Asp.net code not working for implementing rijndael encryption, decryption? - asp.net

Question

I'm reading a book entitled beginning asp.net security from wrox and I'm in this part where it shows a code snippet for using rijndael the problem this example is not included in the downloadable source codes. I decided to seek (professional)help here in the forums.
It would be awesome if you try and test it as well and hopefully give an example(codes) on how I could implement it.
Here is the code:
public class EncryptionRijndael
{
public EncryptionRijndael()
{
//
// TODO: Add constructor logic here
//
}
public static byte[] GenerateRandomBytes(int length)
{
byte[] key = new byte[length];
RNGCryptoServiceProvider provider = new RNGCryptoServiceProvider();
provider.GetBytes(key);
return key;
}
public void GetKeyAndIVFromPasswordAndSalt(string password, byte[] salt,SymmetricAlgorithm symmetricAlgorithm,ref byte[] key, ref byte[] iv)
{
Rfc2898DeriveBytes rfc2898DeriveBytes =
new Rfc2898DeriveBytes(password, salt);
key =
rfc2898DeriveBytes.GetBytes(symmetricAlgorithm.KeySize / 8);
iv =
rfc2898DeriveBytes.GetBytes(symmetricAlgorithm.BlockSize / 8);
}
public static byte[] Encrypt(byte[] clearText, byte[] key, byte[] iv)
{
// Create an instance of our encyrption algorithm.
RijndaelManaged rijndael = new RijndaelManaged();
// Create an encryptor using our key and IV
ICryptoTransform transform = rijndael.CreateEncryptor(key, iv);
// Create the streams for input and output
MemoryStream outputStream = new MemoryStream();
CryptoStream inputStream = new CryptoStream(
outputStream,
transform,
CryptoStreamMode.Write);
// Feed our data into the crypto stream.
inputStream.Write(clearText, 0, clearText.Length);
// Flush the crypto stream.
inputStream.FlushFinalBlock();
// And finally return our encrypted data.
return outputStream.ToArray();
}
static byte[] Decrypt(byte[] cipherText, byte[] key, byte[] iv)
{
// Create an instance of our encyrption algorithm.
RijndaelManaged rijndael = new RijndaelManaged();
// Create an decryptor using our key and IV ;
ICryptoTransform transform = rijndael.CreateDecryptor(key, iv);
// Create the streams for input and output
MemoryStream outputStream = new MemoryStream();
CryptoStream inputStream = new CryptoStream(outputStream,transform,CryptoStreamMode.Write);
// Feed our data into the crypto stream.
inputStream.Write(cipherText, 0, cipher.Length);
// Flush the crypto stream.
inputStream.FlushFinalBlock();
// And finally return our decrypted data.
return outputStream.ToArray();
}
}
Sir/Ma'am your answers would be of great help. Thank you++
(it would be awesome if you could show me how to call encrypt and decrypt properly)

