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∟ DsaKeyGenerator.java - Generating DSA Key Pair. This section provides a tutorial example on how to using the Java default implementation of DSA (Digital Signature Algorithm) to generate DSA key pair, public key and private key. Implementing the DSA digital signature algorithm from scratch is not easy. Java provides KeyGenerator class this class is used to generate secret keys and objects of this class are reusable. To generate keys using the KeyGenerator class follow the steps given below. Step 1: Create a KeyGenerator object. The KeyGenerator class provides getInstance method which accepts a String variable representing the required key-generating algorithm and returns.
In order to be able to create a digital signature, you need a private key. (Its corresponding public key will be needed in order to verify the authenticity of the signature.)
In some cases the key pair (private key and corresponding public key) are already available in files. In that case the program can import and use the private key for signing, as shown in Weaknesses and Alternatives.
In other cases the program needs to generate the key pair. A key pair is generated by using the
KeyPairGenerator
class.In this example you will generate a public/private key pair for the Digital Signature Algorithm (DSA). You will generate keys with a 1024-bit length.
Generating a key pair requires several steps:
Create a Key Pair Generator
The first step is to get a key-pair generator object for generating keys for the DSA signature algorithm.
As with all engine classes, the way to get a
KeyPairGenerator
object for a particular type of algorithm is to call the getInstance
static factory method on the KeyPairGenerator
class. This method has two forms, both of which hava a String algorithm
first argument; one form also has a String provider
second argument.A caller may thus optionally specify the name of a provider, which will guarantee that the implementation of the algorithm requested is from the named provider. The sample code of this lesson always specifies the default SUN provider built into the JDK.
Put the following statement after the
line in the file created in the previous step, Prepare Initial Program Structure:
Initialize the Key Pair Generator
The next step is to initialize the key pair generator. All key pair generators share the concepts of a keysize and a source of randomness. The
KeyPairGenerator
class has an initialize
method that takes these two types of arguments.![Dsa Key Generation In Java Dsa Key Generation In Java](/uploads/1/2/6/3/126386810/943919794.png)
The keysize for a DSA key generator is the key length (in bits), which you will set to 1024.
The source of randomness must be an instance of the
SecureRandom
class that provides a cryptographically strong random number generator (RNG). For more information about SecureRandom
, see the SecureRandom API Specification and the Java Cryptography Architecture Reference Guide .The following example requests an instance of
SecureRandom
that uses the SHA1PRNG algorithm, as provided by the built-in SUN provider. The example then passes this SecureRandom
instance to the key-pair generator initialization method.![Dsa Key Generation In Java Dsa Key Generation In Java](/uploads/1/2/6/3/126386810/418578093.png)
Some situations require strong random values, such as when creating high-value and long-lived secrets like RSA public and private keys. To help guide applications in selecting a suitable strong
SecureRandom
implementation, starting from JDK 8 Java distributions include a list of known strong SecureRandom
implementations in the securerandom.strongAlgorithms
property of the java.security.Security
class. When you are creating such data, you should consider using SecureRandom.getInstanceStrong()
, as it obtains an instance of the known strong algorithms.Generate the Pair of Keys
The final step is to generate the key pair and to store the keys in
PrivateKey
and PublicKey
objects.- Java Cryptography Tutorial
- Message Digest and MAC
- Keys and Key Store
- Generating Keys
- Digital Signature
- Cipher Text
- Java Cryptography Resources
- Selected Reading
Java provides KeyGenerator class this class is used to generate secret keys and objects of this class are reusable.
To generate keys using the KeyGenerator class follow the steps given below.
Step 1: Create a KeyGenerator object
The KeyGenerator class provides getInstance() method which accepts a String variable representing the required key-generating algorithm and returns a KeyGenerator object that generates secret keys.
Create KeyGenerator object using the getInstance() method as shown below.
Step 2: Create SecureRandom object
The SecureRandom class of the java.Security package provides a strong random number generator which is used to generate random numbers in Java. Instantiate this class as shown below.
Step 3: Initialize the KeyGenerator
The KeyGenerator class provides a method named init() this method accepts the SecureRandom object and initializes the current KeyGenerator.
Initialize the KeyGenerator object created in the previous step using the init() method.
Example
Dsa Private Key
Following example demonstrates the key generation of the secret key using the KeyGenerator class of the javax.crypto package.
Rsa And Dsa Keys
Output
Dsa Key Generation In Java 10
The above program generates the following output −