KeyedHashAlgorithm-Klasse
Stellt die abstrakte Klasse dar, von der alle Implementierungen schlüsselgebundener Hashalgorithmen abgeleitet werden müssen.
Namespace: System.Security.Cryptography
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
<ComVisibleAttribute(True)> _
Public MustInherit Class KeyedHashAlgorithm
Inherits HashAlgorithm
'Usage
Dim instance As KeyedHashAlgorithm
[ComVisibleAttribute(true)]
public abstract class KeyedHashAlgorithm : HashAlgorithm
[ComVisibleAttribute(true)]
public ref class KeyedHashAlgorithm abstract : public HashAlgorithm
/** @attribute ComVisibleAttribute(true) */
public abstract class KeyedHashAlgorithm extends HashAlgorithm
ComVisibleAttribute(true)
public abstract class KeyedHashAlgorithm extends HashAlgorithm
Hinweise
Hashfunktionen ordnen binäre Zeichenfolgen beliebiger Länge kleinen binären Zeichenfolgen fester Länge zu. Kryptografische Hashfunktionen sind dadurch gekennzeichnet, das es rechnerisch unmöglich ist, zwei verschiedene Eingabewerte zu ermitteln, die denselben Hashwert bilden. Kleine Änderungen an den Daten führen zu beträchtlichen unvorhersehbaren Änderungen des Hashs.
Ein schlüsselgebundener Hashalgorithmus ist eine schlüsselabhängige Einweg-Hashfunktion, die als Nachrichtenauthentifizierungscode verwendet wird. Der Hash kann nur von der Stelle überprüft werden, der der Schlüssel bekannt ist. Schlüsselgebundene Hashalgorithmen gewährleisten Authentifizierung, jedoch keine Geheimhaltung.
Hashfunktionen werden häufig im Zusammenhang mit digitalen Signaturen und für die Datenintegrität verwendet. Die HMACSHA1-Klasse ist ein Beispiel für einen schlüsselgebundenen Hashalgorithmus.
Beispiel
Im folgenden Codebeispiel wird das Ableiten von der KeyedHashAlgorithm-Klasse veranschaulicht.
Imports System
Imports System.IO
Imports System.Text
Imports System.Collections
Imports System.Security.Cryptography
Namespace Contoso
Public 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 = ""
EncodeMessage()
EncodeStream()
' Reset the cursor and conclude application.
tbxOutput.AppendText(vbCrLf + "This sample completed " + _
"successfully; press Exit to continue.")
tbxOutput.Cursor = Cursors.Default
End Sub
' Compute the hash for a ContosoKeyedHash that has transformed
' a file stream.
Private Sub EncodeStream()
Dim keyData(24) As Byte
RandomNumberGenerator.Create.GetBytes(keyData)
Dim localCrypto As New ContosoKeyedHash(keyData)
Dim filePath As String
filePath = System.IO.Directory.GetCurrentDirectory() + _
"\members.txt"
Try
Dim fileStream As _
New FileStream(filePath, FileMode.Open, FileAccess.Read)
localCrypto.ComputeHash(fileStream)
SummarizeMAC(localCrypto, _
"ContosoKeyedHash after encoding a file stream.")
Catch ex As FileNotFoundException
WriteLine("Specified path was not found: " + filePath)
End Try
End Sub
' Compute the hash for a ContosoKeyedHash that has transformed
' a byte array.
Private Sub EncodeMessage()
Dim keyData(24) As Byte
RandomNumberGenerator.Create().GetBytes(keyData)
Dim localCrypto As New ContosoKeyedHash(keyData)
Dim message As String = "Hello World."
Dim encodedMessage() As Byte = _
EncodeBytes(Encoding.ASCII.GetBytes(message))
localCrypto.ComputeHash(encodedMessage)
SummarizeMAC(localCrypto, _
"ContosoKeyedHash after encoding a message.")
