Question

I have a string that’s encrypted using some crypto classes in Java (RSA/ECB/PKCS1Padding) and a public key we exchanged in advance.

I want to decrypt that string using our private key and this is the code I have.

 X509Certificate2 cert = new X509Certificate2("c:\\test.pfx", "test");
        string s =               "very long encrypted data";

        RSACryptoServiceProvider privateKeyProvider = (RSACryptoServiceProvider)cert.PrivateKey;

        string decryptedTest = System.Text.Encoding.UTF8.GetString(privateKeyProvider.Decrypt(Convert.FromBase64String(s), true));

I get an exception with error message.

“System.Security.Cryptography.CryptographicException: Error occurred while decoding OAEP padding”

What is that I’m doing wrong?

Answer 1

Call Decrypt with the second parameter set to false.
MSDN

…false to use PKCS#1 v1.5 padding.