Connection对象连接加密2
一般情况下，大多数人习惯于将数据库连接写在web.config上里面，理论上讲，将明文存放在该文件里面是安全的，因为web.config文件是不允许被客户端下载，但一旦该文件泄漏出去，哪怕是很短的时间，数据库都将承受巨大的危害，可能花上N年才充实起来的信息在很短时间里毁于一旦。这是任何程序绝对不应该出现的问题。有人用简单的对称加密来将数据库连接字符串的密文存放，但密钥一旦丢失，加密与否，形同虚设，那么如何保证连接字符串的安全性呢。下面这个类就完成这个功能，该类调用系统API，在不同的系统中对相同的连接串会生成不同的密文，即使非法获得该串，不能获得在服务器上的管理员权限，仍然没有能力知道数据库的真正所在。有人说，那服务器管理员权限也被盗用了呢？那盗用者还需要经过一系列复杂的跟踪和总结，来获得系统标识变量。这无疑又是一个难度，等到他真正破解了解该系统的时候，也许你早就在此之前，改正了服务器的配置和密码，还害得人家白忙活了一趟。够阴的！
using System;
using System.Text;
using System.Runtime.InteropServices;
namespace JillZhang.Security
{
public enum Store
{
USE_NACHINE_STORE=1,USE_USER_STORE
};
public class DataProtector
{
[DllImport("Crypt32.dll",SetLastError=true,CharSet=System.Runtime.InteropServices.CharSet.Auto)]
private static extern bool CryptProtectData
(
ref DATA_BLOB pDataIn,
String szDataDecr,
ref DATA_BLOB pOptionEntropy,
IntPtr pvReserved,
ref CRYPTPROTECT_PROMPTSTRUCT pPromptStruct,
int dwFlags,
ref DATA_BLOB pDataOut
);
[DllImport("Crypt32.dll",SetLastError=true,CharSet=System.Runtime.InteropServices.CharSet.Auto)]
private static extern bool CryptUnprotectData
(
ref DATA_BLOB pDataIn,
String szDataDecr,
ref DATA_BLOB pOptionEntropy,
IntPtr pvReserved,
ref CRYPTPROTECT_PROMPTSTRUCT pPromptStruct,
int dwFlags,
ref DATA_BLOB pDataOut
);
[DllImport("kernel32.dll",CharSet=System.Runtime.InteropServices.CharSet.Auto)]
private unsafe static extern int FormatMessage
(
int dwFlags,
ref IntPtr lpSource,
int dwMessageId,
int dwLanguageId,
ref String lpBuffer,
int nSize,
IntPtr *Arguments
);
[StructLayout(LayoutKind.Sequential,CharSet=CharSet.Unicode)]
internal struct DATA_BLOB
{
public int cbData;
public IntPtr pbData;
}
[StructLayout(LayoutKind.Sequential,CharSet=CharSet.Unicode)]
internal struct CRYPTPROTECT_PROMPTSTRUCT
{
public int cbSize;
public int dwPromptFlags;
public IntPtr hwndApp;
public String szPrompt;
}
static private IntPtr NullPtr=((IntPtr)((int)(0)));
private const int CRYPTPROTECT_UI_FORBIDDEN=0x1;
private const int CRYPTPROTECT_LOCAL_MACHINE=0x4;
private Store store;
public DataProtector(Store tempStore)
{
store=tempStore;
}
public byte[] Encrypt(byte[] plainText,byte[] optionalEntropy)
{
bool reVal=false;
DATA_BLOB plainTextBlob = new DATA_BLOB();
DATA_BLOB cipherTextBlob=new DATA_BLOB();
DATA_BLOB entropyBlob = new DATA_BLOB();
CRYPTPROTECT_PROMPTSTRUCT prompt=new CRYPTPROTECT_PROMPTSTRUCT();
InitPromptstruct(ref prompt);
int dwFlags;
try
{
try
{
int byteSize=plainText.Length;
plainTextBlob.pbData=Marshal.AllocHGlobal(byteSize);
if(IntPtr.Zero==plainTextBlob.pbData)
{
throw new Exception("Unable to allocate plaintext buffer:");
}
plainTextBlob.cbData=byteSize;
Marshal.Copy(plainText,0,plainTextBlob.pbData,byteSize);
}
catch(Exception ex)
{
throw new Exception("Exception marshalling data.:"+ex.Message);
}
if(Store.USE_NACHINE_STORE==store)
{
//计算机存储区
dwFlags=CRYPTPROTECT_LOCAL_MACHINE|CRYPTPROTECT_UI_FORBIDDEN;
if(null==optionalEntropy)
{
optionalEntropy=new byte[0];
}
try
{
int byteSize=optionalEntropy.Length;
entropyBlob.pbData=Marshal.AllocHGlobal(optionalEntropy.Length);
if(IntPtr.Zero==entropyBlob.pbData)
{
throw new Exception("Unable to allocate entropy data buffer.");
}
Marshal.Copy(optionalEntropy,0,entropyBlob.pbData,byteSize);
entropyBlob.cbData=byteSize;
}