End Sub
' Transform the byte array using ContosoKeyedHash,
' then summarize its properties.
Private Function EncodeBytes(ByVal sourceBytes As Byte()) As Byte()
Dim currentPosition As Int16 = 0
Dim targetBytes(1024) As Byte
Dim sourceByteLength As Int16 = sourceBytes.Length
' Create an encryptor with a random key and the KeyedHashAlgorithm
' class name.
Dim key(24) As Byte
RandomNumberGenerator.Create().GetBytes(key)
Dim keyedHashName As String
keyedHashName = "System.Security.Cryptography.KeyedHashAlgorithm"
Dim localCrypto As New ContosoKeyedHash(keyedHashName, key)
' Retrieve the block size to read the bytes.
Dim inputBlockSize As Integer = localCrypto.InputBlockSize
Try
' Determine if multiple blocks can be transformed.
If (localCrypto.CanTransformMultipleBlocks) Then
Dim numBytesRead As Int16 = 0
While (sourceByteLength - currentPosition >= _
inputBlockSize)
' Transform the bytes from the currentposition in the
' sourceBytes array, writing the bytes to the
' targetBytes array.
numBytesRead = localCrypto.TransformBlock( _
sourceBytes, _
currentPosition, _
inputBlockSize, _
targetBytes, _
currentPosition)
' Advance the current position in the source array.
currentPosition += numBytesRead
End While
' Transform the final block of bytes.
Dim finalBytes() As Byte
finalBytes = localCrypto.TransformFinalBlock( _
sourceBytes, _
currentPosition, _
sourceByteLength - currentPosition)
' Copy the contents of the finalBytes array to the
' targetBytes array.
finalBytes.CopyTo(targetBytes, currentPosition)
End If
Catch ex As Exception
WriteLine("Caught unexpected exception:" + _
ex.ToString())
End Try
' Find the length of valid bytes (those without zeros).
Dim enum1 As IEnumerator = targetBytes.GetEnumerator()
Dim i As Int16
While (enum1.MoveNext())
If (enum1.Current.ToString().Equals("0")) Then
Exit While
End If
i = i + 1
End While
' Compute the hash based on the valid bytes in the array.
'Dim somebytes() As Byte
'somebytes = localCrypto.ComputeHash(targetBytes, 0, i)
localCrypto.ComputeHash(targetBytes, 0, i)
SummarizeMAC(localCrypto, "ContosoKeyedHash after computing " + _
"hash for specified region of byte array")
' Determine if the current transform can be reused.
If (Not localCrypto.CanReuseTransform) Then
' Free up any used resources.
localCrypto.Clear()
localCrypto.Initialize()
End If
' Create a new array with the number of valid bytes.
Dim returnedArray(i) As Byte
For j As Int16 = 0 To i Step 1
returnedArray(j) = targetBytes(j)
Next
Return returnedArray
End Function
' Write a summary of the specified ContosoKeyedHash to the
' console window.
Private Sub SummarizeMAC( _
ByVal localCrypto As ContosoKeyedHash, _
ByVal description As String)
Dim classDescription As String = localCrypto.ToString()
Dim computedHash() As Byte = localCrypto.Hash
Dim hashSize As Integer = localCrypto.HashSize
Dim outputBlockSize As Integer = localCrypto.OutputBlockSize
' Retrieve the key used in the hash algorithm.
