C＃ - 比较两个证券的平等

Question

我有一个带有两个密码盒的WPF应用程序，一个用于密码，另一个用于第二次输入密码以确认目的。我想使用 PasswordBox.SecurePassword 得到 SecureString 密码，但是我需要能够比较两个密码框的内容，以确保在接受密码之前保持平等。但是，两个相同的证券仪式不相等：

var secString1 = new SecureString();
var secString2 = new SecureString();
foreach (char c in "testing")
{
    secString1.AppendChar(c);
    secString2.AppendChar(c);
}
Assert.AreEqual(secString1, secString2); // This fails

我在想比较 Password 密码盒的属性将失败仅访问的点 SecurePassword 因为我会阅读普通文本密码。我应该怎么做才能在不牺牲的情况下比较两个密码 安全?

编辑: ： 基于 这个问题, ， 我正在结账 这篇博客文章 关于“使用元帅将Securestring转换为ANSI或Unicode或BSTR”，然后我可以比较这些。

Answer 1

看起来您可以使用 这个 比较两者 SecureStrings.

它使用不安全的代码通过字符串迭代：

bool SecureStringEqual(SecureString s1, SecureString s2)  
{  
    if (s1 == null)  
    {  
        throw new ArgumentNullException("s1");  
    }  
    if (s2 == null)  
    {  
        throw new ArgumentNullException("s2");  
    }  

    if (s1.Length != s2.Length)  
    {  
        return false;  
    }  

    IntPtr bstr1 = IntPtr.Zero;  
    IntPtr bstr2 = IntPtr.Zero;  

    RuntimeHelpers.PrepareConstrainedRegions();  

    try 
    {  
        bstr1 = Marshal.SecureStringToBSTR(s1);  
        bstr2 = Marshal.SecureStringToBSTR(s2);  

        unsafe 
        {  
            for (Char* ptr1 = (Char*)bstr1.ToPointer(), ptr2 = (Char*)bstr2.ToPointer();  
                *ptr1 != 0 && *ptr2 != 0;  
                 ++ptr1, ++ptr2)  
            {  
                if (*ptr1 != *ptr2)  
                {  
                    return false;  
                }  
            }  
        }  

        return true;  
    }  
    finally 
    {  
        if (bstr1 != IntPtr.Zero)  
        {  
            Marshal.ZeroFreeBSTR(bstr1);  
        }  

        if (bstr2 != IntPtr.Zero)  
        {  
            Marshal.ZeroFreeBSTR(bstr2);  
        }  
    }  
} 

我在下面修改了它的工作，没有不安全的代码（请注意，在调试时您可以在纯文本中看到字符串）：

  Boolean SecureStringEqual(SecureString secureString1, SecureString secureString2)
  {
     if (secureString1 == null)
     {
        throw new ArgumentNullException("s1");
     }
     if (secureString2 == null)
     {
        throw new ArgumentNullException("s2");
     }

     if (secureString1.Length != secureString2.Length)
     {
        return false;
     }

     IntPtr ss_bstr1_ptr = IntPtr.Zero;
     IntPtr ss_bstr2_ptr = IntPtr.Zero;

     try
     {
        ss_bstr1_ptr = Marshal.SecureStringToBSTR(secureString1);
        ss_bstr2_ptr = Marshal.SecureStringToBSTR(secureString2);

        String str1 = Marshal.PtrToStringBSTR(ss_bstr1_ptr);
        String str2 = Marshal.PtrToStringBSTR(ss_bstr2_ptr);

        return str1.Equals(str2);
     }
     finally
     {
        if (ss_bstr1_ptr != IntPtr.Zero)
        {
           Marshal.ZeroFreeBSTR(ss_bstr1_ptr);
        }

        if (ss_bstr2_ptr != IntPtr.Zero)
        {
           Marshal.ZeroFreeBSTR(ss_bstr2_ptr);
        }
     }
  }

Answer 2

这没有不安全的块，也不会以明文显示密码：

public static bool IsEqualTo(this SecureString ss1, SecureString ss2)
{
 IntPtr bstr1 = IntPtr.Zero;
 IntPtr bstr2 = IntPtr.Zero;
 try
 {
  bstr1 = Marshal.SecureStringToBSTR(ss1);
  bstr2 = Marshal.SecureStringToBSTR(ss2);
  int length1 = Marshal.ReadInt32(bstr1, -4);
  int length2 = Marshal.ReadInt32(bstr2, -4);
  if (length1 == length2)
  {
   for (int x = 0; x < length1; ++x)
   {
    byte b1 = Marshal.ReadByte(bstr1, x);
    byte b2 = Marshal.ReadByte(bstr2, x);
    if (b1 != b2) return false;
   }
  }
  else return false;
  return true;
 }
 finally
 {
  if (bstr2 != IntPtr.Zero) Marshal.ZeroFreeBSTR(bstr2);
  if (bstr1 != IntPtr.Zero) Marshal.ZeroFreeBSTR(bstr1);
 }
}

