HMACMD5 HMACMD5 HMACMD5 HMACMD5 Class

定义

使用 MD5 哈希函数计算基于哈希值的消息验证代码 (HMAC)。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
继承
属性

示例

下面的示例演示如何使用HMACMD5对象对文件进行签名,然后再验证该文件。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.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

    ' 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
    ' 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

注解

HMACMD5加密哈希算法的一种类型,它是从消息摘要算法5(MD5)哈希函数构建的,并用作基于哈希的消息验证代码(HMAC)。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). HMAC 进程将密钥与消息数据混合,使用哈希函数对结果进行哈希运算,再次混合使用密钥的哈希值,然后再次应用哈希函数。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. 输出哈希的长度为128位。The output hash is 128 bits in length.

如果发送方和接收方共享密钥,则可以使用 HMAC 来确定通过不安全通道发送的消息是否已被篡改。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. 发件人计算原始数据的哈希值,并以单个消息形式发送原始数据和哈希值。The sender computes the hash value for the original data and sends both the original data and hash value as a single message. 接收方重新计算收到的消息上的哈希值,并检查计算的 HMAC 是否与传输的 HMAC 匹配。The receiver recalculates the hash value on the received message and checks that the computed HMAC matches the transmitted HMAC.

对数据或哈希值所做的任何更改都将导致不匹配,因为更改消息和重现正确的哈希值需要使用机密密钥知识。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. 因此,如果原始和计算所得的哈希值匹配,则将对消息进行身份验证。Therefore, if the original and computed hash values match, the message is authenticated.

MD5 是在 RSA 实验室开发的加密哈希算法。MD5 is a cryptographic hash algorithm developed at RSA Laboratories. HMACMD5接受任意大小的密钥,并产生长度为128位的哈希序列。HMACMD5 accepts keys of any size, and produces a hash sequence that is 128 bits in length.

由于与 MD5 冲突,Microsoft 建议使用 SHA256。Due to collision problems with MD5, Microsoft recommends SHA256.

构造函数

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

使用随机生成的密钥初始化 HMACMD5 类的新实例。Initializes a new instance of the HMACMD5 class by using a randomly generated key.

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

使用指定的密钥初始化 HMACMD5 类的新实例。Initializes a new instance of the HMACMD5 class by using the specified key.

属性

BlockSizeValue BlockSizeValue BlockSizeValue BlockSizeValue

获取或设置哈希值中使用的块大小。Gets or sets the block size to use in the hash value.

(Inherited from HMAC)
CanReuseTransform CanReuseTransform CanReuseTransform CanReuseTransform

获取一个值,该值指示是否可重复使用当前转换。Gets a value indicating whether the current transform can be reused.

(Inherited from HashAlgorithm)
CanTransformMultipleBlocks CanTransformMultipleBlocks CanTransformMultipleBlocks CanTransformMultipleBlocks

当在派生类中重写时,获取一个值,该值指示是否可以转换多个块。When overridden in a derived class, gets a value indicating whether multiple blocks can be transformed.

(Inherited from HashAlgorithm)
Hash Hash Hash Hash

获取计算所得的哈希代码的值。Gets the value of the computed hash code.

(Inherited from HashAlgorithm)
HashName HashName HashName HashName

获取或设置用于哈希计算的哈希算法的名称。Gets or sets the name of the hash algorithm to use for hashing.

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

当在派生类中重写时,获取输入块的大小。When overridden in a derived class, gets the input block size.

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

当在派生类中重写时,获取输出块的大小。When overridden in a derived class, gets the output block size.

(Inherited from HashAlgorithm)

方法

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

释放 HashAlgorithm 类使用的所有资源。Releases all resources used by the HashAlgorithm class.

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

计算指定字节数组的哈希值。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)

计算指定字节数组的指定区域的哈希值。Computes the hash value for the specified region of the specified byte array.

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

计算指定 Stream 对象的哈希值。Computes the hash value for the specified Stream object.

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

释放 HashAlgorithm 类的当前实例所使用的所有资源。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)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

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

作为默认哈希函数。Serves as the default hash function.

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

获取当前实例的 TypeGets 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()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

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

返回表示当前对象的字符串。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)

计算输入字节数组指定区域的哈希值,并将输入字节数组指定区域复制到输出字节数组的指定区域。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)

计算指定字节数组的指定区域的哈希值。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)

字段

HashSizeValue HashSizeValue HashSizeValue HashSizeValue

表示计算所得的哈希代码的大小(以位为单位)。Represents the size, in bits, of the computed hash code.

(Inherited from HashAlgorithm)
HashValue HashValue HashValue HashValue

表示计算所得的哈希代码的值。Represents the value of the computed hash code.

(Inherited from HashAlgorithm)
KeyValue KeyValue KeyValue KeyValue

用于哈希算法的密钥。The key to use in the hash algorithm.

(Inherited from KeyedHashAlgorithm)
State State State State

表示哈希计算的状态。Represents the state of the hash computation.

(Inherited from HashAlgorithm)

显式界面实现

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

释放由 HashAlgorithm 占用的非托管资源,还可以另外再释放托管资源。Releases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources.

(Inherited from HashAlgorithm)

适用于

另请参阅