Dim key() As Byte = localCrypto.Key
WriteLine(vbCrLf + "**********************************")
WriteLine(classDescription)
WriteLine(description)
WriteLine("----------------------------------")
WriteLine("The size of the computed hash : " + _
hashSize.ToString())
WriteLine("The key used in the hash algorithm : " + _
Encoding.ASCII.GetString(key))
WriteLine("The value of the computed hash : " + _
Encoding.ASCII.GetString(computedHash))
End Sub
Private Sub WriteLine(ByVal Message As String)
tbxOutput.AppendText(Message + vbCrLf)
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
#Region " Windows Form Designer generated code "
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 = "KeyedHashAlgorithm"
Me.Panel2.ResumeLayout(False)
Me.Panel1.ResumeLayout(False)
Me.ResumeLayout(False)
End Sub
#End Region
End Class
End Namespace
using System;
using System.IO;
using System.Text;
using System.Collections;
using System.Security.Cryptography;
namespace Contoso
{
class EncodeWithContoso
{
[STAThread]
static void Main(string[] args)
{
EncodeMessage();
EncodeStream();
Console.WriteLine("This sample completed successfully; " +
"press Enter to exit");
Console.ReadLine();
}
// Compute the hash for a ContosoKeyedHash that has transformed a
// file stream.
private static void EncodeStream()
{
byte[] keyData = new byte[24];
RandomNumberGenerator.Create().GetBytes(keyData);
ContosoKeyedHash localCrypto = new ContosoKeyedHash(keyData);
string filePath = (System.IO.Directory.GetCurrentDirectory() +
"\\members.txt");
try
{
FileStream fileStream =
new FileStream(filePath, FileMode.Open, FileAccess.Read);
localCrypto.ComputeHash(fileStream);
SummarizeMAC(localCrypto,
"ContosoKeyedHash after encoding a file stream.");
}
catch (FileNotFoundException)
{
Console.WriteLine("The specified path was not found: " +
filePath);
}
}
// Compute the hash for a ContosoKeyedHash that has transformed
// a byte array.
private static void EncodeMessage()
{
byte[] keyData = new byte[24];
RandomNumberGenerator.Create().GetBytes(keyData);
ContosoKeyedHash localCrypto = new ContosoKeyedHash(keyData);
string message = "Hello World.";
byte[] encodedMessage =
EncodeBytes(Encoding.ASCII.GetBytes(message));
localCrypto.ComputeHash(encodedMessage);
SummarizeMAC(localCrypto,
"ContosoKeyedHash after encoding a message.");
}
// Transform the byte array using ContosoKeyedHash,
// then summarize its properties.
private static byte[] EncodeBytes(byte[] sourceBytes)
{
int currentPosition = 0;
byte[] targetBytes = new byte[1024];
int sourceByteLength = sourceBytes.Length;
// Create an encryptor with a random key and the
// KeyedHashAlgorithm class name.
byte[] key = new byte[24];
RandomNumberGenerator.Create().GetBytes(key);
string keyedHashName =
"System.Security.Cryptography.KeyedHashAlgorithm";
ContosoKeyedHash localCrypto =
new ContosoKeyedHash(keyedHashName, key);
// Retrieve the block size to read the bytes.
int inputBlockSize = localCrypto.InputBlockSize;
try
{
// Determine if multiple blocks can be transformed.
if (localCrypto.CanTransformMultipleBlocks)
{
int numBytesRead = 0;
while (sourceByteLength - currentPosition >=
inputBlockSize)
{
// Transform the bytes from the currentposition in the
// sourceBytes array, writing the bytes to the
// targetBytes array.
numBytesRead = localCrypto.TransformBlock(
sourceBytes,
currentPosition,
inputBlockSize,
targetBytes,
currentPosition);
// Advance the current position in the source array.
currentPosition += numBytesRead;
}
// Transform the final block of bytes.
byte[] finalBytes = localCrypto.TransformFinalBlock(
sourceBytes,
currentPosition,
sourceByteLength - currentPosition);
// Copy the contents of the finalBytes array to the
// targetBytes array.
finalBytes.CopyTo(targetBytes,currentPosition);
}
}
catch(Exception ex)
{
Console.WriteLine("Caught unexpected exception:" +
ex.ToString());
}
// Find the length of valid bytes (those without zeros).
