            End If
    
            Me._cardInfo = cardInfo
            Me._id = id
            ' The credit card token is not capable of any cryptography.
            Me._securityKeys = New ReadOnlyCollection(Of SecurityKey)(New List(Of SecurityKey)())
        End Sub
    
        Public ReadOnly Property CardInfo() As CreditCardInfo
            Get
                Return Me._cardInfo
            End Get
        End Property
    
        Public Overrides ReadOnly Property SecurityKeys() As ReadOnlyCollection(Of SecurityKey)
            Get
                Return Me._securityKeys
            End Get
        End Property
    
        Public Overrides ReadOnly Property ValidFrom() As DateTime
            Get
                Return Me._effectiveTime
            End Get
        End Property
    
        Public Overrides ReadOnly Property ValidTo() As DateTime
            Get
                Return Me._cardInfo.ExpirationDate
            End Get
        End Property
    
        Public Overrides ReadOnly Property Id() As String
            Get
                Return Me._id
            End Get
        End Property
    End Class
    

When a new security token type is created, it requires an implementation of the SecurityTokenParameters class. The implementation is used in the security binding element configuration to represent the new token type. The security token parameters class serves as a template that is used to match the actual security token instance to when a message is processed. The template provides additional properties that an application can use to specify criteria that the security token must match to be used or authenticated. The following example does not add any additional properties, so only the security token type is matched when the WCF infrastructure searches for a security token instance to use or to validate.

To create a custom security token parameters class

  1. Define a new class derived from the SecurityTokenParameters class.

  2. Implement the CloneCore method. Copy all internal fields defined in your class, if any. This example does not define any additional fields.

  3. Implement the SupportsClientAuthentication read-only property. This property returns true if the security token type represented by this class can be used to authenticate a client to a service. In this example, the credit card security token can be used to authenticate a client to a service.

  4. Implement the SupportsServerAuthentication read-only property. This property returns true if the security token type represented by this class can be used to authenticate a service to a client. In this example, the credit card security token cannot be used to authenticate a service to a client.

  5. Implement the SupportsClientWindowsIdentity read-only property. This property returns true if the security token type represented by this class can be mapped to a Windows account. If so, the authentication result is represented by a WindowsIdentity class instance. In this example, the token cannot be mapped to a Windows account.

  6. Implement the CreateKeyIdentifierClause(SecurityToken, SecurityTokenReferenceStyle) method. This method is called by WCF security framework when it requires a reference to the security token instance represented by this security token parameters class. Both the actual security token instance and SecurityTokenReferenceStyle that specifies the type of the reference that is being requested are passed to this method as arguments. In this example, only internal references are supported by the credit card security token. The SecurityToken class has functionality to create internal references; therefore, the implementation does not require additional code.

  7. Implement the InitializeSecurityTokenRequirement(SecurityTokenRequirement) method. This method is called by WCF to convert the security token parameters class instance into an instance of the SecurityTokenRequirement class. The result is used by security token providers to create the appropriate security token instance.

    public class CreditCardTokenParameters : SecurityTokenParameters
    {
        public CreditCardTokenParameters()
        {
        }
    
        protected CreditCardTokenParameters(CreditCardTokenParameters other)
            : base(other)
        {
        }
    
        protected override SecurityTokenParameters CloneCore()
        {
            return new CreditCardTokenParameters(this);
        }
    
        protected override void InitializeSecurityTokenRequirement(SecurityTokenRequirement requirement)
        {
            requirement.TokenType = Constants.CreditCardTokenType;
            return;
        }
    
        // A credit card token has no cryptography, no windows identity, and supports only client authentication.
        protected override bool HasAsymmetricKey 
        { 
            get { return false; } 
        }
        
        protected override bool SupportsClientAuthentication 
        { 
            get { return true; } 
        }
        
        protected override bool SupportsClientWindowsIdentity 
        { 
            get { return false; } 
        }
        
        protected override bool SupportsServerAuthentication 
        { 
            get { return false; } 
        }
    
        protected override SecurityKeyIdentifierClause CreateKeyIdentifierClause(SecurityToken token, SecurityTokenReferenceStyle referenceStyle)
        {
            if (referenceStyle == SecurityTokenReferenceStyle.Internal)
            {
                return token.CreateKeyIdentifierClause<LocalIdKeyIdentifierClause>();
            }
            else
            {
                throw new NotSupportedException("External references are not supported for credit card tokens");
            }
        }
    }
    
    Public Class CreditCardTokenParameters
        Inherits SecurityTokenParameters
    
        Public Sub New()
        End Sub
    
        Protected Sub New(ByVal other As CreditCardTokenParameters)
            MyBase.New(other)
        End Sub
    
        Protected Overrides Function CloneCore() As SecurityTokenParameters
            Return New CreditCardTokenParameters(Me)
        End Function
    
