作法：使用資料保護

  • 發行項

注意

本文適用於 Windows。

如需 ASP.NET Core 的相關資訊，請參閱 ASP.NET Core 資料保護。

.NET 提供資料保護 API (DPAPI) 的存取，這可讓您使用目前使用者帳戶或電腦的資訊來加密資料。 當您使用 DPAPI 時，會減少明確產生並儲存密碼編譯金鑰的困難問題。

使用 ProtectedData 類別來加密位元組陣列的複本。 您可以指定由目前使用者帳戶加密的資料只能由相同的使用者帳戶解密，或是您可以指定目前使用者帳戶加密的資料可以由電腦上的任何帳戶解密。 請參閱 DataProtectionScope 列舉，以取得 ProtectedData 選項的詳細說明。

使用資料保護將資料加密到檔案或資料流

  1. 建立隨機的 entropy。

  2. 呼叫靜態 Protect 方法並傳遞要加密的位元組陣列、entropy 及資料保護範圍。

  3. 將加密的資料寫入檔案或資料流。

使用資料保護從檔案或資料流解密資料

  1. 從檔案或資料流讀取加密的資料。

  2. 呼叫靜態 Unprotect 方法並傳遞要解密的位元組陣列及資料保護範圍。

範例

下列程式碼範例示範兩種形式的加密和解密。 首先，程式碼範例會加密，然後再解密記憶體中的位元組陣列。 接下來，程式碼範例會加密位元組陣列的複本、將它儲存至檔案、從檔案載入資料，然後再解密資料。 此範例會顯示原始資料、加密的資料和解密的資料。

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

public class MemoryProtectionSample
{
    public static void Main() => Run();

    public static void Run()
    {
        try
        {
            ///////////////////////////////
            //
            // Memory Encryption - ProtectedMemory
            //
            ///////////////////////////////

            // Create the original data to be encrypted (The data length should be a multiple of 16).
            byte[] toEncrypt = UnicodeEncoding.ASCII.GetBytes("ThisIsSomeData16");

            Console.WriteLine($"Original data: {UnicodeEncoding.ASCII.GetString(toEncrypt)}");
            Console.WriteLine("Encrypting...");

            // Encrypt the data in memory.
            EncryptInMemoryData(toEncrypt, MemoryProtectionScope.SameLogon);

            Console.WriteLine($"Encrypted data: {UnicodeEncoding.ASCII.GetString(toEncrypt)}");
            Console.WriteLine("Decrypting...");

            // Decrypt the data in memory.
            DecryptInMemoryData(toEncrypt, MemoryProtectionScope.SameLogon);

            Console.WriteLine($"Decrypted data: {UnicodeEncoding.ASCII.GetString(toEncrypt)}");

            ///////////////////////////////
            //
            // Data Encryption - ProtectedData
            //
            ///////////////////////////////

            // Create the original data to be encrypted
            toEncrypt = UnicodeEncoding.ASCII.GetBytes("This is some data of any length.");

            // Create a file.
            FileStream fStream = new FileStream("Data.dat", FileMode.OpenOrCreate);

            // Create some random entropy.
            byte[] entropy = CreateRandomEntropy();

            Console.WriteLine();
            Console.WriteLine($"Original data: {UnicodeEncoding.ASCII.GetString(toEncrypt)}");
            Console.WriteLine("Encrypting and writing to disk...");

            // Encrypt a copy of the data to the stream.
            int bytesWritten = EncryptDataToStream(toEncrypt, entropy, DataProtectionScope.CurrentUser, fStream);

            fStream.Close();

            Console.WriteLine("Reading data from disk and decrypting...");

            // Open the file.
            fStream = new FileStream("Data.dat", FileMode.Open);

            // Read from the stream and decrypt the data.
            byte[] decryptData = DecryptDataFromStream(entropy, DataProtectionScope.CurrentUser, fStream, bytesWritten);

            fStream.Close();

            Console.WriteLine($"Decrypted data: {UnicodeEncoding.ASCII.GetString(decryptData)}");
        }
        catch (Exception e)
        {
            Console.WriteLine($"ERROR: {e.Message}");
        }
    }

    public static void EncryptInMemoryData(byte[] Buffer, MemoryProtectionScope Scope )
    {
        if (Buffer == null)
            throw new ArgumentNullException(nameof(Buffer));
        if (Buffer.Length <= 0)
            throw new ArgumentException("The buffer length was 0.", nameof(Buffer));

