Encrypt and Decrypt a String in c#

Question

Hi,

How to encrypt and decrypt a given string using any possible algorithm. I need the code in C#. Can someone pls help ?

Thanks

Answer 1

http://www.codeproject.com/Articles/14150/Encrypt-and-Decrypt-Data-with-C

Answer 2

Look here:

http://social.msdn.microsoft.com/Forums/sa/winformsapplications/thread/5aa93269-b0b0-48c3-941c-ade41f3e3f29

 

Noam B.

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Do not Forget to Vote as Answer/Helpful, please. It encourages us to help you...

Answer 3

http://dotnet-snippets.com/dns/encrypt-and-decrypt-strings-SID205.aspx

regards

joon

Answer 4

Here is an encrption using popular RSA Alogorithm.

public string EncryptString( string inputString, int dwKeySize, 
                             string xmlString )
{
        RSACryptoServiceProvider rsaCryptoServiceProvider = 
                                  new RSACryptoServiceProvider( dwKeySize );
    rsaCryptoServiceProvider.FromXmlString( xmlString );
    int keySize = dwKeySize / 8;
    byte[] bytes = Encoding.UTF32.GetBytes( inputString );
    RSACryptoServiceProvider here 
        int maxLength = keySize - 42;
    int dataLength = bytes.Length;
    int iterations = dataLength / maxLength;
    StringBuilder stringBuilder = new StringBuilder();
    for( int i = 0; i <= iterations; i++ )
    {
        byte[] tempBytes = new byte[ 
                ( dataLength - maxLength * i > maxLength ) ? maxLength : 
                                              dataLength - maxLength * i ];
        Buffer.BlockCopy( bytes, maxLength * i, tempBytes, 0, 
                          tempBytes.Length );
        byte[] encryptedBytes = rsaCryptoServiceProvider.Encrypt( tempBytes,
                                                                  true );
                stringBuilder.Append( Convert.ToBase64String( encryptedBytes ) );
    }
    return stringBuilder.ToString();
}
public string DecryptString( string inputString, int dwKeySize, string xmlString )
{
RSACryptoServiceProvider rsaCryptoServiceProvider
                             = new RSACryptoServiceProvider( dwKeySize );
    rsaCryptoServiceProvider.FromXmlString( xmlString );
    int base64BlockSize = ( ( dwKeySize / 8 ) % 3 != 0 ) ?
      ( ( ( dwKeySize / 8 ) / 3 ) * 4 ) + 4 : ( ( dwKeySize / 8 ) / 3 ) * 4;
    int iterations = inputString.Length / base64BlockSize; 
    ArrayList arrayList = new ArrayList();
    for( int i = 0; i < iterations; i++ )
    {
        byte[] encryptedBytes = Convert.FromBase64String( 
             inputString.Substring( base64BlockSize * i, base64BlockSize ) );
                Array.Reverse( encryptedBytes );
        arrayList.AddRange( rsaCryptoServiceProvider.Decrypt( 
                            encryptedBytes, true ) );
    }
    return Encoding.UTF32.GetString( arrayList.ToArray( 
                              Type.GetType( "System.Byte" ) ) as byte[] );
}

2) Here is one example in MSDN for md5

static void Main(string[] args)
        {
            string source = "Hello World!";
            using (MD5 md5Hash = MD5.Create())
            {
                string hash = GetMd5Hash(md5Hash, source);
                Console.WriteLine("The MD5 hash of " + source + " is: " + hash + ".");
                Console.WriteLine("Verifying the hash...");
                if (VerifyMd5Hash(md5Hash, source, hash))
                {
                    Console.WriteLine("The hashes are the same.");
                }
                else
                {
                    Console.WriteLine("The hashes are not same.");
                }
            }
        }
        static string GetMd5Hash(MD5 md5Hash, string input)
        {
            // Convert the input string to a byte array and compute the hash.
            byte[] data = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input));
            // Create a new Stringbuilder to collect the bytes
            // and create a string.
            StringBuilder sBuilder = new StringBuilder();
            // Loop through each byte of the hashed data 
            // and format each one as a hexadecimal string.
            for (int i = 0; i < data.Length; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));
            }
            // Return the hexadecimal string.
            return sBuilder.ToString();
        }
        // Verify a hash against a string.
        static bool VerifyMd5Hash(MD5 md5Hash, string input, string hash)
        {
            // Hash the input.
            string hashOfInput = GetMd5Hash(md5Hash, input);
            // Create a StringComparer an compare the hashes.
            StringComparer comparer = StringComparer.OrdinalIgnoreCase;
            if (0 == comparer.Compare(hashOfInput, hash))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

Answer 5

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Answer 6

Its simple, you can do like this:

public static string Encrypt(string data)
{
    TripleDESCryptoServiceProvider DES = new TripleDESCryptoServiceProvider();

    DES.Mode = CipherMode.ECB;
    DES.Key = GetKey("a1!B78s!5(");

