KeyedHashAlgorithm 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。
代表基底類別，金鑰雜湊演算法的所有實作必須從它衍生。
public ref class KeyedHashAlgorithm abstract : System::Security::Cryptography::HashAlgorithmpublic abstract class KeyedHashAlgorithm : System.Security.Cryptography.HashAlgorithm[System.Runtime.InteropServices.ComVisible(true)]
public abstract class KeyedHashAlgorithm : System.Security.Cryptography.HashAlgorithmtype KeyedHashAlgorithm = class
inherit HashAlgorithm[<System.Runtime.InteropServices.ComVisible(true)>]
type KeyedHashAlgorithm = class
inherit HashAlgorithmPublic MustInherit Class KeyedHashAlgorithm
Inherits HashAlgorithm- 繼承
- 衍生
- 屬性
範例
下列程式碼範例示範如何衍生自 KeyedHashAlgorithm 類別。
using System;
using System.Security.Cryptography;
public class TestHMACMD5
{
static private void PrintByteArray(Byte[] arr)
{
int i;
Console.WriteLine("Length: " + arr.Length);
for (i = 0; i < arr.Length; i++)
{
Console.Write("{0:X}", arr[i]);
Console.Write(" ");
if ((i + 9) % 8 == 0) Console.WriteLine();
}
if (i % 8 != 0) Console.WriteLine();
}
public static void Main()
{
// Create a key.
byte[] key1 = { 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b };
// Pass the key to the constructor of the HMACMD5 class.
HMACMD5 hmac1 = new HMACMD5(key1);
// Create another key.
byte[] key2 = System.Text.Encoding.ASCII.GetBytes("KeyString");
// Pass the key to the constructor of the HMACMD5 class.
HMACMD5 hmac2 = new HMACMD5(key2);
// Encode a string into a byte array, create a hash of the array,
// and print the hash to the screen.
byte[] data1 = System.Text.Encoding.ASCII.GetBytes("Hi There");
PrintByteArray(hmac1.ComputeHash(data1));
// Encode a string into a byte array, create a hash of the array,
// and print the hash to the screen.
byte[] data2 = System.Text.Encoding.ASCII.GetBytes("This data will be hashed.");
PrintByteArray(hmac2.ComputeHash(data2));
}
}
public class HMACMD5 : KeyedHashAlgorithm
{
private MD5 hash1;
private MD5 hash2;
private bool bHashing = false;
private byte[] rgbInner = new byte[64];
private byte[] rgbOuter = new byte[64];
public HMACMD5(byte[] rgbKey)
{
HashSizeValue = 128;
// Create the hash algorithms.
hash1 = MD5.Create();
hash2 = MD5.Create();
// Get the key.
if (rgbKey.Length > 64)
{
KeyValue = hash1.ComputeHash(rgbKey);
// No need to call Initialize; ComputeHash does it automatically.
}
else
{
KeyValue = (byte[])rgbKey.Clone();
}
// Compute rgbInner and rgbOuter.
int i = 0;
for (i = 0; i < 64; i++)
{
rgbInner[i] = 0x36;
rgbOuter[i] = 0x5C;
}
for (i = 0; i < KeyValue.Length; i++)
{
rgbInner[i] ^= KeyValue[i];
rgbOuter[i] ^= KeyValue[i];
}
}
public override byte[] Key
{
get { return (byte[])KeyValue.Clone(); }
set
{
if (bHashing)
{
throw new Exception("Cannot change key during hash operation");
}
if (value.Length > 64)
{
KeyValue = hash1.ComputeHash(value);
// No need to call Initialize; ComputeHash does it automatically.
}
else
{
KeyValue = (byte[])value.Clone();
}
// Compute rgbInner and rgbOuter.
int i = 0;
for (i = 0; i < 64; i++)
{
rgbInner[i] = 0x36;
rgbOuter[i] = 0x5C;
}
for (i = 0; i < KeyValue.Length; i++)
{
rgbInner[i] ^= KeyValue[i];
rgbOuter[i] ^= KeyValue[i];
}
}
}
public override void Initialize()
{
hash1.Initialize();
hash2.Initialize();
bHashing = false;
}
protected override void HashCore(byte[] rgb, int ib, int cb)
{
if (bHashing == false)
{
hash1.TransformBlock(rgbInner, 0, 64, rgbInner, 0);
bHashing = true;
}
hash1.TransformBlock(rgb, ib, cb, rgb, ib);
}
protected override byte[] HashFinal()
{
if (bHashing == false)
{
hash1.TransformBlock(rgbInner, 0, 64, rgbInner, 0);
bHashing = true;
}
// Finalize the original hash.
hash1.TransformFinalBlock(new byte[0], 0, 0);
// Write the outer array.
hash2.TransformBlock(rgbOuter, 0, 64, rgbOuter, 0);
// Write the inner hash and finalize the hash.
hash2.TransformFinalBlock(hash1.Hash, 0, hash1.Hash.Length);
bHashing = false;
return hash2.Hash;
}
}
Imports System.Security.Cryptography
_
Public Class TestHMACMD5
Private Shared Sub PrintByteArray(ByVal arr() As [Byte])
Dim i As Integer
Console.WriteLine(("Length: " + arr.Length.ToString()))
For i = 0 To arr.Length - 1
Console.Write("{0:X}", arr(i))
Console.Write(" ")
If (i + 9) Mod 8 = 0 Then
Console.WriteLine()
End If
Next i
If i Mod 8 <> 0 Then
Console.WriteLine()
End If
End Sub
Public Shared Sub Main()
' Create a key.