        // Encrypt the data in memory. The result is stored in the same array as the original data.
        ProtectedMemory.Protect(Buffer, Scope);
    }

    public static void DecryptInMemoryData(byte[] Buffer, MemoryProtectionScope Scope)
    {
        if (Buffer == null)
            throw new ArgumentNullException(nameof(Buffer));
        if (Buffer.Length <= 0)
            throw new ArgumentException("The buffer length was 0.", nameof(Buffer));

        // Decrypt the data in memory. The result is stored in the same array as the original data.
        ProtectedMemory.Unprotect(Buffer, Scope);
    }

    public static byte[] CreateRandomEntropy()
    {
        // Create a byte array to hold the random value.
        byte[] entropy = new byte[16];

        // Create a new instance of the RNGCryptoServiceProvider.
        // Fill the array with a random value.
        new RNGCryptoServiceProvider().GetBytes(entropy);

        // Return the array.
        return entropy;
    }

    public static int EncryptDataToStream(byte[] Buffer, byte[] Entropy, DataProtectionScope Scope, Stream S)
    {
        if (Buffer == null)
            throw new ArgumentNullException(nameof(Buffer));
        if (Buffer.Length <= 0)
            throw new ArgumentException("The buffer length was 0.", nameof(Buffer));
        if (Entropy == null)
            throw new ArgumentNullException(nameof(Entropy));
        if (Entropy.Length <= 0)
            throw new ArgumentException("The entropy length was 0.", nameof(Entropy));
        if (S == null)
            throw new ArgumentNullException(nameof(S));

        int length = 0;

        // Encrypt the data and store the result in a new byte array. The original data remains unchanged.
        byte[] encryptedData = ProtectedData.Protect(Buffer, Entropy, Scope);

        // Write the encrypted data to a stream.
        if (S.CanWrite && encryptedData != null)
        {
            S.Write(encryptedData, 0, encryptedData.Length);

            length = encryptedData.Length;
        }

        // Return the length that was written to the stream.
        return length;
    }

    public static byte[] DecryptDataFromStream(byte[] Entropy, DataProtectionScope Scope, Stream S, int Length)
    {
        if (S == null)
            throw new ArgumentNullException(nameof(S));
        if (Length <= 0 )
            throw new ArgumentException("The given length was 0.", nameof(Length));
        if (Entropy == null)
            throw new ArgumentNullException(nameof(Entropy));
        if (Entropy.Length <= 0)
            throw new ArgumentException("The entropy length was 0.", nameof(Entropy));

        byte[] inBuffer = new byte[Length];
        byte[] outBuffer;

        // Read the encrypted data from a stream.
        if (S.CanRead)
        {
            S.Read(inBuffer, 0, Length);

            outBuffer = ProtectedData.Unprotect(inBuffer, Entropy, Scope);
        }
        else
        {
            throw new IOException("Could not read the stream.");
        }

        // Return the decrypted data
        return outBuffer;
    }
}

Imports System.IO
Imports System.Text
Imports System.Security.Cryptography



Public Module MemoryProtectionSample

    Sub Main()
        Run()

    End Sub


    Sub Run()
        Try

            ''''''''''''''''''''''''''''''''''''
            '
            ' Memory Encryption - ProtectedMemory
            '
            ''''''''''''''''''''''''''''''''''''
            ' Create the original data to be encrypted (The data length should be a multiple of 16).
            Dim toEncrypt As Byte() = UnicodeEncoding.ASCII.GetBytes("ThisIsSomeData16")

            Console.WriteLine("Original data: " + UnicodeEncoding.ASCII.GetString(toEncrypt))
            Console.WriteLine("Encrypting...")

            ' Encrypt the data in memory.
            EncryptInMemoryData(toEncrypt, MemoryProtectionScope.SameLogon)

            Console.WriteLine("Encrypted data: " + UnicodeEncoding.ASCII.GetString(toEncrypt))
            Console.WriteLine("Decrypting...")

            ' Decrypt the data in memory.
            DecryptInMemoryData(toEncrypt, MemoryProtectionScope.SameLogon)

            Console.WriteLine("Decrypted data: " + UnicodeEncoding.ASCII.GetString(toEncrypt))


            ''''''''''''''''''''''''''''''''''''
            '
            ' Data Encryption - ProtectedData
            '
            ''''''''''''''''''''''''''''''''''''
            ' Create the original data to be encrypted
            toEncrypt = UnicodeEncoding.ASCII.GetBytes("This is some data of any length.")

            ' Create a file.
            Dim fStream As New FileStream("Data.dat", FileMode.OpenOrCreate)

            ' Create some random entropy.
            Dim entropy As Byte() = CreateRandomEntropy()

            Console.WriteLine()
            Console.WriteLine("Original data: " + UnicodeEncoding.ASCII.GetString(toEncrypt))
            Console.WriteLine("Encrypting and writing to disk...")

