Public key cryptographyis a well-known concept, but for some reason theJCE (Java Cryptography Extensionsdocumentationdoesn’t at all make it clear how tointeroperate with common public key formats such as those produced byopenssl.If you try to do a search on the web forRSApublic key cryptography work in Java, you quickly find a lot of peopleasking questions and not a lot of people answering them. In this post,I’m going to try to lay out very clearly how I got this working.

• Openssl Rsa Public And Private Key Generation Using Java Free
• Openssl Rsa Public And Private Key Generation Using Java Pdf
• Public And Private Key Encryption
• Openssl Rsa Public And Private Key Generation Using Java Code
• Openssl Rsa Public And Private Key Generation Using Java Download

Just to set expectations, this is not a tutorial about how touse the cryptography APIs themselves injavax.crypto(look at the JCE tutorials from Sun forthis); nor is this a primer about how public key cryptographyworks. This article is really about how to manage the keys withoff-the-shelf utilities available to your friendly, neighborhoodsysadmin and still make use of them from Java programs. Really, thisboils down to “how do I get these darn keys loaded into a Java programwhere they can be used?” This is the article I wish I had when Istarted trying to muck around with this stuff….

Mar 12, 2014  How to Generate RSA,DSA keys using OpenSSL. Skip navigation Sign in. RSA Key Generation. How To Encrypt And Decrypt Files Using Private Public Keys With OpenSSL.

• Aug 29, 2016 If you want to use public key encryption, you’ll need public and private keys in some format. OpenSSL and many other tools can generate such key pairs as well as java. However, if it comes to interoperability between these tools, you’ll need to be a bit careful.
• With OpenSSL, the private key contains the public key information as well, so a public key doesn’t need to be generated separately. Public keys come in several flavors, using different cryptographic  algorithms. The most popular ones associated with certificates are  RSA and DSA, and this  article will show how to generate each of them.
• 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 provide and writes them to a file. You need to next extract the public key file.
• Mar 15, 2012  Demonstration of using OpenSSL to create RSA public/private key pair, sign and encrypt messages using those keys and then decrypt and verify the.
• Apr 15, 2020  The support for asymmetric keys in AWS KMS has exciting use cases. The ability to create, manage, and use public and private key pairs with KMS enables you to perform digital signing operations using RSA and Elliptic Curve (ECC) keys. You can also perform public key encryption or decryption operations using RSA keys. For example, you can use.

Managing the keys

Openssl. This is the de-facto tool sysadmins use for managingpublic/private keys, X.509 certificates,etc. This is what we want to create/manage our keyswith, so that they can be stored in formats that are common acrossmost Unix systems and utilities (like, say, C programs using theopenssl library…). Java has this notion of its ownkeystore, and Sun will give you thekeytool commandwith Java, but that doesn’t do you much good outside of Java world.

Creating the keypair. We are going to create a keypair, saving itin openssl’s preferred PEM format. PEM formats are ASCII and henceeasy to email around as needed. However, we will need to save the keysin the binary DER format so Java can read them. Without further ado,here is the magical incantation for creating the keys we’ll use:

You keep private_key.pem around for reference, but you handthe DER versions to your Java programs.

Loading the keys into Java

Really, this boils down to knowing what type of KeySpec to use whenreading in the keys. To read in the private key:

And now, to read in the public key:

That’s about it. The hard part was figuring out a compatible set of:

1. openssl DER output options (particularly thePKCS#8 encoding)

2. which type of KeySpec Java needed to use (strangely enough, thepublic key needs the “X509” keyspec, even though you would normallyhandle X.509 certificates with theopenssl x509command, not theopenssl rsacommand. Real intuitive.)

From here, signing and verifying work as described in the JCEdocumentation; the only other thing you need to know is that you canuse the “SHA1withRSA” algorithm when you get yourjava.security.Signatureinstance forsigning/verifying, and that you want the “RSA” algorithm when you getyourjavax.crypto.Cipherinstance for encrypting/decrypting.

