AsymmetricAlgorithm Clase

Definición

Representa la clase base abstracta de la que deben heredarse todas las implementaciones de algoritmos asimétricos.

public ref class AsymmetricAlgorithm abstract : IDisposable
public abstract class AsymmetricAlgorithm : IDisposable
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class AsymmetricAlgorithm : IDisposable
type AsymmetricAlgorithm = class
    interface IDisposable
[<System.Runtime.InteropServices.ComVisible(true)>]
type AsymmetricAlgorithm = class
    interface IDisposable
Public MustInherit Class AsymmetricAlgorithm
Implements IDisposable
Herencia
AsymmetricAlgorithm
Derivado
Atributos
Implementaciones

Ejemplos

En el ejemplo de código siguiente se muestra cómo implementar un algoritmo asimétrico personalizado heredado de la AsymmetricAlgorithm clase . Se proporciona una clase adicional para mostrar cómo usar la clase personalizada.

#using <System.Xml.dll>
#using <System.Security.dll>

using namespace System;
using namespace System::Xml;
using namespace System::Text;
using namespace System::Security::Cryptography;
using namespace System::Reflection;

[assembly: AssemblyKeyFile("CustomCrypto.snk")];
[assembly: AssemblyVersion("1.0.0.0")];
[assembly: CLSCompliant(true)];
namespace Contoso
{
    // Define a CustomCrypto class that inherits from the AsymmetricAlgorithm
    // class.
    public ref class CustomCrypto :
        public System::Security::Cryptography::AsymmetricAlgorithm
        {
            // Declare local member variables.
        private:
            CspParameters^ cryptoServiceParameters;
            array<KeySizes^>^ customValidKeySizes;

            // Initialize a CustomCrypto with the default key size of 8.
        public:
            CustomCrypto()
            {
                customValidKeySizes = 
                    gcnew array<KeySizes^>{gcnew KeySizes(8, 64, 8)};
                this->KeySize = 8;
            }

            // Initialize a CustomCrypto with the specified key size.
        public:
            CustomCrypto(int keySize)
            {
                customValidKeySizes = 
                    gcnew array<KeySizes^>{gcnew KeySizes(8, 64, 8)};
                this->KeySize = keySize;
            }

            // Accessor function for keySizes member variable.
        public:
            property array<KeySizes^>^ LegalKeySizes
            {
                virtual array<KeySizes^>^ get() override
                {
                    return (array<KeySizes^>^)customValidKeySizes->Clone();
                }
            }

            // Modify the KeySizeValue property inherited from the Asymmetric
            // class. Prior to setting the value, ensure it falls within the
            // range identified in the local keySizes member variable.
        public:
            property int KeySize
            {
                virtual int get() override
                {
                    return KeySizeValue;
                }

                virtual void set(int value) override
                {
                    for (int i = 0; i < customValidKeySizes->Length; i++)
                    {
                        if (customValidKeySizes[i]->SkipSize == 0)
                        {
                            if (customValidKeySizes[i]->MinSize == value)
                            {
                                KeySizeValue = value;
                                return;
                            }
                        }
                        else
                        {
                            for (int j = customValidKeySizes[i]->MinSize;
                                j <= customValidKeySizes[i]->MaxSize;
                                j += customValidKeySizes[i]->SkipSize)
                            {
                                if (j == value)
                                {
                                    KeySizeValue = value;
                                    return;
                                }
                            }
                        }
                    }

                    // If the key does not fall within the range identified
                    // in the keySizes member variable, throw an exception.
                    throw gcnew CryptographicException("Invalid key size.");
                }
            }

            // Initialize the parameters with default values.
        public:
            void InitializeParameters()
            {
                cryptoServiceParameters = gcnew CspParameters();
                cryptoServiceParameters->ProviderName = "Contoso";
                cryptoServiceParameters->KeyContainerName = "SecurityBin1";
                cryptoServiceParameters->KeyNumber = 1;
                cryptoServiceParameters->ProviderType = 2;
            }

            // Parse specified xmlString for values to populate the CspParams
            // Expected XML schema:
            //      <ProviderName></ProviderName>
            //      <KeyContainerName></KeyContainerName>
            //      <KeyNumber></KeyNumber>
            //      <ProviderType></ProviderType>
        public:
            virtual void FromXmlString(String^ xmlString) override 
            {
                if (xmlString != nullptr)
                {
                    XmlDocument^ document = gcnew XmlDocument();
                    document->LoadXml(xmlString);
                    XmlNode^ firstNode = document->FirstChild;
                    XmlNodeList^ nodeList;

                    // Assemble parameters from values in each XML element.
                    cryptoServiceParameters = gcnew CspParameters();

                    // KeyContainerName is optional.
                    nodeList = 
                        document->GetElementsByTagName("KeyContainerName");
                    if (nodeList->Count > 0)
                    {
                        cryptoServiceParameters->KeyContainerName =
                            nodeList->Item(0)->InnerText;
                    }

                    // KeyNumber is optional.
                    nodeList = document->GetElementsByTagName("KeyNumber");
                    if (nodeList->Count > 0)
                    {
                        cryptoServiceParameters->KeyNumber =
                            Int32::Parse(nodeList->Item(0)->InnerText);
                    }

                    // ProviderName is optional.
                    nodeList = document->GetElementsByTagName("ProviderName");
                    if (nodeList->Count > 0)
                    {
                        cryptoServiceParameters->ProviderName =
                            nodeList->Item(0)->InnerText;
                    }

                    // ProviderType is optional.
                    nodeList = document->GetElementsByTagName("ProviderType");
                    if (nodeList->Count > 0)
                    {
                        cryptoServiceParameters->ProviderType =
                            Int32::Parse(nodeList->Item(0)->InnerText);
                    }
                }
                else
                {
                    throw gcnew ArgumentNullException("xmlString");
                }
            }

            // Create an XML string representation of the parameters in the
            // current customCrypto object.
        public:
            virtual String^ ToXmlString(bool includePrivateParameters) override
            {
                String^ keyContainerName = "";
                String^ keyNumber = "";
                String^ providerName = "";
                String^ providerType = "";

                if (cryptoServiceParameters != nullptr)
                {
                    keyContainerName = 
                        cryptoServiceParameters->KeyContainerName;
                    keyNumber = cryptoServiceParameters->KeyNumber.ToString();
                    providerName = cryptoServiceParameters->ProviderName;
                    providerType = 
                        cryptoServiceParameters->ProviderType.ToString();
                }

                StringBuilder^ sb = gcnew StringBuilder();
                sb->Append("<CustomCryptoKeyValue>");

                sb->Append("<KeyContainerName>");
                sb->Append(keyContainerName);
                sb->Append("</KeyContainerName>");

                sb->Append("<KeyNumber>");
                sb->Append(keyNumber);
                sb->Append("</KeyNumber>");

                sb->Append("<ProviderName>");
                sb->Append(providerName);
                sb->Append("</ProviderName>");

                sb->Append("<ProviderType>");
                sb->Append(providerType);
                sb->Append("</ProviderType>");

                sb->Append("</CustomCryptoKeyValue>");
                return(sb->ToString());
            }

            // Return the name for the key exchange algorithm.
        public:
            property String^ KeyExchangeAlgorithm 
            {
                virtual String^ get() override
                {
                    return "RSA-PKCS1-KeyEx";
                }
            }

            // Retrieves the name of the signature alogrithm.
            // This example uses the SHA1 algorithm.
            // Due to collision problems with SHA1, Microsoft recommends SHA256 or better.

        public:
            property String^ SignatureAlgorithm
            {
                virtual String^ get() override
                {
                    return "http://www.w3.org/2000/09/xmldsig#rsa-sha1";
                }
            }

            // Required member for implementing the AsymmetricAlgorithm class.
        protected:
            virtual ~CustomCrypto()
            {
            }

            // Call the Create method using the CustomCrypto assembly name.
            // The create function attempts to create a CustomCrypto 
            // object using the assembly name. This functionality requires 
            // modification of the machine.config file. Add the following 
            // section to the configuration element and modify the values 
            // of the cryptoClass to reflect what isinstalled 
            // in your machines GAC.
            //        <cryptoClass CustomCrypto="Contoso.CustomCrypto,
            //          CustomCrypto,
            //          Culture=neutral,
            //          PublicKeyToken=fdb9f9c4851028bf,
            //          Version=1.0.1448.27640" />
            //      <nameEntry name="Contoso.CustomCrypto" 
            //         class="CustomCrypto" />
            //      <nameEntry name="CustomCrypto" class="CustomCrypto" />

        public:
            static CustomCrypto^ Create() 
            {
                return Create("CustomCrypto");
            }

