HMACSHA512 類別
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
使用 SHA512 雜湊函式，計算雜湊式訊息驗證碼 (Hash-based Message Authentication Code，HMAC)。
public ref class HMACSHA512 : System::Security::Cryptography::HMAC[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public class HMACSHA512 : System.Security.Cryptography.HMACpublic class HMACSHA512 : System.Security.Cryptography.HMAC[System.Runtime.InteropServices.ComVisible(true)]
public class HMACSHA512 : System.Security.Cryptography.HMAC[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
type HMACSHA512 = class
inherit HMACtype HMACSHA512 = class
inherit HMAC[<System.Runtime.InteropServices.ComVisible(true)>]
type HMACSHA512 = class
inherit HMACPublic Class HMACSHA512
Inherits HMAC- 繼承
- 屬性
範例
下列範例示範如何使用 對象簽署檔案 HMACSHA512 ，以及如何驗證檔案。
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.
HMACSHA512^ myhmacsha512 = gcnew HMACSHA512( 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 = myhmacsha512->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 );
myhmacsha512->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.
HMACSHA512^ hmacsha512 = gcnew HMACSHA512( key );
// Create an array to hold the keyed hash value read from the file.
array<Byte>^storedHash = gcnew array<Byte>(hmacsha512->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 = hmacsha512->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()
{
array<String^>^Fileargs = Environment::GetCommandLineArgs();
String^ usageText = "Usage: HMACSHA512 inputfile.txt encryptedfile.hsh\nYou must specify the two file names. Only the first file must exist.\n";
//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 HMACSHA512example
{
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 (HMACSHA512 hmac = new HMACSHA512(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 (HMACSHA512 hmac = new HMACSHA512(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 HMACSHA5126example
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 HMACSHA512(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 HMACSHA512(key)
' Create an array to hold the keyed hash value read from the file.
Dim storedHash(hmac.HashSize / 8 - 1) 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
備註
HMACSHA512 是從 SHA-512 哈希函式建構的索引鍵哈希演算法類型，用來做為哈希型訊息驗證程式代碼 (HMAC) 。 HMAC 程式會混合秘密金鑰與訊息數據，並哈希結果。 哈希值會再次與秘密密鑰混合，然後再哈希一次。 輸出哈希的長度為512位。
HMAC 可用來判斷透過不安全通道傳送的訊息是否已遭到竄改，前提是傳送者和接收者共用秘密密鑰。 傳送者會計算原始數據的哈希值，並以單一訊息的形式傳送原始數據和哈希值。 接收者會重新計算所接收訊息上的哈希值，並檢查計算的 HMAC 是否符合傳輸的 HMAC。
如果原始和計算的哈希值相符，則會驗證訊息。 如果它們不相符，則數據或哈希值已變更。 HMAC 提供安全性以防止竄改，因為必須知道秘密密鑰才能變更訊息，並重現正確的哈希值。
HMACSHA512 接受任何大小的索引鍵，併產生長度為512位的哈希序列。
建構函式
| HMACSHA512() |
使用隨機產生的金鑰，初始化 HMACSHA512 類別的新執行個體。 |
| HMACSHA512(Byte[]) |
使用指定的金鑰資料，初始化 HMACSHA512 類別的新執行個體。 |
欄位
| HashSizeInBits |
HMAC SHA512 演算法所產生的哈希大小，以位為單位。 |
| HashSizeInBytes |
HMAC SHA512 演算法所產生的哈希大小，以位元組為單位。 |
| HashSizeValue |
代表計算出來之雜湊碼的大小，以位元為單位。 (繼承來源 HashAlgorithm) |
| HashValue |
表示計算出來的雜湊碼的值。 (繼承來源 HashAlgorithm) |
| KeyValue |
要使用於雜湊演算法的金鑰。 (繼承來源 KeyedHashAlgorithm) |
| State |
表示雜湊計算的狀態。 (繼承來源 HashAlgorithm) |
屬性
| BlockSizeValue |
取得或設定要使用於雜湊值的區塊大小。 (繼承來源 HMAC) |
| CanReuseTransform |
取得值，表示目前的轉換是否可重複使用。 (繼承來源 HashAlgorithm) |
| CanTransformMultipleBlocks |
在衍生類別中覆寫時，取得值以指出是否有多個區塊可被轉換。 (繼承來源 HashAlgorithm) |
| Hash |
取得計算出來之雜湊碼的值。 (繼承來源 HashAlgorithm) |
| HashName |
取得或設定用於雜湊的雜湊演算法名稱。 (繼承來源 HMAC) |
| HashSize |
取得計算出的 HMAC 大小，以位元為單位。 |
| HashSize |
取得計算出來之雜湊碼的大小，以位元為單位。 (繼承來源 HashAlgorithm) |
| InputBlockSize |
在衍生類別中覆寫時，取得輸入區塊的大小。 (繼承來源 HashAlgorithm) |
| Key |
取得或設定要在 HMAC 計算中使用的索引鍵。 |
| Key |
取得或設定要在 HMAC 計算中使用的索引鍵。 (繼承來源 HMAC) |
| OutputBlockSize |
在衍生類別中覆寫時，取得輸出區塊的大小。 (繼承來源 HashAlgorithm) |
| ProduceLegacyHmacValues |
已淘汰.
為演算法的 HMACSHA512 .NET Framework 2.0 實作提供因應措施，這與 .NET Framework 2.0 Service Pack 1 實作不一致。 |
方法
明確介面實作
| IDisposable.Dispose() |
釋放 HashAlgorithm 所使用的 Unmanaged 資源，並選擇性地釋放 Managed 資源。 (繼承來源 HashAlgorithm) |
