HMACMD5 HMACMD5 HMACMD5 HMACMD5 Class

Definition

Berechnet unter Verwendung der MD5-Hashfunktion einen Hash-Nachrichtenauthentifizierungscode (HMAC, Hash-based Message Authentication Code).Computes a Hash-based Message Authentication Code (HMAC) by using the MD5 hash function.

public ref class HMACMD5 : System::Security::Cryptography::HMAC
[System.Runtime.InteropServices.ComVisible(true)]
public class HMACMD5 : System.Security.Cryptography.HMAC
type HMACMD5 = class
    inherit HMAC
Public Class HMACMD5
Inherits HMAC
Vererbung
Attribute

Beispiele

Das folgende Beispiel zeigt, wie Sie sich eine Datei mit den HMACMD5 -Objekt, und klicken Sie dann überprüfen, ob die Datei.The following example shows how to sign a file by using the HMACMD5 object and then how to verify the file.

using namespace System;
using namespace System::IO;
using namespace System::Security::Cryptography;

// Computes a keyed hash for a source file, creates a target file with the keyed hash
// prepended to the contents of the source file, then decrypts the file and compares
// the source and the decrypted files.
void EncodeFile( array<Byte>^key, String^ sourceFile, String^ destFile )
{
   
   // Initialize the keyed hash object.
   HMACMD5^ myhmacMD5 = gcnew HMACMD5( key );
   FileStream^ inStream = gcnew FileStream( sourceFile,FileMode::Open );
   FileStream^ outStream = gcnew FileStream( destFile,FileMode::Create );
   
   // Compute the hash of the input file.
   array<Byte>^hashValue = myhmacMD5->ComputeHash( inStream );
   
   // Reset inStream to the beginning of the file.
   inStream->Position = 0;
   
   // Write the computed hash value to the output file.
   outStream->Write( hashValue, 0, hashValue->Length );
   
   // Copy the contents of the sourceFile to the destFile.
   int bytesRead;
   
   // read 1K at a time
   array<Byte>^buffer = gcnew array<Byte>(1024);
   do
   {
      
      // Read from the wrapping CryptoStream.
      bytesRead = inStream->Read( buffer, 0, 1024 );
      outStream->Write( buffer, 0, bytesRead );
   }
   while ( bytesRead > 0 );

   myhmacMD5->Clear();
   
   // Close the streams
   inStream->Close();
   outStream->Close();
   return;
} // end EncodeFile



// Decrypt the encoded file and compare to original file.
bool DecodeFile( array<Byte>^key, String^ sourceFile )
{
   
   // Initialize the keyed hash object. 
   HMACMD5^ hmacMD5 = gcnew HMACMD5( key );
   
   // Create an array to hold the keyed hash value read from the file.
   array<Byte>^storedHash = gcnew array<Byte>(hmacMD5->HashSize / 8);
   
   // Create a FileStream for the source file.
   FileStream^ inStream = gcnew FileStream( sourceFile,FileMode::Open );
   
   // Read in the storedHash.
   inStream->Read( storedHash, 0, storedHash->Length );
   
   // Compute the hash of the remaining contents of the file.
   // The stream is properly positioned at the beginning of the content, 
   // immediately after the stored hash value.
   array<Byte>^computedHash = hmacMD5->ComputeHash( inStream );
   
   // compare the computed hash with the stored value
   bool err = false;
   for ( int i = 0; i < storedHash->Length; i++ )
   {
      if ( computedHash[ i ] != storedHash[ i ] )
      {
         err = true;
      }
   }
   if (err)
        {
            Console::WriteLine("Hash values differ! Encoded file has been tampered with!");
            return false;
        }
        else
        {
            Console::WriteLine("Hash values agree -- no tampering occurred.");
            return true;
        }

} //end DecodeFile


int main()
{
   String^ usageText = "Usage: HMACMD5 inputfile.txt encryptedfile.hsh\nYou must specify the two file names. Only the first file must exist.\n";
   array<String^>^Fileargs = Environment::GetCommandLineArgs();
   
   //If no file names are specified, write usage text.
   if ( Fileargs->Length < 3 )
   {
      Console::WriteLine( usageText );
   }
   else
   {
      try
      {
         
         // Create a random key using a random number generator. This would be the
         //  secret key shared by sender and receiver.
         array<Byte>^secretkey = gcnew array<Byte>(64);
         
         //RNGCryptoServiceProvider is an implementation of a random number generator.
         RNGCryptoServiceProvider^ rng = gcnew RNGCryptoServiceProvider;
         
         // The array is now filled with cryptographically strong random bytes.
         rng->GetBytes( secretkey );
         
