Question

我有一个PKCS＃12（PFX）文件，该文件是具有CNG RSA密钥的证书，并且想要导出私钥。

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该文件是用于复制的示例，密码为：1234

我已经尝试导出RsaParameters以及从CngKey导出私钥-operation not supported。

问题是缺少CngExportPolicies.AllowPlaintextExport标志。我还没有成功通过本地NCrypt调用设置标志，因为密钥处于最终状态。

在另一个问题注释（Cannot export RSA private key parameters, the requested operation is not supported）中，该过程（导出，导入和设置标记并导出）有一个提示，该提示还指向几行.NET核心代码。

我试图将代码移植到oldschool C＃.NET（例如，没有Span<T>），但在以下调用中得到了invalid argument：

    internal static unsafe bool ExportPkcs8KeyBlob(
        SafeNCryptKeyHandle keyHandle,
        string password,
        int kdfCount,
        out int bytesWritten,
        out byte[] allocated)
    {
      using (var stringHandle = new SafeUnicodeStringHandle(password))
      {
        var pbrParamsPtr =
          Marshal.AllocHGlobal(Marshal.SizeOf(typeof(NativeMethods.NCrypt.PbeParams)));
        var pbeParams = new NativeMethods.NCrypt.PbeParams();
        fixed (byte* oidPtr = s_pkcs12TripleDesOidBytes)
        {

          var salt = new byte[8];
          RandomNumberGenerator.GetBytes(salt);
          pbeParams.rgbSalt = salt;
          pbeParams.Params.cbSalt = pbeParams.rgbSalt.Length;
          pbeParams.Params.iIterations = kdfCount;

          var buffers = stackalloc NativeMethods.NCrypt.NCryptBuffer[3];
          buffers[0] = new NativeMethods.NCrypt.NCryptBuffer
          {
            BufferType = NativeMethods.NCrypt.BufferType.PkcsSecret,
            cbBuffer = checked(2 * (password.Length + 1)),
            pvBuffer = stringHandle.DangerousGetHandle(),
          };

          if (buffers[0].pvBuffer == IntPtr.Zero)
          {
            buffers[0].cbBuffer = 0;
          }

          buffers[1] = new NativeMethods.NCrypt.NCryptBuffer
          {
            BufferType = NativeMethods.NCrypt.BufferType.PkcsAlgOid,
            cbBuffer = s_pkcs12TripleDesOidBytes.Length,
            pvBuffer = (IntPtr)oidPtr,
          };

          Marshal.StructureToPtr(pbeParams, pbrParamsPtr, true);
          buffers[2] = new NativeMethods.NCrypt.NCryptBuffer
          {
            BufferType = NativeMethods.NCrypt.BufferType.PkcsAlgParam,
            cbBuffer = Marshal.SizeOf(typeof(NativeMethods.NCrypt.PbeParams)),
            pvBuffer = pbrParamsPtr
          };

          var desc = new NativeMethods.NCrypt.NCryptBufferDesc
          {
            cBuffers = 3,
            pBuffers = (IntPtr)buffers,
            ulVersion = 0,
          };


          var pbOutput = Array.Empty<byte>();
          var errorCode = NativeMethods.NCrypt.NCryptExportKey(
              keyHandle,
              IntPtr.Zero,
              NCRYPT_PKCS8_PRIVATE_KEY_BLOB,
              ref desc,
              ref pbOutput,
              0,
              out int numBytesNeeded,
              0);

          if (errorCode != 0)
          {
            throw new Win32Exception(errorCode);
...

我为完整的代码创建了一个存储库，并带有一个在github上失败的单元测试：https://github.com/lennybacon/CngPfxKeyExport

任何暗示我从.Net Core转换失败或出现填充错误的数据或指针的提示，因为用法的文档似乎很少见...

Answer 1

您似乎引入了两个主要的移植错误，其中一个调用了本机方法：

1）PbeParams。

您的用户：

[StructLayout(LayoutKind.Sequential)]
internal struct PbeParams
{
    internal const int RgbSaltSize = 8;

    internal CryptPkcs12PbeParams Params;
    internal byte[] rgbSalt;
}

CoreFX：

[StructLayout(LayoutKind.Sequential)]
internal unsafe struct PBE_PARAMS
{
    internal const int RgbSaltSize = 8;

    internal CRYPT_PKCS12_PBE_PARAMS Params;
    internal fixed byte rgbSalt[RgbSaltSize];
}

您的内存布局是，在CRYPT_PKCS12_PBE_PARAMS值之后是指向更多数据的指针。 CoreFX版本的布局是，在CRYPT_PKCS12_PBE_PARAMS之后直接是盐的8个字节的占位符，这是加密API期望的（因为它不需要pbSalt）。

恢复fixed byte rgbSalt[RgbSaltSize]很重要。

2）NCryptExportKey的{{1}}：

您的用户：

pbOutput

CoreFX：

[DllImport("ncrypt.dll", CharSet = CharSet.Unicode)]
internal static extern int NCryptExportKey(
    SafeNCryptKeyHandle hKey,
    IntPtr hExportKey,
    string pszBlobType,
    ref NCryptBufferDesc pParameterList,
    ref byte[] pbOutput,
    int cbOutput,
    [Out] out int pcbResult,
    int dwFlags);

值得注意的是，CoreFX版本为[DllImport(Interop.Libraries.NCrypt, CharSet = CharSet.Unicode)] internal static extern ErrorCode NCryptExportKey( SafeNCryptKeyHandle hKey, IntPtr hExportKey, string pszBlobType, ref NCryptBufferDesc pParameterList, ref byte pbOutput, int cbOutput, [Out] out int pcbResult, int dwFlags);，而您的版本为ref byte pbOutput，这使该值因指针间接寻址而不同。

3）第一次导出调用需要C ref byte[] pbOutput，而不是有效的指针。

将更正后的互操作代码压缩到一个文件中，删除注释和未使用的枚举成员（以减少帖子大小）并进行修复（然后简化用法，因为您可以使用NULL（保证string终止符）而不是\0（无终止符保证））在.NET Framework 4.7.2上产生此错误：

ReadOnlySpan<char>

使用oldschool .NET导出CNG RSA证书的私钥（PKCS＃8）

1 个答案: