Generate Rsa Key Pair Using Java
- Generate Rsa Private Key
- Generate Rsa Key Pair Using Java Download
- Generate Rsa Key Pair Using Java Software
- Java Cryptography Tutorial
- Message Digest and MAC
How do I generate my own SSH key pair? This document will show you how to generate a personal SSH key pair and upload the public key to RightScale for use with Server Login Control. Paste them into the text area labeled Public Key. If you are using the Java Web Start application or the Java applet as your session launcher. The most popular Public Key Algorithms are RSA, Diffie-Hellman, ElGamal, DSS. Generate a Public-Private Key Pair. 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 this example is RSA.
- Keys and Key Store
- Generating Keys
- Digital Signature
- Cipher Text
Generate Rsa Private Key
- Java Cryptography Resources
- Selected Reading
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
Generate Rsa Key Pair Using Java Download
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
The above program generates the following output −
While Encrypting a File with a Password from the Command Line using OpenSSLis very useful in its own right, the real power of the OpenSSL library is itsability to support the use of public key cryptograph for encrypting orvalidating data in an unattended manner (where the password is not required toencrypt) is done with public keys.
The Commands to Run
Generate a 2048 bit RSA Key
You can generate a public and private RSA key pair like this:
openssl genrsa -des3 -out private.pem 2048
That generates a 2048-bit RSA key pair, encrypts them with a password you provideand writes them to a file. You need to next extract the public key file. You willuse this, for instance, on your web server to encrypt content so that it canonly be read with the private key.
Export the RSA Public Key to a File
This is a command that is
openssl rsa -in private.pem -outform PEM -pubout -out public.pem
The -pubout flag is really important. Be sure to include it.
Next open the public.pem and ensure that it starts with-----BEGIN PUBLIC KEY-----. This is how you know that this file is thepublic key of the pair and not a private key.
To check the file from the command line you can use the less command, like this:
less public.pem
Do Not Run This, it Exports the Private Key
A previous version of the post gave this example in error.
openssl rsa -in private.pem -out private_unencrypted.pem -outform PEM
The error is that the -puboutGenerated key column in table comparison excel. was dropped from the end of the command.That changes the meaning of the command from that of exporting the public keyto exporting the private key outside of its encrypted wrapper. Inspecting theoutput file, in this case private_unencrypted.pem clearly shows that the keyis a RSA private key as it starts with -----BEGIN RSA PRIVATE KEY-----.
Visually Inspect Your Key Files
It is important to visually inspect you private and public key files to makesure that they are what you expect. OpenSSL will clearly explain the nature ofthe key block with a -----BEGIN RSA PRIVATE KEY----- or -----BEGIN PUBLIC KEY-----.
You can use less to inspect each of your two files in turn:
less private.pemto verify that it starts with a-----BEGIN RSA PRIVATE KEY-----less public.pemto verify that it starts with a-----BEGIN PUBLIC KEY-----
The next section shows a full example of what each key file should look like.
The Generated Key Files
The generated files are base64-encoded encryption keys in plain text format.If you select a password for your private key, its file will be encrypted withyour password. Be sure to remember this password or the key pair becomes useless.
The private.pem file looks something like this:
The public key, public.pem, file looks like:
Protecting Your Keys
Depending on the nature of the information you will protect, it’s important tokeep the private key backed up and secret. The public key can be distributedanywhere or embedded in your web application scripts, such as in your PHP,Ruby, or other scripts. Again, backup your keys!
Remember, if the key goes away the data encrypted to it is gone. Keeping aprinted copy of the key material in a sealed envelope in a bank safety depositbox is a good way to protect important keys against loss due to fire or harddrive failure.
Generate Rsa Key Pair Using Java Software
Oh, and one last thing.
If you, dear reader, were planning any funny business with the private key that I have just published here. Know that they were made especially for this series of blog posts. I do not use them for anything else.
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