IEnumerator enum1 = targetBytes.GetEnumerator();
int i = 0;
while (enum1.MoveNext())
{
if (enum1.Current.ToString().Equals("0"))
{
break;
}
i++;
}
// Compute the hash based on the valid bytes in the array.
localCrypto.ComputeHash(targetBytes,0,i);
SummarizeMAC(localCrypto, "ContosoKeyedHash after computing " +
"hash for specified region of byte array");
// Determine if the current transform can be reused.
if (!localCrypto.CanReuseTransform)
{
// Free up any used resources.
localCrypto.Clear();
localCrypto.Initialize();
}
// Create a new array with the number of valid bytes.
byte[] returnedArray = new byte[i];
for (int j=0; j<i; j++)
{
returnedArray[j] = targetBytes[j];
}
return returnedArray;
}
// Write a summary of the specified ContosoKeyedHash to the
// console window.
private static void SummarizeMAC(
ContosoKeyedHash localCrypto,
string description)
{
string classDescription = localCrypto.ToString();
byte[] computedHash = localCrypto.Hash;
int hashSize = localCrypto.HashSize;
int outputBlockSize = localCrypto.OutputBlockSize;
// Retrieve the key used in the hash algorithm.
byte[] key = localCrypto.Key;
Console.WriteLine("\n**********************************");
Console.WriteLine(classDescription);
Console.WriteLine(description);
Console.WriteLine("----------------------------------");
Console.WriteLine("The size of the computed hash : " + hashSize);
Console.WriteLine("The key used in the hash algorithm : " +
Encoding.ASCII.GetString(key));
Console.WriteLine("The value of the computed hash : " +
Encoding.ASCII.GetString(computedHash));
}
}
}
#using <System.dll>
#using "contosokeyedhash.dll"
using namespace Contoso;
using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Collections;
using namespace System::Security::Cryptography;
namespace Contoso
{
ref class EncodeWithContoso
{
public:
[STAThread]
static void Main()
{
EncodeMessage();
EncodeStream();
Console::WriteLine( L"This sample completed successfully; "
L"press Enter to exit" );
Console::ReadLine();
}
private:
// Compute the hash for a ContosoKeyedHash that has transformed a
// file stream.
static void EncodeStream()
{
array<Byte>^keyData = gcnew array<Byte>(24);
RandomNumberGenerator::Create()->GetBytes( keyData );
ContosoKeyedHash^ localCrypto = gcnew ContosoKeyedHash( keyData );
String^ filePath = (String::Concat(
System::IO::Directory::GetCurrentDirectory(), L"\\members.txt" ));
try
{
FileStream^ fileStream = gcnew FileStream(
filePath,FileMode::Open,FileAccess::Read );
localCrypto->ComputeHash( fileStream );
SummarizeMAC( localCrypto,
L"ContosoKeyedHash after encoding a file stream." );
}
catch ( FileNotFoundException^ )
{
Console::WriteLine( L"The specified path was not found: {0}", filePath );
}
}
// Compute the hash for a ContosoKeyedHash that has transformed
// a byte array.
static void EncodeMessage()
{
array<Byte>^ keyData = gcnew array<Byte>(24);
RandomNumberGenerator::Create()->GetBytes( keyData );
ContosoKeyedHash^ localCrypto = gcnew ContosoKeyedHash( keyData );
String^ message = L"Hello World.";
array<Byte>^ encodedMessage = EncodeBytes(
Encoding::ASCII->GetBytes( message ) );
localCrypto->ComputeHash( encodedMessage );
SummarizeMAC( localCrypto, L"ContosoKeyedHash after encoding a message." );
}
// Transform the byte array using ContosoKeyedHash,
// then summarize its properties.
static array<Byte>^ EncodeBytes( array<Byte>^ sourceBytes )
{
int currentPosition = 0;
array<Byte>^targetBytes = gcnew array<Byte>(1024);
int sourceByteLength = sourceBytes->Length;
// Create an encryptor with a random key and the
// KeyedHashAlgorithm class name.
