RSA asymmentic encryption exception

Question

I using the following code to generate the public and private key for RSA encryption

  public static string RSA_Decrypt(string encryptedText, string privateKey)
        {
            CspParameters cspParams = new CspParameters { ProviderType = 1 };
            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(cspParams);

            rsaProvider.ImportCspBlob(Convert.FromBase64String(privateKey));

            var buffer = Convert.FromBase64String(encryptedText);

            byte[] plainBytes = rsaProvider.Decrypt(buffer, false);

            string plainText = Encoding.UTF8.GetString(plainBytes, 0, plainBytes.Length);

            return plainText;
        }

        public static string RSA_Encrypt(string data, string publicKey)
        {
            CspParameters cspParams = new CspParameters { ProviderType = 1 };
            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(cspParams);

            rsaProvider.ImportCspBlob(Convert.FromBase64String(publicKey));

            byte[] plainBytes = Encoding.UTF8.GetBytes(data);
            byte[] encryptedBytes = rsaProvider.Encrypt(plainBytes, false);

            return Convert.ToBase64String(encryptedBytes);
        }

        public static Tuple<string, string> CreateKeyPair()
        {
            CspParameters cspParams = new CspParameters { ProviderType = 1 /* PROV_RSA_FULL */ };

            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(2048, cspParams);

            string publicKey = Convert.ToBase64String(rsaProvider.ExportCspBlob(false));
            string privateKey = Convert.ToBase64String(rsaProvider.ExportCspBlob(true));

            return new Tuple<string, string>(privateKey, publicKey);
        }

the decrypt function return this exception exception

"key does not exist"

please advice me to fix this issue.

Answer 1

This code (using the methods you provided) works fine:

static void Main()
{
    var keyPair = CreateKeyPair();
    var encryptedText = Encrypt(keyPair.Item2, "test data");
    var decryptedText = Decrypt(keyPair.Item1, encryptedText);
    Console.WriteLine("Encrypted text: {0}", encryptedText);
    Console.WriteLine("Decrypted text: {0}", decryptedText);
}

public static string RSA_Decrypt(string encryptedText, string privateKey)
{
    CspParameters cspParams = new CspParameters { ProviderType = 1 };
    RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(cspParams);

    rsaProvider.ImportCspBlob(Convert.FromBase64String(privateKey));

    var buffer = Convert.FromBase64String(encryptedText);

    byte[] plainBytes = rsaProvider.Decrypt(buffer, false);

    string plainText = Encoding.UTF8.GetString(plainBytes, 0, plainBytes.Length);

    return plainText;
}

public static string RSA_Encrypt(string data, string publicKey)
{
    CspParameters cspParams = new CspParameters { ProviderType = 1 };
    RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(cspParams);

    rsaProvider.ImportCspBlob(Convert.FromBase64String(publicKey));

    byte[] plainBytes = Encoding.UTF8.GetBytes(data);
    byte[] encryptedBytes = rsaProvider.Encrypt(plainBytes, false);

    return Convert.ToBase64String(encryptedBytes);
}

public static Tuple<string, string> CreateKeyPair()
{
    CspParameters cspParams = new CspParameters { ProviderType = 1 /* PROV_RSA_FULL */ };

    RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(2048, cspParams);

    string publicKey = Convert.ToBase64String(rsaProvider.ExportCspBlob(false));
    string privateKey = Convert.ToBase64String(rsaProvider.ExportCspBlob(true));

    return new Tuple<string, string>(privateKey, publicKey);
}