MACTripleDES 类

定义

使用 TripleDES 计算输入数据 CryptoStream 的消息验证代码 (MAC)。Computes a Message Authentication Code (MAC) using TripleDES for the input data CryptoStream.

public ref class MACTripleDES : System::Security::Cryptography::KeyedHashAlgorithm
[System.Runtime.InteropServices.ComVisible(true)]
public class MACTripleDES : System.Security.Cryptography.KeyedHashAlgorithm
type MACTripleDES = class
    inherit KeyedHashAlgorithm
Public Class MACTripleDES
Inherits KeyedHashAlgorithm
继承
属性

示例

下面的示例为一个名input.txt为的文件创建 MAC, 该文件位于包含可执行文件示例的文件夹中。The following example creates a MAC for a file named input.txt, which is located in the folder that contains the example executable. MAC 和原始文本会写入同一文件夹中名为encrypted.hsh的文件。The MAC and the original text are written to a file named encrypted.hsh in the same folder. 然后, 将读取签名文件, 并为文件的文本部分计算 MAC, 并将其与随文本附带的 MAC 进行比较。The signed file is then read, and the MAC is calculated for the text portion of the file and compared to the MAC that is included with the text.

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

public class MACTripleDESexample
{

    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[24];
            //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 (MACTripleDES hmac = new MACTripleDES(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 (MACTripleDES hmac = new MACTripleDES(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 MACTripleDESexample

    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](23) {}
            '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 MACTripleDES(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 MACTripleDES(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
'end class

注解

如果发送方和接收方共享了密钥, 则可以使用 MAC 来确定通过不安全通道发送的消息是否已被篡改。A MAC 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 MAC, 并将两者都作为单个消息发送。The sender computes the MAC for the original data, and sends both as a single message. 接收方在收到的消息上重新计算 MAC, 并检查计算的 MAC 是否与传输的 MAC 匹配。The receiver recomputes the MAC on the received message, and checks that the computed MAC matches the transmitted MAC.

对数据或 MAC 的任何更改都将导致不匹配, 因为更改消息和重现正确的 MAC 需要密钥知识。Any change to the data or the MAC results in a mismatch, because knowledge of the secret key is required to change the message and reproduce the correct MAC. 因此, 如果代码匹配, 则对消息进行身份验证。Therefore, if the codes match, the message is authenticated.

MACTripleDES使用长度为16或24个字节的密钥, 并产生长度为8个字节的哈希序列。MACTripleDES uses a key that is 16 or 24 bytes long, and produces a hash sequence that is 8 bytes long.

构造函数

MACTripleDES()

初始化 MACTripleDES 类的新实例。Initializes a new instance of the MACTripleDES class.

MACTripleDES(Byte[])

使用指定的密钥数据初始化 MACTripleDES 类的新实例。Initializes a new instance of the MACTripleDES class with the specified key data.

MACTripleDES(String, Byte[])

使用 MACTripleDES 的指定实现,用指定的密钥数据初始化 TripleDES 类的新实例。Initializes a new instance of the MACTripleDES class with the specified key data and using the specified implementation of TripleDES.

字段

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.

(继承自 HashAlgorithm)
HashValue

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

(继承自 HashAlgorithm)
KeyValue

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

(继承自 KeyedHashAlgorithm)
State

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

(继承自 HashAlgorithm)

属性

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.

(继承自 HashAlgorithm)
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.

(继承自 HashAlgorithm)
Hash

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

(继承自 HashAlgorithm)
HashSize

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

(继承自 HashAlgorithm)
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.

(继承自 HashAlgorithm)
Key

获取或设置用于哈希算法的密钥。Gets or sets the key to use in the hash algorithm.

(继承自 KeyedHashAlgorithm)
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.

(继承自 HashAlgorithm)
Padding

获取或设置哈希算法中使用的填充模式。Gets or sets the padding mode used in the hashing algorithm.

方法

Clear()

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

(继承自 HashAlgorithm)
ComputeHash(Byte[])

计算指定字节数组的哈希值。Computes the hash value for the specified byte array.

(继承自 HashAlgorithm)
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.

(继承自 HashAlgorithm)
ComputeHash(Stream)

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

(继承自 HashAlgorithm)
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.

(继承自 HashAlgorithm)
Dispose(Boolean)

释放 MACTripleDES 实例使用的资源。Releases the resources used by the MACTripleDES instance.

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.

(继承自 Object)
Finalize()

释放 MACTripleDES 使用的非托管资源。Releases the unmanaged resources used by the MACTripleDES.

GetHashCode()

用作默认哈希函数。Serves as the default hash function.

(继承自 Object)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
HashCore(Byte[], Int32, Int32)

将写入对象的数据路由到 TripleDES 加密器以计算消息验证代码 (MAC)。Routes data written to the object into the TripleDES encryptor for computing the Message Authentication Code (MAC).

HashCore(ReadOnlySpan<Byte>) (继承自 HashAlgorithm)
HashFinal()

在所有数据写入对象后返回计算所得的消息验证代码 (MAC)。Returns the computed Message Authentication Code (MAC) after all data is written to the object.

Initialize()

初始化 MACTripleDES 的实例。Initializes an instance of MACTripleDES.

MemberwiseClone()

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

(继承自 Object)
ToString()

返回一个表示当前对象的 string。Returns a string that represents the current object.

(继承自 Object)
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.

(继承自 HashAlgorithm)
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.

(继承自 HashAlgorithm)
TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) (继承自 HashAlgorithm)
TryHashFinal(Span<Byte>, Int32) (继承自 HashAlgorithm)

显式界面实现

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.

(继承自 HashAlgorithm)

适用于