array<Byte>^ key = gcnew array<Byte>(24);
RandomNumberGenerator::Create()->GetBytes( key );
String^ keyedHashName = L"System.Security.Cryptography.KeyedHashAlgorithm";
ContosoKeyedHash^ localCrypto = gcnew ContosoKeyedHash( keyedHashName,key );
// Retrieve the block size to read the bytes.
int inputBlockSize = localCrypto->InputBlockSize;
try
{
// Determine if multiple blocks can be transformed.
if ( localCrypto->CanTransformMultipleBlocks )
{
int numBytesRead = 0;
while ( sourceByteLength - currentPosition >= inputBlockSize )
{
// Transform the bytes from the currentposition in the
// sourceBytes array, writing the bytes to the
// targetBytes array.
numBytesRead = localCrypto->TransformBlock(
sourceBytes,
currentPosition,
inputBlockSize,
targetBytes,
currentPosition );
// Advance the current position in the source array.
currentPosition += numBytesRead;
}
// Transform the final block of bytes.
array<Byte>^ finalBytes = localCrypto->TransformFinalBlock(
sourceBytes,
currentPosition,
sourceByteLength - currentPosition );
// Copy the contents of the finalBytes array to the
// targetBytes array.
finalBytes->CopyTo( targetBytes, currentPosition );
}
}
catch ( Exception^ ex )
{
Console::WriteLine( L"Caught unexpected exception:{0}",
ex->ToString() );
}
// Find the length of valid bytes (those without zeros).
IEnumerator^ enum1 = targetBytes->GetEnumerator();
int i = 0;
while ( enum1->MoveNext() )
{
if ( enum1->Current->ToString()->Equals( L"0" ) )
{
break;
}
i++;
}
// Compute the hash based on the valid bytes in the array.
localCrypto->ComputeHash( targetBytes, 0, i );
SummarizeMAC( localCrypto, L"ContosoKeyedHash after computing "
L"hash for specified region of byte array" );
// Determine if the current transform can be reused.
if ( !localCrypto->CanReuseTransform )
{
// Free up any used resources.
localCrypto->Clear();
localCrypto->Initialize();
}
// Create a new array with the number of valid bytes.
array<Byte>^returnedArray = gcnew array<Byte>(i);
for ( int j = 0; j < i; j++ )
{
returnedArray[ j ] = targetBytes[ j ];
}
return returnedArray;
}
// Write a summary of the specified ContosoKeyedHash to the
// console window.
static void SummarizeMAC( ContosoKeyedHash^ localCrypto,
String^ description )
{
String^ classDescription = localCrypto->ToString();
array<Byte>^computedHash = localCrypto->Hash;
int hashSize = localCrypto->HashSize;
int outputBlockSize = localCrypto->OutputBlockSize;
// Retrieve the key used in the hash algorithm.
array<Byte>^key = localCrypto->Key;
Console::WriteLine( L"\n**********************************" );
Console::WriteLine( classDescription );
Console::WriteLine( description );
Console::WriteLine( L"----------------------------------" );
Console::WriteLine( L"The size of the computed hash : {0}",
hashSize );
Console::WriteLine( L"The key used in the hash algorithm : {0}",
Encoding::ASCII->GetString( key ) );
Console::WriteLine( L"The value of the computed hash : {0}",
Encoding::ASCII->GetString( computedHash ) );
}
};
}
int main()
{
EncodeWithContoso::Main();
}
import System.*;
import System.IO.*;
import System.Text.*;
import System.Collections.*;
import System.Security.Cryptography.*;
class EncodeWithContoso
{
/** @attribute STAThread()
*/
public static void main(String[] args)
{
EncodeMessage();
EncodeStream();
Console.WriteLine("This sample completed successfully; "
+ "press Enter to exit");
Console.ReadLine();
} //main
// Compute the hash for a ContosoKeyedHash that has transformed a
// file stream.