            // Create a CustomCrypto object by calling CrytoConfig's
            // CreateFromName method and casting the type to CustomCrypto.
            // The create function attempts to create a CustomCrypto object 
            // using the assembly name. This functionality requires 
            // modification of the machine.config file. Add the following 
            // section to the configuration element and modify the values 
            // of the cryptoClass to reflect what is installed 
            // in your machines GAC.
            //       <cryptoClass CustomCrypto="Contoso.CustomCrypto,
            //         CustomCrypto,
            //         Culture=neutral,
            //         PublicKeyToken=fdb9f9c4851028bf,
            //         Version=1.0.1448.27640" />
            //     <nameEntry name="Contoso.CustomCrypto" 
            //        class="CustomCrypto" />
            //     <nameEntry name="CustomCrypto" class="CustomCrypto" />

        public:
            static CustomCrypto^ Create(String^ algorithmName) 
            {
                return (CustomCrypto^) 
                    CryptoConfig::CreateFromName(algorithmName);
            }
        };
}
using System;
using System.Xml;
using System.Text;
using System.Security.Cryptography;
using System.Reflection;

[assembly: AssemblyKeyFile("CustomCrypto.snk")]
[assembly: AssemblyVersion("1.0.0.0")]
[assembly: CLSCompliant(true)]
namespace Contoso
{
    // Define a CustomCrypto class that inherits from the AsymmetricAlgorithm
    // class.
    public class CustomCrypto : 
        System.Security.Cryptography.AsymmetricAlgorithm
    {
        // Declare local member variables.
        private CspParameters cspParameters;
        private readonly KeySizes[] keySizes = {new KeySizes(8, 64, 8)};

        // Initialize a CustomCrypto with the default key size of 8.
        public CustomCrypto()
        {
            this.KeySize = 8;
        }

        // Initialize a CustomCrypto with the specified key size.
        public CustomCrypto(int keySize)
        {
            this.KeySize = keySize;
        }

        // Accessor function for keySizes member variable.
        public override KeySizes[] LegalKeySizes 
        { 
            get { return (KeySizes[])keySizes.Clone(); }
        }

        // Modify the KeySizeValue property inherited from the Asymmetric
        // class. Prior to setting the value, ensure it falls within the
        // range identified in the local keySizes member variable.
        public override int KeySize 
        {
            get { return KeySizeValue; }
            set
            {
                for (int i=0; i < keySizes.Length; i++)
                {
                    if (keySizes[i].SkipSize == 0) 
                    {
                        if (keySizes[i].MinSize == value)
                        {
                            KeySizeValue = value;
                            return;
                        }
                    }
                    else
                    {
                        for (int j = keySizes[i].MinSize;
                            j <= keySizes[i].MaxSize;
                            j += keySizes[i].SkipSize)
                        {
                            if (j == value)
                            {
                                KeySizeValue = value;
                                return;
                            }
                        }
                    }
                }

                // If the key does not fall within the range identified 
                // in the keySizes member variable, throw an exception.
                throw new CryptographicException("Invalid key size.");
            }
        }

        // Initialize the parameters with default values.
        public void InitializeParameters()
        {
            cspParameters = new CspParameters();
            cspParameters.ProviderName = "Contoso";
            cspParameters.KeyContainerName = "SecurityBin1";
            cspParameters.KeyNumber = 1;
            cspParameters.ProviderType = 2;
        }

        // Parse specified xmlString for values to populate the CspParams
        // Expected XML schema:
        //      <ProviderName></ProviderName>
        //      <KeyContainerName></KeyContainerName>
        //      <KeyNumber></KeyNumber>
        //      <ProviderType></ProviderType>
        public override void FromXmlString(string xmlString)
        {
            if (xmlString != null)
            {
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(xmlString);
                XmlNode firstNode = doc.FirstChild;
                XmlNodeList nodeList;

                // Assemble parameters from values in each XML element.
                cspParameters = new CspParameters();

                // KeyContainerName is optional.
                nodeList = doc.GetElementsByTagName("KeyContainerName");
                string keyName = nodeList.Item(0).InnerText;
                if (keyName != null) 
                {
                    cspParameters.KeyContainerName = keyName;
                }

                // KeyNumber is optional.
                nodeList = doc.GetElementsByTagName("KeyNumber");
                string keyNumber = nodeList.Item(0).InnerText;
                if (keyNumber != null) 
                {
                    cspParameters.KeyNumber = Int32.Parse(keyNumber);
                }

                // ProviderName is optional.
                nodeList = doc.GetElementsByTagName("ProviderName");
                string providerName = nodeList.Item(0).InnerText;
                if (providerName != null) 
                {
                    cspParameters.ProviderName = providerName;
                }

                // ProviderType is optional.
                nodeList = doc.GetElementsByTagName("ProviderType");
                string providerType = nodeList.Item(0).InnerText;
                if (providerType != null) 
                {
                    cspParameters.ProviderType = Int32.Parse(providerType);
                }
            }
            else
            {
                throw new ArgumentNullException("xmlString");
            }
        }

        // Create an XML string representation of the parameters in the
        // current customCrypto object.
        public override string ToXmlString(bool includePrivateParameters)
        {
            string keyContainerName = "";
            string keyNumber = "";
            string providerName = "";
            string providerType = "";

            if (cspParameters != null)
            {
                keyContainerName = cspParameters.KeyContainerName;
                keyNumber = cspParameters.KeyNumber.ToString();
                providerName = cspParameters.ProviderName;
                providerType = cspParameters.ProviderType.ToString();
            }

            StringBuilder sb = new StringBuilder();
            sb.Append("<CustomCryptoKeyValue>");

            sb.Append("<KeyContainerName>");
            sb.Append(keyContainerName);
            sb.Append("</KeyContainerName>");

            sb.Append("<KeyNumber>");
            sb.Append(keyNumber);
            sb.Append("</KeyNumber>");

            sb.Append("<ProviderName>");
            sb.Append(providerName);
            sb.Append("</ProviderName>");

            sb.Append("<ProviderType>");
            sb.Append(providerType);
            sb.Append("</ProviderType>");

            sb.Append("</CustomCryptoKeyValue>");
            return(sb.ToString());
        }

        // Return the name for the key exchange algorithm.
        public override string KeyExchangeAlgorithm
        {
            get {return "RSA-PKCS1-KeyEx";}
        }

        // Retrieves the name of the signature alogrithm.
        // This example uses the SHA1 algorithm.
        // Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
        public override string SignatureAlgorithm 
        {
            get {return "http://www.w3.org/2000/09/xmldsig#rsa-sha1";}
        }

        // Required member for implementing the AsymmetricAlgorithm class.
        protected override void Dispose(bool disposing) {}

        // Call the Create method using the CustomCrypto assembly name.
        // The create function attempts to create a CustomCrypto object using
        // the assembly name. This functionality requires modification of the
        // machine.config file. Add the following section to the configuration
        // element and modify the values of the cryptoClass to reflect what is
        // installed in your machines GAC.
        //        <cryptoClass CustomCrypto="Contoso.CustomCrypto, 
        //          CustomCrypto, 
        //          Culture=neutral, 
        //          PublicKeyToken=fdb9f9c4851028bf, 
        //          Version=1.0.1448.27640" />
        //      <nameEntry name="Contoso.CustomCrypto" class="CustomCrypto" />
        //      <nameEntry name="CustomCrypto" class="CustomCrypto" />
        new static public CustomCrypto Create() 
        {
            return Create("CustomCrypto");
        }

