public byte[] GetPrivateKeyBlob(IntPtr context, KeyDerivation derive)
{
bool result, shouldFree = false;
NativeMethods.KeySpec addInfo = 0;
IntPtr hProv = IntPtr.Zero, hExportKey = IntPtr.Zero,
phSessionKey = IntPtr.Zero, userKey = IntPtr.Zero;
try {
result = NativeMethods.CryptAcquireCertificatePrivateKey(context, 0, IntPtr.Zero, ref hProv, ref addInfo, ref shouldFree);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
result = NativeMethods.CryptGetUserKey(hProv, (uint)addInfo, ref userKey);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
CheckPermission(userKey);
result = NativeMethods.CryptGenKey(hProv, EphemAlgId, 0, out phSessionKey);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
uint dhOIDsz = 50;
var dhOID = new byte[dhOIDsz];
result = NativeMethods.CryptGetKeyParam(phSessionKey, NativeMethods.KP_DHOID, dhOID, ref dhOIDsz, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
dhOID = dhOID.Take((int)dhOIDsz - 1).ToArray();
var dhOIDstr = Encoding.ASCII.GetString(dhOID);
uint hashOIDsz = 50;
var hashOID = new byte[hashOIDsz];
result = NativeMethods.CryptGetKeyParam(phSessionKey, NativeMethods.KP_HASHOID, hashOID, ref hashOIDsz, 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
hashOID = hashOID.Take((int)hashOIDsz - 1).ToArray();
var hashOIDstr = Encoding.ASCII.GetString(hashOID);
uint pbdatalen = 0;
result = NativeMethods.CryptExportKey(phSessionKey, IntPtr.Zero, NativeMethods.PUBLICKEYBLOB, 0, null, ref pbdatalen);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
SessionKey = new byte[pbdatalen];
result = NativeMethods.CryptExportKey(phSessionKey, IntPtr.Zero, NativeMethods.PUBLICKEYBLOB, 0, SessionKey, ref pbdatalen);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
var blob = new CRYPT_PUBLICKEYBLOB {
reserved = 0,
bType = 6,
aiKeyAlg = (uint)KeyAlgId,
bVersion = 0x20,
Magic = NativeMethods.GR3410_1_MAGIC,
BitLen = PublicKeyLength
};
var dhOid = new DerObjectIdentifier(dhOIDstr);
var hashOid = new DerObjectIdentifier(hashOIDstr);
var seq = new DerSequence(dhOid, hashOid);
var keyData = seq.GetDerEncoded();
Array.Resize(ref keyData, 24);
blob.KeyData1 = BitConverter.ToUInt64(keyData, 0);
blob.KeyData2 = BitConverter.ToUInt64(keyData, 8);
blob.KeyData3 = BitConverter.ToUInt64(keyData, 16);
var blobData = blob.GetBytes();
var pbdata2 = new byte[BlobLength];
for (int i = 0; i < KeyOffset; ++i)
{
pbdata2[i] = blobData[i];
}
derive.Init(dhOid, hashOid);
var genkey = derive.GetPublicKeyBytes();
for (int i = 0, j = KeyOffset; i < genkey.Length; ++i, ++j)
{
pbdata2[j] = genkey[i];
}
result = NativeMethods.CryptImportKey(hProv, pbdata2, BlobLength, phSessionKey, 0, ref hExportKey);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
result = NativeMethods.CryptSetKeyParam(hExportKey, (int)NativeMethods.KP_ALGID, BitConverter.GetBytes((uint)ExportAlgId), 0);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
uint pkSize = 0;
result = NativeMethods.CryptExportKey(userKey, hExportKey, NativeMethods.PRIVATEKEYBLOB, 0, null, ref pkSize);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
var ret = new byte[pkSize];
result = NativeMethods.CryptExportKey(userKey, hExportKey, NativeMethods.PRIVATEKEYBLOB, 0, ret, ref pkSize);
if (!result)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return(ret);
} catch (Win32Exception e) {
throw new CryptographicException(e.Message, e);
} finally {
if (shouldFree)
{
NativeMethods.CryptReleaseContext(hProv, 0);
}
if (hExportKey != IntPtr.Zero)
{
NativeMethods.CryptDestroyKey(hExportKey);
}
if (phSessionKey != IntPtr.Zero)
{
NativeMethods.CryptDestroyKey(phSessionKey);
}
if (userKey != IntPtr.Zero)
{
NativeMethods.CryptDestroyKey(userKey);
}
}
}