private static void EncodeStream()
{
ubyte keyData[] = new ubyte[24];
RandomNumberGenerator.Create().GetBytes(keyData);
ContosoKeyedHash localCrypto = new ContosoKeyedHash(keyData);
String filePath = System.IO.Directory.GetCurrentDirectory()
+ "\\members.txt";
try {
FileStream fileStream = new FileStream(filePath, FileMode.Open,
FileAccess.Read);
localCrypto.ComputeHash(fileStream);
SummarizeMAC(localCrypto,
"ContosoKeyedHash after encoding a file stream.");
}
catch (FileNotFoundException exp) {
Console.WriteLine("The specified path was not found: " + filePath);
}
} //EncodeStream
// Compute the hash for a ContosoKeyedHash that has transformed
// a byte array.
private static void EncodeMessage()
{
ubyte keyData[] = new ubyte[24];
RandomNumberGenerator.Create().GetBytes(keyData);
ContosoKeyedHash localCrypto = new ContosoKeyedHash(keyData);
String message = "Hello World.";
ubyte encodedMessage[] = EncodeBytes(Encoding.get_ASCII().
GetBytes(message));
localCrypto.ComputeHash(encodedMessage);
SummarizeMAC(localCrypto,
"ContosoKeyedHash after encoding a message.");
} //EncodeMessage
// Transform the byte array using ContosoKeyedHash,
// then summarize its properties.
private static ubyte[] EncodeBytes(ubyte sourceBytes[])
{
int currentPosition = 0;
ubyte targetBytes[] = new ubyte[1024];
int sourceByteLength = sourceBytes.get_Length();
// Create an encryptor with a random key and the
// KeyedHashAlgorithm class name.
ubyte key[] = new ubyte[24];
RandomNumberGenerator.Create().GetBytes(key);
String keyedHashName = "System.Security.Cryptography.KeyedHashAlgorithm";
ContosoKeyedHash localCrypto = new ContosoKeyedHash(keyedHashName, key);
// Retrieve the block size to read the bytes.
int inputBlockSize = localCrypto.get_InputBlockSize();
try {
// Determine if multiple blocks can be transformed.
if (localCrypto.get_CanTransformMultipleBlocks()) {
int numBytesRead = 0;
while (sourceByteLength - currentPosition >= inputBlockSize) {
// Transform the bytes from the currentposition in the
// sourceBytes array, writing the bytes to the
// targetBytes array.
numBytesRead = localCrypto.TransformBlock(sourceBytes,
currentPosition, inputBlockSize, targetBytes,
currentPosition);
// Advance the current position in the source array.
currentPosition += numBytesRead;
}
// Transform the final block of bytes.
ubyte finalBytes[] = localCrypto.TransformFinalBlock(sourceBytes,
currentPosition, sourceByteLength - currentPosition);
// Copy the contents of the finalBytes array to the
// targetBytes array.
finalBytes.CopyTo(targetBytes, currentPosition);
}
}
catch (System.Exception ex) {
Console.WriteLine("Caught unexpected exception:" + ex.ToString());
}
// Find the length of valid bytes (those without zeros).
IEnumerator enum1 = targetBytes.GetEnumerator();
int i = 0;
while (enum1.MoveNext()) {
if (enum1.get_Current().ToString().Equals("0")) {
break;
}
i++;
}
// Compute the hash based on the valid bytes in the array.
localCrypto.ComputeHash(targetBytes, 0, i);
SummarizeMAC(localCrypto, "ContosoKeyedHash after computing "
+ "hash for specified region of byte array");
// Determine if the current transform can be reused.
if (!(localCrypto.get_CanReuseTransform())) {
// Free up any used resources.
localCrypto.Clear();
localCrypto.Initialize();
}
// Create a new array with the number of valid bytes.
ubyte returnedArray[] = new ubyte[i];
for (int j = 0; j < i; j++) {
returnedArray.set_Item(j, targetBytes.get_Item(j));
}
return returnedArray;
} //EncodeBytes
// Write a summary of the specified ContosoKeyedHash to the
// console window.