Many happy security returns to you.

The openssl program provides a rich variety of commands, each of which often has a wealth of options and arguments. Many commands use an external configuration file for some or all of their arguments and have a -config option to specify that file. The environment variable OPENSSL_CONF can be used to specify the location of the configuration file. If the environment variable is not specified, a default file is created in the default certificate storage area called openssl.cnf. The settings in this default configuration file depend on the flags set when the version of OpenSSL being used was built.

This article is an overview of the available tools provided by openssl. For all of the details on usage and implementation, you can find the manpages which are automatically generated from the source code at the official OpenSSL project home. Likewise, the source code itself may be found on the OpenSSL project home page, as well as on the OpenSSL Github. The main OpenSSL site also includes an overview of the command-line utilities, as well as links to all of their respective documentation.

• 2Basic Tasks
  • 2.5Generating Keys Based on Elliptic Curves
    • 2.5.1Generating the Curve Parameters
• 3Commands

The entry point for the OpenSSL library is the openssl binary, usually /usr/bin/openssl on Linux. The general syntax for calling openssl is as follows:

Alternatively, you can call openssl without arguments to enter the interactive mode prompt. You may then enter commands directly, exiting with either a quit command or by issuing a termination signal with either Ctrl+C or Ctrl+D. The following is a sample interactive session in which the user invokes the prime command twice before using the quit command to terminate the session.

This section is a brief tutorial on performing the most basic tasks using OpenSSL. For a detailed explanation of the rationale behind the syntax and semantics of the commands shown here, see the section on Commands.

Getting Help[edit]

As mentioned previously, the general syntax of a command is openssl command [ command_options ] [ command_arguments ]. The help command is no different, but it does have its idiosyncrasies. To view the top-level help menu, you can call openssl as follows.

This query will print all of the available commands, like so:

Note the above output was truncated, so only the first four lines of output are shown.

A help menu for each command may be requested in two different ways. First, the same command used above may be repeated, followed by the name of the command to print help for. /bn-products-generator-twist-key.html.

The program will then display the valid options for the given command.

The second way of requesting the help menu for a particular command is by using the first option in the output shown above, namely openssl command -help. Both commands will yield the same output; the help menu displayed will be exactly the same.

For additional information on the usage of a particular command, the project manpages are a great source of information. Another excellent source of information is the project perldocs. perldoc is a utility included with most if not all Perl distributions, and it's capable of displaying documentation information in a variety of formats, one of which is as manpages. Not surprisingly, the project documentation is generated from the pod files located in the doc directory of the source code.

Getting Library Version Information[edit]

As mentioned above, the version command's help menu may be queried for additional options like so:

Using the -a option to show all version information yields the following output on my current machine:

Generating an RSA Private Key[edit]

Generating a private key can be done in a variety of different ways depending on the type of key, algorithm, bits, and other options your specific use case may require. In this example, we are generating a private key using RSA and a key size of 2048 bits.

To generate a password protected private key, the previous command may be slightly amended as follows:

The addition of the -aes256 option specifies the cipher to use to encrypt the private key file. For a list of available ciphers in the library, you can run the following command:

With your private key in hand, you can use the following command to see the key's details, such as its modulus and its constituent primes. Remember to change the name of the input file to the file name of your private key.

The above command yields the following output in my specific case. Your output will differ but should be structurally similar.

Keep in mind the above key was generated solely for pedagogical purposes; never give anyone access to your private keys.

Generating a Public Key[edit]

Having previously generated your private key, you may generate the corresponding public key using the following command.

You may once again view the key details, using a slightly different command this time.

The output for the public key will be shorter, as it carries much less information, and it will look something like this.

For more information on generating keys, see the source code documentation, located in the doc/HOWTO/keys.txt file.

Generating Keys Based on Elliptic Curves[edit]

There are essentially two steps to generating a key:

1. Generate the parameters for the specific curve you are using
2. Use those parameters to generate the key

To see the list of curves instrinsically supported by openssl, you can use the -list_curves</t> option when calling the <tt>ecparam command.