    DES.Padding = PaddingMode.PKCS7;
    ICryptoTransform DESEncrypt = DES.CreateEncryptor();
    Byte[] Buffer = ASCIIEncoding.ASCII.GetBytes(data);

    return Convert.ToBase64String(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length));
}

public static string Decrypt(string data)
{
    TripleDESCryptoServiceProvider DES = new TripleDESCryptoServiceProvider();

    DES.Mode = CipherMode.ECB;
    DES.Key = GetKey("a1!B78s!5(");
   
    DES.Padding = PaddingMode.PKCS7;
    ICryptoTransform DESEncrypt = DES.CreateDecryptor();
    Byte[] Buffer = Convert.FromBase64String(data.Replace(" ","+"));

    return Encoding.UTF8.GetString(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length));
}

And when you want call you make: Encrypt("blablablabla") or Decrypt("891bw01s13")

Answer 7

Hi, 

Check with, 

you can change these 

static readonly string PasswordHash = "P@@Sw0rd";
static readonly string SaltKey = "S@LT&KEY";
static readonly string VIKey = "@1B2c3D4e5F6g7H8";

for encrypt

	public static string Encrypt(string plainText)
		{
			byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

			byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);
			var symmetricKey = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.Zeros };
			var encryptor = symmetricKey.CreateEncryptor(keyBytes, Encoding.ASCII.GetBytes(VIKey));
			
			byte[] cipherTextBytes;

			using (var memoryStream = new MemoryStream())
			{
				using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
				{
					cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
					cryptoStream.FlushFinalBlock();
					cipherTextBytes = memoryStream.ToArray();
					cryptoStream.Close();
				}
				memoryStream.Close();
			}
			return Convert.ToBase64String(cipherTextBytes);
		}

to decrypt

	public static string Decrypt(string encryptedText)
		{
			byte[] cipherTextBytes = Convert.FromBase64String(encryptedText);
			byte[] keyBytes = new Rfc2898DeriveBytes(PasswordHash, Encoding.ASCII.GetBytes(SaltKey)).GetBytes(256 / 8);
			var symmetricKey = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.None };

			var decryptor = symmetricKey.CreateDecryptor(keyBytes, Encoding.ASCII.GetBytes(VIKey));
			var memoryStream = new MemoryStream(cipherTextBytes);
			var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);
			byte[] plainTextBytes = new byte[cipherTextBytes.Length];

			int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
			memoryStream.Close();
			cryptoStream.Close();
			return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount).TrimEnd("\0".ToCharArray());
		}

I hope this helps you...

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Answer 8

what is GetKey("...") actually calling when you do DES.Key.  There is not method in your code called GetKey.

Answer 9

@Kris444

Great piece of code, I've used it in a messaging program across my network.
What is this encryption method called? Like if I wanted to decrypt messages in another program, not written in C#, like on a Mac for example, how would I go about doing that?

Thanks :D

Answer 10

There's a bug above in the EncryptString() function:  You need to comment out the line with:

"RSACryptoServiceProvider here"

This was inadvertently left behind as part of an earlier comment.

Answer 11

Hi, can this be used for commercial use?

Thanks

Answer 12

found the missing peace here:

http://stackoverflow.com/a/30187412/1411724

Answer 13

The encryption used here is how many bit encryption 

Answer 14

I keep getting error saying in quotes "specified initialization vector (IV) does not match the block size for this algorithm." 

Please help

Answer 15

please, what algorithm or method that you had use in this encrypt, decrypt

Answer 16

Encrypt/Decrypt is different from encode/decode.

You need passkey to encrypt/decrypt a message so only people who hold the key can get the original message, while you don't need one to encode/decode a message so anyone can get the original one.

Btw, don't needlessly dig an old thread.

Answer 17

I know that this is from 2012 but im getting an error on the GetKey, do you still have the metod?

Thanks

Answer 18

You can use the below method.

public static byte[] GetKey(string strKey)
        {
            byte[] Key = Convert.FromBase64String(strKey);
            return Key;
        }

Answer 19

using System;

using System.Xml;

using System.Security.Cryptography;

using System.IO;

using System.Text;

　

class

Program

{

   

privatestaticRSAParameterspublicKey;

   

privatestaticRSAParametersprivateKey;

   

publicenumKeySizes

    {

        SIZE_512 = 512,

        SIZE_1024 = 1024,

        SIZE_2048 = 2048,

        SIZE_4096 = 4096

    }

   

staticvoidMain(string[] args)

    {

       

stringprivateKeyFile = System.AppDomain.CurrentDomain.BaseDirectory + "PrivateKey2.xml";

       

//string publicKeyFile = System.AppDomain.CurrentDomain.BaseDirectory + "PublicKey2.xml";

       

////GenerateRsa(privateKeyPath, publicKeyPath, 2048)