Answer 1

I have found that it is best to create a class to wrap your credentials and a separate one to do the encryption. Here is what I created... sorry it's in vb instead of c#:
Public Class SymmetricEncryptionCredentials
Private _keyIterations As Integer
Public ReadOnly Property ivString As String
Get
Return Convert.ToBase64String(Me.iv)
End Get
End Property
Public ReadOnly Property saltString() As String
Get
Return Convert.ToBase64String(Me.salt)
End Get
End Property
Public ReadOnly Property keyIterations As Integer
Get
Return _keyIterations
End Get
End Property
Private Property keyPassword() As String
Private Property salt() As Byte()
Private ReadOnly Property key() As Security.Cryptography.Rfc2898DeriveBytes
Get
Return New Security.Cryptography.Rfc2898DeriveBytes(keyPassword, salt, keyIterations)
End Get
End Property
Private Property iv() As Byte()
''' <summary>
''' Creates a set of encryption credentials based on the
''' provided key, ivPassword, and salt string.
''' </summary>
''' <param name="keyPassword">The Secret key used for encryption</param>
''' <param name="salt">The salt string (not secret) from which the salt
''' bytes are derived.</param>
''' <remarks></remarks>
Public Sub New(ByVal keyPassword As String, ByVal salt As String, ByVal iv As String, ByVal keyIterations As Integer)
Me.keyPassword = keyPassword
Me.iv = Convert.FromBase64String(iv)
Me.salt = Convert.FromBase64String(salt)
_keyIterations = keyIterations
End Sub
''' <summary>
''' Creates a new set of encryption credentials based on the
''' provided key, while making a ivPassword and salt.
''' </summary>
''' <param name="keyPassword">The Secret key used for encryption</param>
''' <remarks>Creates a new set of encryption credentials based on the
''' provided key password, while making a ivPassword and salt.</remarks>
Public Sub New(ByVal keyPassword As String, ByVal keyIterations As Integer)
Me.keyPassword = keyPassword
Me.iv = Passwords.GetRandomPassword(16, 16)
Me.salt = Passwords.GetRandomPassword()
_keyIterations = keyIterations
End Sub
''' <summary>
''' Creates a new set of encryption credentials based on the
''' provided key, while making a ivPassword and salt. Uses
''' default PBKDF iteration count.
''' </summary>
''' <param name="keyPassword">The Secret key used for encryption</param>
''' <remarks>Creates a new set of encryption credentials based on the
''' provided key password, while making a ivPassword and salt.</remarks>
Public Sub New(ByVal keyPassword As String)
Me.New(keyPassword, AppSettings("defaultKeyPBKDFIterations"))
End Sub
''' <summary>
''' Gets an AES Encryptor with key derived from RFC2898.
''' </summary>
''' <returns></returns>
''' <remarks></remarks>
Public Function GetAESEncryptor() As Security.Cryptography.ICryptoTransform
Dim aes As New Security.Cryptography.AesManaged
aes.KeySize = 256
aes.Key = Me.key.GetBytes(aes.KeySize / 8)
aes.IV = Me.iv
Return aes.CreateEncryptor()
End Function
Public Function GetAESDecryptor() As Security.Cryptography.ICryptoTransform
Dim aes As New Security.Cryptography.AesManaged
aes.KeySize = 256
aes.Key = Me.key.GetBytes(aes.KeySize / 8)
aes.IV = Me.iv
Return aes.CreateDecryptor
End Function
End Class
Public Class SymmetricEncryption
Public Shared Function Encrypt(ByVal unencryptedValue As String, creds As SymmetricEncryptionCredentials) As String
Dim inBytes() As Byte = System.Text.Encoding.UTF8.GetBytes(unencryptedValue)
Dim outBytes() As Byte
Using outStream As New IO.MemoryStream()
Using encryptStream As New System.Security.Cryptography.CryptoStream(outStream, creds.GetAESEncryptor, Security.Cryptography.CryptoStreamMode.Write)
encryptStream.Write(inBytes, 0, inBytes.Length)
encryptStream.FlushFinalBlock()
outBytes = outStream.ToArray
encryptStream.Close()
End Using
outStream.Close()
End Using
Dim outString As String = Convert.ToBase64String(outBytes)
Return outString
End Function
Public Shared Function Decrypt(ByVal encryptedValue As String, creds As SymmetricEncryptionCredentials) As String
Dim inBytes() As Byte = Convert.FromBase64String(encryptedValue)
Dim outString As String
Using outStream As New IO.MemoryStream
Using decryptionStream As New System.Security.Cryptography.CryptoStream(outStream, creds.GetAESDecryptor, Security.Cryptography.CryptoStreamMode.Write)
decryptionStream.Write(inBytes, 0, inBytes.Length)
decryptionStream.FlushFinalBlock()
Dim outBytes() As Byte = outStream.ToArray
outString = System.Text.Encoding.UTF8.GetString(outBytes)
decryptionStream.Close()
End Using
outStream.Close()
End Using
Return outString
End Function
End Class
Public Class Passwords
Public Shared Function GetRandomPassword(minLength As Integer, maxlength As Integer) As Byte()
' *** 1. Get how long the password will be
Dim rand As New Random
Dim passLength As Integer = rand.Next(minLength, maxlength)
' *** 2. Create an array of Bytes to hold the
' random numbers used to make the string's chars
Dim passBytes(passLength - 1) As Byte
' *** 3. Fill the array with random bytes.
Dim rng As New Security.Cryptography.RNGCryptoServiceProvider
rng.GetBytes(passBytes)
Return passBytes
End Function
Public Shared Function GetRandomPassword() As Byte()
Return GetRandomPassword(12, 32)
End Function
End Class