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.
Let's assume we want to generate encryption key and initialization vector (IV) for AES encryption based on some passphrase. And we want to be able to generate the same key and IV for the same passphrase in.NET and Java - maybe we have Android app written in Java that needs to decrypt message from ASP.NET web app. AES Key Generator Devon 2019-04-27T15:14:21-07:00. Below is a Base64 Encoded AES-256 key which was been generated using the secure javax KeyGenerator. This key will work perfectly with any of the AES encryption code elsewhere on my site, and probably most of yours as well. This key is secure, randomly generated, and has been generated just for you. Mar 12, 2020 Run the madpwd3 utility to generate the encrypted password. The madpwd3 utility allows for the key and iv to be entered either from a file or directly on the command line. Use the -keyfile and -ivfile options to specify as a file or use the -key and -iv options to enter them at the command prompt. There is no limit on the length of the password. Mar 12, 2020 Run the madpwd3 utility to generate the encrypted password. The madpwd3 utility allows for the key and iv to be entered either from a file or directly on the command line. Use the -keyfile and -ivfile options to specify as a file or use the -key and -iv options to enter them at the command prompt. There is no limit on the length of the password input and the output length is variable. The point is: They encrypt using AES-128, generate a (not cryptographic secure) key and use this as encryption key AND initialization vector. I'm not a crypto expert, but I know that this is bad (aside of the insecure generation of the key). The problem is, that I don't know what the concrete consequences are? Generate an AES key plus Initialization vector (iv) with openssl and; how to encode/decode a file with the generated key/iv pair; Note: AES is a symmetric-key algorithm which means it uses the same key during encryption/decryption. Generating key/iv pair. We want to generate a 256-bit key and use Cipher Block Chaining (CBC).
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.
Generate Aes Key And Iv Code
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.