Java Program To Generate Keys For Asymmetric Encryption
May 13, 2012 105 Responses to Revisited: PGP Encryption/Decryption in Java. Pingback: PGP Encryption/Decryption in Java. But while decrypting the file, the program is trying to use asymmetric key tag algorithm (Elgamal. I am bit confused here. Can someone explain me clearly? This is the same PASSPHRASE which is used to generate the keys. Introduction To Asymmetric Encryption. Asymmetric cryptography which can be also called as public key cryptography, uses private and public keys for encryption and decryption of the data. The keys are simply large numbers which are paired together however they are asymmetric means not identical. The example program SymmetricCipherTest.java illustrates symmetric encryption and decryption. This program generates a secret key for DES algorithm, encrypts the bytes corresponding to a string value using the generated key and finally decrypts the encrypted bytes to obtain the original bytes. Asymmetric (public key) encryption in Java. Java - encrypt string with existing public key file. I have a pre-existing set of public / private keys (google for 'java encrypt rsa example' if this link, this section provides a tutorial example on how to run jcakeypair.java to generate a diffiehellman private key and public key pair sample. Keys are stored pkcs#8 and); the java cryptography api. It can be used to store both asymmetric and symmetric keys. One option is to make your program (or server) ask for this keystore passphrase upon startup. Keys to better encryption.
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.
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.
Key generator download. 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.