[C#] RSACryptoServiceProvider Using the Public Key to decrypt Private Key encrypted Data ?

Posted by prixone on Stack Overflow See other posts from Stack Overflow or by prixone
Published on 2010-05-17T04:24:29Z Indexed on 2010/05/17 4:30 UTC
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privatekey

Hello,

i went thru lots and lots of searchs and results and pages considering this matter but havent found the solution yet.

Like i described in the title i want to decrypt data using my Public Key which is something i am able to do with my PHP code, my certificate is generated from my PHP page.

Here is a sample of what i am trying:

public string Decrypt(string data)
{
    X509Certificate2 cert = new X509Certificate2();
    cert.Import(Encoding.ASCII.GetBytes(webApi["PublicDefaultKey"]));

    RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)cert.PublicKey.Key;
    byte[] ciphertextBytes = Convert.FromBase64String(data);
    byte[] plaintextBytes = rsa.Decrypt(ciphertextBytes, false);
    return System.Text.Encoding.UTF8.GetString(plaintextBytes);
}
MessageBox.Show(Decrypt("pgcl93TpVfyHubuRlL72/PZN0nA4Q+HHx8Y15qGvUyTNpI6y7J13YG07ZVEyB7Dbgx63FSw9vEw1D1Z3bvNbI0gqalVfKTfHv5tKVc7Y6nQwQYwoODpUhVpa/K9OP1lqx4esnxqwJx95G0rqgJTdS+Yo773s5UcJrHzzbsX2z+w="));

here is the public key i am using for tests:

-----BEGIN CERTIFICATE----- MIIDxDCCAy2gAwIBAgIBADANBgkqhkiG9w0BAQUFADCBozELMAkGA1UEBhMCVUsx EDAOBgNVBAgTB0VuZ2xhbmQxDzANBgNVBAcTBkxvbmRvbjESMBAGA1UEChMJTU1P Q2xldmVyMSMwIQYDVQQLExpNTU9DbGV2ZXIgRGV2ZWxvcGVyJ3MgVGVhbTESMBAG A1UEAxMJTU1PQ2xldmVyMSQwIgYJKoZIhvcNAQkBFhVzdXBwb3J0QG1tb2NsZXZl ci5jb20wHhcNMTAwNTE2MTkxNDQ4WhcNMTEwNTE2MTkxNDQ4WjCBozELMAkGA1UE BhMCVUsxEDAOBgNVBAgTB0VuZ2xhbmQxDzANBgNVBAcTBkxvbmRvbjESMBAGA1UE ChMJTU1PQ2xldmVyMSMwIQYDVQQLExpNTU9DbGV2ZXIgRGV2ZWxvcGVyJ3MgVGVh bTESMBAGA1UEAxMJTU1PQ2xldmVyMSQwIgYJKoZIhvcNAQkBFhVzdXBwb3J0QG1t b2NsZXZlci5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMozHr17PL+N seZyadobUmpIV+RKqmRUGX0USIdj0i0yvwvltu3AIKAyRhGz16053jZV2WeglCEj qfiewF9sYTAAoIVGtdd/sZvO4uUcng9crSzDo0CrEPs/Tn5SunmlmyFlZfdlqpAM XXLno/HMo9cza0CrcMnRokaTiu8szBeBAgMBAAGjggEEMIIBADAdBgNVHQ4EFgQU zip+3/hBIpjvdcSoWQ2rW+xDEWAwgdAGA1UdIwSByDCBxYAUzip+3/hBIpjvdcSo WQ2rW+xDEWChgamkgaYwgaMxCzAJBgNVBAYTAlVLMRAwDgYDVQQIEwdFbmdsYW5k MQ8wDQYDVQQHEwZMb25kb24xEjAQBgNVBAoTCU1NT0NsZXZlcjEjMCEGA1UECxMa TU1PQ2xldmVyIERldmVsb3BlcidzIFRlYW0xEjAQBgNVBAMTCU1NT0NsZXZlcjEk MCIGCSqGSIb3DQEJARYVc3VwcG9ydEBtbW9jbGV2ZXIuY29tggEAMAwGA1UdEwQF MAMBAf8wDQYJKoZIhvcNAQEFBQADgYEAyU6RLifBXSyQUkBFnTcI6h5ryujh+6o6 eQ1wuPOPmRdYJZuWx/5mjMpIF13sYlNorcOv5WaEnp8/Jfuwc9h/jXlcujser0UE WoaaFwK81O801Xkv2zEm2UUWiOabrGTIT4FVy3gCUXJYjaCnvfSdmkfLJOQxNHVt 4NTMp7IeF60= -----END CERTIFICATE-----

by default, the PHP generates the key in PKCS as far as i know, from my C# code i can encrypt using my publick key with out any problems and decrypt it on my php page but so far i was not able to decrypt data sent from my php page encrypted with the private key which is something i can do on my php...

i did like some help to understand what i am doing wrong...

the error when i run the functions is "bad data" at rsa.Decrypt(ciphertextBytes, false); which i couldnt found anymore information at it...

Thanks for any and all the help :)

Developer IT