CODEWITHSUNDEEP
c#winformscryptographyrsasha512
Fath Bakri
Fath Bakri

Reputation: 191

rsacryptoserviceprovider verifydata SHA512CryptoServiceProvider always false c#

i have two forms the first produce hard disk serial number and encrypt it with public key, the second is like a key generator it receive the encrypted hard disk serial number, then it decrypt it with private key, and sign the plain text hard disk serial number with SHA512CryptoServiceProvider , and then in first form i verify the signed data with SHA512CryptoServiceProvider but always return false here is code of first form:

string PCSerialNumber = HardwareIdentifier.identifier("Win32_DiskDrive", "SerialNumber");
                                string Encrypted_PCSerialNumber = DoSecure.Encrypt_PCSerialNumber(PCSerialNumber);
//Encrypted_PCSerialNumber will send to second form
....
//we get ProductKey from user, it is a signed data with private key and SHA512CryptoServiceProvider 
bool   IsActivated = DoSecure.Verify_PCSerialNumber(ProductKey, PCSerialNumber);

here is class DoSecure :

  public class DoSecure
    {
       
        public const string RSA_CurrentPublicKey_XML = "";

        public const string RSA_CurrentPrivateKey_XML = "";

        // Create byte array for additional entropy when using Protect method.
        private static byte[] s_aditionalEntropy = { 9, 8, 7, 6, 5 };

        //get public key as rsa obejct
        private static RSACryptoServiceProvider GetPublicKey()
        {
            try
            {
                //define rsa object
                RSACryptoServiceProvider cipher = new RSACryptoServiceProvider();

                //import public key from xml string
                cipher.FromXmlString(RSA_CurrentPublicKey_XML);

                return cipher;
            }
            catch (Exception ex)
            {
                FRM_MSG f = new FRM_MSG();
                f.ShowDLG(" ",
                ex.Message + "\n" + ex.StackTrace.ToString(),
                    FRM_MSG.MSGIcon.Error,
                    FRM_MSG.BTNS.One,
                    new string[] { "Ok" });
                throw ex;
            }
        }

      
     
       
        
        }


        private static RSACryptoServiceProvider GetPrivateKey()
        {
            try
            {
                RSACryptoServiceProvider cipher = new RSACryptoServiceProvider();
                cipher.FromXmlString(DoSecure.RSA_CurrentPrivateKey_XML);
                return cipher;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message + "\n" + ex.StackTrace.ToString(),
                    "",
                             MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
                throw ex;
            }
        }
        public static string Sign_PCSerialNumber_WithPrivateKey(string PCSerialNumber)
        {
            try
            {
                RSACryptoServiceProvider cipher = DoSecure.GetPrivateKey();
                byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
                byte[] cipherText = cipher.SignData(data, new SHA512CryptoServiceProvider());
                return Convert.ToBase64String(cipherText);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message + "\n" + ex.StackTrace.ToString(),
                    "",
                             MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
                throw ex;
            }
        }
        public static string Decrypt_PCSerialNumber_WithPrivateKey(string Cipher_PCSerialNumber)
        {
            try
            {
                RSACryptoServiceProvider cipher = GetPrivateKey();
                byte[] data = Convert.FromBase64String(Cipher_PCSerialNumber);
                byte[] original = cipher.Decrypt(data, false);
                return Encoding.Unicode.GetString(original);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message + "\n" + ex.StackTrace.ToString(),
                    "",
                             MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
                throw ex;
            }
        }


        public static string Encrypt_PCSerialNumber(string PCSerialNumber)
        {
            try
            {
                RSACryptoServiceProvider cipher = GetPublicKey();

                byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
                byte[] cipherText = cipher.Encrypt(data, false);
                
                return Convert.ToBase64String(cipherText);
            }
            catch (Exception ex)
            {
                FRM_MSG f = new FRM_MSG();
                f.ShowDLG(AssemblyInfo.AssemblyTitle,
                ex.Message + "\n" + ex.StackTrace.ToString(),
                    FRM_MSG.MSGIcon.Error,
                    FRM_MSG.BTNS.One,
                    new string[] { "Ok" });
                throw ex;
            }
        }


        public static bool Verify_PCSerialNumber(string Cipher_PCSerialNumber, string PCSerialNumber)
        {
            try
            {
                RSACryptoServiceProvider cipher = GetPublicKey();
                byte[] SignedData;
                try
                {
                    SignedData = Convert.FromBase64String(Cipher_PCSerialNumber);
                }
                catch
                {
                    SignedData = Encoding.Unicode.GetBytes(Cipher_PCSerialNumber);
                }
                byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
                return cipher.VerifyData(data, new SHA512CryptoServiceProvider(), SignedData);
               
