Java Generate Certificate And Private Key

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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.

Java Create Keystore From Certificate And Private Key

Nov 01, 2018  A private key can be use to sign a document and the public key is use to verify that the signature of the document is valid. The API we use to generate the key pairs is in the java.security package. That’s mean we have to import this package into our code. The class for generating the key pairs is KeyPairGenerator. A self signed certificate is that the issuer of the certificate is the subject of the certificate, i.e, you sign your own certificate with your own private key. In Java, there is a class named CertAndKeyGen which can be used to generate keys and certificates. Generate a pair of keys, and provide access to them.

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).

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.

Free download timer for mac. 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.

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.

Java Generate Certificate And Private Keyboard

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 Windows 8 ultimate product key generator. in your home directory). Required values include dname, storepass, and keypass.

Securing your Java application with an SSL certificate can be extremely important. Fortunately, it is (usually) quite simple to do using Java Keytool. Most situations require that you buy a trusted certificate, but there are many cases when you can generate and use a self signed certificate for free.

When to Use a Keytool Self Signed Certificate

An SSL certificate serves two essential purposes: distributing the public key and verifying the identity of the server so users know they aren't sending their information to the wrong server. It can only properly verify the identity of the server when it is signed by a trusted third party. A self signed certificate is a certificate that is signed by itself rather than a trusted authority. Since any attacker can create a self signed certificate and launch a man-in-the-middle attack, a user can't know whether they are sending their encrypted information to the server or an attacker. Because of this, you will almost never want to use a self signed certificate on a public Java server that requires anonymous visitors to connect to your site. However, self signed certificates have their place:

Never use a self signed certificate on an e-commerce site or any site that transfers valuable personal information like credit cards, social security numbers, etc.

  • An Intranet. When clients only have to go through a local Intranet to get to the server, there is virtually no chance of a man-in-the-middle attack.
  • A Java development server. There is no need to spend extra cash buying a trusted certificate when you are just developing or testing an application.
  • Personal sites with few visitors. If you have a small personal site that transfers non-critical information, there is very little incentive for someone to attack the connection.

Just keep in mind that visitors will see a warning in their browsers (like the one below) when connecting to a server that uses a self signed certificate until it is permanently stored in their certificate store.

Generate a Self Signed Certificate using Java Keytool

Now that you know when to use a Keytool self signed certificate, let's create one using a simple Java Keytool command:

  1. Open the command console on whatever operating system you are using and navigate to the directory where keytool.exe is located (usually where the JRE is located, e.g. c:Program FilesJavajre6bin on Windows machines).
  2. Run the following command (where validity is the number of days before the certificate will expire):
    keytool -genkey -keyalg RSA -alias selfsigned -keystore keystore.jks -storepass password -validity 360 -keysize 2048
  3. Fill in the prompts for your organization information. When it asks for your first and last name, enter the domain name of the server that users will be entering to connect to your application (e.g. www.google.com)

This will create a keystore.jks file containing a private key and your sparklingly fresh self signed certificate. Now you just need to configure your Java application to use the .jks file. If you are using Tomcat, you can follow our Tomcat SSL Installation Instructions.

For more information on creating a Java Keytool Self Signed Certificate, see the following links:

Originally posted on Sat Oct 30, 2010

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