编辑： 修复了Alex J.建议的泄漏。

Answer 3

翻译 @nikolanovák答案简单的powershell：

param(
[Parameter(mandatory=$true,position=0)][SecureString]$ss1,
[Parameter(mandatory=$true,position=1)][SecureString]$ss2
)

function IsEqualTo{
   param(
    [Parameter(mandatory=$true,position=0)][SecureString]$ss1,
    [Parameter(mandatory=$true,position=1)][SecureString]$ss2
   )

  begin{
    [IntPtr] $bstr1 = [IntPtr]::Zero;
    [IntPtr] $bstr2 = [IntPtr]::Zero;
    [bool]$answer=$true;
  }

  process{
    try{
        $bstr1 = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($ss1);
        $bstr2 = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($ss2);
        [int]$length1 = [System.Runtime.InteropServices.Marshal]::ReadInt32($bstr1, -4);
        [int]$length2 = [System.Runtime.InteropServices.Marshal]::ReadInt32($bstr2, -4);

        if ($length1 -eq $length2){
            for ([int]$x -eq 0; $x -lt $length1; ++$x){
                [byte]$b1 = [System.Runtime.InteropServices.Marshal]::ReadByte($bstr1, $x);
                [byte]$b2 = [System.Runtime.InteropServices.Marshal]::ReadByte($bstr2, $x);
                if ($b1  -ne $b2){
                    $answer=$false;
                }
            }
        }
        else{ $answer=$false;}
    }
    catch{
    }
    finally
    {
        if ($bstr2 -ne [IntPtr]::Zero){ [System.Runtime.InteropServices.Marshal]::ZeroFreeBSTR($bstr2)};
        if ($bstr1 -ne [IntPtr]::Zero){ [System.Runtime.InteropServices.Marshal]::ZeroFreeBSTR($bstr1)};
    }
  }
  END{
    return $answer
  }
}
IsEqualTo -ss1 $ss1  -ss2 $ss2

Answer 4

您可以采取不同的方法。我在代码中遇到了相同的问题，密码的比较和确认，这两种类型 Securestring. 。我意识到最终目标是需要将新密码作为基本64字符串存储在数据库中。因此，我所做的只是将确认字符串通过相同的代码，就像我要将其写入数据库一样。然后，当我有两个基本64字符串时，我在此时进行比较，这是一个简单的字符串比较。

将任何故障一直返回到UI层确实需要更多的管道，但是最终结果似乎是可以接受的。希望该代码足以给出基本想法。

private string CalculateHash( SecureString securePasswordString, string saltString )
{
    IntPtr unmanagedString = IntPtr.Zero;
    try
    {
        unmanagedString = Marshal.SecureStringToGlobalAllocUnicode( securePasswordString );
        byte[] passwordBytes = Encoding.UTF8.GetBytes( Marshal.PtrToStringUni( unmanagedString ) );
        byte[] saltBytes = Encoding.UTF8.GetBytes( saltString );
        byte[] passwordPlusSaltBytes = new byte[ passwordBytes.Length + saltBytes.Length ];
        Buffer.BlockCopy( passwordBytes, 0, passwordPlusSaltBytes, 0, passwordBytes.Length );
        Buffer.BlockCopy( saltBytes, 0, passwordPlusSaltBytes, passwordBytes.Length, saltBytes.Length );
        HashAlgorithm algorithm = new SHA256Managed();
        return Convert.ToBase64String( algorithm.ComputeHash( passwordPlusSaltBytes ) );
    }
    finally
    {
        if( unmanagedString != IntPtr.Zero )
            Marshal.ZeroFreeGlobalAllocUnicode( unmanagedString );
    }
}

string passwordSalt = "INSERT YOUR CHOSEN METHOD FOR CONSTRUCTING A PASSWORD SALT HERE";
string passwordHashed = CalculateHash( securePasswordString, passwordSalt );
string confirmPasswordHashed = CalculateHash( secureConfirmPasswordString, passwordSalt );
if( passwordHashed == confirmPasswordHashed )
{
    // Both matched so go ahead and persist the new password.
}
else
{
    // Strings don't match, so communicate the failure back to the UI.
}

我在安全节目中有点新手，因此我欢迎任何改进建议。

Answer 5

如果代码在Windows Vista或更高版本上运行，以下是基于 比较曲目 Windows功能，因此没有纯文本，所有缓冲区都保持不受管理。奖金是支持细菌不敏感的比较。

public static bool EqualsOrdinal(this SecureString text1, SecureString text2, bool ignoreCase = false)
{
    if (text1 == text2)
        return true;

    if (text1 == null)
        return text2 == null;

    if (text2 == null)
        return false;

    if (text1.Length != text2.Length)
        return false;

    var b1 = IntPtr.Zero;
    var b2 = IntPtr.Zero;
    try
    {
        b1 = Marshal.SecureStringToBSTR(text1);
        b2 = Marshal.SecureStringToBSTR(text2);
        return CompareStringOrdinal(b1, text1.Length, b2, text2.Length, ignoreCase) == CSTR_EQUAL;
    }
    finally
    {
        if (b1 != IntPtr.Zero)
        {
            Marshal.ZeroFreeBSTR(b1);
        }

        if (b2 != IntPtr.Zero)
        {
            Marshal.ZeroFreeBSTR(b2);
        }
    }
}

public static bool EqualsOrdinal(this SecureString text1, string text2, bool ignoreCase = false)
{
    if (text1 == null)
        return text2 == null;

    if (text2 == null)
        return false;

    if (text1.Length != text2.Length)
        return false;

    var b = IntPtr.Zero;
    try
    {
        b = Marshal.SecureStringToBSTR(text1);
        return CompareStringOrdinal(b, text1.Length, text2, text2.Length, ignoreCase) == CSTR_EQUAL;
    }
    finally
    {
        if (b != IntPtr.Zero)
        {
            Marshal.ZeroFreeBSTR(b);
        }
    }
}

private const int CSTR_EQUAL = 2;

[DllImport("kernel32")]
private static extern int CompareStringOrdinal(IntPtr lpString1, int cchCount1, IntPtr lpString2, int cchCount2, bool bIgnoreCase);

[DllImport("kernel32")]
private static extern int CompareStringOrdinal(IntPtr lpString1, int cchCount1, [MarshalAs(UnmanagedType.LPWStr)] string lpString2, int cchCount2, bool bIgnoreCase);