        // Create a CustomCrypto object by calling CrytoConfig's
        // CreateFromName method and casting the type to CustomCrypto.
        // The create function attempts to create a CustomCrypto object using
        // the assembly name. This functionality requires modification of the
        // machine.config file. Add the following section to the configuration
        // element and modify the values of the cryptoClass to reflect what is
        // installed in your machines GAC.
        //       <cryptoClass CustomCrypto="Contoso.CustomCrypto, 
        //         CustomCrypto, 
        //         Culture=neutral, 
        //         PublicKeyToken=fdb9f9c4851028bf, 
        //         Version=1.0.1448.27640" />
        //     <nameEntry name="Contoso.CustomCrypto" class="CustomCrypto" />
        //     <nameEntry name="CustomCrypto" class="CustomCrypto" />
        new static public CustomCrypto Create(String algorithmName) 
        {
            return (CustomCrypto) CryptoConfig.CreateFromName(algorithmName);
        }
    }
    class CustomCryptoImpl
    {
        [STAThread]
        static void Main(string[] args)
        {
            // Construct a CustomCrypto object and initialize its
            // CspParameters.
            CustomCrypto customCrypto = new CustomCrypto();
            customCrypto.InitializeParameters();

            // Display properties of the current customCrypto object.
            Console.WriteLine("*** CustomCrypto created with default " + 
                "parameters:");
            DisplayProperties(customCrypto);

            // Release all the resources used by this instance of 
            // CustomCrytpo.
            customCrypto.Clear();

            customCrypto = new CustomCrypto(64);
            // Create new parameters and set them by using the FromXmlString
            // method.
            string parameterXml = "<CustomCryptoKeyValue>";
            parameterXml += "<ProviderName>Contoso</ProviderName>";
            parameterXml += "<KeyContainerName>SecurityBin2";
            parameterXml += "</KeyContainerName>";
            parameterXml += "<KeyNumber>1</KeyNumber>";
            parameterXml += "<ProviderType>2</ProviderType>";
            parameterXml += "</CustomCryptoKeyValue>";
            customCrypto.FromXmlString(parameterXml);

            // Display the properties of a customCrypto object created with
            // custom parameters.
            Console.WriteLine("\n*** " + 
                "CustomCrypto created with custom parameters:");
            DisplayProperties(customCrypto);

            // Create an object by using the assembly name.
            try
            {
                CustomCrypto myCryptoA = CustomCrypto.Create("CustomCrypto");
                if (myCryptoA != null)
                {
                    Console.Write("\n*** " + 
                        "Successfully created CustomCrytpo from");
                    Console.WriteLine(" the Create method.");

                    DisplayProperties(myCryptoA);
                }
                else
                {
                    Console.Write("Unable to create CustomCrytpo from ");
                    Console.WriteLine(" the Create method.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            
            Console.WriteLine("This sample completed successfully; " +
                "press Enter to exit.");
            Console.ReadLine();
        }
        // Display the properties of the specified CustomCrypto object to the
        // console.
        public static void DisplayProperties(CustomCrypto customCrypto)
        {
            try
            {
                // Retrieve the class description for the customCrypto object.
                string classDescription = customCrypto.ToString();

                Console.WriteLine(classDescription);
                Console.Write("KeyExchangeAlgorithm: ");
                Console.WriteLine(customCrypto.KeyExchangeAlgorithm);
                Console.Write("SignatureAlgorithm: ");
                Console.WriteLine(customCrypto.SignatureAlgorithm);
                Console.WriteLine("KeySize: " + customCrypto.KeySize);
                Console.WriteLine("Parameters described in Xml format:");
                Console.WriteLine(customCrypto.ToXmlString(true));

                // Display the MinSize, MaxSize, and SkipSize properties of 
                // each KeySize item in the local keySizes member variable.
                KeySizes[] legalKeySizes = customCrypto.LegalKeySizes;
                if (legalKeySizes.Length > 0)
                {
                    for (int i=0; i < legalKeySizes.Length; i++)
                    {
                        Console.Write("Keysize" + i + " min, max, step: ");
                        Console.Write(legalKeySizes[i].MinSize + ", ");
                        Console.Write(legalKeySizes[i].MaxSize + ", ");
                        Console.WriteLine(legalKeySizes[i].SkipSize + ", ");
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Caught unexpected exception: " + 
                    ex.ToString());
            }
        }
    }
}
//
// This sample produces the following output:
//
// *** CustomCrypto created with default parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 8
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin1</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8, 
// 
// *** CustomCrypto created with custom parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 64
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin2</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8, 
// Unable to create CustomCrytpo from  the Create method
// This sample completed successfully; press Exit to continue.
Imports System.Xml
Imports System.Text
Imports System.Security.Cryptography
Imports System.Reflection

<Assembly: AssemblyKeyFile("CustomCrypto.snk")> 
<Assembly: AssemblyVersion("1.0.0.0")> 
<Assembly: CLSCompliant(True)> 
Namespace Contoso
    ' Define a vbCustomCrypto class that inherits from the AsymmetricAlgorithm
    ' class.
    Class vbCustomCrypto
        Inherits System.Security.Cryptography.AsymmetricAlgorithm

        ' Declare local member variables.
        Private cspParameters As CspParameters
        Private ReadOnly keySizes() As keySizes = {New keySizes(8, 64, 8)}

        ' Initialize a vbCustomCrypto with the default key size of 8.
        Public Sub New()
            Me.KeySize = 8
        End Sub

        ' Initialize a vbCustomCrypto with the specified key size.
        Public Sub New(ByVal keySize As Integer)
            Me.KeySize = keySize
        End Sub

        ' Modify the KeySizeValue property inherited from the Asymmetric
        ' class. Prior to setting the value, ensure it falls within the
        ' range identified in the local keySizes member variable.
        Public Overrides Property KeySize() As Integer
            Get
                Return KeySizeValue
            End Get
            Set(ByVal Value As Integer)
                For i As Int16 = 0 To keySizes.Length - 1 Step i
                    If (keySizes(i).SkipSize.Equals(0)) Then
                        If (keySizes(i).MinSize.Equals(Value)) Then
                            KeySizeValue = Value
                            Return
                        End If
                    Else
                        For j As Integer = keySizes(i).MinSize _
                            To keySizes(i).MaxSize _
                            Step keySizes(i).SkipSize
                            If (j.Equals(Value)) Then
                                KeySizeValue = Value
                                Return
                            End If
                        Next
                    End If
                Next
                ' If the key does not fall within the range identified 
                ' in the keySizes member variable, throw an exception.
                Throw New CryptographicException("Invalid key size.")
            End Set
        End Property
        ' Accessor function for keySizes member variable.
        public Overrides Readonly Property LegalKeySizes as KeySizes()
            Get
                Return keySizes
            End Get
        End Property
        ' Initialize the parameters with default values.
        Public Sub InitializeParameters()
            cspParameters = New CspParameters
            cspParameters.ProviderName = "Contoso"
            cspParameters.KeyContainerName = "SecurityBin1"
            cspParameters.KeyNumber = 1
            cspParameters.ProviderType = 2
        End Sub

        ' Parse specified xmlString for values to populate the CspParams
        ' Expected XML schema:
        '      <ProviderName></ProviderName>
        '      <KeyContainerName></KeyContainerName>
        '      <KeyNumber></KeyNumber>
        '      <ProviderType></ProviderType>
        Public Overrides Sub FromXmlString(ByVal xmlString As String)
            If Not xmlString Is Nothing Then
                Dim doc As New XmlDocument
                doc.LoadXml(xmlString)
                Dim firstNode As XmlNode = doc.FirstChild
                Dim nodeList As XmlNodeList

                ' Assemble parameters from values in each XML element.
                cspParameters = New CspParameters

                ' KeyContainerName is optional.
                nodeList = doc.GetElementsByTagName("KeyContainerName")
                Dim keyName As String = nodeList.Item(0).InnerText
                If Not keyName Is Nothing Then
                    cspParameters.KeyContainerName = keyName
                End If

                ' KeyNumber is optional.
                nodeList = doc.GetElementsByTagName("KeyNumber")
                Dim keyNumber As String = nodeList.Item(0).InnerText
                If Not keyNumber Is Nothing Then
                    cspParameters.KeyNumber = Int32.Parse(keyNumber)
                End If

                ' ProviderName is optional.
                nodeList = doc.GetElementsByTagName("ProviderName")
                Dim providerName As String = nodeList.Item(0).InnerText
                If Not providerName Is Nothing Then
                    cspParameters.ProviderName = providerName
                End If

                ' ProviderType is optional.
                nodeList = doc.GetElementsByTagName("ProviderType")
                Dim providerType As String = nodeList.Item(0).InnerText
                If Not providerType Is Nothing Then
                    cspParameters.ProviderType = Int32.Parse(providerType)
                End If
            Else
                Throw New ArgumentNullException("xmlString")
            End If
        End Sub