private static void SummarizeMAC(ContosoKeyedHash localCrypto,
String description)
{
String classDescription = localCrypto.ToString();
ubyte computedHash[] = localCrypto.get_Hash();
int hashSize = localCrypto.get_HashSize();
int outputBlockSize = localCrypto.get_OutputBlockSize();
// Retrieve the key used in the hash algorithm.
ubyte key[] = localCrypto.get_Key();
Console.WriteLine("\n**********************************");
Console.WriteLine(classDescription);
Console.WriteLine(description);
Console.WriteLine("----------------------------------");
Console.WriteLine("The size of the computed hash : " + hashSize);
Console.WriteLine("The key used in the hash algorithm : "
+ Encoding.get_ASCII().GetString(key));
Console.WriteLine("The value of the computed hash : "
+ Encoding.get_ASCII().GetString(computedHash));
} //SummarizeMAC
} //EncodeWithContoso
Imports System
Imports System.Security.Cryptography
Namespace Contoso
Public Class ContosoKeyedHash
Inherits KeyedHashAlgorithm
Dim keyedCrypto As KeyedHashAlgorithm
Public Sub New(ByVal rgbKey() As Byte)
Me.New("System.Security.Cryptography.KeyedHashAlgorithm", rgbKey)
End Sub
Public Sub New(ByVal keyedHashName As String, ByVal rgbKey() As Byte)
' Make sure we know which algorithm to use
If (Not rgbKey Is Nothing) Then
KeyValue = rgbKey
HashSizeValue = 160
' Create a KeyedHashAlgorithm encryptor
If (keyedHashName Is Nothing) Then
keyedCrypto = KeyedHashAlgorithm.Create()
Else
keyedCrypto = KeyedHashAlgorithm.Create(keyedHashName)
End If
' keyedCrypto.Key = rgbKey
Else
Throw New ArgumentNullException("rgbKey")
End If
End Sub
' Override abstract methods from the HashAlgorithm class.
Public Overrides Sub Initialize()
End Sub
' Override the Key property to use the local key from keyedCrypto.
Public Overrides Property Key() As Byte()
Get
Return CType(keyedCrypto.Key.Clone(), Byte())
End Get
Set(ByVal Value As Byte())
keyedCrypto.Key = CType(Value.Clone(), Byte())
End Set
End Property
Protected Overrides Sub HashCore( _
ByVal rgbData() As Byte, _
ByVal ibStart As Integer, _
ByVal cbSize As Integer)
End Sub
Protected Overrides Function HashFinal() As Byte()
Dim returnBytes(0) As Byte
Return returnBytes
End Function
End Class
End Namespace
using System;
using System.Security.Cryptography;
namespace Contoso
{
class ContosoKeyedHash : KeyedHashAlgorithm
{
private KeyedHashAlgorithm keyedCrypto;
public ContosoKeyedHash(byte[] rgbKey)
: this("System.Security.Cryptography.KeyedHashAlgorithm", rgbKey)
{
}
public ContosoKeyedHash(String keyedHashName, byte[] rgbKey)
{
// Make sure we know which algorithm to use
if (rgbKey != null)
{
KeyValue = rgbKey;
HashSizeValue = 160;
// Create a KeyedHashAlgorithm encryptor
if (keyedHashName == null)
{
keyedCrypto = KeyedHashAlgorithm.Create();
}
else
{
keyedCrypto = KeyedHashAlgorithm.Create(keyedHashName);
}
}
else
{
throw new ArgumentNullException("rgbKey");
}
}
// Override abstract methods from the HashAlgorithm class.
