I'm working on a program that sends and receives messages just like messengers, and I need to encrypt the message on send button and decrypt the message when received. I'm using the RijndaelManaged class and the following methods to encrypt/decrypt
public byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
byte[] encrypted;
// Create an RijndaelManaged object
// with the specified key and IV.
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Key = Key;
rijAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
And
public string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an RijndaelManaged object
// with the specified key and IV.
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Key = Key;
rijAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
Here's how I invoke the previous methods:
private void SendMessage()
{
string str;
System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
str = enc.GetString(this.EncryptStringToBytes(this.txtNewMessage.Text, myRijndael.Key, myRijndael.IV ));
if ( this.remoteClient.Connected && this.txtNewMessage.Text.Trim() != "")
{
this.remoteClient.SendCommand(new Proshot.CommandClient.Command(Proshot.CommandClient.CommandType.Message, this.targetIP,str));
this.txtMessages.Text += this.remoteClient.NetworkName + ": " + this.txtNewMessage.Text.Trim() + "//---SENT" + Environment.NewLine;
this.txtNewMessage.Text = "";
this.txtNewMessage.Focus();
}
}
private void private_CommandReceived(object sender , CommandEventArgs e)
{
string str;
byte[] byteString;
str = e.Command.MetaData;
System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
byteString = encoding.GetBytes(str);
switch ( e.Command.CommandType )
{
case ( CommandType.Message ):
if ( !e.Command.Target.Equals(IPAddress.Broadcast) && e.Command.SenderIP.Equals(this.targetIP))
{
//myRijndael.Padding = PaddingMode.Zeros;
this.txtMessages.Text += e.Command.SenderName + ": " + this.DecryptStringFromBytes(byteString, myRijndael.Key, myRijndael.IV) + "//---Received" + Environment.NewLine;
if ( !this.activated)
{
if(this.WindowState == FormWindowState.Normal || this.WindowState == FormWindowState.Maximized)
ShareUtils.PlaySound(ShareUtils.SoundType.NewMessageReceived);
else
ShareUtils.PlaySound(ShareUtils.SoundType.NewMessageWithPow);
this.Flash(this.Handle , FlashMode.FLASHW_ALL , 3);
}
}
break;
}
}
The problem is I'm getting exception when decrypting Cryptographic Exception - Length of the data to decrypt is invalid, I can't figure out why ?
Probably you should flush your CryptoStream while encrypting before you set the encrypted byte array:
...
csEncrypt.FlushFinalBlock();
encrypted = msEncrypt.ToArray();
...
An extract from CryptoStream.FlushFinalBlock Method:
Calling the Close method will call FlushFinalBlock. If you do not call
Close, call FlushFinalBlock to complete flushing the buffer. Call
FlushFinalBlock only when all stream activity is complete.
Obviously, if you call Close, all data will be lost, as it will close the underlying MemoryStream as well.
Related
I call this function EncryptStringToBytes_Aes to encrypt ID, when I convert to Base64 string, it looks like that: "Zr3EChQwtq1Wl/XLhBGSIZnHI098DKJaeujDmFfS25s="; "rGp5t04HgiKSkM10ImhOEwXZTc/eawOwlZTySRp6ZMk=", how to create string without "/" or "=", later I have to decrypt the ID.
string original = "IDNumber";
// Create a new instance of the AesCryptoServiceProvider
// class. This generates a new key and initialization
// vector (IV).
using (AesCryptoServiceProvider myAes = new AesCryptoServiceProvider())
{
Console.WriteLine("Original: {0} \n", original);
// Encrypt the string to an array of bytes.
byte[] encrypted = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV);
Console.WriteLine("Encrypted: {0} \n", Convert.ToBase64String(encrypted));
}
static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("IV");
byte[] encrypted;
// Create an AesCryptoServiceProvider object
// with the specified key and IV.
using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
{
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("IV");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an AesCryptoServiceProvider object
// with the specified key and IV.
using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
{
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
Thank you "Progman", you are smart, fixed my problem.
Now use class Base64UrlEncoder from namespace Microsoft.IdentityModel.Tokens
const string StringToEncode = "Zr3EChQwtq1Wl/XLhBGSIZnHI098DKJaeujDmFfS25s=";
var encodedStr = Base64UrlEncoder.Encode(StringToEncode);
var decodedStr = Base64UrlEncoder.Decode(encodedStr);
The following string contains 20 bytes (160 bits). Do I have to make my keys and initialization vectors 128,192, or 256 or is there something I can do to make it 256 and keep the same key:
byte[] bbb = Encoding.ASCII.GetBytes("abcdefghijklmnopqrst");
// Define other methods and classes here
static string EncryptStringToBytes(string plainText, string Key, string IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
string encrypted;
// Create an RijndaelManaged object
// with the specified key and IV.
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Mode = CipherMode.CBC;
rijAlg.BlockSize = 256;
rijAlg.KeySize = 256;
rijAlg.Key = Encoding.ASCII.GetBytes(Key);
rijAlg.IV = Encoding.ASCII.GetBytes(IV);
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = Convert.ToBase64String(msEncrypt.ToArray());
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
static string DecryptStringFromBytes(string cipherText,string Key, string IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an RijndaelManaged object
// with the specified key and IV.
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Mode = CipherMode.CBC;
rijAlg.BlockSize = 256;
rijAlg.KeySize = 256;
rijAlg.Key = Encoding.ASCII.GetBytes(Key);
rijAlg.IV = Encoding.ASCII.GetBytes(IV);
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(Convert.FromBase64String(cipherText)))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
It depends on which implementation of System.Security.Cryptography.SymmetricAlgorithm you're using. The legal key and block sizes are dependent upon the algorith. You can check the LegalKeySizes and LegalBlockSizes property to check what sizes are supported by your particular algorithm. You can also use the ValidKeySize() method to check if a particular key size is valid for your algorithm.