        Protected Overrides Sub InitializeSecurityTokenRequirement(ByVal requirement As SecurityTokenRequirement)
            requirement.TokenType = Constants.CreditCardTokenType
            Return
        End Sub
    
        ' A credit card token has no cryptography, no windows identity, and supports only client authentication.
        Protected Overrides ReadOnly Property HasAsymmetricKey() As Boolean
            Get
                Return False
            End Get
        End Property
    
        Protected Overrides ReadOnly Property SupportsClientAuthentication() As Boolean
            Get
                Return True
            End Get
        End Property
    
        Protected Overrides ReadOnly Property SupportsClientWindowsIdentity() As Boolean
            Get
                Return False
            End Get
        End Property
    
        Protected Overrides ReadOnly Property SupportsServerAuthentication() As Boolean
            Get
                Return False
            End Get
        End Property
    
        Protected Overrides Function CreateKeyIdentifierClause(ByVal token As SecurityToken, _
                                                               ByVal referenceStyle As SecurityTokenReferenceStyle) As SecurityKeyIdentifierClause
            If referenceStyle = SecurityTokenReferenceStyle.Internal Then
                Return token.CreateKeyIdentifierClause(Of LocalIdKeyIdentifierClause)()
            Else
                Throw New NotSupportedException("External references are not supported for credit card tokens")
            End If
        End Function
    
    End Class
    

Security tokens are transmitted inside SOAP messages, which requires a translation mechanism between the in-memory security token representation and the on-the-wire representation. WCF uses a security token serializer to accomplish this task. Every custom token must be accompanied by a custom security token serializer that can serialize and deserialize the custom security token from the SOAP message.

Note

Derived keys are enabled by default. If you create a custom security token and use it as the primary token, WCF derives a key from it. While doing so, it calls the custom security token serializer to write the SecurityKeyIdentifierClause for the custom security token while serializing the DerivedKeyToken to the wire. On the receiving end, when deserializing the token off the wire, the DerivedKeyToken serializer expects a SecurityTokenReference element as the top-level child under itself. If the custom security token serializer did not add a SecurityTokenReference element while serializing its clause type, an exception is thrown.

To create a custom security token serializer

  1. Define a new class derived from the WSSecurityTokenSerializer class.

  2. Override the CanReadTokenCore(XmlReader) method, which relies on an XmlReader to read the XML stream. The method returns true if the serializer implementation can deserialize the security token based given its current element. In this example, this method checks whether the XML reader's current XML element has the correct element name and namespace. If it does not, it calls the base class implementation of this method to handle the XML element.

  3. Override the ReadTokenCore(XmlReader, SecurityTokenResolver) method. This method reads the XML content of the security token and constructs the appropriate in-memory representation for it. If it does not recognize the XML element on which the passed-in XML reader is standing, it calls the base class implementation to process the system-provided token types.

  4. Override the CanWriteTokenCore(SecurityToken) method. This method returns true if it can convert the in-memory token representation (passed in as an argument) to the XML representation. If it cannot convert, it calls the base class implementation.

  5. Override the WriteTokenCore(XmlWriter, SecurityToken) method. This method converts an in-memory security token representation into an XML representation. If the method cannot convert, it calls the base class implementation.

    public class CreditCardSecurityTokenSerializer : WSSecurityTokenSerializer
    {
        public CreditCardSecurityTokenSerializer(SecurityTokenVersion version) : base() { }
    
        protected override bool CanReadTokenCore(XmlReader reader)
        {
            XmlDictionaryReader localReader = XmlDictionaryReader.CreateDictionaryReader(reader);
            if (reader == null)
            {
                throw new ArgumentNullException("reader");
            }
            if (reader.IsStartElement(Constants.CreditCardTokenName, Constants.CreditCardTokenNamespace))
            {
                return true;
            }
            return base.CanReadTokenCore(reader);
        }
    
        protected override SecurityToken ReadTokenCore(XmlReader reader, SecurityTokenResolver tokenResolver)
        {
            if (reader == null)
            {
                throw new ArgumentNullException("reader");
            }
            if (reader.IsStartElement(Constants.CreditCardTokenName, Constants.CreditCardTokenNamespace))
            {
                string id = reader.GetAttribute(Constants.Id, Constants.WsUtilityNamespace);
    
                reader.ReadStartElement();
    
                // Read the credit card number.
                string creditCardNumber = reader.ReadElementString(Constants.CreditCardNumberElementName, Constants.CreditCardTokenNamespace);
    
                // Read the expiration date.
                string expirationTimeString = reader.ReadElementString(Constants.CreditCardExpirationElementName, Constants.CreditCardTokenNamespace);
                DateTime expirationTime = XmlConvert.ToDateTime(expirationTimeString, XmlDateTimeSerializationMode.Utc);
    