public override void Initialize() {}
public override byte[] Key
{
get
{
return (byte[]) keyedCrypto.Key.Clone();
}
set
{
keyedCrypto.Key = (byte[]) value.Clone();
}
}
protected override void HashCore(
byte[] rgbData,
int ibStart,
int cbSize)
{
}
protected override byte[] HashFinal()
{
return new byte[0];
}
}
}
using namespace System;
using namespace System::Security::Cryptography;
namespace Contoso
{
public ref class ContosoKeyedHash: public KeyedHashAlgorithm
{
private:
KeyedHashAlgorithm^ keyedCrypto;
public:
ContosoKeyedHash( array<Byte>^ rgbKey )
{
Init( L"System.Security.Cryptography.KeyedHashAlgorithm", rgbKey );
}
ContosoKeyedHash( String^ keyedHashName, array<Byte>^ rgbKey )
{
Init( keyedHashName, rgbKey );
}
void Init( String^ keyedHashName, array<Byte>^ rgbKey )
{
// Make sure we know which algorithm to use
if ( rgbKey != nullptr )
{
KeyValue = rgbKey;
HashSizeValue = 160;
// Create a KeyedHashAlgorithm encryptor
if ( keyedHashName == nullptr )
{
keyedCrypto = KeyedHashAlgorithm::Create();
}
else
{
keyedCrypto = KeyedHashAlgorithm::Create( keyedHashName );
}
}
else
{
throw gcnew ArgumentNullException( L"rgbKey" );
}
}
// Override abstract methods from the HashAlgorithm class.
virtual void Initialize() override {}
property array<Byte>^ Key
{
virtual array<Byte>^ get() override
{
return dynamic_cast<array<Byte>^>(keyedCrypto->Key->Clone());
}
virtual void set( array<Byte>^value ) override
{
keyedCrypto->Key = dynamic_cast<array<Byte>^>(value->Clone());
}
}
protected:
virtual void HashCore( array<Byte>^ , int /*ibStart*/, int /*cbSize*/ ) override {}
virtual array<Byte>^ HashFinal() override
{
return gcnew array<Byte>(0);
}
};
}
import System.*;
import System.Security.Cryptography.*;
class ContosoKeyedHash extends KeyedHashAlgorithm
{
private KeyedHashAlgorithm keyedCrypto;
public ContosoKeyedHash(ubyte rgbKey[])
{
this("System.Security.Cryptography.KeyedHashAlgorithm", rgbKey);
} //ContosoKeyedHash
public ContosoKeyedHash(String keyedHashName, ubyte rgbKey[])
{
// Make sure we know which algorithm to use
if (rgbKey != null) {
KeyValue = rgbKey;
HashSizeValue = 160;
// Create a KeyedHashAlgorithm encryptor
if (keyedHashName == null) {
keyedCrypto = KeyedHashAlgorithm.Create();
}
else {
keyedCrypto = KeyedHashAlgorithm.Create(keyedHashName);
}
}
else {
throw new ArgumentNullException("rgbKey");
}
} //ContosoKeyedHash
// Override abstract methods from the HashAlgorithm class.
public void Initialize()
{
} //Initialize
/** @property
*/
public ubyte[] get_Key()
{
return (ubyte[])keyedCrypto.get_Key().Clone();
} //get_Key
/** @property
*/
public void set_Key(ubyte value[])
{
keyedCrypto.set_Key((ubyte[])(value.Clone()));
} //set_Key
protected void HashCore(ubyte rgbData[], int ibStart, int cbSize)
{
} //HashCore
protected ubyte[] HashFinal()
{
return new ubyte[0];
} //HashFinal
} //ContosoKeyedHash
Vererbungshierarchie
System.Object
System.Security.Cryptography.HashAlgorithm
System.Security.Cryptography.KeyedHashAlgorithm
System.Security.Cryptography.HMAC
System.Security.Cryptography.MACTripleDES
Threadsicherheit
Alle öffentlichen statischen (Shared in Visual Basic) Member dieses Typs sind threadsicher. Bei Instanzmembern ist die Threadsicherheit nicht gewährleistet.
Plattformen
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
KeyedHashAlgorithm-Member
System.Security.Cryptography-Namespace