        ' Create an XML string representation of the parameters in the current
        ' vbCustomCrypto object.
        Public Overrides Function ToXmlString( _
            ByVal includePrivateParameters As Boolean) As String

            Dim keyContainerName As String = ""
            Dim keyNumber As String = ""
            Dim providerName As String = ""
            Dim providerType As String = ""

            If Not cspParameters Is Nothing Then
                keyContainerName = cspParameters.KeyContainerName
                keyNumber = cspParameters.KeyNumber.ToString()
                providerName = cspParameters.ProviderName
                providerType = cspParameters.ProviderType.ToString()
            End If

            Dim xmlBuilder As New StringBuilder
            xmlBuilder.Append("<CustomCryptoKeyValue>")

            xmlBuilder.Append("<KeyContainerName>")
            xmlBuilder.Append(keyContainerName)
            xmlBuilder.Append("</KeyContainerName>")

            xmlBuilder.Append("<KeyNumber>")
            xmlBuilder.Append(keyNumber)
            xmlBuilder.Append("</KeyNumber>")

            xmlBuilder.Append("<ProviderName>")
            xmlBuilder.Append(providerName)
            xmlBuilder.Append("</ProviderName>")

            xmlBuilder.Append("<ProviderType>")
            xmlBuilder.Append(providerType)
            xmlBuilder.Append("</ProviderType>")

            xmlBuilder.Append("</CustomCryptoKeyValue>")
            Return (xmlBuilder.ToString())
        End Function

        ' Return the name for the key exchange algorithm.
        Public Overrides ReadOnly Property KeyExchangeAlgorithm() As String
            Get
                Return "RSA-PKCS1-KeyEx"
            End Get
        End Property

        ' Retrieves the name of the signature alogrithm.
        ' This example uses the SHA1 algorithm.
        ' Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
        Public Overrides ReadOnly Property SignatureAlgorithm() As String
            Get
                Return "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
            End Get
        End Property

        ' Required member for implementing the AsymmetricAlgorithm class.
        Protected Overrides Sub Dispose(ByVal disposing As Boolean)

        End Sub

        ' The create function attempts to create a vbCustomCrypto object using
        ' the assembly name. This functionality requires modification of the
        ' machine.config file. Add the following section to the configuration
        ' element and modify the values of the cryptoClass to reflect what is
        ' installed in your machines GAC.
        '          <cryptoClass vbCustomCrypto="Contoso.vbCustomCrypto, 
        '            vbCustomCrypto, 
        '            Culture=neutral, 
        '            PublicKeyToken=fdb9f9c4851028bf, 
        '            Version=1.0.1448.27640" />
        '        <nameEntry name="Contoso.vbCustomCrypto" 
        '                   class="vbCustomCrypto" />
        '        <nameEntry name="vbCustomCrypto" class="vbCustomCrypto" />
        Public Shadows Function Create() As vbCustomCrypto
            Return Create("vbCustomCrypto")
        End Function

        ' Create a CustomCrypto object by calling CrytoConfig's
        ' CreateFromName method and casting the type to CustomCrypto.
        ' The create function attempts to create a vbCustomCrypto object using
        ' the assembly name. This functionality requires modification of the
        ' machine.config file. Add the following section to the configuration
        ' element and modify the values of the cryptoClass to reflect what is
        ' installed in your machines GAC.
        '          <cryptoClass vbCustomCrypto="Contoso.vbCustomCrypto, 
        '            vbCustomCrypto, 
        '            Culture=neutral, 
        '            PublicKeyToken=fdb9f9c4851028bf, 
        '            Version=1.0.1448.27640" />
        '        <nameEntry name="Contoso.vbCustomCrypto" 
        '                   class="vbCustomCrypto" />
        '        <nameEntry name="vbCustomCrypto" class="vbCustomCrypto" />
        Public Shadows Function Create( _
            ByVal algorithmName As String) As vbCustomCrypto

            Return CType( _
                CryptoConfig.CreateFromName(algorithmName), _
                vbCustomCrypto)

        End Function
    End Class
    Class Form1
        Inherits System.Windows.Forms.Form

        ' Event handler for Run button.
        Private Sub Button1_Click( _
            ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button1.Click

            tbxOutput.Cursor = Cursors.WaitCursor
            tbxOutput.Text = ""

            ' Construct a CustomCrypto object and initialize its
            ' CspParameters.
            Dim customCrypto As New Contoso.vbCustomCrypto
            customCrypto.InitializeParameters()

            ' Display properties of the current vbCustomCrypto object.
            WriteLine("*** CustomCrypto created with default parameters:")
            DisplayProperties(customCrypto)

            ' Release all the resources used by this instance of CustomCrytpo.
            customCrypto.Clear()

            customCrypto = New Contoso.vbCustomCrypto(64)
            ' Create new parameters and set them by using the
            ' FromXmlString method.
            Dim parameterXml As String = "<CustomCryptoKeyValue>"
            parameterXml += "<ProviderName>Contoso</ProviderName>"
            parameterXml += "<KeyContainerName>SecurityBin2"
            parameterXml += "</KeyContainerName>"
            parameterXml += "<KeyNumber>1</KeyNumber>"
            parameterXml += "<ProviderType>2</ProviderType>"
            parameterXml += "</CustomCryptoKeyValue>"
            customCrypto.FromXmlString(parameterXml)

            ' Display the properties of a customCrypto object created with
            ' custom parameters.
            WriteLine(vbCrLf + "*** " + _
                "CustomCrypto created with custom parameters:")
            DisplayProperties(customCrypto)

            ' Create an object by using the assembly name.
            Try
                Dim createdCrypto As Contoso.vbCustomCrypto
                createdCrypto = customCrypto.Create("vbCustomCrypto")

                If (Not createdCrypto Is Nothing) Then
                    Write(vbCrLf + "*** Successfully created vbCustomCrytpo ")
                    WriteLine("from the Create method.")

                    DisplayProperties(createdCrypto)
                Else
                    Write("Unable to create CustomCrytpo from ")
                    WriteLine(" the Create method.")
                End If
            Catch ex As Exception
                WriteLine(ex.ToString())
            End Try

            ' Align interface and conclude application.
            WriteLine("This sample completed successfully;" + _
                " press Exit to continue.")

            ' Reset the cursor.
            tbxOutput.Cursor = Cursors.Default
        End Sub
        ' Display the properties of the specified CustomCrypto object to
        ' the output texbox.
        Public Sub DisplayProperties( _
            ByVal customCrypto As Contoso.vbCustomCrypto)

            Try
                ' Retrieve the class description for the customCrypto object.
                Dim classDescription As String = customCrypto.ToString()

                WriteLine(classDescription)
                WriteLine("KeyExchangeAlgorithm: " + _
                    customCrypto.KeyExchangeAlgorithm)
                WriteLine("SignatureAlgorithm: " + _
                    customCrypto.SignatureAlgorithm)
                WriteLine("KeySize: " + customCrypto.KeySize.ToString())
                WriteLine("Parameters described in Xml format:")
                WriteLine(customCrypto.ToXmlString(True))

                ' Display the MinSize, MaxSize, and SkipSize properties of 
                ' each KeySize item in the local keySizes member variable.
                Dim legalKeySizes() As KeySizes = customCrypto.LegalKeySizes
                If (legalKeySizes.Length > 0) Then
                    For i As Integer = 0 To legalKeySizes.Length - 1 Step 1
                        Write("Keysize" + i.ToString() + " min, max, step: ")
                        Write(legalKeySizes(i).MinSize.ToString() + ", ")
                        Write(legalKeySizes(i).MaxSize.ToString() + ", ")
                        Write(legalKeySizes(i).SkipSize.ToString() + ", ")
                        WriteLine("")
                    Next
                End If
            Catch ex As Exception
                WriteLine("Caught unexpected exception: " + ex.ToString())
            End Try
        End Sub
        ' Write the specified message and carriage return to the output
        ' textbox.
        Private Sub WriteLine(ByVal message As String)
            tbxOutput.AppendText(message + vbCrLf)
        End Sub
        ' Write the specified message to the output textbox.
        Private Sub Write(ByVal message As String)
            tbxOutput.AppendText(message)
        End Sub
        ' Event handler for Exit button.
        Private Sub Button2_Click( _
            ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button2.Click

            Application.Exit()
        End Sub


        Public Sub New()
            MyBase.New()

            'This call is required by the Windows Form Designer.
            InitializeComponent()