                // Read the issuer of the credit card.
                string creditCardIssuer = reader.ReadElementString(Constants.CreditCardIssuerElementName, Constants.CreditCardTokenNamespace);
                reader.ReadEndElement();
    
                CreditCardInfo cardInfo = new CreditCardInfo(creditCardNumber, creditCardIssuer, expirationTime);
    
                return new CreditCardToken(cardInfo, id);
            }
            else
            {
                return WSSecurityTokenSerializer.DefaultInstance.ReadToken(reader, tokenResolver);
            }
        }
    
        protected override bool CanWriteTokenCore(SecurityToken token)
        {
            if (token is CreditCardToken)
            {
                return true;
            }
            else
            {
                return base.CanWriteTokenCore(token);
            }
        }
    
        protected override void WriteTokenCore(XmlWriter writer, SecurityToken token)
        {
            if (writer == null) 
            { 
                throw new ArgumentNullException("writer"); 
            }
            if (token == null) 
            { 
                throw new ArgumentNullException("token"); 
            }
    
            CreditCardToken c = token as CreditCardToken;
            if (c != null)
            {
                writer.WriteStartElement(Constants.CreditCardTokenPrefix, Constants.CreditCardTokenName, Constants.CreditCardTokenNamespace);
                writer.WriteAttributeString(Constants.WsUtilityPrefix, Constants.Id, Constants.WsUtilityNamespace, token.Id);
                writer.WriteElementString(Constants.CreditCardNumberElementName, Constants.CreditCardTokenNamespace, c.CardInfo.CardNumber);
                writer.WriteElementString(Constants.CreditCardExpirationElementName, Constants.CreditCardTokenNamespace, XmlConvert.ToString(c.CardInfo.ExpirationDate, XmlDateTimeSerializationMode.Utc));
                writer.WriteElementString(Constants.CreditCardIssuerElementName, Constants.CreditCardTokenNamespace, c.CardInfo.CardIssuer);
                writer.WriteEndElement();
                writer.Flush();
            }
            else
            {
                base.WriteTokenCore(writer, token);
            }
        }
    }
    
    Public Class CreditCardSecurityTokenSerializer
        Inherits WSSecurityTokenSerializer
    
        Public Sub New(ByVal version As SecurityTokenVersion)
            MyBase.New()
        End Sub
    
        Protected Overrides Function CanReadTokenCore(ByVal reader As XmlReader) As Boolean
            Dim localReader = XmlDictionaryReader.CreateDictionaryReader(reader)
            If reader Is Nothing Then
                Throw New ArgumentNullException("reader")
            End If
            If reader.IsStartElement(Constants.CreditCardTokenName, _
                                     Constants.CreditCardTokenNamespace) Then
                Return True
            End If
            Return MyBase.CanReadTokenCore(reader)
        End Function
    
        Protected Overrides Function ReadTokenCore(ByVal reader As XmlReader, _
                                                   ByVal tokenResolver As SecurityTokenResolver) As SecurityToken
            If reader Is Nothing Then
                Throw New ArgumentNullException("reader")
            End If
            If reader.IsStartElement(Constants.CreditCardTokenName, _
                                     Constants.CreditCardTokenNamespace) Then
    
                Dim id = reader.GetAttribute(Constants.Id, _
                                             Constants.WsUtilityNamespace)
                reader.ReadStartElement()
    
                ' Read the credit card number.
                Dim creditCardNumber = reader.ReadElementString(Constants.CreditCardNumberElementName, _
                                                                Constants.CreditCardTokenNamespace)
    
                ' Read the expiration date.
                Dim expirationTimeString = reader.ReadElementString(Constants.CreditCardExpirationElementName, _
                                                                    Constants.CreditCardTokenNamespace)
                Dim expirationTime As DateTime = XmlConvert.ToDateTime(expirationTimeString, _
                                                                       XmlDateTimeSerializationMode.Utc)
    
                ' Read the issuer of the credit card.
                Dim creditCardIssuer = reader.ReadElementString(Constants.CreditCardIssuerElementName, _
                                                                Constants.CreditCardTokenNamespace)
                reader.ReadEndElement()
    
                Dim cardInfo As New CreditCardInfo(creditCardNumber, _
                                                   creditCardIssuer, _
                                                   expirationTime)
    
                Return New CreditCardToken(cardInfo, id)
            Else
                Return WSSecurityTokenSerializer.DefaultInstance.ReadToken(reader, _
                                                                           tokenResolver)
            End If
        End Function
    
        Protected Overrides Function CanWriteTokenCore(ByVal token As SecurityToken) As Boolean
            If TypeOf token Is CreditCardToken Then
                Return True
            Else
                Return MyBase.CanWriteTokenCore(token)
            End If
        End Function
    
