Encryption and Decryption between C++ and C#

vipin_nvk

Hi We need to encrypt a string and send across to a web service in C# over the internet. The webservice would decrpt the string and process it. How can I ensure that I use common encryption/decryption algorithms on both the client (C++, win32) and server side (C#) I have tried to build a C++ dll with the enc/dec interfaces and give it to the C# service to call them using marshaling, but I am failing to get the desired result. Please help Thanks in advance

Orjan Westin

Use a standard algorithm. C#/.NET has a fair few in the System.Security.Cryptography namespace. On the C++ side you just need to use the same algorithm. Check out Crypto++ for good and free implementations. There is no need to have the exact same source code used in both C++ and C#, provided you use a well documented and standardised algorithm.

vipin_nvk

Thanx Orjan Cant we use Microsoft Cryptographic API's on the C++ win32 application for the same? Like the one here http://msdn.microsoft.com/en-us/library/aa380255(v=VS.85).aspx[^]

Orjan Westin

CAPICOM has been deprecated by Microsoft, and is not available on Windows 7. I wouldn't use it myself since it's limited in capability and a bit of a mess to use, if I recall correctly (haven't looked at it for years). Oh, it says here that "only CAPICOM can decrypt a CAPICOM EncryptedData object" which would rule it out for you, if you need it to interop with C# (unless you wrap it in a DLL and call that from the server - was that what you tried?) Since they recommend you use .NET crypto for any new development, you might as well create a simple DLL in C# or C++/CLI that exposes the same to the desktop application. (Which is the opposite of what you've tried already, but this way around it's likely easier to test and debug on a desktop.)

vipin_nvk

Thanx Orjan I will try that out

MicroVirus

You could also look at Cryptography API: Next Generation[^] which is the replacement for CAPI. I have no idea how 'good' it is, but I do know that the .NET framework has some CNG implementations of various standard algorithms. Though, I must admit, it might just be easier to write the C# dll and interop with that.