       

stringCiphertext = "PLLX2FuYEYmLD08eD56bgz/xYJJv4Cmtz9S96bm2wgvi4QN8YJ9XggAlkqkwEE+DKPGIY7S2FZc3djswFPn2bv8pNteA6xNcJZEIA4gF57ekBZh6lzoLFXex3kQO0v4g3iWqPfmuN62oEkAhLe3DYaIgt19AX8DJKPEfP/UNyikrAn6YA73kSLePogZHszDXGLMSHrZS1QdLnhEbkVRVQr8iCi2pcsChNR1ZqiObFQp2ErJ6JFqrFEoX8Dbm88Xam/pubtxPX6e5EPxIyB+YmliDVeGm/RL5+LOf7sSospoQPl3oKeummtWHInaLTHEJ58FYOMdEn6oTYykkTiKxsQ==";

       

byte[] Encrypted = Convert.FromBase64String(Ciphertext);

       

byte[] decrypted =  Decrypt(privateKeyFile, Encrypted);

       

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

       

Console.ReadLine();

    }

   

privatestaticbyte[] Decrypt(stringprivateKeyFile, byte[] Encrypted)

    {

       

byte[] decodedtxt;

       

using(varrsa = newRSACryptoServiceProvider((int)2048))

        {

            rsa.PersistKeyInCsp =

false;

           

stringprivateKey = File.ReadAllText(privateKeyFile);

            rsa.FromXmlString(privateKey);           

            decodedtxt = rsa.Decrypt(Encrypted,

false);

        }

       

returndecodedtxt;

　

        }

   

    }

For Encryption below is the code

void Encrypt(public_key);

public voidEncrypt(stringpublic_key)

{

           

privateRSACryptoServiceProvidercipher = null;

RSACryptoServiceProvider cipher = newRSACryptoServiceProvider();

cipher.FromXmlString(public_key);

       

byte[] data = Encoding.UTF8.GetBytes(txtUnencrypt.Text);

byte[] cipherText = cipher.Encrypt(data, false);

lblUnencryptMessage.Text = Convert.ToBase64String(cipherText);

        }

Answer 20

using System;

using System.Xml;

using System.Security.Cryptography;

using System.IO;

using System.Text;

　

class

Program

{

   

privatestaticRSAParameterspublicKey;

   

privatestaticRSAParametersprivateKey;

   

publicenumKeySizes

    {

        SIZE_512 = 512,

        SIZE_1024 = 1024,

        SIZE_2048 = 2048,

        SIZE_4096 = 4096

    }

   

staticvoidMain(string[] args)

    {

       

stringprivateKeyFile = System.AppDomain.CurrentDomain.BaseDirectory + "PrivateKey2.xml";

       

//string publicKeyFile = System.AppDomain.CurrentDomain.BaseDirectory + "PublicKey2.xml";

       

////GenerateRsa(privateKeyPath, publicKeyPath, 2048)

       

stringCiphertext = "PLLX2FuYEYmLD08eD56bgz/xYJJv4Cmtz9S96bm2wgvi4QN8YJ9XggAlkqkwEE+DKPGIY7S2FZc3djswFPn2bv8pNteA6xNcJZEIA4gF57ekBZh6lzoLFXex3kQO0v4g3iWqPfmuN62oEkAhLe3DYaIgt19AX8DJKPEfP/UNyikrAn6YA73kSLePogZHszDXGLMSHrZS1QdLnhEbkVRVQr8iCi2pcsChNR1ZqiObFQp2ErJ6JFqrFEoX8Dbm88Xam/pubtxPX6e5EPxIyB+YmliDVeGm/RL5+LOf7sSospoQPl3oKeummtWHInaLTHEJ58FYOMdEn6oTYykkTiKxsQ==";

       

byte[] Encrypted = Convert.FromBase64String(Ciphertext);

       

byte[] decrypted =  Decrypt(privateKeyFile, Encrypted);

       

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

       

Console.ReadLine();

    }

   

privatestaticbyte[] Decrypt(stringprivateKeyFile, byte[] Encrypted)

    {

       

byte[] decodedtxt;

       

using(varrsa = newRSACryptoServiceProvider((int)2048))

        {

            rsa.PersistKeyInCsp =

false;

           

stringprivateKey = File.ReadAllText(privateKeyFile);

            rsa.FromXmlString(privateKey);           

            decodedtxt = rsa.Decrypt(Encrypted,

false);

        }

       

returndecodedtxt;

　

        }

   

    }

For Encryption below is the code

void Encrypt(public_key);

public voidEncrypt(stringpublic_key)

{

           

privateRSACryptoServiceProvidercipher = null;

RSACryptoServiceProvider cipher = newRSACryptoServiceProvider();

cipher.FromXmlString(public_key);

       

byte[] data = Encoding.UTF8.GetBytes(txtUnencrypt.Text);

byte[] cipherText = cipher.Encrypt(data, false);

lblUnencryptMessage.Text = Convert.ToBase64String(cipherText);

        }

Hello,

When posting code, please use the code button and not simply pasted code directly into a post.

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Answer 21

Padding = PaddingMode.None on Decrypt should be set to Zero, as in Encrypt
Otherwise some text decrypt will fail (such as containing 0)