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Openssl Rsa Public And Private Key Generation Using Java

 

Contents

  1. Openssl Rsa Public And Private Key Generation Using Java Download
  2. Openssl Rsa Public And Private Key Generation Using Java Pdf
  3. Openssl Rsa Public And Private Key Generation Using Java Server
  4. Openssl Rsa Public And Private Key Generation Using Java Code
  • 3. Saving the Keys in Binary Format
  • Source Code

May 15, 2009  Public key cryptography is a well-known concept, but for some reason the JCE (Java Cryptography Extensions documentation doesn’t at all make it clear how to interoperate with common public key formats such as those produced by openssl. If you try to do a search on the web for RSA public key cryptography work in Java, you quickly find a lot of people asking questions and not a lot of. If you are using Dynamic DNS, your CN should have a wild-card, for example:.api.com. Otherwise, use the hostname or IP address set in your Gateway Cluster (for example. 192.16.183.131 or dp1.acme.com). Run the following OpenSSL command to generate your private key and public certificate. Answer the questions and enter the Common Name when. Oct 26, 2004 I am looking the similar kind of requirement, where i need to generate the keys in java (public and private) and data (some raw text) should be encrypted with public key in java. Now the respective private key should be loaded in.Net and decrypt the data. Mar 03, 2020 Cloud IoT Core uses public key (or asymmetric) authentication: The device uses a private key to sign a JSON Web Token (JWT). The token is passed to Cloud IoT Core as proof of the device's identity. The service uses the device public key (uploaded before the JWT is sent) to verify the device's identity.

1. Introduction

Let us learn the basics of generating and using RSA keys in Java.

  • I need to replace the encrypt and decrypt step from Unix to java code with the rsaprivatekey.pem and rsapublickey.pem keys generated with openssl. I generate the keys. Openssl genrsa -out /tmp/rsaprivatekey.pem -des3 1024 openssl rsa -in /tmp/rsaprivatekey.pem -pubout -out /tmp/rsapublickey.pem i use the keys in unix (i need do it in java).
  • First of all, I'm confused why you are planning to use a Cipher to encrypt with a private key, rather than signing with a Signature.I'm not sure that all RSA Cipher providers will use the correct block type for setup, but it's worth a try. Setting that aside, though, I think that you are trying to load a non-standard OpenSSL-format key.
  • Private RSA key uses PKCS8EncodedKeySpec Public RSA key uses X509EncodedKeySpec The files generated by ssh-keygen -t rsa -b 1024 need some parsing to remove newline characters as well as inline comments. Further the keys generated are 'bare' PKCS1 formatted whereas Java needs PKCS8 format.

Java provides classes for the generation of RSA public and private key pairs with the package java.security. You can use RSA keys pairs in public key cryptography.

Public key cryptography uses a pair of keys for encryption. Distribute the public key to whoever needs it but safely secure the private key.

Openssl Rsa Public And Private Key Generation Using Java Download

Public key cryptography can be used in two modes:

Encryption: Only the private key can decrypt the data encrypted with the public key.

Authentication: Data encrypted with the private key can only be decrypted with the public key thus proving who the data came from.

2. Generating a Key Pair

First step in creating an RSA Key Pair is to create a KeyPairGeneratorfrom a factory method by specifying the algorithm (“RSA” in this instance):

Initialize the KeyPairGenerator with the key size. Use a key size of 1024 or 2048. Currently recommended key size for SSL certificates used in e-commerce is 2048 so that is what we use here.

From the KeyPair object, get the public key using getPublic() and the private key using getPrivate().

Openssl Rsa Public And Private Key Generation Using Java Pdf

3. Saving the Keys in Binary Format

Save the keys to hard disk once they are obtained. This allows re-using the keys for encryption, decryption and authentication.

What is the format of the saved files? The key information is encoded in different formats for different types of keys. Here is how you can find what format the key was saved in. On my machine, the private key was saved in PKCS#8 format and the public key in X.509 format. We need this information below to load the keys.

3.1. Load Private Key from File

After saving the private key to a file (or a database), you might need to load it at a later time. You can do that using the following code. Note that you need to know what format the data was saved in: PKCS#8 in our case.

3.2 Load Public Key from File

Load the public key from a file as follows. The public key has been saved in X.509 format so we use the X509EncodedKeySpec class to convert it.

4. Use Base64 for Saving Keys as Text

Save the keys in text format by encoding the data in Base64. Java 8 provides a Base64 class which can be used for the purpose. Save the private key with a comment as follows:

And the public key too (with a comment):

5. Generating a Digital Signature

As mentioned above, one of the purposes of public key cryptography is digital signature i.e. you generate a digital signature from a file contents, sign it with your private key and send the signature along with the file. The recipient can then use your public key to verify that the signature matches the file contents.

Here is how you can do it. Use the signature algorithm “SHA256withRSA” which is guaranteed to be supported on all JVMs. Use the private key (either generated or load from file as shown above) to initialize the Signatureobject for signing. It is then updated with contents from the data file and the signature is generated and written to the output file. This output file contains the digital signature and must be sent to the recipient for verification.

6. Verifying the Digital Signature

The recipient uses the digital signature sent with a data file to verify that the data file has not been tampered with. It requires access to the sender’s public key and can be loaded from a file if necessary as presented above.

The code below updates the Signature object with data from the data file. It then loads the signature from file and uses Signature.verify() to check if the signature is valid.

And that in a nutshell is how you can use RSA public and private keys for digital signature and verification.

Source Code

Go here for the source code.

To perform the following actions for Windows or Linux, you must have OpenSSL installed on your system.

Generating the Private Key -- Windows

Openssl Rsa Public And Private Key Generation Using Java Server

In Windows:

1. Open the Command Prompt (Start > Programs > Accessories > Command Prompt).

2. Navigate to the following folder:

C:Program FilesListManagertclwebbincerts

3. Type the following:

Openssl Rsa Public And Private Key Generation Using Java Code

openssl genrsa -out rsa.private 1024

4. Press ENTER. The private key is generated and saved in a file named 'rsa.private' located in the same folder.

NOTE The number '1024' in the above command indicates the size of the private key. You can choose one of five sizes: 512, 758, 1024, 1536 or 2048 (these numbers represent bits). The larger sizes offer greater security, but this is offset by a penalty in CPU performance. We recommend the best practice size of 1024.

Generating the Public Key -- Windows

1. At the command prompt, type the following:

openssl rsa -in rsa.private -out rsa.public -pubout -outform PEM

2. Press ENTER. The public key is saved in a file named rsa.public located in the same folder.

Generating the Private Key -- Linux

1. Open the Terminal.

2. Navigate to the folder with the ListManager directory.

3. Type the following:

openssl genrsa -out rsa.private 1024

4. Press ENTER. The private key is generated and saved in a file named 'rsa.private' located in the same folder.

Generating the Public Key -- Linux

1. Open the Terminal.

2. Type the following:

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openssl rsa -in rsa.private -out rsa.public -pubout -outform PEM

2. Press ENTER. The public key is saved in a file named rsa.public located in the same folder.

Key