X509Certificate2.使用 NCRYPT_ALLOW_PLAINTEXT
我有一个 PFX 证书，里面有 CNG 密钥（KSP 提供商信息在 PFX 中指定）。我找不到在 .NET 中导入证书的方法，以允许以纯文本（MS-CAPI 格式）导出私钥。
var cert = new X509Certificate2(pfxBytes,password,X509KeyStorageFlags.Exportable);
然后我使用此句柄通过调用带有启用标志以允许 CNG 密钥的CryptAcquireCertificatePrivateKey函数来获取私钥上下文。调用成功。
当我调用NCryptExportKey时，调用失败并出现 0x8009000b 错误：
密钥在指定状态下无效。
为了调试这个问题，我调用了NCryptGetProperty函数来获取导出策略，实际上，NCRYPT_ALLOW_EXPORT_FLAG标志已启用，但NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAG没有启用。尝试调用NCryptSetProperty函数以在导出策略属性中启用此标志，但调用失败并出现相同的 0x8009000b 错误。
问题：如何从文件导入 .NET 中的 pfx 文件而不保留NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAGCNG 密钥的密钥和启用标志？
ps 由于某些原因，我仅限于 .NET 4.0/4.5。
慕码人8056858浏览 82回答 0
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慕田峪4524236
我发现的最好的流程：打开 PFX 可导出（设置可导出位，但不设置明文可导出位）导出加密的 PKCS#8导入加密的 PKCS#8 并覆盖，无最终确定改变出口政策完成（提交覆盖）现在，如果您向证书询问其密钥，它是可以纯文本导出的。在 net45 中，这需要大量代码（值得庆幸的是，使用 oldschool .NET 导出 CNG RSA 证书的私钥（PKCS#8）为我做了很多工作）。netcoreapp30 会做得更好，只是 import+alter+finalize 仍然需要手动 P/Invoke。使用 ECDsa 进行测试，因为这是强制不使用 CNG->CAPI 桥的最简单方法：internal static partial class Program{ internal static void Main(string[] args) { X509Certificate2 cert = ImportExportable(ECDsaP256_DigitalSignature_Pfx_Windows, "Test", machineScope: false); try { bool gotKey = NativeMethods.Crypt32.CryptAcquireCertificatePrivateKey( cert.Handle, NativeMethods.Crypt32.AcquireCertificateKeyOptions.CRYPT_ACQUIRE_ONLY_NCRYPT_KEY_FLAG, IntPtr.Zero, out SafeNCryptKeyHandle keyHandle, out int keySpec, out bool callerFree); using (CngKey cngKey = CngKey.Open(keyHandle, 0)) { Console.WriteLine(cngKey.ExportPolicy); Console.WriteLine( Convert.ToBase64String( cngKey.Export(CngKeyBlobFormat.Pkcs8PrivateBlob))); } } finally { cert.Reset(); } } private static X509Certificate2 ImportExportable(byte[] pfxBytes, string password, bool machineScope) { X509KeyStorageFlags flags = X509KeyStorageFlags.Exportable; if (machineScope) { flags |= X509KeyStorageFlags.MachineKeySet; } else { flags |= X509KeyStorageFlags.UserKeySet; } X509Certificate2 cert = new X509Certificate2(pfxBytes, password, flags); try { bool gotKey = NativeMethods.Crypt32.CryptAcquireCertificatePrivateKey( cert.Handle, NativeMethods.Crypt32.AcquireCertificateKeyOptions.CRYPT_ACQUIRE_ONLY_NCRYPT_KEY_FLAG, IntPtr.Zero, out SafeNCryptKeyHandle keyHandle, out int keySpec, out bool callerFree); if (!gotKey) { keyHandle.Dispose(); throw new InvalidOperationException("No private key"); } if (!callerFree) { keyHandle.SetHandleAsInvalid(); keyHandle.Dispose(); throw new InvalidOperationException("Key is not persisted"); } using (keyHandle) { // -1 == CNG, otherwise CAPI if (keySpec == -1) { using (CngKey cngKey = CngKey.Open(keyHandle, CngKeyHandleOpenOptions.None)) { // If the CNG->CAPI bridge opened the key then AllowPlaintextExport is already set. if ((cngKey.ExportPolicy & CngExportPolicies.AllowPlaintextExport) == 0) { FixExportability(cngKey, machineScope); } } } } } catch { cert.Reset(); throw; } return cert; } internal static void FixExportability(CngKey cngKey, bool machineScope) { string password = nameof(NativeMethods.Crypt32.AcquireCertificateKeyOptions); byte[] encryptedPkcs8 = ExportEncryptedPkcs8(cngKey, password, 1); string keyName = cngKey.KeyName; using (SafeNCryptProviderHandle