Aes Key And Iv Generator
Creating and managing keys is an important part of the cryptographic process. Symmetric algorithms require the creation of a key and an initialization vector (IV). The key must be kept secret from anyone who should not decrypt your data. The IV does not have to be secret, but should be changed for each session. Asymmetric algorithms require the creation of a public key and a private key. The public key can be made public to anyone, while the private key must known only by the party who will decrypt the data encrypted with the public key. This section describes how to generate and manage keys for both symmetric and asymmetric algorithms.
Generating Symmetric Private Key In C# and.NET. Major symmetric algorithms are AES, DES, RC2, Rijndael, and TripleDES. The GenerateKey and GenerateIV methods return the private secret key and initialization vector. With AES-CBC you usually need a random IV. However, in the case where you use each key only once, like when using password-based encryption with random salts for each file, you can use a fixed, zero IV. If you don't make the IV random (i.e., you use some repeating group of numbers), it will be easier to figure out the key if the cookie always start with the same clear text. The IV size for AES-128 is 128 bits. IIRC, the IV is the same size as the cipher block. 128 bits is 16 bytes. 32 bytes if you store it as a ASCII hex string. Apr 27, 2016 Encrypt data using AES and 256-bit keys. AES stands for Advanced Encryption Standard and is an industry-standard algorithm for encrypting data symmetrically which even the US government has approved for SECRET documents. If you don’t know what symmetrical encryption is, it means that you use the same key or password to encrypt the data as you. Generating an IV for AES-CBC. Ask Question Asked 3 years, 10 months ago. Active 3 years, 10 months ago. Viewed 1k times 6 $begingroup$ I am faced with the task of generating a secure 256-bit IV for AES-CBC. AES key equal to IV (CBC mode) 7. Best way to generate a IV for AES-CBC when encrypting files? AES CBC with unique key per message.
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Symmetric Keys
The symmetric encryption classes supplied by the .NET Framework require a key and a new initialization vector (IV) to encrypt and decrypt data. Whenever you create a new instance of one of the managed symmetric cryptographic classes using the parameterless constructor, a new key and IV are automatically created. Anyone that you allow to decrypt your data must possess the same key and IV and use the same algorithm. Generally, a new key and IV should be created for every session, and neither the key nor IV should be stored for use in a later session.
To communicate a symmetric key and IV to a remote party, you would usually encrypt the symmetric key by using asymmetric encryption. Sending the key across an insecure network without encrypting it is unsafe, because anyone who intercepts the key and IV can then decrypt your data. For more information about exchanging data by using encryption, see Creating a Cryptographic Scheme.
The following example shows the creation of a new instance of the TripleDESCryptoServiceProvider class that implements the TripleDES algorithm.
When the previous code is executed, a new key and IV are generated and placed in the Key and IV properties, respectively.
Sometimes you might need to generate multiple keys. In this situation, you can create a new instance of a class that implements a symmetric algorithm and then create a new key and IV by calling the GenerateKey and GenerateIV methods. The following code example illustrates how to create new keys and IVs after a new instance of the symmetric cryptographic class has been made.
When the previous code is executed, a key and IV are generated when the new instance of TripleDESCryptoServiceProvider is made. Another key and IV are created when the GenerateKey and GenerateIV methods are called.
Asymmetric Keys
The .NET Framework provides the RSACryptoServiceProvider and DSACryptoServiceProvider classes for asymmetric encryption. These classes create a public/private key pair when you use the parameterless constructor to create a new instance. Asymmetric keys can be either stored for use in multiple sessions or generated for one session only. While the public key can be made generally available, the private key should be closely guarded.
A public/private key pair is generated whenever a new instance of an asymmetric algorithm class is created. After a new instance of the class is created, the key information can be extracted using one of two methods:
The ToXmlString method, which returns an XML representation of the key information.
The ExportParameters method, which returns an RSAParameters structure that holds the key information.
Both methods accept a Boolean value that indicates whether to return only the public key information or to return both the public-key and the private-key information. An RSACryptoServiceProvider class can be initialized to the value of an RSAParameters structure by using the ImportParameters method.
Asymmetric private keys should never be stored verbatim or in plain text on the local computer. If you need to store a private key, you should use a key container. For more on how to store a private key in a key container, see How to: Store Asymmetric Keys in a Key Container.
The following code example creates a new instance of the RSACryptoServiceProvider class, creating a public/private key pair, and saves the public key information to an RSAParameters structure.