            'Add any initialization after the InitializeComponent() call

        End Sub

        'Form overrides dispose to clean up the component list.
        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If disposing Then
                If Not (components Is Nothing) Then
                    components.Dispose()
                End If
            End If
            MyBase.Dispose(disposing)
        End Sub

        'Required by the Windows Form Designer
        Private components As System.ComponentModel.IContainer

        'NOTE: The following procedure is required by the Windows Form 
        'Designer. It can be modified using the Windows Form Designer. 
        'Do not modify it using the code editor.
        Friend WithEvents Panel2 As System.Windows.Forms.Panel
        Friend WithEvents Panel1 As System.Windows.Forms.Panel
        Friend WithEvents Button1 As System.Windows.Forms.Button
        Friend WithEvents Button2 As System.Windows.Forms.Button
        Friend WithEvents tbxOutput As System.Windows.Forms.RichTextBox
        <System.Diagnostics.DebuggerStepThrough()> _
        Private Sub InitializeComponent()
            Me.Panel2 = New System.Windows.Forms.Panel
            Me.Button1 = New System.Windows.Forms.Button
            Me.Button2 = New System.Windows.Forms.Button
            Me.Panel1 = New System.Windows.Forms.Panel
            Me.tbxOutput = New System.Windows.Forms.RichTextBox
            Me.Panel2.SuspendLayout()
            Me.Panel1.SuspendLayout()
            Me.SuspendLayout()
            '
            'Panel2
            '
            Me.Panel2.Controls.Add(Me.Button1)
            Me.Panel2.Controls.Add(Me.Button2)
            Me.Panel2.Dock = System.Windows.Forms.DockStyle.Bottom
            Me.Panel2.DockPadding.All = 20
            Me.Panel2.Location = New System.Drawing.Point(0, 320)
            Me.Panel2.Name = "Panel2"
            Me.Panel2.Size = New System.Drawing.Size(616, 64)
            Me.Panel2.TabIndex = 1
            '
            'Button1
            '
            Me.Button1.Dock = System.Windows.Forms.DockStyle.Right
            Me.Button1.Font = New System.Drawing.Font( _
                "Microsoft Sans Serif", _
                9.0!, _
                System.Drawing.FontStyle.Regular, _
                System.Drawing.GraphicsUnit.Point, _
                CType(0, Byte))
            Me.Button1.Location = New System.Drawing.Point(446, 20)
            Me.Button1.Name = "Button1"
            Me.Button1.Size = New System.Drawing.Size(75, 24)
            Me.Button1.TabIndex = 2
            Me.Button1.Text = "&Run"
            '
            'Button2
            '
            Me.Button2.Dock = System.Windows.Forms.DockStyle.Right
            Me.Button2.Font = New System.Drawing.Font( _
                "Microsoft Sans Serif", _
                9.0!, _
                System.Drawing.FontStyle.Regular, _
                System.Drawing.GraphicsUnit.Point, _
                CType(0, Byte))
            Me.Button2.Location = New System.Drawing.Point(521, 20)
            Me.Button2.Name = "Button2"
            Me.Button2.Size = New System.Drawing.Size(75, 24)
            Me.Button2.TabIndex = 3
            Me.Button2.Text = "E&xit"
            '
            'Panel1
            '
            Me.Panel1.Controls.Add(Me.tbxOutput)
            Me.Panel1.Dock = System.Windows.Forms.DockStyle.Fill
            Me.Panel1.DockPadding.All = 20
            Me.Panel1.Location = New System.Drawing.Point(0, 0)
            Me.Panel1.Name = "Panel1"
            Me.Panel1.Size = New System.Drawing.Size(616, 320)
            Me.Panel1.TabIndex = 2
            '
            'tbxOutput
            '
            Me.tbxOutput.AccessibleDescription = _
                "Displays output from application."
            Me.tbxOutput.AccessibleName = "Output textbox."
            Me.tbxOutput.Dock = System.Windows.Forms.DockStyle.Fill
            Me.tbxOutput.Location = New System.Drawing.Point(20, 20)
            Me.tbxOutput.Name = "tbxOutput"
            Me.tbxOutput.Size = New System.Drawing.Size(576, 280)
            Me.tbxOutput.TabIndex = 1
            Me.tbxOutput.Text = "Click the Run button to run the application."
            '
            'Form1
            '
            Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15)
            Me.ClientSize = New System.Drawing.Size(616, 384)
            Me.Controls.Add(Me.Panel1)
            Me.Controls.Add(Me.Panel2)
            Me.Name = "Form1"
            Me.Text = "AsymmetricAlgorithm"
            Me.Panel2.ResumeLayout(False)
            Me.Panel1.ResumeLayout(False)
            Me.ResumeLayout(False)

        End Sub

    End Class
End Namespace
'
' This sample produces the following output:
'
' *** CustomCrypto created with default parameters:
' Contoso.vbCustomCrypto
' KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
' SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
' KeySize: 8
' Parameters described in Xml format:
' <CustomCryptoKeyValue><KeyContainerName>SecurityBin1</KeyContainerName>
' <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
' <ProviderType>2</ProviderType></CustomCryptoKeyValue>
' Keysize0 min, max, step: 8, 64, 8, 
' 
' *** CustomCrypto created with custom parameters:
' Contoso.vbCustomCrypto
' KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
' SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
' KeySize: 64
' Parameters described in Xml format:
' <CustomCryptoKeyValue><KeyContainerName>SecurityBin2</KeyContainerName>
' <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
' <ProviderType>2</ProviderType></CustomCryptoKeyValue>
' Keysize0 min, max, step: 8, 64, 8, 
' Unable to create CustomCrytpo from  the Create method
' This sample completed successfully; press Enter to exit.

Esta es una clase adicional que muestra cómo usar la clase personalizada.

#using <System.Xml.dll>
#using <System.Security.dll>

using namespace System;
using namespace System::Xml;
using namespace System::Text;
using namespace System::Security::Cryptography;

// Display the properties of the specified CustomCrypto object to the
// console.
static void DisplayProperties(Contoso::CustomCrypto^ customCryptoAlgorithm)
{
    // Retrieve the class description for the customCrypto object.
    String^ classDescription = customCryptoAlgorithm->ToString();

    Console::WriteLine(classDescription);
    Console::WriteLine("KeyExchangeAlgorithm: {0}",
        customCryptoAlgorithm->KeyExchangeAlgorithm);
    Console::WriteLine("SignatureAlgorithm: {0}",
        customCryptoAlgorithm->SignatureAlgorithm);
    Console::WriteLine("KeySize: {0}",
        customCryptoAlgorithm->KeySize);
    Console::WriteLine("Parameters described in Xml format:");
    Console::WriteLine(customCryptoAlgorithm->ToXmlString(true));

    // Display the MinSize, MaxSize, and SkipSize properties of
    // each KeySize item in the local keySizes member variable.
    array<KeySizes^>^ legalKeySizes = customCryptoAlgorithm->LegalKeySizes;
    for (int i = 0; i < legalKeySizes->Length; i++)
    {
        Console::WriteLine(
            "Keysize{0} min, max, step: {1}, {2}, {3}, ", i,
            legalKeySizes[i]->MinSize,
            legalKeySizes[i]->MaxSize,
            legalKeySizes[i]->SkipSize);
    }
}

[STAThread]
int main()
{
    // Construct a CustomCrypto object and initialize its
    // CspParameters.
    Contoso::CustomCrypto^ customCryptoAlgorithm = gcnew Contoso::CustomCrypto();
    customCryptoAlgorithm->InitializeParameters();

    // Display properties of the current customCrypto object.
    Console::WriteLine(
        "*** CustomCrypto created with default parameters:");
    DisplayProperties(customCryptoAlgorithm);

    // Release all the resources used by this instance of
    // CustomCrypto.
    customCryptoAlgorithm->Clear();

    customCryptoAlgorithm = gcnew Contoso::CustomCrypto(64);
    // Create new parameters and set them by using the FromXmlString
    // method.
    String^ parameterXml = "<CustomCryptoKeyValue>" +
        "<ProviderName>Contoso</ProviderName>" +
        "<KeyContainerName>SecurityBin2</KeyContainerName>" +
        "<KeyNumber>1</KeyNumber>" +
        "<ProviderType>2</ProviderType>" +
        "</CustomCryptoKeyValue>";
    customCryptoAlgorithm->FromXmlString(parameterXml);