provHandle = cngKey.ProviderHandle) { ImportEncryptedPkcs8Overwrite( encryptedPkcs8, keyName, provHandle, machineScope, password); } } internal const string NCRYPT_PKCS8_PRIVATE_KEY_BLOB = "PKCS8_PRIVATEKEY"; private static readonly byte[] s_pkcs12TripleDesOidBytes = System.Text.Encoding.ASCII.GetBytes("1.2.840.113549.1.12.1.3\0"); private static unsafe byte[] ExportEncryptedPkcs8( CngKey cngKey, string password, int kdfCount) { var pbeParams = new NativeMethods.NCrypt.PbeParams(); NativeMethods.NCrypt.PbeParams* pbeParamsPtr = &pbeParams; byte[] salt = new byte[NativeMethods.NCrypt.PbeParams.RgbSaltSize]; using (RandomNumberGenerator rng = RandomNumberGenerator.Create()) { rng.GetBytes(salt); } pbeParams.Params.cbSalt = salt.Length; Marshal.Copy(salt, 0, (IntPtr)pbeParams.rgbSalt, salt.Length); pbeParams.Params.iIterations = kdfCount; fixed (char* stringPtr = password) fixed (byte* oidPtr = s_pkcs12TripleDesOidBytes) { NativeMethods.NCrypt.NCryptBuffer* buffers = stackalloc NativeMethods.NCrypt.NCryptBuffer[3]; buffers[0] = new NativeMethods.NCrypt.NCryptBuffer { BufferType = NativeMethods.NCrypt.BufferType.PkcsSecret, cbBuffer = checked(2 * (password.Length + 1)), pvBuffer = (IntPtr)stringPtr, }; 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, }; buffers[2] = new NativeMethods.NCrypt.NCryptBuffer { BufferType = NativeMethods.NCrypt.BufferType.PkcsAlgParam, cbBuffer = sizeof(NativeMethods.NCrypt.PbeParams), pvBuffer = (IntPtr)pbeParamsPtr, }; var desc = new NativeMethods.NCrypt.NCryptBufferDesc { cBuffers = 3, pBuffers = (IntPtr)buffers, ulVersion = 0, }; using (var keyHandle = cngKey.Handle) { int result = NativeMethods.NCrypt.NCryptExportKey( keyHandle, IntPtr.Zero, NCRYPT_PKCS8_PRIVATE_KEY_BLOB, ref desc, null, 0, out int bytesNeeded, 0); if (result != 0) { throw new Win32Exception(result); } byte[] exported = new byte[bytesNeeded]; result = NativeMethods.NCrypt.NCryptExportKey( keyHandle, IntPtr.Zero, NCRYPT_PKCS8_PRIVATE_KEY_BLOB, ref desc, exported, exported.Length, out bytesNeeded, 0); if (result != 0) { throw new Win32Exception(result); } if (bytesNeeded != exported.Length) { Array.Resize(ref exported, bytesNeeded); } return exported; } } } private static unsafe void ImportEncryptedPkcs8Overwrite( byte[] encryptedPkcs8, string keyName, SafeNCryptProviderHandle provHandle, bool machineScope, string password) { SafeNCryptKeyHandle keyHandle; fixed (char* passwordPtr = password) fixed (char* keyNamePtr = keyName) fixed (byte* blobPtr = encryptedPkcs8) { NativeMethods.NCrypt.NCryptBuffer* buffers = stackalloc NativeMethods.NCrypt.NCryptBuffer[2]; buffers[0] = new NativeMethods.NCrypt.NCryptBuffer { BufferType = NativeMethods.NCrypt.BufferType.PkcsSecret, cbBuffer = checked(2 * (password.Length + 1)), pvBuffer = new IntPtr(passwordPtr), }; if (buffers[0].pvBuffer == IntPtr.Zero) { buffers[0].cbBuffer = 0; } buffers[1] = new NativeMethods.NCrypt.NCryptBuffer { BufferType = NativeMethods.NCrypt.BufferType.PkcsName, cbBuffer = checked(2 * (keyName.Length + 1)), pvBuffer = new IntPtr(keyNamePtr), }; NativeMethods.NCrypt.NCryptBufferDesc desc = new NativeMethods.NCrypt.NCryptBufferDesc { cBuffers = 2, pBuffers = (IntPtr)buffers, ulVersion = 0, }; NativeMethods.NCrypt.NCryptImportFlags flags = NativeMethods.NCrypt.NCryptImportFlags.NCRYPT_OVERWRITE_KEY_FLAG | NativeMethods.NCrypt.NCryptImportFlags.NCRYPT_DO_NOT_FINALIZE_FLAG; if (machineScope) { flags |= NativeMethods.NCrypt.NCryptImportFlags.NCRYPT_MACHINE_KEY_FLAG; } int errorCode = NativeMethods.NCrypt.NCryptImportKey( provHandle, IntPtr.Zero, NCRYPT_PKCS8_PRIVATE_KEY_BLOB, ref desc, out keyHandle, new IntPtr(blobPtr), encryptedPkcs8.Length, flags); if (errorCode != 0) { keyHandle.Dispose(); throw new Win32Exception(errorCode); } using (keyHandle) using (CngKey cngKey = CngKey.Open(keyHandle, CngKeyHandleOpenOptions.None)) { const CngExportPolicies desiredPolicies = CngExportPolicies.AllowExport | CngExportPolicies.AllowPlaintextExport; cngKey.SetProperty( new CngProperty( "Export Policy", BitConverter.GetBytes((int)desiredPolicies), CngPropertyOptions.Persist)); int error = NativeMethods.NCrypt.NCryptFinalizeKey(keyHandle, 0); if (error != 0) { throw new Win32Exception(error); } } } }}internal static class NativeMethods{ internal static class Crypt32 { internal enum AcquireCertificateKeyOptions { None = 0x00000000, CRYPT_ACQUIRE_ONLY_NCRYPT_KEY_FLAG = 0x00040000, } [DllImport("crypt32.dll", SetLastError = true)] internal static extern bool CryptAcquireCertificatePrivateKey( IntPtr pCert, AcquireCertificateKeyOptions dwFlags, IntPtr pvReserved, out SafeNCryptKeyHandle phCryptProvOrNCryptKey, out int dwKeySpec, out bool pfCallerFreeProvOrNCryptKey); } internal static class NCrypt { [DllImport("ncrypt.dll", CharSet = CharSet.Unicode)] internal static extern int NCryptExportKey( SafeNCryptKeyHandle hKey, IntPtr hExportKey, string pszBlobType, ref NCryptBufferDesc pParameterList, byte[] pbOutput, int cbOutput, [Out] out int pcbResult, int dwFlags); [StructLayout(LayoutKind.Sequential)] internal unsafe struct PbeParams { internal const int RgbSaltSize = 8; internal CryptPkcs12PbeParams Params; internal fixed byte rgbSalt[RgbSaltSize]; } [StructLayout(LayoutKind.Sequential)] internal struct CryptPkcs12PbeParams { internal int iIterations; internal int cbSalt; } [StructLayout(LayoutKind.Sequential)] internal struct NCryptBufferDesc { public int ulVersion; public int cBuffers; public IntPtr pBuffers; } [StructLayout(LayoutKind.Sequential)] internal struct NCryptBuffer { public int cbBuffer; public BufferType BufferType; public IntPtr pvBuffer; } internal enum BufferType { PkcsAlgOid = 41, PkcsAlgParam = 42, PkcsName = 45, PkcsSecret = 46, } [DllImport("ncrypt.dll", CharSet = CharSet.Unicode)] internal static extern int NCryptOpenStorageProvider( out SafeNCryptProviderHandle phProvider, string pszProviderName, int dwFlags); internal enum NCryptImportFlags { None = 0, NCRYPT_MACHINE_KEY_FLAG = 0x00000020, NCRYPT_OVERWRITE_KEY_FLAG = 0x00000080, NCRYPT_DO_NOT_FINALIZE_FLAG = 0x00000400, } [DllImport("ncrypt.dll", CharSet = CharSet.Unicode)] internal static extern int NCryptImportKey( SafeNCryptProviderHandle hProvider, IntPtr hImportKey, string pszBlobType, ref NCryptBufferDesc pParameterList, out SafeNCryptKeyHandle phKey, IntPtr pbData, int cbData, NCryptImportFlags dwFlags); [DllImport("ncrypt.dll", CharSet = CharSet.Unicode)] internal static extern int NCryptFinalizeKey(SafeNCryptKeyHandle hKey, int dwFlags); }}
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