         // Use the secret key to encode the message file.
         EncodeFile( secretkey, Fileargs[ 1 ], Fileargs[ 2 ] );
         
         // Take the encoded file and decode
         DecodeFile( secretkey, Fileargs[ 2 ] );
      }
      catch ( IOException^ e ) 
      {
         Console::WriteLine( "Error: File not found", e );
      }

   }
} //end main


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

public class HMACMD5example
{

    public static void Main(string[] Fileargs)
    {
        string dataFile;
        string signedFile;
        //If no file names are specified, create them.
        if (Fileargs.Length < 2)
        {
            dataFile = @"text.txt";
            signedFile = "signedFile.enc";

            if (!File.Exists(dataFile))
            {
                // Create a file to write to.
                using (StreamWriter sw = File.CreateText(dataFile))
                {
                    sw.WriteLine("Here is a message to sign");
                }
            }

        }
        else
        {
            dataFile = Fileargs[0];
            signedFile = Fileargs[1];
        }
        try
        {
            // Create a random key using a random number generator. This would be the
            //  secret key shared by sender and receiver.
            byte[] secretkey = new Byte[64];
            //RNGCryptoServiceProvider is an implementation of a random number generator.
            using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
            {
                // The array is now filled with cryptographically strong random bytes.
                rng.GetBytes(secretkey);

                // Use the secret key to sign the message file.
                SignFile(secretkey, dataFile, signedFile);

                // Verify the signed file
                VerifyFile(secretkey, signedFile);
            }
        }
        catch (IOException e)
        {
            Console.WriteLine("Error: File not found", e);
        }

    }  //end main
    // Computes a keyed hash for a source file and creates a target file with the keyed hash
    // prepended to the contents of the source file. 
    public static void SignFile(byte[] key, String sourceFile, String destFile)
    {
        // Initialize the keyed hash object.
        using (HMACMD5 hmac = new HMACMD5(key))
        {
            using (FileStream inStream = new FileStream(sourceFile, FileMode.Open))
            {
                using (FileStream outStream = new FileStream(destFile, FileMode.Create))
                {
                    // Compute the hash of the input file.
                    byte[] hashValue = hmac.ComputeHash(inStream);
                    // Reset inStream to the beginning of the file.
                    inStream.Position = 0;
                    // Write the computed hash value to the output file.
                    outStream.Write(hashValue, 0, hashValue.Length);
                    // Copy the contents of the sourceFile to the destFile.
                    int bytesRead;
                    // read 1K at a time
                    byte[] buffer = new byte[1024];
                    do
                    {
                        // Read from the wrapping CryptoStream.
                        bytesRead = inStream.Read(buffer, 0, 1024);
                        outStream.Write(buffer, 0, bytesRead);
                    } while (bytesRead > 0);
                }
            }
        }
        return;
    } // end SignFile


    // Compares the key in the source file with a new key created for the data portion of the file. If the keys 
    // compare the data has not been tampered with.
    public static bool VerifyFile(byte[] key, String sourceFile)
    {
        bool err = false;
        // Initialize the keyed hash object. 
        using (HMACMD5 hmac = new HMACMD5(key))
        {
            // Create an array to hold the keyed hash value read from the file.
            byte[] storedHash = new byte[hmac.HashSize / 8];
            // Create a FileStream for the source file.
            using (FileStream inStream = new FileStream(sourceFile, FileMode.Open))
            {
                // Read in the storedHash.
                inStream.Read(storedHash, 0, storedHash.Length);
                // Compute the hash of the remaining contents of the file.
                // The stream is properly positioned at the beginning of the content, 
                // immediately after the stored hash value.
                byte[] computedHash = hmac.ComputeHash(inStream);
                // compare the computed hash with the stored value

                for (int i = 0; i < storedHash.Length; i++)
                {
                    if (computedHash[i] != storedHash[i])
                    {
                        err = true;
                    }
                }
            }
        }
        if (err)
        {
            Console.WriteLine("Hash values differ! Signed file has been tampered with!");
            return false;
        }
        else
        {
            Console.WriteLine("Hash values agree -- no tampering occurred.");
            return true;
        }

    } //end VerifyFile

} //end class
Imports System
Imports System.IO
Imports System.Security.Cryptography

Public Class HMACMD5example

    Public Shared Sub Main(ByVal Fileargs() As String)
        Dim dataFile As String
        Dim signedFile As String
        'If no file names are specified, create them.
        If Fileargs.Length < 2 Then
            dataFile = "text.txt"
            signedFile = "signedFile.enc"