        Protected Overrides Sub WriteTokenCore(ByVal writer As XmlWriter, _
                                               ByVal token As SecurityToken)
            If writer Is Nothing Then
                Throw New ArgumentNullException("writer")
            End If
            If token Is Nothing Then
                Throw New ArgumentNullException("token")
            End If
    
            Dim c = TryCast(token, CreditCardToken)
            If c IsNot Nothing Then
                With writer
                    .WriteStartElement(Constants.CreditCardTokenPrefix, _
                                       Constants.CreditCardTokenName, _
                                       Constants.CreditCardTokenNamespace)
                    .WriteAttributeString(Constants.WsUtilityPrefix, _
                                          Constants.Id, _
                                          Constants.WsUtilityNamespace, _
                                          token.Id)
                    .WriteElementString(Constants.CreditCardNumberElementName, _
                                        Constants.CreditCardTokenNamespace, _
                                        c.CardInfo.CardNumber)
                    .WriteElementString(Constants.CreditCardExpirationElementName, _
                                        Constants.CreditCardTokenNamespace, _
                                        XmlConvert.ToString(c.CardInfo.ExpirationDate, _
                                                            XmlDateTimeSerializationMode.Utc))
                    .WriteElementString(Constants.CreditCardIssuerElementName, _
                                        Constants.CreditCardTokenNamespace, _
                                        c.CardInfo.CardIssuer)
                    .WriteEndElement()
                    .Flush()
                End With
            Else
                MyBase.WriteTokenCore(writer, token)
            End If
        End Sub
    
    End Class
    

After completing the four previous procedures, integrate the custom security token with the security token provider, authenticator, manager, and client and service credentials.

To integrate the custom security token with a security token provider

  1. The security token provider creates, modifies (if necessary), and returns an instance of the token. To create a custom provider for the custom security token, create a class that inherits from the SecurityTokenProvider class. The following example overrides the GetTokenCore method to return an instance of the CreditCardToken. For more information about custom security token providers, see How to: Create a Custom Security Token Provider.

    class CreditCardTokenProvider : SecurityTokenProvider
    {
        CreditCardInfo creditCardInfo;
    
        public CreditCardTokenProvider(CreditCardInfo creditCardInfo)
            : base()
        {
            if (creditCardInfo == null)
            {
                throw new ArgumentNullException("creditCardInfo");
            }
            this.creditCardInfo = creditCardInfo;
        }
    
        protected override SecurityToken GetTokenCore(TimeSpan timeout)
        {
            SecurityToken result = new CreditCardToken(this.creditCardInfo);
            return result;
        }
    }
    
    Friend Class CreditCardTokenProvider
        Inherits SecurityTokenProvider
    
        Private creditCardInfo As CreditCardInfo
    
        Public Sub New(ByVal creditCardInfo As CreditCardInfo)
            MyBase.New()
            If creditCardInfo Is Nothing Then
                Throw New ArgumentNullException("creditCardInfo")
            End If
            Me.creditCardInfo = creditCardInfo
        End Sub
    
        Protected Overrides Function GetTokenCore(ByVal timeout As TimeSpan) As SecurityToken
            Return TryCast(New CreditCardToken(Me.creditCardInfo), SecurityToken)
        End Function
    
    End Class
    

To integrate the custom security token with a security token authenticator

  1. The security token authenticator validates the content of the security token when it is extracted from the message. To create a custom authenticator for the custom security token, create a class that inherits from the SecurityTokenAuthenticator class. The following example overrides the ValidateTokenCore method. For more information about custom security token authenticators, see How to: Create a Custom Security Token Authenticator.

    class CreditCardTokenAuthenticator : SecurityTokenAuthenticator
    {
        string creditCardsFile;
        public CreditCardTokenAuthenticator(string creditCardsFile)
        {
            this.creditCardsFile = creditCardsFile;
        }
    
        protected override bool CanValidateTokenCore(SecurityToken token)
        {
            return (token is CreditCardToken);
        }
    
        protected override ReadOnlyCollection<IAuthorizationPolicy> ValidateTokenCore(SecurityToken token)
        {
            CreditCardToken creditCardToken = token as CreditCardToken;
    
            if (creditCardToken.CardInfo.ExpirationDate < DateTime.UtcNow)
            {
                throw new SecurityTokenValidationException("The credit card has expired");
            }
            if (!IsCardNumberAndExpirationValid(creditCardToken.CardInfo))
            {
                throw new SecurityTokenValidationException("Unknown or invalid credit card");
            }
    
            // The credit card token has only 1 claim: the card number. The issuer for the claim is the
            // credit card issuer.
            DefaultClaimSet cardIssuerClaimSet = new DefaultClaimSet(new Claim(ClaimTypes.Name, creditCardToken.CardInfo.CardIssuer, Rights.PossessProperty));
            DefaultClaimSet cardClaimSet = new DefaultClaimSet(cardIssuerClaimSet, new Claim(Constants.CreditCardNumberClaim, creditCardToken.CardInfo.CardNumber, Rights.PossessProperty));
            List<IAuthorizationPolicy> policies = new List<IAuthorizationPolicy>(1);
            policies.Add(new CreditCardTokenAuthorizationPolicy(cardClaimSet));
            return policies.AsReadOnly();
        }
    