            ' Encrypt a copy of the data to the stream.
            Dim bytesWritten As Integer = EncryptDataToStream(toEncrypt, entropy, DataProtectionScope.CurrentUser, fStream)

            fStream.Close()

            Console.WriteLine("Reading data from disk and decrypting...")

            ' Open the file.
            fStream = New FileStream("Data.dat", FileMode.Open)

            ' Read from the stream and decrypt the data.
            Dim decryptData As Byte() = DecryptDataFromStream(entropy, DataProtectionScope.CurrentUser, fStream, bytesWritten)

            fStream.Close()

            Console.WriteLine("Decrypted data: " + UnicodeEncoding.ASCII.GetString(decryptData))


        Catch e As Exception
            Console.WriteLine("ERROR: " + e.Message)
        End Try

    End Sub



    Sub EncryptInMemoryData(ByVal Buffer() As Byte, ByVal Scope As MemoryProtectionScope)
        If Buffer Is Nothing Then
            Throw New ArgumentNullException("Buffer")
        End If
        If Buffer.Length <= 0 Then
            Throw New ArgumentException("Buffer")
        End If

        ' Encrypt the data in memory. The result is stored in the same array as the original data.
        ProtectedMemory.Protect(Buffer, Scope)

    End Sub


    Sub DecryptInMemoryData(ByVal Buffer() As Byte, ByVal Scope As MemoryProtectionScope)
        If Buffer Is Nothing Then
            Throw New ArgumentNullException("Buffer")
        End If
        If Buffer.Length <= 0 Then
            Throw New ArgumentException("Buffer")
        End If

        ' Decrypt the data in memory. The result is stored in the same array as the original data.
        ProtectedMemory.Unprotect(Buffer, Scope)

    End Sub


    Function CreateRandomEntropy() As Byte()
        ' Create a byte array to hold the random value.
        Dim entropy(15) As Byte

        ' Create a new instance of the RNGCryptoServiceProvider.
        ' Fill the array with a random value.
        Dim RNG As New RNGCryptoServiceProvider()

        RNG.GetBytes(entropy)

        ' Return the array.
        Return entropy

    End Function 'CreateRandomEntropy



    Function EncryptDataToStream(ByVal Buffer() As Byte, ByVal Entropy() As Byte, ByVal Scope As DataProtectionScope, ByVal S As Stream) As Integer
        If Buffer Is Nothing Then
            Throw New ArgumentNullException("Buffer")
        End If
        If Buffer.Length <= 0 Then
            Throw New ArgumentException("Buffer")
        End If
        If Entropy Is Nothing Then
            Throw New ArgumentNullException("Entropy")
        End If
        If Entropy.Length <= 0 Then
            Throw New ArgumentException("Entropy")
        End If
        If S Is Nothing Then
            Throw New ArgumentNullException("S")
        End If
        Dim length As Integer = 0

        ' Encrypt the data and store the result in a new byte array. The original data remains unchanged.
        Dim encryptedData As Byte() = ProtectedData.Protect(Buffer, Entropy, Scope)

        ' Write the encrypted data to a stream.
        If S.CanWrite AndAlso Not (encryptedData Is Nothing) Then
            S.Write(encryptedData, 0, encryptedData.Length)

            length = encryptedData.Length
        End If

        ' Return the length that was written to the stream. 
        Return length

    End Function 'EncryptDataToStream


    Function DecryptDataFromStream(ByVal Entropy() As Byte, ByVal Scope As DataProtectionScope, ByVal S As Stream, ByVal Length As Integer) As Byte()
        If S Is Nothing Then
            Throw New ArgumentNullException("S")
        End If
        If Length <= 0 Then
            Throw New ArgumentException("Length")
        End If
        If Entropy Is Nothing Then
            Throw New ArgumentNullException("Entropy")
        End If
        If Entropy.Length <= 0 Then
            Throw New ArgumentException("Entropy")
        End If


        Dim inBuffer(Length - 1) As Byte
        Dim outBuffer() As Byte

        ' Read the encrypted data from a stream.
        If S.CanRead Then
            S.Read(inBuffer, 0, Length)

            outBuffer = ProtectedData.Unprotect(inBuffer, Entropy, Scope)
        Else
            Throw New IOException("Could not read the stream.")
        End If

        ' Return the unencrypted data as byte array. 
        Return outBuffer

    End Function 'DecryptDataFromStream 
End Module 'MemoryProtectionSample

編譯程式碼

此範例只有在以 .NET Framework 為目標且在 Windows 上執行時，才會編譯和執行。

另請參閱