            If Not File.Exists(dataFile) Then
                ' Create a file to write to.
                Using sw As StreamWriter = File.CreateText(dataFile)
                    sw.WriteLine("Here is a message to sign")
                End Using
            End If

        Else
            dataFile = Fileargs(0)
            signedFile = Fileargs(1)
        End If
        Try
            ' Create a random key using a random number generator. This would be the
            '  secret key shared by sender and receiver.
            Dim secretkey() As Byte = New [Byte](63) {}
            'RNGCryptoServiceProvider is an implementation of a random number generator.
            Using rng As New RNGCryptoServiceProvider()
                ' The array is now filled with cryptographically strong random bytes.
                rng.GetBytes(secretkey)

                ' Use the secret key to encode the message file.
                SignFile(secretkey, dataFile, signedFile)

                ' Take the encoded file and decode
                VerifyFile(secretkey, signedFile)
            End Using
        Catch e As IOException
            Console.WriteLine("Error: File not found", e)
        End Try

    End Sub 'Main

    ' Computes a keyed hash for a source file and creates a target file with the keyed hash
    ' prepended to the contents of the source file. 
    Public Shared Sub SignFile(ByVal key() As Byte, ByVal sourceFile As String, ByVal destFile As String)
        ' Initialize the keyed hash object.
        Using myhmac As New HMACMD5(key)
            Using inStream As New FileStream(sourceFile, FileMode.Open)
                Using outStream As New FileStream(destFile, FileMode.Create)
                    ' Compute the hash of the input file.
                    Dim hashValue As Byte() = myhmac.ComputeHash(inStream)
                    ' Reset inStream to the beginning of the file.
                    inStream.Position = 0
                    ' Write the computed hash value to the output file.
                    outStream.Write(hashValue, 0, hashValue.Length)
                    ' Copy the contents of the sourceFile to the destFile.
                    Dim bytesRead As Integer
                    ' read 1K at a time
                    Dim buffer(1023) As Byte
                    Do
                        ' Read from the wrapping CryptoStream.
                        bytesRead = inStream.Read(buffer, 0, 1024)
                        outStream.Write(buffer, 0, bytesRead)
                    Loop While bytesRead > 0
                End Using
            End Using
        End Using
        Return

    End Sub 'SignFile
    ' end SignFile

    ' Compares the key in the source file with a new key created for the data portion of the file. If the keys 
    ' compare the data has not been tampered with.
    Public Shared Function VerifyFile(ByVal key() As Byte, ByVal sourceFile As String) As Boolean
        Dim err As Boolean = False
        ' Initialize the keyed hash object. 
        Using hmac As New HMACMD5(key)
            ' Create an array to hold the keyed hash value read from the file.
            Dim storedHash(hmac.HashSize / 8) As Byte
            ' Create a FileStream for the source file.
            Using inStream As New FileStream(sourceFile, FileMode.Open)
                ' Read in the storedHash.
                inStream.Read(storedHash, 0, storedHash.Length - 1)
                ' Compute the hash of the remaining contents of the file.
                ' The stream is properly positioned at the beginning of the content, 
                ' immediately after the stored hash value.
                Dim computedHash As Byte() = hmac.ComputeHash(inStream)
                ' compare the computed hash with the stored value
                Dim i As Integer
                For i = 0 To storedHash.Length - 2
                    If computedHash(i) <> storedHash(i) Then
                        err = True
                    End If
                Next i
            End Using
        End Using
        If err Then
            Console.WriteLine("Hash values differ! Signed file has been tampered with!")
            Return False
        Else
            Console.WriteLine("Hash values agree -- no tampering occurred.")
            Return True
        End If

    End Function 'VerifyFile 
End Class 'HMACMD5example 'end VerifyFile
'end class

Hinweise

HMACMD5 ist eine Art schlüsselgebundenen Hashalgorithmus, der von der Hashfunktion Message Digest Algorithm 5 (MD5) erstellt und als ein Hash-based Message Authentication Code (HMAC) verwendet.HMACMD5 is a type of keyed hash algorithm that is constructed from the Message Digest Algorithm 5 (MD5) hash function and used as a Hash-based Message Authentication Code (HMAC). Der HMAC-Prozess kombiniert einen geheimen Schlüssel mit den Nachrichtendaten, das Ergebnis wird mithilfe der Hashfunktion, kombiniert diesen Hashwert mit dem geheimen Schlüssel erneut aus und wendet dann die Hash-Funktion ein zweites Mal.The HMAC process mixes a secret key with the message data, hashes the result with the hash function, mixes that hash value with the secret key again, and then applies the hash function a second time. Die Ausgabehash ist 128 Bits lang.The output hash is 128 bits in length.

Um zu bestimmen, ob eine über einen unsicheren Kanal gesendete Nachricht manipuliert wurde, vorausgesetzt, dass Sender und Empfänger einen gemeinsamen geheimen Schlüssel besitzen, kann ein HMAC, der verwendet werden.An HMAC can be used to determine whether a message sent over an insecure channel has been tampered with, provided that the sender and receiver share a secret key. Der Absender berechnet den Hashwert für die ursprünglichen Daten und sendet als einzelne Nachricht sowohl die ursprünglichen Daten als auch der Hashwert.The sender computes the hash value for the original data and sends both the original data and hash value as a single message. Der Empfänger berechnet den Hashwert für die empfangene Nachricht und stellt sicher, dass der berechnete HMAC den übertragenen HMAC entspricht.The receiver recalculates the hash value on the received message and checks that the computed HMAC matches the transmitted HMAC.

Jede Änderung an den Daten oder der Hashwert führt keine Übereinstimmung gefunden, da Kenntnisse des geheimen Schlüssels erforderlich sind, ändern Sie die Nachricht und reproduzieren den richtigen Hashwert.Any change to the data or the hash value results in a mismatch, because knowledge of the secret key is required to change the message and reproduce the correct hash value. Aus diesem Grund: Wenn die ursprüngliche und der berechnete Hashwerte übereinstimmen, wird die Nachricht authentifiziert.Therefore, if the original and computed hash values match, the message is authenticated.

MD5 handelt es sich um einen kryptografischen Hash-Algorithmus RSA Laboratories entwickelt.MD5 is a cryptographic hash algorithm developed at RSA Laboratories. HMACMD5 akzeptiert eine beliebige Größe-Schlüssel, und erzeugt eine Hashsequenz, die 128-Bit lang ist.HMACMD5 accepts keys of any size, and produces a hash sequence that is 128 bits in length.

Konstruktoren

HMACMD5() HMACMD5() HMACMD5() HMACMD5()

Initialisiert eine neue Instanz der HMACMD5-Klasse mit einem zufällig erzeugten Schlüssel.Initializes a new instance of the HMACMD5 class by using a randomly generated key.

HMACMD5(Byte[]) HMACMD5(Byte[]) HMACMD5(Byte[]) HMACMD5(Byte[])

Initialisiert eine neue Instanz der HMACMD5-Klasse mit dem angegebenen Schlüssel.Initializes a new instance of the HMACMD5 class by using the specified key.

Eigenschaften

BlockSizeValue BlockSizeValue BlockSizeValue BlockSizeValue

Ruft die für den Hashwert verwendete Blockgröße ab oder legt diese fest.Gets or sets the block size to use in the hash value.

(Inherited from HMAC)
CanReuseTransform CanReuseTransform CanReuseTransform CanReuseTransform

Ruft einen Wert ab, der angibt, ob die aktuelle Transformation wiederverwendet werden kann.Gets a value indicating whether the current transform can be reused.

(Inherited from HashAlgorithm)
CanTransformMultipleBlocks CanTransformMultipleBlocks CanTransformMultipleBlocks CanTransformMultipleBlocks

Ruft beim Überschreiben in einer abgeleiteten Klasse einen Wert ab, der angibt, ob mehrere Blöcke transformiert werden können.When overridden in a derived class, gets a value indicating whether multiple blocks can be transformed.

(Inherited from HashAlgorithm)
Hash Hash Hash Hash

Ruft den Wert des berechneten Hashcodes ab.Gets the value of the computed hash code.

(Inherited from HashAlgorithm)
HashName HashName HashName HashName

Ruft den Namen des für die Hashoperation verwendeten Hashalgorithmus ab oder legt diesen fest.Gets or sets the name of the hash algorithm to use for hashing.

(Inherited from HMAC)
HashSize HashSize HashSize HashSize
InputBlockSize InputBlockSize InputBlockSize InputBlockSize

Ruft beim Überschreiben in einer abgeleiteten Klasse die Eingabeblockgröße ab.When overridden in a derived class, gets the input block size.

(Inherited from HashAlgorithm)
Key Key Key Key
OutputBlockSize OutputBlockSize OutputBlockSize OutputBlockSize

Ruft beim Überschreiben in einer abgeleiteten Klasse die Ausgabeblockgröße ab.When overridden in a derived class, gets the output block size.

(Inherited from HashAlgorithm)

Methoden

Clear() Clear() Clear() Clear()

Gibt alle von der HashAlgorithm-Klasse verwendeten Ressourcen frei.Releases all resources used by the HashAlgorithm class.

