DataProtector Klas

Definitie

public ref class DataProtector abstract

public abstract class DataProtector

type DataProtector = class

Public MustInherit Class DataProtector

Overname

Object

DataProtector

Afgeleid

System.Security.Cryptography.DpapiDataProtector

Voorbeelden

In het volgende voorbeeld ziet u hoe u een gegevensbeveiliging maakt die gebruikmaakt van een beveiligingsklasse met een optie voor extra entropie. DataProtector De klasse prependeert standaard de hash van de doeleigenschappen voor de gegevens die moeten worden versleuteld. U kunt deze functionaliteit uitschakelen en het hash-doel gebruiken als extra entropie bij het aanroepen van een gegevensbeveiliging met een extra entropieoptie.

using System;
using System.Security.Permissions;

namespace System.Security.Cryptography
{
    public sealed class MyDataProtector : DataProtector
    {
        public DataProtectionScope Scope { get; set; }
        // This implementation gets the HashedPurpose from the base class and passes it as OptionalEntropy to ProtectedData.
        // The default for DataProtector is to prepend the hash to the plain text, but because we are using the hash
        // as OptionalEntropy there is no need to prepend it.
        protected override bool PrependHashedPurposeToPlaintext
        {
            get
            {
                return false;
            }
        }
        // To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
        // in the constructor, but Assert the permission when ProviderProtect is called.  This is similar to FileStream
        // where access is checked at time of creation, not time of use.
        [SecuritySafeCritical]
        [DataProtectionPermission(SecurityAction.Assert, ProtectData = true)]
        protected override byte[] ProviderProtect(byte[] userData)
        {
            // Delegate to ProtectedData
            return ProtectedData.Protect(userData, GetHashedPurpose(), Scope);
        }
        // To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
        // in the constructor, but Assert the permission when ProviderUnProtect is called.  This is similar to FileStream
        // where access is checked at time of creation, not time of use.
        [SecuritySafeCritical]
        [DataProtectionPermission(SecurityAction.Assert, UnprotectData = true)]
        protected override byte[] ProviderUnprotect(byte[] encryptedData)
        {
            // Delegate to ProtectedData
            return ProtectedData.Unprotect(encryptedData, GetHashedPurpose(), Scope);
        }
        public override bool IsReprotectRequired(byte[] encryptedData)
        {
            // For now, this cannot be determined, so always return true;
            return true;
        }
        // Public constructor
        // The Demand for DataProtectionPermission is in the constructor because we Assert this permission
        // in the ProviderProtect/ProviderUnprotect methods.
        [DataProtectionPermission(SecurityAction.Demand, Unrestricted = true)]
        [SecuritySafeCritical]
        public MyDataProtector(string appName, string primaryPurpose, params string[] specificPurpose)
            : base(appName, primaryPurpose, specificPurpose)
        {
        }
    }
}

Imports System.Security
Imports System.Security.Cryptography
Imports System.Security.Permissions



Public NotInheritable Class MyDataProtector
    Inherits DataProtector

    Public Property Scope() As DataProtectionScope
        Get
            Return Scope
        End Get
        Set(value As DataProtectionScope)
        End Set
    End Property ' This implementation gets the HashedPurpose from the base class and passes it as OptionalEntropy to ProtectedData.
    ' The default for DataProtector is to prepend the hash to the plain text, but because we are using the hash 
    ' as OptionalEntropy there is no need to prepend it.

    Protected Overrides ReadOnly Property PrependHashedPurposeToPlaintext() As Boolean
        Get
            Return False
        End Get
    End Property

    ' To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission 
    ' in the constructor, but Assert the permission when ProviderProtect is called.  This is similar to FileStream
    ' where access is checked at time of creation, not time of use.
    <SecuritySafeCritical(), DataProtectionPermission(SecurityAction.Assert, ProtectData:=True)> _
    Protected Overrides Function ProviderProtect(ByVal userData() As Byte) As Byte()
        ' Delegate to ProtectedData
        Return ProtectedData.Protect(userData, GetHashedPurpose(), Scope)

    End Function 'ProviderProtect

    ' To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission 
    ' in the constructor, but Assert the permission when ProviderUnProtect is called.  This is similar to FileStream
    ' where access is checked at time of creation, not time of use.
    <SecuritySafeCritical(), DataProtectionPermission(SecurityAction.Assert, UnprotectData:=True)> _
    Protected Overrides Function ProviderUnprotect(ByVal encryptedData() As Byte) As Byte()
        ' Delegate to ProtectedData
        Return ProtectedData.Unprotect(encryptedData, GetHashedPurpose(), Scope)

    End Function 'ProviderUnprotect

    Public Overrides Function IsReprotectRequired(ByVal encryptedData() As Byte) As Boolean
        ' For now, this cannot be determined, so always return true;
        Return True

    End Function 'IsReprotectRequired

    ' Public constructor
    ' The Demand for DataProtectionPermission is in the constructor because we Assert this permission 
    ' in the ProviderProtect/ProviderUnprotect methods. 
    <DataProtectionPermission(SecurityAction.Demand, Unrestricted:=True), SecuritySafeCritical()> _
    Public Sub New(ByVal appName As String, ByVal primaryPurpose As String, ParamArray specificPurpose() As String)
        MyBase.New(appName, primaryPurpose, specificPurpose)