For this example I will use the prime256v1 curve, which is an X9.62/SECG curve over a 256 bit prime field.

Generating the Curve Parameters[edit]

Having selected our curve, we now call ecparam to generate our parameters file.

Printing Parameters to Standard Out[edit]

You can print the generated curve parameters to the terminal output with the following command:

Printing Parameters as C Code[edit]

Analogously, you may also output the generated curve parameters as C code. The parameters can then be loaded by calling the get_ec_group_XXX() function. To print the C code to the current terminal's output, the following command may be used:

And here are the first few lines of the corresponding output:

Generating the Key[edit]

With the curve parameters in hand, we are now free to generate the key. Just as with the [#Generating an RSA Private Key RSA] example above, we may optionally specify a cipher algorithm with which to encrypt the private key. The call to generate the key using the elliptic curve parameters generated in the example above looks like this:

Putting it All Together[edit]

The process of generation a curve based on elliptic-curves can be streamlined by calling the genpkey command directly and specifying both the algorithm and the name of the curve to use for parameter generation. In it's simplest form, the command to generate a key based on the same curve as in the example above looks like this:

This command will result in the generated key being printed to the terminal's output.

Remember that you can specify a cipher algorithm to encrypt the key with, which something you may or may not want to do, depending on your specific use case. Here is a slightly more complete example showing a key generated with a password and written to a specific output file.

Just as with the previous example, you can use the pkey command to inspect your newly-generated key.

For more details on elliptic curve cryptography or key generation, check out the manpages.

Base64 Encoding Strings[edit]

For simple string encoding, you can use 'here string' syntax with the base64 command as below. Intuitively, the -e flag specifies the action to be encoding.

Similarly, the base64 command's -d flag may be used to indicate decoding mode.

Generating a File Hash[edit]

One of the most basic uses of the dgst command (short for digest) is viewing the hash of a given file. To do this, simply invoke the command with the specified digest algorithm to use. For this example, I will be hashing an arbitrary file on my system using the MD5, SHA1, and SHA384 algorithms.

For a list of the available digest algorithms, you can use the following command.

You can also use a similar command to see the available digest commands:

Below are three sample invocations of the md5, sha1, and sha384 digest commands using the same file as the dgst command invocation above. Openssl generate self signed certificate and key.

Openssl Rsa Public And Private Key Generation Using Java Free

File Encryption and Decryption[edit]

The following example demonstrates a simple file encryption and decryption using the enc command. The first argument is the cipher algorithm to use for encrypting the file. For this example I carefully selected the AES-256 algorithm in CBC Mode by looking up the available ciphers and picking out the first one I saw. To see the list of available ciphers, you can use the following command.

Openssl Rsa Public And Private Key Generation Using Java Pdf

You can also use the following command:

Having selected an encryption algorithm, you must then specify whether the action you are taking is either encryption or decryption via the -e or -d flags, respectively. The -iter flag specifies the number of iterations on the password used for deriving the encryption key. A higher iteration count increases the time required to brute-force the resulting file. Using this option implies enabling use of the Password-Based Key Derivation Function 2, usually set using the -pbkdf2 flag. We then use the -salt flag to enable the use of a randomly generated salt in the key-derivation function.

Putting it all together, you can see the command to encrypt a file and the corresponding output below. Note that the passwords entered by the user are blank, just as they would usually be in a terminal session.

The analogous decryption command is as follows:

There are three different kinds of commands. These are standard commands, cipher commands, and digest commands. Calling the OpenSSL top-level help command with no arguments will result in openssl printing all available commands by group, sorted alphabetically.

Public And Private Key Encryption

Standard Commands[edit]

Openssl Rsa Public And Private Key Generation Using Java Code

• Paul Heinlein. 'OpenSSL Command-Line HOWTO'. Has many quick cookbook-style recipes for doing common tasks using the 'oppenssl' command-line application.

Openssl Rsa Public And Private Key Generation Using Java Download