Openssl Rsa_generate_key_ex

Posted on 11.12.202022.08.2017by admin

Openssl Rsa_generate_key_ex Version
Openssl Rsa_generate_key_ex Error
Openssl Rsa_generate_key_ex Download
Openssl Syntax

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.

Apr 22, 2017 Introduction Microsoft Crypto API (CAPI) was first released with the Windows NT4 operating system in 1996. The OpenSSL project, that was originally a fork of SSLeay by Eric Young and Tim Hudson, was initiated in 1998 and has since become one of the most widely distributed cryptographic libraries available. I recently required a Windows application. There is no way that RSAgeneratekeyex function is going to be able to do anything with it except attempt to use it and as you see, crash. So read the docs on that function as to what the first parameter is supposed to be. If I understood this correctly, Fortresslinux OpenSSL packages have been compiled without support for deprecated (=compatibility) functions. In our case, one such function is RSAgeneratekey, and we should switch to RSAgeneratekeyex instead. You'll find the example code that comes with OpenSSL more useful than the documentation. For example, documentation of encryption with RSA is shows in apps/rsa.c.It may help to work out the OpenSSL command lines to perform each function you want to do with the command line tool and then figure out what the code actually does (by inspecting it) so you can make your code do the same thing.

RSAgeneratekeyex generates a 2-prime RSA key pair and stores it in the RSA structure provided in rsa. The pseudo-random number generator must be seeded prior to calling RSAgeneratekeyex. If I understood this correctly, Fortresslinux OpenSSL packages have been compiled without support for deprecated (=compatibility) functions. In our case, one such function is RSAgeneratekey, and we should switch to RSAgeneratekeyex instead.

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 -pubout 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.pem to verify that it starts with a -----BEGIN RSA PRIVATE KEY-----
less public.pem to 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. Make a code generator based on key.

Openssl Rsa_generate_key_ex Version

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.

Oh, and one last thing.

Openssl Rsa_generate_key_ex Error

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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