        // This helper method checks whether a given credit card entry is present in the user database.
        private bool IsCardNumberAndExpirationValid(CreditCardInfo cardInfo)
        {
            try
            {
                using (StreamReader myStreamReader = new StreamReader(this.creditCardsFile))
                {
                    string line = "";
                    while ((line = myStreamReader.ReadLine()) != null)
                    {
                        string[] splitEntry = line.Split('#');
                        if (splitEntry[0] == cardInfo.CardNumber)
                        {
                            string expirationDateString = splitEntry[1].Trim();
                            DateTime expirationDateOnFile = DateTime.Parse(expirationDateString, System.Globalization.DateTimeFormatInfo.InvariantInfo, System.Globalization.DateTimeStyles.AdjustToUniversal);
                            if (cardInfo.ExpirationDate == expirationDateOnFile)
                            {
                                string issuer = splitEntry[2];
                                return issuer.Equals(cardInfo.CardIssuer, StringComparison.InvariantCultureIgnoreCase);
                            }
                            else
                            {
                                return false;
                            }
                        }
                    }
                    return false;
                }
            }
            catch (Exception e)
            {
                throw new Exception("BookStoreService: Error while retrieving credit card information from User DB " + e.ToString());
            }
        }
    }
    
    Friend Class CreditCardTokenAuthenticator
        Inherits SecurityTokenAuthenticator
    
        Private creditCardsFile As String
    
        Public Sub New(ByVal creditCardsFile As String)
            Me.creditCardsFile = creditCardsFile
        End Sub
    
        Protected Overrides Function CanValidateTokenCore(ByVal token As SecurityToken) As Boolean
            Return (TypeOf token Is CreditCardToken)
        End Function
    
        Protected Overrides Function ValidateTokenCore(ByVal token As SecurityToken) As ReadOnlyCollection(Of IAuthorizationPolicy)
    
            Dim creditCardToken = TryCast(token, CreditCardToken)
    
            If creditCardToken.CardInfo.ExpirationDate < DateTime.UtcNow Then
                Throw New SecurityTokenValidationException("The credit card has expired")
            End If
            If Not IsCardNumberAndExpirationValid(creditCardToken.CardInfo) Then
                Throw New SecurityTokenValidationException("Unknown or invalid credit card")
            End If
    
            ' The credit card token has only 1 claim: the card number. The issuer for the claim is the
            ' credit card issuer.
            Dim cardIssuerClaimSet As New DefaultClaimSet(New Claim(ClaimTypes.Name, _
                                                                    creditCardToken.CardInfo.CardIssuer, _
                                                                    Rights.PossessProperty))
            Dim cardClaimSet As New DefaultClaimSet(cardIssuerClaimSet, _
                                                    New Claim(Constants.CreditCardNumberClaim, _
                                                              creditCardToken.CardInfo.CardNumber, _
                                                              Rights.PossessProperty))
            Dim policies As New List(Of IAuthorizationPolicy)(1)
            policies.Add(New CreditCardTokenAuthorizationPolicy(cardClaimSet))
            Return policies.AsReadOnly()
        End Function
    
        ' This helper method checks whether a given credit card entry is present in the user database.
        Private Function IsCardNumberAndExpirationValid(ByVal cardInfo As CreditCardInfo) As Boolean
            Try
                Using myStreamReader As New StreamReader(Me.creditCardsFile)
                    Dim line = String.Empty
                    line = myStreamReader.ReadLine()
                    Do While line IsNot Nothing
                        Dim splitEntry() = line.Split("#"c)
                        If splitEntry(0) = cardInfo.CardNumber Then
                            Dim expirationDateString = splitEntry(1).Trim()
                            Dim expirationDateOnFile As DateTime = DateTime.Parse(expirationDateString, _
                                                                                  System.Globalization.DateTimeFormatInfo.InvariantInfo, _
                                                                                  System.Globalization.DateTimeStyles.AdjustToUniversal)
                            If cardInfo.ExpirationDate = expirationDateOnFile Then
                                Dim issuer = splitEntry(2)
                                Return issuer.Equals(cardInfo.CardIssuer, _
                                                     StringComparison.InvariantCultureIgnoreCase)
                            Else
                                Return False
                            End If
                        End If
                        line = myStreamReader.ReadLine()
                    Loop
                    Return False
                End Using
            Catch e As Exception
                Throw New Exception("BookStoreService: Error while retrieving credit card information from User DB " & e.ToString())
            End Try
        End Function
    