catch(Exception ex)
{
throw new Exception("Exception entropy marshalling data."+ex.Message);
}
}
else
{
dwFlags=CRYPTPROTECT_UI_FORBIDDEN;
}
reVal=CryptProtectData(ref plainTextBlob,"",ref entropyBlob,IntPtr.Zero,ref prompt,dwFlags,ref cipherTextBlob);
if(false == reVal)
{
throw new Exception("Encryption failed."+GetErrorMessage(Marshal.GetLastWin32Error()));
}
}
catch(Exception ex)
{
throw new Exception("Exception encrypting:"+ex.Message);
}
byte[] cipherText = new byte[cipherTextBlob.cbData];
Marshal.Copy(cipherTextBlob.pbData,cipherText,0,cipherTextBlob.cbData);
return cipherText;
}
public byte[] Decrypt(byte[] ciperText,byte[] optionalEntropy)
{
bool reVal=false;
DATA_BLOB plainTextBlob=new DATA_BLOB();
DATA_BLOB cipherBlob=new DATA_BLOB();
CRYPTPROTECT_PROMPTSTRUCT prompt=new CRYPTPROTECT_PROMPTSTRUCT();
InitPromptstruct(ref prompt);
try
{
try
{
int cipherTextSize=ciperText.Length;
cipherBlob.pbData=Marshal.AllocHGlobal(cipherTextSize);
if(IntPtr.Zero==cipherBlob.pbData)
{
throw new Exception("unable to allocate cipherText buffer.");
}
cipherBlob.cbData=cipherTextSize;
Marshal.Copy(ciperText,0,cipherBlob.pbData,cipherBlob.cbData);
}
catch(Exception ex)
{
throw new Exception("Exception marshalling data."+ex.Message);
}
DATA_BLOB entropyBlob=new DATA_BLOB();
int dwFlags;
if(Store.USE_NACHINE_STORE==store)
{
dwFlags=CRYPTPROTECT_LOCAL_MACHINE|CRYPTPROTECT_UI_FORBIDDEN;
if(null==optionalEntropy)
{
optionalEntropy=new byte[0];
}
try
{
int byteSize=optionalEntropy.Length;
entropyBlob.pbData=Marshal.AllocHGlobal(byteSize);
if(IntPtr.Zero==entropyBlob.pbData)
{
throw new Exception("Unable to allocate entropy buffer.");
}
entropyBlob.cbData=byteSize;
Marshal.Copy(optionalEntropy,0,entropyBlob.pbData,byteSize);
}
catch(Exception ex)
{
throw new Exception("Exception entropy marshalling data."+ex.Message);
}
}
else
{
dwFlags=CRYPTPROTECT_UI_FORBIDDEN;
}
reVal=CryptUnprotectData(ref cipherBlob,null,ref entropyBlob,IntPtr.Zero,ref prompt,dwFlags,ref plainTextBlob);
if(false==reVal)
{
throw new Exception("Decryption failed."+GetErrorMessage(Marshal.GetLastWin32Error()));
}
if(IntPtr.Zero!=cipherBlob.pbData)
{
Marshal.FreeHGlobal(cipherBlob.pbData);
}
if(IntPtr.Zero!=entropyBlob.pbData)
{
Marshal.FreeHGlobal(entropyBlob.pbData);
}
}
catch(Exception ex)
{
throw new Exception("Exception decrypting."+ex.Message);
}
byte[] plainText=new byte[plainTextBlob.cbData];
Marshal.Copy(plainTextBlob.pbData,plainText,0,plainTextBlob.cbData);
return plainText;
}
private void InitPromptstruct(ref CRYPTPROTECT_PROMPTSTRUCT ps)
{
ps.cbSize=Marshal.SizeOf(typeof(CRYPTPROTECT_PROMPTSTRUCT));
ps.dwPromptFlags=0;
ps.hwndApp=NullPtr;
ps.szPrompt=null;
}
private unsafe static String GetErrorMessage(int errorCode)
{
int FORMAT_MESSAGE_ALLOCATE_BUFFER=0x00000100;
int FORMAT_MESSAGE_IGNORE_INSERTS=0x00000200;
int FORMAT_MESSAGE_FROM_SYSTEM=0x00001000;
int messageSize=255;
String lpMsgBuf="";
int dwFlags=FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS;
IntPtr ptrlpSource=new IntPtr();
IntPtr ptrArgument=new IntPtr();
int retVal=FormatMessage(dwFlags,ref ptrlpSource,errorCode,0,ref lpMsgBuf,messageSize,&ptrArgument);
if(0==retVal)
{
throw new Exception("Failed to format message for error code"+errorCode+".");
}
return lpMsgBuf;
}
}
}
