Java Generate Key Pair Programmatically
If a code signer does not yet have a suitable private key for signing the code, the key must first be generated, along with a corresponding public key that can be used by the code receiver's runtime system to verify the signature. /generate-ssh-public-key-rhel.html.
- 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.
- The Java Keytool is a command line tool which can generate public key / private key pairs and store them in a Java KeyStore.The Keytool executable is distributed with the Java SDK (or JRE), so if you have an SDK installed you will also have the Keytool executable.
Since this lesson assumes that you don't yet have such keys, you are going to create a keystore named examplestore
and create an entry with a newly generated public/private key pair (with the public key in a certificate).
I would like to generate a key pair and insert it into a Java KeyStore programmatically. I can use the command line to do exactly what I want, but how to do that using Java code? Here is the command line: keytool -genkeypair -dname 'cn=Unknown' -alias main -keyalg RSA -keysize 4096 -keypas. Nov 29, 2016 There are several ways to generate a Public-Private Key Pair depending on your platform. In this example, we will create a pair using Java. The Cryptographic Algorithm we will use in.
Type the following command in your command window to create a keystore named examplestore
and to generate keys:
You will be prompted to enter passwords for the key and keystore.
Subparts of the keytool Command
Let's look at what each of the keytool
subparts mean.
- The command for generating keys is -genkey.
- The -alias signFiles subpart indicates the alias to be used in the future to refer to the keystore entry containing the keys that will be generated.
- The -keystore examplestore subpart indicates the name (and optionally path) of the keystore you are creating or already using.
- The storepass value that you are promted for specifies the keystore password.
- The keypass value that you are prompted for specifies a password for the private key about to be generated. You will always need this password in order to access the keystore entry containing that key. The entry doesn't have to have its own password. When you are prompted for the key password, you are given the option of letting it be the same as the keystore password.
Note: For security reasons you should not set your key or keystore passwords on the command line, because they can be intercepted more easily that way.
Java Generate Key Pair Programmatically Free
Distinguished-Name Information
If you use the preceding keystore
command, you will be prompted for your distinguished-name information. Following are the prompts; the bold indicates what you should type.
Command Results
The keytool
command creates the keystore named examplestore
(if it doesn't already exist) in the same directory in which the command is executed. The command generates a public/private key pair for the entity whose distinguished name has a common name of Susan Jones and the organizational unit of Purchasing.
The command creates a self-signed certificate that includes the public key and the distinguished-name information. (The distinguished name you supply will be used as the 'subject' field in the certificate.) This certificate will be valid for 90 days, the default validity period if you don't specify a -validity option. The certificate is associated with the private key in a keystore entry referred to by the alias signFiles
.
Self-signed certificates are useful for developing and testing an application. However, users are warned that the application is signed with an untrusted certificate and asked if they want to run the application. To provide users with more confidence to run your application, use a certificate issued by a recognized certificate authority.
Note: The command could be shorter if option defaults are accepted or you wish to be prompted for various values. Whenever you execute a keytool
command, defaults are used for unspecified options that have default values, and you are prompted for any required values. For the genkey
command, options with default values include alias (whose default is mykey
), validity (90 days), and keystore (the file named .keystore
in your home directory). Required values include dname, storepass, and keypass.
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:
Java Generate Key Pair Programmatically Code
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.

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.
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 Key Code
Generate the Pair of Keys
Java Generate Key Pair
The final step is to generate the key pair and to store the keys in PrivateKey
and PublicKey
objects.