(Inherited from HashAlgorithm)
ComputeHash(Byte[]) ComputeHash(Byte[]) ComputeHash(Byte[]) ComputeHash(Byte[])

Berechnet den Hashwert für das angegebene Bytearray.Computes the hash value for the specified byte array.

(Inherited from HashAlgorithm)
ComputeHash(Byte[], Int32, Int32) ComputeHash(Byte[], Int32, Int32) ComputeHash(Byte[], Int32, Int32) ComputeHash(Byte[], Int32, Int32)

Berechnet den Hashwert für den angegebenen Bereich des angegebenen Bytearrays.Computes the hash value for the specified region of the specified byte array.

(Inherited from HashAlgorithm)
ComputeHash(Stream) ComputeHash(Stream) ComputeHash(Stream) ComputeHash(Stream)

Berechnet den Hashwert für das angegebene Stream-Objekt.Computes the hash value for the specified Stream object.

(Inherited from HashAlgorithm)
Dispose() Dispose() Dispose() Dispose()

Gibt alle von der aktuellen Instanz der HashAlgorithm-Klasse verwendeten Ressourcen frei.Releases all resources used by the current instance of the HashAlgorithm class.

(Inherited from HashAlgorithm)
Dispose(Boolean) Dispose(Boolean) Dispose(Boolean) Dispose(Boolean)
Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Bestimmt, ob das angegebene Objekt mit dem aktuellen Objekt identisch ist.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Fungiert als die Standardhashfunktion.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Ruft den Type der aktuellen Instanz ab.Gets the Type of the current instance.

(Inherited from Object)
HashCore(Byte[], Int32, Int32) HashCore(Byte[], Int32, Int32) HashCore(Byte[], Int32, Int32) HashCore(Byte[], Int32, Int32)
HashCore(ReadOnlySpan<Byte>) HashCore(ReadOnlySpan<Byte>) HashCore(ReadOnlySpan<Byte>) HashCore(ReadOnlySpan<Byte>)
HashFinal() HashFinal() HashFinal() HashFinal()
Initialize() Initialize() Initialize() Initialize()
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Erstellt eine flache Kopie des aktuellen Object.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Gibt eine Zeichenfolge zurück, die das aktuelle Objekt darstellt.Returns a string that represents the current object.

(Inherited from Object)
TransformBlock(Byte[], Int32, Int32, Byte[], Int32) TransformBlock(Byte[], Int32, Int32, Byte[], Int32) TransformBlock(Byte[], Int32, Int32, Byte[], Int32) TransformBlock(Byte[], Int32, Int32, Byte[], Int32)

Berechnet den Hashwert für den angegebenen Bereich des Eingabebytearrays und kopiert den angegebenen Bereich des Eingabebytearrays in den angegebenen Bereich des Ausgabebytearrays.Computes the hash value for the specified region of the input byte array and copies the specified region of the input byte array to the specified region of the output byte array.

(Inherited from HashAlgorithm)
TransformFinalBlock(Byte[], Int32, Int32) TransformFinalBlock(Byte[], Int32, Int32) TransformFinalBlock(Byte[], Int32, Int32) TransformFinalBlock(Byte[], Int32, Int32)

Berechnet den Hashwert für den angegebenen Bereich des angegebenen Bytearrays.Computes the hash value for the specified region of the specified byte array.

(Inherited from HashAlgorithm)
TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) Inherited from HashAlgorithm
TryHashFinal(Span<Byte>, Int32) TryHashFinal(Span<Byte>, Int32) TryHashFinal(Span<Byte>, Int32) TryHashFinal(Span<Byte>, Int32)

Felder

HashSizeValue HashSizeValue HashSizeValue HashSizeValue

Stellt die Größe des berechneten Hashcodes in Bits dar.Represents the size, in bits, of the computed hash code.

(Inherited from HashAlgorithm)
HashValue HashValue HashValue HashValue

Stellt den Wert des errechneten Hashcodes dar.Represents the value of the computed hash code.

(Inherited from HashAlgorithm)
KeyValue KeyValue KeyValue KeyValue

Der im Hashalgorithmus zu verwendende Schlüssel.The key to use in the hash algorithm.

(Inherited from KeyedHashAlgorithm)
State State State State

Stellt den Zustand der Hashberechnung dar.Represents the state of the hash computation.

(Inherited from HashAlgorithm)

Explizite Schnittstellenimplementierungen

IDisposable.Dispose() IDisposable.Dispose() IDisposable.Dispose() IDisposable.Dispose()

Gibt die von HashAlgorithm verwendeten nicht verwalteten Ressourcen und optional die verwalteten Ressourcen frei.Releases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources.

(Inherited from HashAlgorithm)

Gilt für:

Siehe auch