Dim key1 As Byte() = {&HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB, &HB}
' Pass the key to the constructor of the HMACMD5 class.
Dim hmac1 As New HMACMD5(key1)
' Create another key.
Dim key2 As Byte() = System.Text.Encoding.ASCII.GetBytes("KeyString")
' Pass the key to the constructor of the HMACMD5 class.
Dim hmac2 As New HMACMD5(key2)
' Encode a string into a byte array, create a hash of the array,
' and print the hash to the screen.
Dim data1 As Byte() = System.Text.Encoding.ASCII.GetBytes("Hi There")
PrintByteArray(hmac1.ComputeHash(data1))
' Encode a string into a byte array, create a hash of the array,
' and print the hash to the screen.
Dim data2 As Byte() = System.Text.Encoding.ASCII.GetBytes("This data will be hashed.")
PrintByteArray(hmac2.ComputeHash(data2))
End Sub
End Class
_
Public Class HMACMD5
Inherits KeyedHashAlgorithm
Private hash1 As MD5
Private hash2 As MD5
Private bHashing As Boolean = False
Private rgbInner(64) As Byte
Private rgbOuter(64) As Byte
Public Sub New(ByVal rgbKey() As Byte)
HashSizeValue = 128
' Create the hash algorithms.
hash1 = MD5.Create()
hash2 = MD5.Create()
' Get the key.
If rgbKey.Length > 64 Then
KeyValue = hash1.ComputeHash(rgbKey)
' No need to call Initialize; ComputeHash does it automatically.
Else
KeyValue = CType(rgbKey.Clone(), Byte())
End If
' Compute rgbInner and rgbOuter.
Dim i As Integer = 0
For i = 0 To 63
rgbInner(i) = &H36
rgbOuter(i) = &H5C
Next i
i = 0
For i = 0 To KeyValue.Length - 1
rgbInner(i) = rgbInner(i) Xor KeyValue(i)
rgbOuter(i) = rgbOuter(i) Xor KeyValue(i)
Next i
End Sub
Public Overrides Property Key() As Byte()
Get
Return CType(KeyValue.Clone(), Byte())
End Get
Set(ByVal Value As Byte())
If bHashing Then
Throw New Exception("Cannot change key during hash operation")
End If
If value.Length > 64 Then
KeyValue = hash1.ComputeHash(value)
' No need to call Initialize; ComputeHash does it automatically.
Else
KeyValue = CType(value.Clone(), Byte())
End If
' Compute rgbInner and rgbOuter.
Dim i As Integer = 0
For i = 0 To 63
rgbInner(i) = &H36
rgbOuter(i) = &H5C
Next i
For i = 0 To KeyValue.Length - 1
rgbInner(i) ^= KeyValue(i)
rgbOuter(i) ^= KeyValue(i)
Next i
End Set
End Property
Public Overrides Sub Initialize()
hash1.Initialize()
hash2.Initialize()
bHashing = False
End Sub
Protected Overrides Sub HashCore(ByVal rgb() As Byte, ByVal ib As Integer, ByVal cb As Integer)
If bHashing = False Then
hash1.TransformBlock(rgbInner, 0, 64, rgbInner, 0)
bHashing = True
End If
hash1.TransformBlock(rgb, ib, cb, rgb, ib)
End Sub
Protected Overrides Function HashFinal() As Byte()
If bHashing = False Then
hash1.TransformBlock(rgbInner, 0, 64, rgbInner, 0)
bHashing = True
End If
' Finalize the original hash.
hash1.TransformFinalBlock(New Byte(0) {}, 0, 0)
' Write the outer array.
hash2.TransformBlock(rgbOuter, 0, 64, rgbOuter, 0)
' Write the inner hash and finalize the hash.
hash2.TransformFinalBlock(hash1.Hash, 0, hash1.Hash.Length)
bHashing = False
Return hash2.Hash
End Function
End Class
備註
雜湊函式會將任意長度的二進位字串對應至固定長度的小型二進位字串。 密碼編譯雜湊函式具有無法計算的 屬性，可尋找雜湊為相同值的兩個相異輸入。 對資料的小型變更會導致雜湊中發生大型、無法預測的變更。
金鑰雜湊演算法是金鑰相依的單向雜湊函式，用來作為訊息驗證碼。 只有知道金鑰的人可以驗證雜湊。 索引雜湊演算法提供沒有秘密的真確性。
雜湊函式經常被用於數位簽章與資料完整性用途。 類別 HMACSHA1 是索引雜湊演算法的範例。
由於 SHA1 的衝突問題，Microsoft 建議您使用以 SHA256 或更好的加密方式為基礎的安全性模型。
建構函式
| KeyedHashAlgorithm() |
初始化 KeyedHashAlgorithm 類別的新執行個體。 |
欄位
| 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。 |
| State |
表示雜湊計算的狀態。 (繼承來源 HashAlgorithm) |
屬性
| 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) |
| 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 |
取得或設定要使用於雜湊演算法的金鑰。 |
| OutputBlockSize |
在衍生類別中覆寫時，取得輸出區塊的大小。 (繼承來源 HashAlgorithm) |
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) |