Encrypt and decrypt a string in C#?

There is a limit to the size of data you can encrypt with the RSA encryption, KeySize - MinimumPadding. e.g. 256 bytes (assuming 2048 bit key) - 42 bytes (min OEAP padding) = 214 bytes (max plaintext size)

Replace your_rsa_key with your RSA key.

var provider = new System.Security.Cryptography.RSACryptoServiceProvider();

provider.ImportParameters(your_rsa_key);



var encryptedBytes = provider.Encrypt(

    System.Text.Encoding.UTF8.GetBytes("Hello World!"), true);



string decryptedTest = System.Text.Encoding.UTF8.GetString(

    provider.Decrypt(encryptedBytes, true));

4 years ago

Here is an example using RSA.

Important: There is a limit to the size of data you can encrypt with the RSA encryption, KeySize - MinimumPadding. e.g. 256 bytes (assuming 2048 bit key) - 42 bytes (min OEAP padding) = 214 bytes (max plaintext size)

Replace your_rsa_key with your RSA key.

var provider = new System.Security.Cryptography.RSACryptoServiceProvider();

provider.ImportParameters(your_rsa_key);



var encryptedBytes = provider.Encrypt(

    System.Text.Encoding.UTF8.GetBytes("Hello World!"), true);



string decryptedTest = System.Text.Encoding.UTF8.GetString(

    provider.Decrypt(encryptedBytes, true));

For more info, visit MSDN - RSACryptoServiceProvider

4 years ago

You can try this:

using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;



public class Program

{

    public static void Main()

    {

        var key = Encoding.UTF8.GetBytes("SUkbqO2ycDo7QwpR25kfgmC7f8CoyrZy");

        var data = Encoding.UTF8.GetBytes("testData");



        //Encrypt data

        var encrypted = CryptoHelper.EncryptData(data,key);



        //Decrypt data

        var decrypted = CryptoHelper.DecryptData(encrypted,key);



        //Display result

        Console.WriteLine(Encoding.UTF8.GetString(decrypted));

    }

}



public static class CryptoHelper

{

    public static byte[] EncryptData(byte[] data, byte[] key)

    {

        using (var aesAlg = Aes.Create())

        {

            aesAlg.Mode = CipherMode.CBC;

            using (var encryptor = aesAlg.CreateEncryptor(key, aesAlg.IV))

            {

                using (var msEncrypt = new MemoryStream())

                {

                    msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);



                    using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))

                        csEncrypt.Write(data, 0, data.Length);



                    return msEncrypt.ToArray();

                }

            }

        }



    }



    public static byte[] DecryptData(byte[] encrypted, byte[] key)

    {

        var iv = new byte[16];

        Buffer.BlockCopy(encrypted, 0, iv, 0, iv.Length);

        using (var aesAlg = Aes.Create())

        {

            aesAlg.Mode = CipherMode.CBC;

            using (var decryptor = aesAlg.CreateDecryptor(key, iv))

            {

                using (var msDecrypt = new MemoryStream(encrypted, iv.Length, encrypted.Length - iv.Length))

                {

                    using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))

                    {

                        using (var resultStream = new MemoryStream())

                        {

                            csDecrypt.CopyTo(resultStream);

                            return resultStream.ToArray();

                        }

                    }

                }

            }

        }

    }

}

4 years ago