    // Display the properties of a customCrypto object created with
    // custom parameters.
    Console::WriteLine(
        "{0}*** CustomCrypto created with custom parameters:", Environment::NewLine);
    DisplayProperties(customCryptoAlgorithm);

    // Create an object by using the assembly name.
    Contoso::CustomCrypto^ cryptoFromAssembly =
        Contoso::CustomCrypto::Create("CustomCrypto");
    if (cryptoFromAssembly != nullptr)
    {
        Console::WriteLine("{0}*** Successfully created " +
            "CustomCrypto from the Create method.", Environment::NewLine);
        DisplayProperties(cryptoFromAssembly);
    }
    else
    {
        Console::WriteLine("Unable to create CustomCrypto from " +
            "the Create method.");
    }

    Console::WriteLine(
        "This sample completed successfully; press Enter to exit.");
    Console::ReadLine();
}

//
// This sample produces the following output:
//
// *** CustomCrypto created with default parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 8
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin1</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8,
//
// *** CustomCrypto created with custom parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 64
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin2</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8,
// Unable to create CustomCrypto from the Create method
// This sample completed successfully; press Enter to exit.
    class CustomCryptoImpl
    {
        [STAThread]
        static void Main(string[] args)
        {
            // Construct a CustomCrypto object and initialize its
            // CspParameters.
            CustomCrypto customCrypto = new CustomCrypto();
            customCrypto.InitializeParameters();

            // Display properties of the current customCrypto object.
            Console.WriteLine("*** CustomCrypto created with default " + 
                "parameters:");
            DisplayProperties(customCrypto);

            // Release all the resources used by this instance of 
            // CustomCrytpo.
            customCrypto.Clear();

            customCrypto = new CustomCrypto(64);
            // Create new parameters and set them by using the FromXmlString
            // method.
            string parameterXml = "<CustomCryptoKeyValue>";
            parameterXml += "<ProviderName>Contoso</ProviderName>";
            parameterXml += "<KeyContainerName>SecurityBin2";
            parameterXml += "</KeyContainerName>";
            parameterXml += "<KeyNumber>1</KeyNumber>";
            parameterXml += "<ProviderType>2</ProviderType>";
            parameterXml += "</CustomCryptoKeyValue>";
            customCrypto.FromXmlString(parameterXml);

            // Display the properties of a customCrypto object created with
            // custom parameters.
            Console.WriteLine("\n*** " + 
                "CustomCrypto created with custom parameters:");
            DisplayProperties(customCrypto);

            // Create an object by using the assembly name.
            try
            {
                CustomCrypto myCryptoA = CustomCrypto.Create("CustomCrypto");
                if (myCryptoA != null)
                {
                    Console.Write("\n*** " + 
                        "Successfully created CustomCrytpo from");
                    Console.WriteLine(" the Create method.");

                    DisplayProperties(myCryptoA);
                }
                else
                {
                    Console.Write("Unable to create CustomCrytpo from ");
                    Console.WriteLine(" the Create method.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            
            Console.WriteLine("This sample completed successfully; " +
                "press Enter to exit.");
            Console.ReadLine();
        }
        // Display the properties of the specified CustomCrypto object to the
        // console.
        public static void DisplayProperties(CustomCrypto customCrypto)
        {
            try
            {
                // Retrieve the class description for the customCrypto object.
                string classDescription = customCrypto.ToString();

                Console.WriteLine(classDescription);
                Console.Write("KeyExchangeAlgorithm: ");
                Console.WriteLine(customCrypto.KeyExchangeAlgorithm);
                Console.Write("SignatureAlgorithm: ");
                Console.WriteLine(customCrypto.SignatureAlgorithm);
                Console.WriteLine("KeySize: " + customCrypto.KeySize);
                Console.WriteLine("Parameters described in Xml format:");
                Console.WriteLine(customCrypto.ToXmlString(true));

                // Display the MinSize, MaxSize, and SkipSize properties of 
                // each KeySize item in the local keySizes member variable.
                KeySizes[] legalKeySizes = customCrypto.LegalKeySizes;
                if (legalKeySizes.Length > 0)
                {
                    for (int i=0; i < legalKeySizes.Length; i++)
                    {
                        Console.Write("Keysize" + i + " min, max, step: ");
                        Console.Write(legalKeySizes[i].MinSize + ", ");
                        Console.Write(legalKeySizes[i].MaxSize + ", ");
                        Console.WriteLine(legalKeySizes[i].SkipSize + ", ");
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Caught unexpected exception: " + 
                    ex.ToString());
            }
        }
    }
}
//
// This sample produces the following output:
//
// *** CustomCrypto created with default parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 8
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin1</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8, 
// 
// *** CustomCrypto created with custom parameters:
// Contoso.vbCustomCrypto
// KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
// SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
// KeySize: 64
// Parameters described in Xml format:
// <CustomCryptoKeyValue><KeyContainerName>SecurityBin2</KeyContainerName>
// <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
// <ProviderType>2</ProviderType></CustomCryptoKeyValue>
// Keysize0 min, max, step: 8, 64, 8, 
// Unable to create CustomCrytpo from  the Create method
// This sample completed successfully; press Exit to continue.
    Class Form1
        Inherits System.Windows.Forms.Form

        ' Event handler for Run button.
        Private Sub Button1_Click( _
            ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button1.Click

            tbxOutput.Cursor = Cursors.WaitCursor
            tbxOutput.Text = ""

            ' Construct a CustomCrypto object and initialize its
            ' CspParameters.
            Dim customCrypto As New Contoso.vbCustomCrypto
            customCrypto.InitializeParameters()

            ' Display properties of the current vbCustomCrypto object.
            WriteLine("*** CustomCrypto created with default parameters:")
            DisplayProperties(customCrypto)

            ' Release all the resources used by this instance of CustomCrytpo.
            customCrypto.Clear()

            customCrypto = New Contoso.vbCustomCrypto(64)
            ' Create new parameters and set them by using the
            ' FromXmlString method.
            Dim parameterXml As String = "<CustomCryptoKeyValue>"
            parameterXml += "<ProviderName>Contoso</ProviderName>"
            parameterXml += "<KeyContainerName>SecurityBin2"
            parameterXml += "</KeyContainerName>"
            parameterXml += "<KeyNumber>1</KeyNumber>"
            parameterXml += "<ProviderType>2</ProviderType>"
            parameterXml += "</CustomCryptoKeyValue>"
            customCrypto.FromXmlString(parameterXml)

            ' Display the properties of a customCrypto object created with
            ' custom parameters.
            WriteLine(vbCrLf + "*** " + _
                "CustomCrypto created with custom parameters:")
            DisplayProperties(customCrypto)

            ' Create an object by using the assembly name.
            Try
                Dim createdCrypto As Contoso.vbCustomCrypto
                createdCrypto = customCrypto.Create("vbCustomCrypto")

                If (Not createdCrypto Is Nothing) Then
                    Write(vbCrLf + "*** Successfully created vbCustomCrytpo ")
                    WriteLine("from the Create method.")

                    DisplayProperties(createdCrypto)
                Else
                    Write("Unable to create CustomCrytpo from ")
                    WriteLine(" the Create method.")
                End If
            Catch ex As Exception
                WriteLine(ex.ToString())
            End Try

            ' Align interface and conclude application.
            WriteLine("This sample completed successfully;" + _
                " press Exit to continue.")

