HMACSHA1 コンストラクタ (Byte[])
キー データを指定して、HMACSHA1 クラスの新しいインスタンスを初期化します。
名前空間: System.Security.Cryptography
アセンブリ: mscorlib (mscorlib.dll 内)
構文
'宣言
Public Sub New ( _
key As Byte() _
)
'使用
Dim key As Byte()
Dim instance As New HMACSHA1(key)
public HMACSHA1 (
byte[] key
)
public:
HMACSHA1 (
array<unsigned char>^ key
)
public HMACSHA1 (
byte[] key
)
public function HMACSHA1 (
key : byte[]
)
適用できません。
パラメータ
- key
HMACSHA1 暗号化の共有キー。キーは任意の長さにできますが、64 バイトを超えた場合は、SHA-1 を使用してハッシュされ、最終的には 64 バイトのキーが生成されます。したがって、共有キーの推奨サイズは 64 バイトです。
例外
| 例外の種類 | 条件 |
|---|---|
key パラメータが null 参照 (Visual Basic では Nothing) です。 |
解説
HMACSHA1 は、SHA1 ハッシュ関数から構築され、ハッシュ メッセージ認証コード (HMAC) として使用されるキー付きハッシュ アルゴリズムの一種です。HMAC プロセスでは、共有キーとメッセージ データを合成して、その結果にハッシュ関数を適用し、ハッシュ値と共有キーを再び合成した上で、もう一度ハッシュ関数を適用します。出力されるハッシュは 160 ビット (20 バイト) 長になります。
使用例
HMACSHA1 を使用してファイルをエンコードしたり、エンコード済みのファイルをデコードしたりする方法を次のコード例に示します。
Imports System
Imports System.IO
Imports System.Security.Cryptography
Public Class HMACSHA1example
' 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.
Public Shared Sub EncodeFile(ByVal key() As Byte, ByVal sourceFile As String, ByVal destFile As String)
' Initialize the keyed hash object.
Dim myhmacsha1 As New HMACSHA1(key)
Dim inStream As New FileStream(sourceFile, FileMode.Open)
Dim outStream As New FileStream(destFile, FileMode.Create)
' Compute the hash of the input file.
Dim hashValue As Byte() = myhmacsha1.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
myhmacsha1.Clear()
' Close the streams
inStream.Close()
outStream.Close()
Return
End Sub
' Decrypt the encoded file and compare to original file.
Public Shared Function DecodeFile(ByVal key() As Byte, ByVal sourceFile As String) As Boolean
' Initialize the keyed hash object.
Dim hmacsha1 As New HMACSHA1(key)
' Create an array to hold the keyed hash value read from the file.
Dim storedHash(hmacsha1.HashSize / 8) As Byte
' Create a FileStream for the source file.
Dim inStream As 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.
Dim computedHash As Byte() = hmacsha1.ComputeHash(inStream)
' compare the computed hash with the stored value
Dim i As Integer
For i = 0 To storedHash.Length
If computedHash(i) <> storedHash(i) Then
Console.WriteLine("Hash values differ! Encoded file has been tampered with!")
Return False
End If
Next i
Console.WriteLine("Hash values agree -- no tampering occurred.")
Return True
End Function
Private Const usageText As String = "Usage: HMACSHA1 inputfile.txt encryptedfile.hsh" + vbLf + "You must specify the two file names. Only the first file must exist." + vbLf
Public Shared Sub Main(ByVal Fileargs() As String)
'If no file names are specified, write usage text.
If Fileargs.Length < 2 Then
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.
Dim secretkey() As Byte = New [Byte](63) {}
'RNGCryptoServiceProvider is an implementation of a random number generator.
Dim 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.
EncodeFile(secretkey, Fileargs(0), Fileargs(1))
' Take the encoded file and decode
DecodeFile(secretkey, Fileargs(1))
Catch e As IOException
Console.WriteLine("Error: File not found", e)
End Try
End If
End Sub
End Class
using System;
using System.IO;
using System.Security.Cryptography;
public class HMACSHA1example
{
// 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.
public static void EncodeFile(byte[] key, String sourceFile, String destFile)
{
// Initialize the keyed hash object.
HMACSHA1 myhmacsha1 = new HMACSHA1(key);
FileStream inStream = new FileStream(sourceFile, FileMode.Open);
FileStream outStream = new FileStream(destFile, FileMode.Create);
// Compute the hash of the input file.
byte[] hashValue = myhmacsha1.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);
myhmacsha1.Clear();
// Close the streams
inStream.Close();
outStream.Close();
return;
} // end EncodeFile
// Decrypt the encoded file and compare to original file.
public static bool DecodeFile(byte[] key, String sourceFile)
{
// Initialize the keyed hash object.
HMACSHA1 hmacsha1 = new HMACSHA1(key);
// Create an array to hold the keyed hash value read from the file.
byte[] storedHash = new byte[hmacsha1.HashSize/8];
// Create a FileStream for the source file.