    End Sub
End Class

In het volgende voorbeeld ziet u een eenvoudige gegevensbeveiliging die gebruikmaakt van de PrependHashedPurposeToPlaintext functionaliteit van de DataProtector klasse.

using System;
using System.Security.Permissions;

namespace System.Security.Cryptography
{
    public sealed class MemoryProtector : DataProtector
    {
        public MemoryProtectionScope Scope { get; set; }
        protected override bool PrependHashedPurposeToPlaintext
        {
            get
            {
                // Signal the DataProtector to prepend the hash of the purpose to the data.
                return true;
            }
        }
        // To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
        // in the constructor, but Assert the permission when ProviderProtect is called.  This is similar to FileStream
        // where access is checked at time of creation, not time of use.
        [SecuritySafeCritical]
        [DataProtectionPermission(SecurityAction.Assert, ProtectData = true)]
        protected override byte[] ProviderProtect(byte[] userData)
        {

            // Delegate to ProtectedData
            ProtectedMemory.Protect(userData, Scope);
            return userData;
        }
        // To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
        // in the constructor, but Assert the permission when ProviderUnprotect is called..  This is similar to FileStream
        // where access is checked at time of creation, not time of use.
        [SecuritySafeCritical]
        [DataProtectionPermission(SecurityAction.Assert, UnprotectData = true)]
        protected override byte[] ProviderUnprotect(byte[] encryptedData)
        {

            ProtectedMemory.Unprotect(encryptedData,Scope);
                return encryptedData;
        }

        public override bool IsReprotectRequired(byte[] encryptedData)
        {
            // For now, this cannot be determined so always return true.
            return true;
        }
        // Public constructor
        // The Demand for DataProtectionPermission is in the constructor because we Assert this permission
        // in the ProviderProtect/ProviderUnprotect methods.
        [DataProtectionPermission(SecurityAction.Demand, Unrestricted = true)]
        [SecuritySafeCritical]
        public MemoryProtector(string appName, string primaryPurpose, params string[] specificPurpose)
            : base(appName, primaryPurpose, specificPurpose)
        {
        }
    }
}

Imports System.Security
Imports System.Security.Permissions
Imports System.Security.Cryptography



Public NotInheritable Class MemoryProtector
    Inherits DataProtector

    Public Property Scope() As MemoryProtectionScope
        Get
            Return Scope
        End Get
        Set(value As MemoryProtectionScope)
        End Set
    End Property

    Protected Overrides ReadOnly Property PrependHashedPurposeToPlaintext() As Boolean
        Get
            ' Signal the DataProtector to prepend the hash of the purpose to the data.
            Return True
        End Get
    End Property

    ' To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission 
    ' in the constructor, but Assert the permission when ProviderProtect is called.  This is similar to FileStream
    ' where access is checked at time of creation, not time of use.
    <SecuritySafeCritical(), DataProtectionPermission(SecurityAction.Assert, ProtectData:=True)> _
    Protected Overrides Function ProviderProtect(ByVal userData() As Byte) As Byte()

        ' Delegate to ProtectedData
        ProtectedMemory.Protect(userData, Scope)
        Return userData

    End Function 'ProviderProtect

    ' To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission 
    ' in the constructor, but Assert the permission when ProviderUnprotect is called..  This is similar to FileStream
    ' where access is checked at time of creation, not time of use.
    <SecuritySafeCritical(), DataProtectionPermission(SecurityAction.Assert, UnprotectData:=True)> _
    Protected Overrides Function ProviderUnprotect(ByVal encryptedData() As Byte) As Byte()

        ProtectedMemory.Unprotect(encryptedData, Scope)
        Return encryptedData

    End Function 'ProviderUnprotect

    Public Overrides Function IsReprotectRequired(ByVal encryptedData() As Byte) As Boolean
        ' For now, this cannot be determined so always return true.
        Return True

    End Function 'IsReprotectRequired

    ' Public constructor
    ' The Demand for DataProtectionPermission is in the constructor because we Assert this permission 
    ' in the ProviderProtect/ProviderUnprotect methods. 
    <DataProtectionPermission(SecurityAction.Demand, Unrestricted:=True), SecuritySafeCritical()> _
    Public Sub New(ByVal appName As String, ByVal primaryPurpose As String, ParamArray specificPurpose() As String)
        MyBase.New(appName, primaryPurpose, specificPurpose)

    End Sub
End Class

Opmerkingen

Deze klasse beschermt opgeslagen gegevens tegen weergave en manipulatie. De toegang tot de beveiligde gegevens wordt verkregen door een exemplaar van deze klasse te maken en de exacte doeltekenreeksen te gebruiken die zijn gebruikt om de gegevens te beveiligen. De beller heeft geen sleutel nodig om de gegevens te beveiligen of op te heffen. De sleutel wordt geleverd door het versleutelingsalgoritmen.

Afgeleide klassen moeten de ProviderProtect en Unprotect methoden overschrijven die de DataProtector basisklasse weer aanroept. Ze moeten ook de IsReprotectRequired methode overschrijven, die altijd kan worden geretourneerd true met een potentieel klein verlies van efficiëntie wanneer toepassingen hun database met opgeslagen coderingstekst vernieuwen. Afgeleide klassen moeten een constructor bieden die de basisklasseconstructor aanroept, waarmee de ApplicationName, SpecificPurposesen PrimaryPurpose eigenschappen worden ingesteld.