            ' Reset the cursor.
            tbxOutput.Cursor = Cursors.Default
        End Sub
        ' Display the properties of the specified CustomCrypto object to
        ' the output texbox.
        Public Sub DisplayProperties( _
            ByVal customCrypto As Contoso.vbCustomCrypto)

            Try
                ' Retrieve the class description for the customCrypto object.
                Dim classDescription As String = customCrypto.ToString()

                WriteLine(classDescription)
                WriteLine("KeyExchangeAlgorithm: " + _
                    customCrypto.KeyExchangeAlgorithm)
                WriteLine("SignatureAlgorithm: " + _
                    customCrypto.SignatureAlgorithm)
                WriteLine("KeySize: " + customCrypto.KeySize.ToString())
                WriteLine("Parameters described in Xml format:")
                WriteLine(customCrypto.ToXmlString(True))

                ' Display the MinSize, MaxSize, and SkipSize properties of 
                ' each KeySize item in the local keySizes member variable.
                Dim legalKeySizes() As KeySizes = customCrypto.LegalKeySizes
                If (legalKeySizes.Length > 0) Then
                    For i As Integer = 0 To legalKeySizes.Length - 1 Step 1
                        Write("Keysize" + i.ToString() + " min, max, step: ")
                        Write(legalKeySizes(i).MinSize.ToString() + ", ")
                        Write(legalKeySizes(i).MaxSize.ToString() + ", ")
                        Write(legalKeySizes(i).SkipSize.ToString() + ", ")
                        WriteLine("")
                    Next
                End If
            Catch ex As Exception
                WriteLine("Caught unexpected exception: " + ex.ToString())
            End Try
        End Sub
        ' Write the specified message and carriage return to the output
        ' textbox.
        Private Sub WriteLine(ByVal message As String)
            tbxOutput.AppendText(message + vbCrLf)
        End Sub
        ' Write the specified message to the output textbox.
        Private Sub Write(ByVal message As String)
            tbxOutput.AppendText(message)
        End Sub
        ' Event handler for Exit button.
        Private Sub Button2_Click( _
            ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button2.Click

            Application.Exit()
        End Sub


        Public Sub New()
            MyBase.New()

            'This call is required by the Windows Form Designer.
            InitializeComponent()

            'Add any initialization after the InitializeComponent() call

        End Sub

        'Form overrides dispose to clean up the component list.
        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If disposing Then
                If Not (components Is Nothing) Then
                    components.Dispose()
                End If
            End If
            MyBase.Dispose(disposing)
        End Sub

        'Required by the Windows Form Designer
        Private components As System.ComponentModel.IContainer

        'NOTE: The following procedure is required by the Windows Form 
        'Designer. It can be modified using the Windows Form Designer. 
        'Do not modify it using the code editor.
        Friend WithEvents Panel2 As System.Windows.Forms.Panel
        Friend WithEvents Panel1 As System.Windows.Forms.Panel
        Friend WithEvents Button1 As System.Windows.Forms.Button
        Friend WithEvents Button2 As System.Windows.Forms.Button
        Friend WithEvents tbxOutput As System.Windows.Forms.RichTextBox
        <System.Diagnostics.DebuggerStepThrough()> _
        Private Sub InitializeComponent()
            Me.Panel2 = New System.Windows.Forms.Panel
            Me.Button1 = New System.Windows.Forms.Button
            Me.Button2 = New System.Windows.Forms.Button
            Me.Panel1 = New System.Windows.Forms.Panel
            Me.tbxOutput = New System.Windows.Forms.RichTextBox
            Me.Panel2.SuspendLayout()
            Me.Panel1.SuspendLayout()
            Me.SuspendLayout()
            '
            'Panel2
            '
            Me.Panel2.Controls.Add(Me.Button1)
            Me.Panel2.Controls.Add(Me.Button2)
            Me.Panel2.Dock = System.Windows.Forms.DockStyle.Bottom
            Me.Panel2.DockPadding.All = 20
            Me.Panel2.Location = New System.Drawing.Point(0, 320)
            Me.Panel2.Name = "Panel2"
            Me.Panel2.Size = New System.Drawing.Size(616, 64)
            Me.Panel2.TabIndex = 1
            '
            'Button1
            '
            Me.Button1.Dock = System.Windows.Forms.DockStyle.Right
            Me.Button1.Font = New System.Drawing.Font( _
                "Microsoft Sans Serif", _
                9.0!, _
                System.Drawing.FontStyle.Regular, _
                System.Drawing.GraphicsUnit.Point, _
                CType(0, Byte))
            Me.Button1.Location = New System.Drawing.Point(446, 20)
            Me.Button1.Name = "Button1"
            Me.Button1.Size = New System.Drawing.Size(75, 24)
            Me.Button1.TabIndex = 2
            Me.Button1.Text = "&Run"
            '
            'Button2
            '
            Me.Button2.Dock = System.Windows.Forms.DockStyle.Right
            Me.Button2.Font = New System.Drawing.Font( _
                "Microsoft Sans Serif", _
                9.0!, _
                System.Drawing.FontStyle.Regular, _
                System.Drawing.GraphicsUnit.Point, _
                CType(0, Byte))
            Me.Button2.Location = New System.Drawing.Point(521, 20)
            Me.Button2.Name = "Button2"
            Me.Button2.Size = New System.Drawing.Size(75, 24)
            Me.Button2.TabIndex = 3
            Me.Button2.Text = "E&xit"
            '
            'Panel1
            '
            Me.Panel1.Controls.Add(Me.tbxOutput)
            Me.Panel1.Dock = System.Windows.Forms.DockStyle.Fill
            Me.Panel1.DockPadding.All = 20
            Me.Panel1.Location = New System.Drawing.Point(0, 0)
            Me.Panel1.Name = "Panel1"
            Me.Panel1.Size = New System.Drawing.Size(616, 320)
            Me.Panel1.TabIndex = 2
            '
            'tbxOutput
            '
            Me.tbxOutput.AccessibleDescription = _
                "Displays output from application."
            Me.tbxOutput.AccessibleName = "Output textbox."
            Me.tbxOutput.Dock = System.Windows.Forms.DockStyle.Fill
            Me.tbxOutput.Location = New System.Drawing.Point(20, 20)
            Me.tbxOutput.Name = "tbxOutput"
            Me.tbxOutput.Size = New System.Drawing.Size(576, 280)
            Me.tbxOutput.TabIndex = 1
            Me.tbxOutput.Text = "Click the Run button to run the application."
            '
            'Form1
            '
            Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15)
            Me.ClientSize = New System.Drawing.Size(616, 384)
            Me.Controls.Add(Me.Panel1)
            Me.Controls.Add(Me.Panel2)
            Me.Name = "Form1"
            Me.Text = "AsymmetricAlgorithm"
            Me.Panel2.ResumeLayout(False)
            Me.Panel1.ResumeLayout(False)
            Me.ResumeLayout(False)

        End Sub

    End Class
End Namespace
'
' This sample produces the following output:
'
' *** CustomCrypto created with default parameters:
' Contoso.vbCustomCrypto
' KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
' SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
' KeySize: 8
' Parameters described in Xml format:
' <CustomCryptoKeyValue><KeyContainerName>SecurityBin1</KeyContainerName>
' <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
' <ProviderType>2</ProviderType></CustomCryptoKeyValue>
' Keysize0 min, max, step: 8, 64, 8, 
' 
' *** CustomCrypto created with custom parameters:
' Contoso.vbCustomCrypto
' KeyExchangeAlgorithm: RSA-PKCS1-KeyEx
' SignatureAlgorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1
' KeySize: 64
' Parameters described in Xml format:
' <CustomCryptoKeyValue><KeyContainerName>SecurityBin2</KeyContainerName>
' <KeyNumber>1</KeyNumber><ProviderName>Contoso</ProviderName>
' <ProviderType>2</ProviderType></CustomCryptoKeyValue>
' Keysize0 min, max, step: 8, 64, 8, 
' Unable to create CustomCrytpo from  the Create method
' This sample completed successfully; press Enter to exit.

Comentarios

Los algoritmos criptográficos asimétricos, también conocidos como algoritmos de clave pública, requieren que tanto el remitente como el receptor mantengan un par de claves relacionadas: una clave privada y una clave pública. Ambas claves son únicas para la entidad. La clave pública se puede poner a disposición de cualquier persona; esta clave se usa para codificar los datos que se envían a un receptor. El receptor debe mantener la clave privada; esta clave se usa para descodificar mensajes codificados mediante la clave pública del receptor. La RSACryptoServiceProvider clase es una implementación de un algoritmo de clave pública. Para obtener una explicación detallada del cifrado y los algoritmos de clave pública, consulte la sección "Cifrado de clave pública" en Servicios criptográficos. Para obtener información sobre cómo usar la herramienta de nombre seguro (Sn.exe) para crear pares de claves, vea How to: Create a Public-Private Key Pair.