    End Class
    
    public class CreditCardTokenAuthorizationPolicy : IAuthorizationPolicy
    {
        string id;
        ClaimSet issuer;
        IEnumerable<ClaimSet> issuedClaimSets;
    
        public CreditCardTokenAuthorizationPolicy(ClaimSet issuedClaims)
        {
            if (issuedClaims == null)
                throw new ArgumentNullException("issuedClaims");
            this.issuer = issuedClaims.Issuer;
            this.issuedClaimSets = new ClaimSet[] { issuedClaims };
            this.id = Guid.NewGuid().ToString();
        }
    
        public ClaimSet Issuer { get { return this.issuer; } }
    
        public string Id { get { return this.id; } }
    
        public bool Evaluate(EvaluationContext context, ref object state)
        {
            foreach (ClaimSet issuance in this.issuedClaimSets)
            {
                context.AddClaimSet(this, issuance);
            }
    
            return true;
        }
    }
    
    Public Class CreditCardTokenAuthorizationPolicy
        Implements IAuthorizationPolicy
    
        Private _id As String
        Private _issuer As ClaimSet
        Private _issuedClaimSets As IEnumerable(Of ClaimSet)
    
        Public Sub New(ByVal issuedClaims As ClaimSet)
            If issuedClaims Is Nothing Then
                Throw New ArgumentNullException("issuedClaims")
            End If
            Me._issuer = issuedClaims.Issuer
            Me._issuedClaimSets = New ClaimSet() {issuedClaims}
            Me._id = Guid.NewGuid().ToString()
        End Sub
    
        Public ReadOnly Property Issuer() As ClaimSet Implements IAuthorizationPolicy.Issuer
            Get
                Return Me._issuer
            End Get
        End Property
    
        Public ReadOnly Property Id() As String Implements System.IdentityModel.Policy.IAuthorizationComponent.Id
            Get
                Return Me._id
            End Get
        End Property
    
        Public Function Evaluate(ByVal context As EvaluationContext, _
                                 ByRef state As Object) As Boolean Implements IAuthorizationPolicy.Evaluate
            For Each issuance In Me._issuedClaimSets
                context.AddClaimSet(Me, issuance)
            Next issuance
    
            Return True
        End Function
    
    End Class
    

To integrate the custom security token with a security token manager

  1. The security token manager creates the appropriate token provider, security authenticator, and token serializer instances. To create a custom token manager, create a class that inherits from the ClientCredentialsSecurityTokenManager class. The primary methods of the class use a SecurityTokenRequirement to create the appropriate provider and client or service credentials. For more information about custom security token managers, see Walkthrough: Creating Custom Client and Service Credentials.

    public class CreditCardClientCredentialsSecurityTokenManager : ClientCredentialsSecurityTokenManager
    {
        CreditCardClientCredentials creditCardClientCredentials;
    
        public CreditCardClientCredentialsSecurityTokenManager(CreditCardClientCredentials creditCardClientCredentials)
            : base(creditCardClientCredentials)
        {
            this.creditCardClientCredentials = creditCardClientCredentials;
        }
    
        public override SecurityTokenProvider CreateSecurityTokenProvider(SecurityTokenRequirement tokenRequirement)
        {
            if (tokenRequirement.TokenType == Constants.CreditCardTokenType)
            {
                // Handle this token for Custom.
                return new CreditCardTokenProvider(this.creditCardClientCredentials.CreditCardInfo);
            }
            else if (tokenRequirement is InitiatorServiceModelSecurityTokenRequirement)
            {
                // Return server certificate.
                if (tokenRequirement.TokenType == SecurityTokenTypes.X509Certificate)
                {
                    return new X509SecurityTokenProvider(creditCardClientCredentials.ServiceCertificate.DefaultCertificate);
                }
            }
            return base.CreateSecurityTokenProvider(tokenRequirement);
        }
    
        public override SecurityTokenSerializer CreateSecurityTokenSerializer(SecurityTokenVersion version)
        {
            return new CreditCardSecurityTokenSerializer(version);
        }
    
    }
    
    Public Class CreditCardClientCredentialsSecurityTokenManager
        Inherits ClientCredentialsSecurityTokenManager
    
        Private creditCardClientCredentials As CreditCardClientCredentials
    
        Public Sub New(ByVal creditCardClientCredentials As CreditCardClientCredentials)
            MyBase.New(creditCardClientCredentials)
            Me.creditCardClientCredentials = creditCardClientCredentials
        End Sub
    
        Public Overrides Function CreateSecurityTokenProvider(ByVal tokenRequirement As SecurityTokenRequirement) As SecurityTokenProvider
    
