The KeyPairGenerator class is used to generate pairs of public and private keys. Key pair generators are constructed using the

Generate DSA key pair: 4. KeyPair Generator For Private Key: 5. KeyPair Generator For Public Key: 6. Wrap And Unwrap Key: 7. Generate a 576-bit DH key pair: 8. Generate a 1024-bit RSA key pair: 9. Getting the Bytes of a Generated Key Pair: 10. Get the bytes of the public and private keys: 11. The bytes can be converted back to public. Dec 30, 2016  Private Key. The private key is a secret key that is used to decrypt the message and the party knows it that exchange message. In the traditional method, a secret key is shared within communicators to enable encryption and decryption the message, but if the key is lost, the system becomes void. To avoid this weakness, PKI (public key infrastructure) came into force where a public. Every public key is in turn linked to a private key. A private key can always be used to generate its associated public key, but not vice versa. (A private key and its associated public key make up a key pair.) All your public keys are visible by everyone using the network. The private keys, however, should never be shared or given away.

getInstance factory methods (static methods that return instances of a given class).

A Key pair generator for a particular algorithm creates a public/private key pair that can be used with this algorithm. It also associates algorithm-specific parameters with each of the generated keys.

There are two ways to generate a key pair: in an algorithm-independent manner, and in an algorithm-specific manner. The only difference between the two is the initialization of the object:

• Algorithm-Independent Initialization

  All key pair generators share the concepts of a keysize and a source of randomness. The keysize is interpreted differently for different algorithms (e.g., in the case of the DSA algorithm, the keysize corresponds to the length of the modulus). There is an initialize method in this KeyPairGenerator class that takes these two universally shared types of arguments. There is also one that takes just a keysize argument, and uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness is used.)

  Since no other parameters are specified when you call the above algorithm-independent initialize methods, it is up to the provider what to do about the algorithm-specific parameters (if any) to be associated with each of the keys.

  If the algorithm is the DSA algorithm, and the keysize (modulus size) is 512, 768, or 1024, then the Sun provider uses a set of precomputed values for the p, q, and g parameters. If the modulus size is not one of the above values, the Sun provider creates a new set of parameters. Other providers might have precomputed parameter sets for more than just the three modulus sizes mentioned above. Still others might not have a list of precomputed parameters at all and instead always create new parameter sets.

• Algorithm-Specific Initialization

  For situations where a set of algorithm-specific parameters already exists (e.g., so-called community parameters in DSA), there are two initialize methods that have an AlgorithmParameterSpec argument. One also has a SecureRandom argument, while the the other uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness is used.)

In case the client does not explicitly initialize the KeyPairGenerator (via a call to an initialize method), each provider must supply (and document) a default initialization. For example, the Sun provider uses a default modulus size (keysize) of 1024 bits.

Note that this class is abstract and extends from KeyPairGeneratorSpi for historical reasons. Application developers should only take notice of the methods defined in this KeyPairGenerator/trend-micro-antivirus-serial-key-generator.html. class; all the methods in the superclass are intended for cryptographic service providers who wish to supply their own implementations of key pair generators.

Every implementation of the Java platform is required to support the following standard KeyPairGenerator algorithms and keysizes in parentheses:

• DiffieHellman (1024)
• DSA (1024)
• RSA (1024, 2048)

These algorithms are described in the KeyPairGenerator section of the Java Cryptography Architecture Standard Algorithm Name Documentation. Consult the release documentation for your implementation to see if any other algorithms are supported.

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Java provides the KeyPairGenerator class. This class is used to generate pairs of public and private keys. To generate keys using the KeyPairGenerator class, follow the steps given below.

Step 1: Create a KeyPairGenerator object

The KeyPairGenerator class provides getInstance() method which accepts a String variable representing the required key-generating algorithm and returns a KeyPairGenerator object that generates keys.

Create KeyPairGenerator object using the getInstance() method as shown below.

Step 2: Initialize the KeyPairGenerator object

The KeyPairGenerator class provides a method named initialize() this method is used to initialize the key pair generator. This method accepts an integer value representing the key size.

Initialize the KeyPairGenerator object created in the previous step using this method as shown below.

Step 3: Generate the KeyPairGenerator

You can generate the KeyPair using the generateKeyPair() method of the KeyPairGenerator class. Generate the key pair using this method as shown below.

Step 4: Get the private key/public key

Rsa Public Key Generator Java

You can get the private key from the generated KeyPair object using the getPrivate() method as shown below.

You can get the public key from the generated KeyPair object using the getPublic() method as shown below.

Example

Following example demonstrates the key generation of the secret key using the KeyPairGenerator class of the javax.crypto package.

Output

Public Private Key Generator Java Tutorial

The above program generates the following output −