Puede usar sistemas de clave pública para formar firmas digitales. Las firmas digitales se usan para ayudar a proteger la integridad de los datos. Por ejemplo, para usar un sistema de clave pública para firmar digitalmente un mensaje, el remitente aplica primero una función hash al mensaje para crear un resumen de mensaje. A continuación, el remitente cifra el resumen del mensaje con la clave privada del remitente para crear la firma personal del remitente. Al recibir el mensaje y la firma, el receptor descifra la firma mediante la clave pública del remitente para recuperar el resumen del mensaje y aplica un algoritmo hash al mensaje con el mismo algoritmo hash que usó el remitente. Si el resumen del mensaje que el receptor calcula coincide con el resumen del mensaje recibido del remitente, el receptor puede suponer que el mensaje no se modificó durante el tránsito. Tenga en cuenta que cualquier persona puede comprobar una firma, ya que la clave pública del remitente es un conocimiento común. Esta técnica no conserva el secreto del mensaje; para que el mensaje sea secreto, también debe cifrarse.

El .NET Framework proporciona las siguientes clases que implementan algoritmos de firma digital: DSACryptoServiceProvider, , RSACryptoServiceProviderECDsa (clase base) y ECDsaCng.

El System.Security.Cryptography espacio de nombres proporciona clases concretas solo para RSA y DSA .

Para obtener información sobre cómo usar el algoritmo RSA para cifrar y descifrar datos XML, y crear y comprobar firmas digitales XML, consulte estos artículos:

Constructores

AsymmetricAlgorithm()

Inicializa una nueva instancia de la clase AsymmetricAlgorithm.

Campos

KeySizeValue

Representa el tamaño, en bits, del módulo de claves que usa el algoritmo asimétrico.

LegalKeySizesValue

Especifica los tamaños de clave admitidos por el algoritmo asimétrico.

Propiedades

KeyExchangeAlgorithm

Cuando se invalida en una clase derivada, obtiene el nombre del algoritmo de intercambio de claves. En caso contrario, produce una excepción NotImplementedException.

KeySize

Obtiene o establece el tamaño, en bits, del módulo de claves que usa el algoritmo asimétrico.

LegalKeySizes

Obtiene los tamaños de clave que admite el algoritmo asimétrico.

SignatureAlgorithm

Cuando se implementa en una clase derivada, obtiene el nombre del algoritmo de signatura. En caso contrario, produce siempre una NotImplementedException.

Métodos

Clear()

Libera todos los recursos que utiliza la clase AsymmetricAlgorithm.

Create()
Obsoleto.
Obsoleto.

Crea un objeto criptográfico predeterminado que se usa para realizar el algoritmo asimétrico.

Create(String)

Crea una instancia de la implementación especificada de un algoritmo asimétrico.

Dispose()

Libera todos los recursos usados por la instancia actual de la clase AsymmetricAlgorithm.

Dispose(Boolean)

Libera los recursos no administrados utilizados por la clase AsymmetricAlgorithm y, de forma opcional, libera los recursos administrados.

Equals(Object)

Determina si el objeto especificado es igual que el objeto actual.

(Heredado de Object)
ExportEncryptedPkcs8PrivateKey(ReadOnlySpan<Byte>, PbeParameters)

Exporta la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 con una contraseña basada en bytes.

ExportEncryptedPkcs8PrivateKey(ReadOnlySpan<Char>, PbeParameters)

Exporta la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 con una contraseña basada en caracteres.

ExportEncryptedPkcs8PrivateKeyPem(ReadOnlySpan<Char>, PbeParameters)

Exporta la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 con una contraseña basada en caracteres, codificada en PEM.

ExportPkcs8PrivateKey()

Exporta la clave actual en el formato PrivateKeyInfo de PKCS#8.

ExportPkcs8PrivateKeyPem()

Exporta la clave actual en el formato PrivateKeyInfo PKCS#8, codificado en PEM.

ExportSubjectPublicKeyInfo()

Exporta la parte de la clave pública de la clave actual en el formato SubjectPublicKeyInfo de X.509.

ExportSubjectPublicKeyInfoPem()

Exporta la parte de clave pública de la clave actual en el formato SubjectPublicKeyInfo X.509, codificado en PEM.

FromXmlString(String)

Cuando se invalida en una clase derivada, reconstruye un objeto AsymmetricAlgorithm a partir de una cadena XML. En caso contrario, produce una excepción NotImplementedException.

GetHashCode()

Sirve como la función hash predeterminada.

(Heredado de Object)
GetType()

Obtiene el Type de la instancia actual.

(Heredado de Object)
ImportEncryptedPkcs8PrivateKey(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Int32)

Cuando se reemplaza en una clase derivada, importa el par de claves pública/privada desde una estructura EncryptedPrivateKeyInfo de PKCS#8 después de descifrar con una contraseña basada en bytes, reemplazando las claves de este objeto.

ImportEncryptedPkcs8PrivateKey(ReadOnlySpan<Char>, ReadOnlySpan<Byte>, Int32)

Cuando se reemplaza en una clase derivada, importa el par de claves pública/privada desde una estructura EncryptedPrivateKeyInfo de PKCS#8 después de descifrar con una contraseña basada en caracteres, reemplazando las claves de este objeto.

ImportFromEncryptedPem(ReadOnlySpan<Char>, ReadOnlySpan<Byte>)

Cuando se invalida en una clase derivada, importa una clave con codificación PEM de RFC 7468 cifrada, reemplazando las claves para este objeto.

ImportFromEncryptedPem(ReadOnlySpan<Char>, ReadOnlySpan<Char>)

Cuando se invalida en una clase derivada, importa una clave con codificación PEM de RFC 7468 cifrada, reemplazando las claves para este objeto.

ImportFromPem(ReadOnlySpan<Char>)

Cuando se reemplaza en una clase derivada, importa una clave codificada textualmente de RFC 7468, reemplazando las claves para este objeto.

ImportPkcs8PrivateKey(ReadOnlySpan<Byte>, Int32)

Cuando se reemplaza en una clase derivada, importa el par de claves pública/privada desde una estructura PrivateKeyInfo de PKCS#8 después del descifrado, reemplazando las claves de este objeto.

ImportSubjectPublicKeyInfo(ReadOnlySpan<Byte>, Int32)

Cuando se reemplaza en una clase derivada, importa la clave pública desde una estructura SubjectPublicKeyInfo de X.509 después del descifrado, reemplazando las claves de este objeto.

MemberwiseClone()

Crea una copia superficial del Object actual.

(Heredado de Object)
ToString()

Devuelve una cadena que representa el objeto actual.

(Heredado de Object)
ToXmlString(Boolean)

Cuando se invalida en una clase derivada, crea y devuelve una representación en forma de cadena XML del objeto AsymmetricAlgorithm actual. En caso contrario, produce una excepción NotImplementedException.

TryExportEncryptedPkcs8PrivateKey(ReadOnlySpan<Byte>, PbeParameters, Span<Byte>, Int32)

Cuando se reemplaza en una clase derivada, intenta exportar la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 a un búfer proporcionado, utilizando una contraseña basada en bytes.

TryExportEncryptedPkcs8PrivateKey(ReadOnlySpan<Char>, PbeParameters, Span<Byte>, Int32)

Cuando se reemplaza en una clase derivada, intenta exportar la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 a un búfer proporcionado, utilizando una contraseña basada en caracteres.

TryExportEncryptedPkcs8PrivateKeyPem(ReadOnlySpan<Char>, PbeParameters, Span<Char>, Int32)

Exporta la clave actual en el formato EncryptedPrivateKeyInfo de PKCS#8 con una contraseña basada en caracteres, codificada en PEM.

TryExportPkcs8PrivateKey(Span<Byte>, Int32)

Cuando se reemplaza en una clase derivada, intenta exportar la clave actual en el formato PrivateKeyInfo de PKCS#8 a un búfer proporcionado.

TryExportPkcs8PrivateKeyPem(Span<Char>, Int32)

Intenta exportar la clave actual en el formato PKCS#8 PrivateKeyInfo codificado en PEM en un búfer proporcionado.

TryExportSubjectPublicKeyInfo(Span<Byte>, Int32)

Cuando se reemplaza en una clase derivada, intenta exportar la clave actual en el formato SubjectPublicKeyInfo de X.509 a un búfer proporcionado.

TryExportSubjectPublicKeyInfoPem(Span<Char>, Int32)

Intenta exportar la clave actual en el formato X.509 SubjectPublicKeyInfo codificado en PEM en un búfer proporcionado.

Implementaciones de interfaz explícitas

IDisposable.Dispose()

Esta API admite la infraestructura de producto y no está pensada para usarse directamente en el código.

Para obtener una descripción de este miembro, vea Dispose().

Se aplica a

Consulte también