IIRC, the IV needs to be sized the same size as the block size in use.
Also, normally, you'd gen up an instance of your particular algorithm and let it create a random key and IV, which you can then save for later use.
I am trying to decode an AES cipher in C#. If I use the same AES object as when I encode them, everything is fine. But as soon as I create a different instance of AES, it does not work:
string original = "username,password,companyID";
byte[] encrypted;
using (Aes myAes1 = Aes.Create()) {
encrypted = EncryptStringToBytes_Aes(original, GetBytes("password"), myAes1.IV);
//test1
string test1 = DecryptStringFromBytes_Aes(encrypted, GetBytes("password"), myAes1.IV);
}
using (Aes myAes2 = Aes.Create()) {
//test2
string test2 = DecryptStringFromBytes_Aes(encrypted, GetBytes("password"), myAes2.IV);
}
So in this code, test1 uses myAes1 and it works out fine because the encryption also used myAes1. However test2 uses myAes2 and it doesn't work, here is the output:
test1 = username,password,companyID
test2 = t0�V�e]��Ԅ��yd,companyID
what am I doing wrong?
Here are the supporting functions, which I copied from online:
static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key,byte[] IV) {
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
byte[] encrypted;
// Create an Aes object
// with the specified key and IV.
using (Aes aesAlg = Aes.Create()) {
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream()) {
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)) {
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt)) {
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV) {
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an Aes object
// with the specified key and IV.
using (Aes aesAlg = Aes.Create()) {
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText)) {
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)) {
using (StreamReader srDecrypt = new StreamReader(csDecrypt)) {
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
static byte[] GetBytes(string str) {
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
If you don't specify an IV, then one is randomly generated. You are using 2 different IV values when decrypting, which is why you are seeing different results.
I am trying to decode an AES cipher in C#. If I use the same AES object as when I encode them, everything is fine. But as soon as I create a different instance of AES, it does not work:
string original = "username,password,companyID";
byte[] encrypted;
using (Aes myAes1 = Aes.Create()) {
encrypted = EncryptStringToBytes_Aes(original, GetBytes("password"), myAes1.IV);
//test1
string test1 = DecryptStringFromBytes_Aes(encrypted, GetBytes("password"), myAes1.IV);
}
using (Aes myAes2 = Aes.Create()) {
//test2
string test2 = DecryptStringFromBytes_Aes(encrypted, GetBytes("password"), myAes2.IV);
}
So in this code, test1 uses myAes1 and it works out fine because the encryption also used myAes1. However test2 uses myAes2 and it doesn't work, here is the output:
test1 = username,password,companyID
test2 = t0�V�e]��Ԅ��yd,companyID
what am I doing wrong?
Here are the supporting functions, which I copied from online:
static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key,byte[] IV) {
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
byte[] encrypted;
// Create an Aes object
// with the specified key and IV.
using (Aes aesAlg = Aes.Create()) {
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream()) {
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)) {
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt)) {
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV) {
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an Aes object
// with the specified key and IV.
using (Aes aesAlg = Aes.Create()) {
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText)) {
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)) {
using (StreamReader srDecrypt = new StreamReader(csDecrypt)) {
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
static byte[] GetBytes(string str) {
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
If you don't specify an IV, then one is randomly generated. You are using 2 different IV values when decrypting, which is why you are seeing different results.
I use the function EncryptStringToBytes to encrypt plain text to array of bytes and
finally convert array of bytes to string and return it then.
I use another function to Decrypt Encrypted text to plaint text.
I try to scramble a text with RC2 but it raises this error:
Rijndael class to encrypt and then decrypt data
Here's the code:
using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
namespace RC2CryptoServiceProvider_Examples
{
class MyMainClass
{
static string EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
byte[] encrypted;
// Create an Rijndael object
// with the specified key and IV.
using (Rijndael rijAlg = Rijndael.Create())
{
rijAlg.Key = Key;
rijAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
**// Return the encrypted bytes from the memory stream.
return System.Text.Encoding.UTF8.GetString(encrypted);**
}
static string DecryptStringFromBytes(string Codedtext, byte[] Key, byte[] IV)
{
byte[] cipherText = System.Text.Encoding.UTF8.GetBytes(Codedtext);
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an Rijndael object
// with the specified key and IV.
using (Rijndael rijAlg = Rijndael.Create())
{
rijAlg.Key = Key;
rijAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
public static void Main()
{
try
{
System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
string original = "Here is some data to encrypt!";
// Create a new instance of the Rijndael
// class. This generates a new key and initialization
// vector (IV).
using (Rijndael myRijndael = Rijndael.Create())
{
// Encrypt the string to an array of bytes.
string encrypted = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV);
// Decrypt the bytes to a string.
string roundtrip = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV);
//Display the original data and the decrypted data.
Console.WriteLine("Original: {0}", original);
Console.WriteLine("Round Trip: {0}", roundtrip);
}
}
catch (Exception e)
{
Console.WriteLine("Error: {0}", e.Message);
}
Console.ReadLine();
}
}
}
This is the problem (or at least a problem):
return System.Text.Encoding.UTF8.GetString(encrypted);
The encrypted data isn't UTF-8 text. It's arbitrary binary data. Don't treat it as if it were encoded text.
If you really need to pass arbitrary binary data around as a string, use Base64:
return Convert.ToBase64String(encrypted);
Then in DecryptStringFromBytes, you'd use:
byte[] cipherText = Convert.FromBase64String(codedText);
(Parameter name changed to comply with conventions.)