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 = hmacsha1.ComputeHash(inStream);
// compare the computed hash with the stored value
for (int i =0; i < storedHash.Length; i++)
{
if (computedHash[i] != storedHash[i])
{
Console.WriteLine("Hash values differ! Encoded file has been tampered with!");
return false;
}
}
Console.WriteLine("Hash values agree -- no tampering occurred.");
return true;
} //end DecodeFile
private const string usageText = "Usage: HMACSHA1 inputfile.txt encryptedfile.hsh\nYou must specify the two file names. Only the first file must exist.\n";
public static void Main(string[] Fileargs)
{
//If no file names are specified, write usage text.
if (Fileargs.Length < 2)
{
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.
byte[] secretkey = new Byte[64];
//RNGCryptoServiceProvider is an implementation of a random number generator.
RNGCryptoServiceProvider rng = new 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[0], Fileargs[1]);
// Take the encoded file and decode
DecodeFile(secretkey, Fileargs[1]);
}
catch (IOException e)
{
Console.WriteLine("Error: File not found",e);
}
} //end if-else
} //end main
} //end class
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.
HMACSHA1^ myhmacsha1 = gcnew HMACSHA1( 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 = myhmacsha1->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 );
myhmacsha1->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.
HMACSHA1^ hmacsha1 = gcnew HMACSHA1( key );
// Create an array to hold the keyed hash value read from the file.
array<Byte>^storedHash = gcnew array<Byte>(hmacsha1->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 = hmacsha1->ComputeHash( inStream );
// compare the computed hash with the stored value
for ( int i = 0; i < storedHash->Length; i++ )
{
if ( computedHash[ i ] != storedHash[ i ] )
{
Console::WriteLine( "Hash values differ! Encoded file has been tampered with!" );
return false;
}
}
Console::WriteLine( "Hash values agree -- no tampering occurred." );
return true;
} //end DecodeFile
int main()
{
array<String^>^Fileargs = Environment::GetCommandLineArgs();
String^ usageText = "Usage: HMACSHA1 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
import System.*;
import System.IO.*;
import System.Security.Cryptography.*;
public class HMACSHA1Example
{
// 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.
public static void EncodeFile(ubyte key[], String sourceFile,
String destFile)
{
// Initialize the keyed hash object.
HMACSHA1 myhmacsha1 = new HMACSHA1(key);
FileStream inStream = new FileStream(sourceFile, FileMode.Open);
FileStream outStream = new FileStream(destFile, FileMode.Create);
// Compute the hash of the input file.
ubyte hashValue[] = myhmacsha1.ComputeHash(inStream);
// Reset inStream to the beginning of the file.
inStream.set_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
ubyte buffer[] = new ubyte[1024];
do {
// Read from the wrapping CryptoStream.
bytesRead = inStream.Read(buffer, 0, 1024);
outStream.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
myhmacsha1.Clear();
// Close the streams
inStream.Close();
outStream.Close();
return;
} // end EncodeFile
// Decrypt the encoded file and compare to original file.
public static boolean DecodeFile(ubyte key[], String sourceFile)
{
// Initialize the keyed hash object.
HMACSHA1 hmacsha1 = new HMACSHA1(key);
// Create an array to hold the keyed hash value read from the file.
ubyte storedHash[] = new ubyte[hmacsha1.get_HashSize() / 8];
// Create a FileStream for the source file.
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.
ubyte computedHash[] = hmacsha1.ComputeHash(inStream);
// compare the computed hash with the stored value
for (int i = 0; i < storedHash.length; i++) {
if (computedHash.get_Item(i) != storedHash.get_Item(i)) {
Console.WriteLine("Hash values differ! Encoded file has been "
+ " tampered with!");
return false;
}
}
Console.WriteLine("Hash values agree -- no tampering occurred.");
return true;
} //DecodeFile //end DecodeFile
private static String usageText = "Usage: HMACSHA1 inputfile.txt "
+ "encryptedfile.hsh\nYou must specify the two file names. Only "
+ "the first file must exist.\n";
public static void main(String[] fileargs)
{
//If no file names are specified, write usage text.
if (fileargs.length < 2) {
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.
ubyte secretKey[] = new ubyte[64];
// RNGCryptoServiceProvider is an implementation of a random
// number generator.
RNGCryptoServiceProvider rng = new 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[0], fileargs[1]);
// Take the encoded file and decode
DecodeFile(secretKey, fileargs[1]);
}
catch (IOException e) {
Console.WriteLine("Error: File not found", e);
}
}//end if-else
} //end main
} //end class HMACSHA1Example
プラットフォーム
Windows 98,Windows Server 2000 SP4,Windows CE,Windows Millennium Edition,Windows Mobile for Pocket PC,Windows Mobile for Smartphone,Windows Server 2003,Windows XP Media Center Edition,Windows XP Professional x64 Edition,Windows XP SP2,Windows XP Starter Edition
Microsoft .NET Framework 3.0 は Windows Vista,Microsoft Windows XP SP2,および Windows Server 2003 SP1 でサポートされています。
バージョン情報
.NET Framework
サポート対象 : 3.0,2.0,1.1,1.0
参照
関連項目
HMACSHA1 クラス
HMACSHA1 メンバ
System.Security.Cryptography 名前空間