public static bool ToSecretariumKey(this X509Certificate2 x509, string password, out ScpConfig.SecretariumKeyConfig config)
{
config = null;
var publicKey = x509.GetECDsaPublicKey() as ECDsaCng;
if (publicKey == null)
{
return(false);
}
if (publicKey.HashAlgorithm != CngAlgorithm.Sha256 || publicKey.KeySize != 256 || publicKey.Key.Algorithm != CngAlgorithm.ECDsaP256)
{
return(false);
}
var publicKeyRaw = publicKey.ExportPublicKeyRaw();
if (publicKeyRaw == null)
{
return(false);
}
var privateKey = x509.GetECDsaPrivateKey() as ECDsaCng;
if (privateKey == null)
{
return(false);
}
var privatKeyRaw = privateKey.ExportPrivateKeyRaw();
if (privatKeyRaw == null)
{
return(false);
}
// Built pkcs8 manually because privateKey.Key.ForceExport(CngKeyBlobFormat.Pkcs8PrivateBlob) return 165 bytes instead of 138. TODO investigate
var privatKeyPkcs8 = ByteHelper.Combine(
new byte[] { 48, 129, 135, 2, 1, 0, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 4, 109, 48, 107, 2, 1, 1, 4, 32 },
privatKeyRaw,
new byte[] { 161, 68, 3, 66, 0, 4 },
publicKeyRaw
);
var salt = ByteHelper.GetRandom(32);
var iv = ByteHelper.GetRandom(12);
var strongPwd = ByteHelper.Combine(salt, password.ToBytes()).HashSha256();
var keys = ByteHelper.Combine(new byte[] { 4 }, publicKeyRaw, privatKeyPkcs8);
var encryptedKeys = AESGCMHelper.AesGcmEncrypt(keys, strongPwd, iv);
config = new ScpConfig.SecretariumKeyConfig
{
iv = iv.ToBase64String(false),
salt = salt.ToBase64String(false),
keys = encryptedKeys.ToBase64String(false)
};
return(true);
}
public static unsafe byte[] ForceExport(this CngKey key, CngKeyBlobFormat format)
{
if ((key.ExportPolicy & CngExportPolicies.AllowPlaintextExport) != 0)
{
return(key.Export(format));
}
// The key is not exportable, lets hack. Thanks @bartonjs
// https://stackoverflow.com/questions/57269726/x509certificate2-import-with-ncrypt-allow-plaintext-export-flag
// https://stackoverflow.com/questions/55236230/export-private-key-pkcs8-of-cng-rsa-certificate-with-oldschool-net
string blobType = "PKCS8_PRIVATEKEY";
try
{
byte[] exported;
fixed(byte *oidPtr = CryptNativeHelpers.PKCS12_3DES_OID)
{
var salt = ByteHelper.GetRandom(CryptNativeHelpers.NCrypt.PbeParams.RgbSaltSize);
var pbeParams = new CryptNativeHelpers.NCrypt.PbeParams();
pbeParams.Params.iIterations = 1;
pbeParams.Params.cbSalt = salt.Length;
Marshal.Copy(salt, 0, (IntPtr)pbeParams.rgbSalt, salt.Length);
var buffers = stackalloc CryptNativeHelpers.NCrypt.NCryptBuffer[3];
buffers[0] = new CryptNativeHelpers.NCrypt.NCryptBuffer
{
BufferType = CryptNativeHelpers.NCrypt.BufferType.PkcsSecret,
cbBuffer = 0,
pvBuffer = IntPtr.Zero,
};
buffers[1] = new CryptNativeHelpers.NCrypt.NCryptBuffer
{
BufferType = CryptNativeHelpers.NCrypt.BufferType.PkcsAlgOid,
cbBuffer = CryptNativeHelpers.PKCS12_3DES_OID.Length,
pvBuffer = (IntPtr)oidPtr,
};
buffers[2] = new CryptNativeHelpers.NCrypt.NCryptBuffer
{
BufferType = CryptNativeHelpers.NCrypt.BufferType.PkcsAlgParam,
cbBuffer = sizeof(CryptNativeHelpers.NCrypt.PbeParams),
pvBuffer = (IntPtr)(&pbeParams),
};
var desc = new CryptNativeHelpers.NCrypt.NCryptBufferDesc
{
cBuffers = 3,
pBuffers = (IntPtr)buffers,
ulVersion = 0,
};
if (CryptNativeHelpers.NCrypt.NCryptExportKey(key.Handle, IntPtr.Zero, blobType, ref desc, null, 0, out int bytesNeeded, 0) != 0)
{
return(null);
}
exported = new byte[bytesNeeded];
if (CryptNativeHelpers.NCrypt.NCryptExportKey(key.Handle, IntPtr.Zero, blobType, ref desc, exported, exported.Length, out bytesNeeded, 0) != 0)
{
return(null);
}
}
fixed(char *keyNamePtr = key.KeyName)
fixed(byte *blobPtr = exported)
{
var buffers = stackalloc CryptNativeHelpers.NCrypt.NCryptBuffer[2];
buffers[0] = new CryptNativeHelpers.NCrypt.NCryptBuffer
{
BufferType = CryptNativeHelpers.NCrypt.BufferType.PkcsSecret,
cbBuffer = 0,
pvBuffer = IntPtr.Zero,
};
buffers[1] = new CryptNativeHelpers.NCrypt.NCryptBuffer
{
BufferType = CryptNativeHelpers.NCrypt.BufferType.PkcsName,
cbBuffer = checked (2 * (key.KeyName.Length + 1)),
pvBuffer = new IntPtr(keyNamePtr),
};
var desc = new CryptNativeHelpers.NCrypt.NCryptBufferDesc
{
cBuffers = 2,
pBuffers = (IntPtr)buffers,
ulVersion = 0,
};
SafeNCryptKeyHandle keyHandle;
if (CryptNativeHelpers.NCrypt.NCryptImportKey(key.ProviderHandle, IntPtr.Zero, blobType, ref desc, out keyHandle, new IntPtr(blobPtr), exported.Length,
CryptNativeHelpers.NCrypt.NCryptImportFlags.NCRYPT_OVERWRITE_KEY_FLAG | CryptNativeHelpers.NCrypt.NCryptImportFlags.NCRYPT_DO_NOT_FINALIZE_FLAG) != 0)
{
keyHandle.Dispose();
return(null);
}
using (keyHandle)
using (CngKey cngKey = CngKey.Open(keyHandle, CngKeyHandleOpenOptions.None))
{
cngKey.SetProperty(new CngProperty("Export Policy", BitConverter.GetBytes((int)CngExportPolicies.AllowPlaintextExport), CngPropertyOptions.Persist));
if (CryptNativeHelpers.NCrypt.NCryptFinalizeKey(keyHandle, 0) != 0)
{
return(null);
}
return(cngKey.Export(format));
}
}
}
catch (Exception)
{
return(null);
}
}