            If tokenRequirement.TokenType = Constants.CreditCardTokenType Then
                ' Handle this token for Custom.
                Return New CreditCardTokenProvider(Me.creditCardClientCredentials.CreditCardInfo)
            ElseIf TypeOf tokenRequirement Is InitiatorServiceModelSecurityTokenRequirement Then
                ' Return server certificate.
                If tokenRequirement.TokenType = SecurityTokenTypes.X509Certificate Then
                    Return New X509SecurityTokenProvider(creditCardClientCredentials.ServiceCertificate.DefaultCertificate)
                End If
            End If
            Return MyBase.CreateSecurityTokenProvider(tokenRequirement)
        End Function
    
        Public Overloads Overrides Function CreateSecurityTokenSerializer(ByVal version As SecurityTokenVersion) As SecurityTokenSerializer
            Return New CreditCardSecurityTokenSerializer(version)
        End Function
    
    End Class
    
    public class CreditCardServiceCredentialsSecurityTokenManager : ServiceCredentialsSecurityTokenManager
    {
        CreditCardServiceCredentials creditCardServiceCredentials;
    
        public CreditCardServiceCredentialsSecurityTokenManager(CreditCardServiceCredentials creditCardServiceCredentials)
            : base(creditCardServiceCredentials)
        {
            this.creditCardServiceCredentials = creditCardServiceCredentials;
        }
    
        public override SecurityTokenAuthenticator CreateSecurityTokenAuthenticator(SecurityTokenRequirement tokenRequirement, out SecurityTokenResolver outOfBandTokenResolver)
        {
            if (tokenRequirement.TokenType == Constants.CreditCardTokenType)
            {
                outOfBandTokenResolver = null;
                return new CreditCardTokenAuthenticator(creditCardServiceCredentials.CreditCardDataFile);
            }
            return base.CreateSecurityTokenAuthenticator(tokenRequirement, out outOfBandTokenResolver);
        }
    
        public override SecurityTokenSerializer CreateSecurityTokenSerializer(SecurityTokenVersion version)
        {
            return new CreditCardSecurityTokenSerializer(version);
        }
    }
    
    Public Class CreditCardServiceCredentialsSecurityTokenManager
        Inherits ServiceCredentialsSecurityTokenManager
    
        Private creditCardServiceCredentials As CreditCardServiceCredentials
    
        Public Sub New(ByVal creditCardServiceCredentials As CreditCardServiceCredentials)
            MyBase.New(creditCardServiceCredentials)
            Me.creditCardServiceCredentials = creditCardServiceCredentials
        End Sub
    
        Public Overrides Function CreateSecurityTokenAuthenticator(ByVal tokenRequirement As SecurityTokenRequirement, _
                                                                   <System.Runtime.InteropServices.Out()> ByRef outOfBandTokenResolver As SecurityTokenResolver) As SecurityTokenAuthenticator
            If tokenRequirement.TokenType = Constants.CreditCardTokenType Then
                outOfBandTokenResolver = Nothing
                Return New CreditCardTokenAuthenticator(creditCardServiceCredentials.CreditCardDataFile)
            End If
            Return MyBase.CreateSecurityTokenAuthenticator(tokenRequirement, outOfBandTokenResolver)
        End Function
    
        Public Overrides Function CreateSecurityTokenSerializer(ByVal version As SecurityTokenVersion) As SecurityTokenSerializer
            Return New CreditCardSecurityTokenSerializer(version)
        End Function
    
    End Class
    

To integrate the custom security token with custom client and service credentials

  1. The custom client and service credentials must be added to provide an API for the application to allow specifying custom token information that is used by the custom security token infrastructure created previously to provide and authenticate the custom security token content. The following samples show how this can be done. For more information about custom client and service credentials, see Walkthrough: Creating Custom Client and Service Credentials.

    public class CreditCardClientCredentials : ClientCredentials
    {
        CreditCardInfo creditCardInfo;
    
        public CreditCardClientCredentials(CreditCardInfo creditCardInfo)
            : base()
        {
            if (creditCardInfo == null)
            {
                throw new ArgumentNullException("creditCardInfo");
            }
    
            this.creditCardInfo = creditCardInfo;
        }
    
        public CreditCardInfo CreditCardInfo
        {
            get { return this.creditCardInfo; }
        }
    
        protected override ClientCredentials CloneCore()
        {
            return new CreditCardClientCredentials(this.creditCardInfo);
        }
    
        public override SecurityTokenManager CreateSecurityTokenManager()
        {
            return new CreditCardClientCredentialsSecurityTokenManager(this);
        }
    }
    
    Public Class CreditCardClientCredentials
        Inherits ClientCredentials
    
        Private _creditCardInfo As CreditCardInfo
    
        Public Sub New(ByVal creditCardInfo As CreditCardInfo)
            MyBase.New()
            If creditCardInfo Is Nothing Then
                Throw New ArgumentNullException("creditCardInfo")
            End If
    
