如何：使用数据保护
更新：2007 年 11 月
.NET Framework 提供了对数据保护 API (DPAPI) 的访问。通过 DPAPI，可以使用来自当前用户帐户或计算机的信息对数据进行加密。 使用 DPAPI 可以减轻显式生成和存储加密密钥的难题。
使用 ProtectedMemory 类对内存中字节数组进行加密。 Microsoft Windows XP 和更高版本的操作系统中具有该功能。 您可以指定由当前进程加密的内存只能由当前进程解密、可以由所有进程解密，或者可以从相同的用户上下文解密。 有关 ProtectedMemory 选项的详细说明，请参见 MemoryProtectionScope 枚举。
使用对 ProtectedData 类字节数组的副本进行加密。Microsoft Windows 2000 和更高版本的操作系统中具有该功能。 您可以指定由当前用户帐户加密的数据只能由同一用户帐户解密，或者可以指定由当前用户帐户加密的数据可以由计算机上的任何帐户解密。 有关 ProtectedData 选项的详细说明，请参见 DataProtectionScope 枚举。
使用数据保护对内存中数据进行加密
- 调用静态 Protect 方法，传递要加密的字节数组、平均信息量和内存保护范围。
使用数据保护对内存中数据进行解密
- 调用静态 Unprotect 方法，传递要解密的字节数组和内存保护范围。
使用数据保护将数据加密到文件或流
创建随机平均信息量。
调用静态 Protect 方法，传递要加密的字节数组、平均信息量和数据保护范围。
将加密的数据写入文件或流。
使用数据保护从文件或流中解密数据
从文件或流中读取加密的数据。
调用静态 Unprotect 方法，传递要解密的字节数组和数据保护范围。
示例
下面的代码示例演示两种形式的加密和解密。 首先，代码示例对内存中字节数组进行加密，然后将其解密。 接下来，代码示例对字节数组的副本进行加密，将加密后的副本保存到文件中，从该文件加载回数据，然后对数据进行解密。 此示例显示原始数据、加密的数据和解密的数据。
Imports System
Imports System.IO
Imports System.Text
Imports System.Security.Cryptography
Public Module MemoryProtectionSample
Sub Main()
Run()
End Sub 'Main
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 'Run
Sub EncryptInMemoryData(ByVal Buffer() As Byte, ByVal Scope As MemoryProtectionScope)
If Buffer.Length <= 0 Then
Throw New ArgumentException("Buffer")
End If
If Buffer Is Nothing Then
Throw New ArgumentNullException("Buffer")
End If
' Encrypt the data in memory. The result is stored in the same same array as the original data.
ProtectedMemory.Protect(Buffer, Scope)
End Sub 'EncryptInMemoryData
Sub DecryptInMemoryData(ByVal Buffer() As Byte, ByVal Scope As MemoryProtectionScope)
If Buffer.Length <= 0 Then
Throw New ArgumentException("Buffer")
End If
If Buffer Is Nothing Then
Throw New ArgumentNullException("Buffer")
End If
' Decrypt the data in memory. The result is stored in the same same array as the original data.
ProtectedMemory.Unprotect(Buffer, Scope)
End Sub 'DecryptInMemoryData
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.Length <= 0 Then
Throw New ArgumentException("Buffer")
End If
If Buffer Is Nothing Then
Throw New ArgumentNullException("Buffer")
End If
If Entropy.Length <= 0 Then
Throw New ArgumentException("Entropy")
End If
If Entropy Is Nothing Then
Throw New ArgumentNullException("Entropy")
End If
If S Is Nothing Then
Throw New ArgumentNullException("S")
End If
Dim length As Integer = 0
' Encrypt the data in memory. The result is stored in the same same array as the original data.
Dim encrptedData As Byte() = ProtectedData.Protect(Buffer, Entropy, Scope)
' Write the encrypted data to a stream.
If S.CanWrite AndAlso Not (encrptedData Is Nothing) Then
S.Write(encrptedData, 0, encrptedData.Length)
length = encrptedData.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) 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 length that was written to the stream.
Return outBuffer
End Function 'DecryptDataFromStream
End Module 'MemoryProtectionSample
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.Length <= 0)
throw new ArgumentException("Buffer");
if (Buffer == null)
throw new ArgumentNullException("Buffer");
// Encrypt the data in memory. The result is stored in the same same array as the original data.
ProtectedMemory.Protect(Buffer, Scope);
}
public static void DecryptInMemoryData(byte[] Buffer, MemoryProtectionScope Scope)
{
if (Buffer.Length <= 0)
throw new ArgumentException("Buffer");
if (Buffer == null)
throw new ArgumentNullException("Buffer");
// Decrypt the data in memory. The result is stored in the same 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.Length <= 0)
throw new ArgumentException("Buffer");
if (Buffer == null)
throw new ArgumentNullException("Buffer");
if (Entropy.Length <= 0)
throw new ArgumentException("Entropy");
if (Entropy == null)
throw new ArgumentNullException("Entropy");
if (S == null)
throw new ArgumentNullException("S");
int length = 0;
// Encrypt the data in memory. The result is stored in the same same array as the original data.
byte[] encrptedData = ProtectedData.Protect(Buffer, Entropy, Scope);
// Write the encrypted data to a stream.
if (S.CanWrite && encrptedData != null)
{
S.Write(encrptedData, 0, encrptedData.Length);
length = encrptedData.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("S");
if (Length <= 0 )
throw new ArgumentException("Length");
if (Entropy == null)
throw new ArgumentNullException("Entropy");
if (Entropy.Length <= 0)
throw new ArgumentException("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 length that was written to the stream.
return outBuffer;
}
}
编译代码
包括对 System.Security.dll 的引用。
包括 System、System.IO、System.Security.Cryptography 和 System.Text 命名空间。