See also
AES Decryption using the MachineKey DecryptionKey
Dec 04, 2007 11:02 PMtom.hundleyLINK
Hi. I'm trying to figure out how to use AES encyption and decryption using the DecryptionKey in the MachineKey. I think I'm on the right track, but I don't know how to get a proper Key and IV from the DecryptionKey to set in my Rijndael manager.
Here is my web config:
<machineKeyvalidationKey='3EF4FE4BD3F9A1CA4F293F521B8E3F492ED855FA4029511934BF221FCE80AE6A13252ED080EE6423A69EC96A3AB6E8F6E3A1B90AE70C97CC3C33FD4E51041879'decryption='AES'decryptionKey='D2B115C0460D0DA0F84A4DC2713435A3B4C49C734E1D7E33'validation='AES'/>
My 'Rijndael Manager' is below. Here is what I'm stuck on right now. I know this Manager class works great if I create a seperate Key and IV in my webconfig that looks like this (actually those are 256 bit not 128 as the class below shows).
<addkey='Key'value='JQZqQLLTQ+yV3jfvwPK7PXlJEiKQqDA9bld/ePSyx+E='/>
<addkey='IV'value='P1I/4wNHVbpM4/o7DwuCi83YAfOLpBwJyPBVkvRX7vs='/>
BUT, the problem with this is if I do that, I'm using two different keys for encryption- one for Membership and one with my own Rijnadael manager. I want to use the same shared DecrytpionKey in the MachineConfig for ALL of my encryption.
This is what I normally do:
RijndaelManagedManagercipherManager = new RijndaelManagedManager(Convert.FromBase64String(ConfigurationManager.AppSettings.Get('Key')), Convert.FromBase64String(ConfigurationManager.AppSettings.Get('IV')));
This is what I WANT to do, using the DecryptKey.
RijndaelManagedManager cipherManager = newRijndaelManagedManager();
cipherManager.IV = ??? Get me from the Machine Key Please!
cipherManager.Key = ??? Get e from the Machine Key Please!
THANK YOU in advance for any help you can give me.
--Tom
____________________________________________________________________
using System.Security.Cryptography;
namespace DOR.Security.Cryptography
///<summary>/// Manages simple encrypt and decrypt functions using the RijndaelManaged provider
///</summary>
publicclassRijndaelManagedManager
{
RijndaelManaged _cipher = null;///<summary>
/// Empty constructor
///</summary>
public RijndaelManagedManager(){
_cipher = InitCipher();
}
///<summary>
/// Pass key and iv to use in operations
///</summary>
///<param name='key'></param>
///<param name='iv'></param>
public RijndaelManagedManager(byte[] key, byte[] iv){
_cipher = InitCipher(key, iv);
}
///<summary>
///
///</summary>
publicbyte[] Key{
get { return _cipher.Key; }set { _cipher.Key = value; }}
///<summary>
///
///</summary>
publicbyte[] IV{
get { return _cipher.IV; }set { _cipher.IV = value; }}
///<summary>
/// Encrypt the passed byte array
///</summary>
///<param name='plainText'></param>
///<returns></returns>
publicbyte[] Encrypt(byte[] plainText){
ICryptoTransform transform = _cipher.CreateEncryptor();byte[] cipherText = transform.TransformFinalBlock(plainText, 0, plainText.Length);
return cipherText;}
///<summary>
/// Decrypt the passed byte array
///</summary>
///<param name='cipherText'></param>
///<returns></returns>
publicbyte[] Decrypt(byte[] cipherText){
ICryptoTransform transform = _cipher.CreateDecryptor();byte[] plainText = transform.TransformFinalBlock(cipherText, 0, cipherText.Length);
return
plainText;}
Aes Key Gen
privateRijndaelManaged InitCipher(){
RijndaelManaged cipher = CreateCipher();cipher.GenerateKey();
cipher.GenerateIV();
return cipher;}
privateRijndaelManaged InitCipher(byte[] key, byte[] iv){
RijndaelManaged cipher = CreateCipher();cipher.Key = key;
cipher.IV = iv;
return cipher;}
privateRijndaelManaged CreateCipher(){
RijndaelManaged cipher = newRijndaelManaged();cipher.KeySize = 128;
cipher.BlockSize = 128;
cipher.Mode =Aes 128 Key Generator
CipherMode.CBC;cipher.Padding = PaddingMode.ISO10126;
return cipher;}
}
}