            Me._creditCardInfo = creditCardInfo
        End Sub
    
        Public ReadOnly Property CreditCardInfo() As CreditCardInfo
            Get
                Return Me._creditCardInfo
            End Get
        End Property
    
        Protected Overrides Function CloneCore() As ClientCredentials
            Return New CreditCardClientCredentials(Me._creditCardInfo)
        End Function
    
        Public Overrides Function CreateSecurityTokenManager() As SecurityTokenManager
            Return New CreditCardClientCredentialsSecurityTokenManager(Me)
        End Function
    
    End Class
    
    public class CreditCardServiceCredentials : ServiceCredentials
    {
        string creditCardFile;
    
        public CreditCardServiceCredentials(string creditCardFile)
            : base()
        {
            if (creditCardFile == null)
            {
                throw new ArgumentNullException("creditCardFile");
            }
    
            this.creditCardFile = creditCardFile;
        }
    
        public string CreditCardDataFile
        {
            get { return this.creditCardFile; }
        }
    
        protected override ServiceCredentials CloneCore()
        {
            return new CreditCardServiceCredentials(this.creditCardFile);
        }
    
        public override SecurityTokenManager CreateSecurityTokenManager()
        {
            return new CreditCardServiceCredentialsSecurityTokenManager(this);
        }
    }
    
    Public Class CreditCardServiceCredentials
        Inherits ServiceCredentials
    
        Private creditCardFile As String
    
        Public Sub New(ByVal creditCardFile As String)
            MyBase.New()
            If creditCardFile Is Nothing Then
                Throw New ArgumentNullException("creditCardFile")
            End If
    
            Me.creditCardFile = creditCardFile
        End Sub
    
        Public ReadOnly Property CreditCardDataFile() As String
            Get
                Return Me.creditCardFile
            End Get
        End Property
    
        Protected Overrides Function CloneCore() As ServiceCredentials
            Return New CreditCardServiceCredentials(Me.creditCardFile)
        End Function
    
        Public Overrides Function CreateSecurityTokenManager() As SecurityTokenManager
            Return New CreditCardServiceCredentialsSecurityTokenManager(Me)
        End Function
    
    End Class
    

The custom security token parameters class created previously is used to tell the WCF security framework that a custom security token must be used when communicating with a service. The following procedure shows how this can be done.

To integrate the custom security token with the binding

  1. The custom security token parameters class must be specified in one of the token parameters collections that are exposed on the SecurityBindingElement class. The following example uses the collection returned by SignedEncrypted. The code adds the credit card custom token to every message sent from the client to the service with its content automatically signed and encrypted.

    public static class BindingHelper
    {
        public static Binding CreateCreditCardBinding()
        {
            HttpTransportBindingElement httpTransport = new HttpTransportBindingElement();
    
            // The message security binding element is configured to require a credit card
            // token that is encrypted with the service's certificate. 
            SymmetricSecurityBindingElement messageSecurity = new SymmetricSecurityBindingElement();
            messageSecurity.EndpointSupportingTokenParameters.SignedEncrypted.Add(new CreditCardTokenParameters());
            X509SecurityTokenParameters x509ProtectionParameters = new X509SecurityTokenParameters();
            x509ProtectionParameters.InclusionMode = SecurityTokenInclusionMode.Never;
            messageSecurity.ProtectionTokenParameters = x509ProtectionParameters;
            return new CustomBinding(messageSecurity, httpTransport);
        }
    }
    
    Public NotInheritable Class BindingHelper
    
        Private Sub New()
        End Sub
    
        Public Shared Function CreateCreditCardBinding() As Binding
            Dim httpTransport As New HttpTransportBindingElement()
    
            ' The message security binding element is configured to require a credit card
            ' token that is encrypted with the service's certificate. 
            Dim messageSecurity As New SymmetricSecurityBindingElement()
            messageSecurity.EndpointSupportingTokenParameters.SignedEncrypted.Add(New CreditCardTokenParameters())
            Dim x509ProtectionParameters As New X509SecurityTokenParameters()
            x509ProtectionParameters.InclusionMode = SecurityTokenInclusionMode.Never
            messageSecurity.ProtectionTokenParameters = x509ProtectionParameters
            Return New CustomBinding(messageSecurity, httpTransport)
        End Function
    
    End Class
    

This topic shows the various pieces of code necessary to implement and use a custom token. To see a complete example of how all these pieces of code fit together see, Custom Token.

See Also

SecurityToken
SecurityTokenParameters
WSSecurityTokenSerializer
SecurityTokenProvider
SecurityTokenAuthenticator
IAuthorizationPolicy
SecurityTokenRequirement
SecurityTokenManager
ClientCredentials
ServiceCredentials
SecurityBindingElement
Walkthrough: Creating Custom Client and Service Credentials
How to: Create a Custom Security Token Authenticator
How to: Create a Custom Security Token Provider
Security Architecture