            }
            catch (Exception ex)
            {
                FRM_MSG f = new FRM_MSG();
                f.ShowDLG(AssemblyInfo.AssemblyTitle,
                ex.Message + "\n" + ex.StackTrace.ToString(),
                    FRM_MSG.MSGIcon.Error,
                    FRM_MSG.BTNS.One,
                    new string[] { "Ok" });
                return false;
            }
        }


    }

here is second form :

 string PCSerialNumber = DoSecure.Decrypt_PCSerialNumber_WithPrivateKey(TXT_EncryptedPCSerialNumber.Text);
                TXT_DecryptedPCSerial.Text = PCSerialNumber;
                TXT_ProductKey.Text = DoSecure. Sign_PCSerialNumber_WithPrivateKey(PCSerialNumber);

//the TXT_ProductKey is send to first form as ProductKey

but the :

if(DoSecure.Verify_PCSerialNumber(TXT_ActivationCode.Text, TXT_PCSerialNumber.Text))

always return false, what the wrong and how fix it ,i hope you help me. Thanks

Upvotes: 0

Views: 373

Answers (1)

Wajdy Essam
Wajdy Essam

Reputation: 4340

I test your code and its working fine, maybe you have an issue when loading keys? or the text you get from UI elements (TXT_ActivationCode.Text, TXT_PCSerialNumber.Text) having an issue (not filled or having space at begining or end)?

Try this, it should give you True:

static void Main(string[] args)
{
    var doSecure = new DoSecure();
    string PCSerialNumber = Guid.NewGuid().ToString();

    // Encryption
    string Encrypted_PCSerialNumber = doSecure.Encrypt_PCSerialNumber(PCSerialNumber);
    string clearSerialNumber = doSecure.Decrypt_PCSerialNumber_WithPrivateKey(Encrypted_PCSerialNumber);

    // Sign
    string productKey = doSecure.Sign_PCSerialNumber_WithPrivateKey(clearSerialNumber);
    bool IsActivated = doSecure.Verify_PCSerialNumber(productKey, clearSerialNumber);
    Console.WriteLine(IsActivated);

    Console.ReadKey();
}

And this is your class:

public class DoSecure
{

    public string RSA_CurrentPublicKey_XML = "";
    public string RSA_CurrentPrivateKey_XML = "";

    public DoSecure()
    {
        RSA_CurrentPublicKey_XML = File.ReadAllText(@"C:/Keys/public.xml");
        RSA_CurrentPrivateKey_XML = File.ReadAllText(@"C:/Keys/private.xml");
    }

    private RSACryptoServiceProvider GetPublicKey()
    {
        try
        {
            RSACryptoServiceProvider cipher = new RSACryptoServiceProvider();
            cipher.FromXmlString(RSA_CurrentPublicKey_XML);
            return cipher;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    private RSACryptoServiceProvider GetPrivateKey()
    {
        try
        {
            RSACryptoServiceProvider cipher = new RSACryptoServiceProvider();
            cipher.FromXmlString(RSA_CurrentPrivateKey_XML);
            return cipher;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    public string Sign_PCSerialNumber_WithPrivateKey(string PCSerialNumber)
    {
        try
        {
            RSACryptoServiceProvider cipher = GetPrivateKey();
            byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
            byte[] cipherText = cipher.SignData(data, new SHA512CryptoServiceProvider());
            return Convert.ToBase64String(cipherText);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    public string Decrypt_PCSerialNumber_WithPrivateKey(string Cipher_PCSerialNumber)
    {
        try
        {
            RSACryptoServiceProvider cipher = GetPrivateKey();
            byte[] data = Convert.FromBase64String(Cipher_PCSerialNumber);
            byte[] original = cipher.Decrypt(data, false);
            return Encoding.Unicode.GetString(original);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }


    public string Encrypt_PCSerialNumber(string PCSerialNumber)
    {
        try
        {
            RSACryptoServiceProvider cipher = GetPublicKey();
            byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
            byte[] cipherText = cipher.Encrypt(data, false);
            return Convert.ToBase64String(cipherText);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    public bool Verify_PCSerialNumber(string Cipher_PCSerialNumber, string PCSerialNumber)
    {
        try
        {
            RSACryptoServiceProvider cipher = GetPublicKey();
            byte[] SignedData;
            SignedData = Convert.FromBase64String(Cipher_PCSerialNumber);
            byte[] data = Encoding.Unicode.GetBytes(PCSerialNumber);
            return cipher.VerifyData(data, new SHA512CryptoServiceProvider(), SignedData);
        }
        catch (Exception ex)
        {               
            return false;
        }
    }
}

Upvotes: 1

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