I have created an encryption class whose main encryption method encrypts
small amounts of bytes (in this case the Key & IV for Rijndael encryption of
main data) using .NET's RSA methods.
This had all been working fine until I tried using the class within a
"Windows Service" application. The application fails on a Decrypt with a "bad
key" error in the "Windows Service" but runs fine (with same key & encrypted
data) in a normal windows application.
The main sections of code from within my class are the following:-
I generate my Public / Private keys in a function like this:-
// Create RSA Crypto object
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
// get public & private key xml
sPublicKeyXml = rsaCSP.ToXmlString(false);
sPrivateKeyXml = rsaCSP.ToXmlString(true);
I encrypt like this:-
// encrypt symmetric key
// Create CSPParameters required object
CspParameters cspParam = new CspParameters();
cspParam.Flags = CspProviderFlags.UseDefaultKeyContainer;
// encrypt byte[] using asymmetric method RSA
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider(cspParam);
// load the private key
rsaCSP.FromXmlString(sPrivateKeyXml);
// encrypt using private key
byte[] byteEncrypted = rsaCSP.Encrypt(byteToEncrypt, false);
And I decrypt later like this:-
// Create CSPParameters required object
CspParameters cspParam = new CspParameters();
cspParam.Flags = CspProviderFlags.UseDefaultKeyContainer;
// decrypt byte[] using method RSA
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider(cspParam);
// load the public key
rsaCSP.FromXmlString(sPublicKeyXml);
// decrypt using public key
byte[] byteDecrypt = rsaCSP.Decrypt(byteEncrypted, false);
I have tried running the Windows Service as Administrator but got the same
"bad key" error.
The stack trace here is
"System.Security.Cryptography.RSACryptoServiceProvider._DecryptPKWin2KEnh(IntPtr hPubKey, Byte[] rgbKey, Boolean fOAEP)"
I also tried :-
* changing the CspProviderFlags property to to "UseMachineKeyStore" and the
code doesn't work at all, even in the normal windows application running as
my user.
* Importing key using RSAParameters object - will not work encrypting with
private key / decrypting with public key - works other way round.
* Various combinations of setting up CspParameters - with KeyContainerName
set, Flags = UseMachineKeyStore, to no avail
My suspicion is that Key stores are somehow involved but with a deadline
looming I now require someone with more knowledge on the subject to help me!
Also, can you encrypt using the private key and decrypt using the public
key? The above code works like this, but the UseMachineStore solution would
only work encrypting with Public Key & decrypting with the Private Key.
Really, I need to be able to Encrypt with the Private Key.
The customer requirement is to be able to receive encrypted (& signed) data
packages where I can also verify they have come from a specific sender.
My solution is to encrypt the data with Rijndael encryption, encrypt the
Rijndael Key & IV with the RSA Private Key & package that up in one file. To
decrypt this use the public key to obtain the Rijndael Key & IV (and know who
that this can only have come from someone with the private key) & then
finally retrieve the data.
Sorry for such a long posting, and there are probably multiple issues here
but any help would be hugely appreciated!
--
Best Regards,
Pike :-)