Openssl Generate Certificate And Private Key

Sep 11, 2018 SSL certificates are verified and issued by a Certificate Authority (CA). You apply by generating a CSR with a key pair on your server that would, ideally, hold the SSL certificate. The CSR contains crucial organization details which the CA verifies. Generate a CSR and key. Dec 01, 2015 Iguana supports OpenSSL SSH-2 private keys and certificates in PEM format, these must not be password protected. How to create self-certified SSL certificate and public/private key files. Iguana supports OpenSSL SSH-2 private keys and certificates in PEM format, these must not be password protected. OpenSSL: Create a public/private key file.

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 -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:

Visually Inspect Your Key FilesIt is important to visually inspect you private and public key files to makesure that they are what you expect. Be sure to include it.Next open the public.pem and ensure that it starts with-BEGIN PUBLIC KEY-. Inspecting theoutput file, in this case privateunencrypted.pem clearly shows that the keyis a RSA private key as it starts with -BEGIN RSA PRIVATE KEY-. Openssl rsa key generation c. 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 KeyA previous version of the post gave this example in error.openssl rsa -in private.pem -out privateunencrypted.pem -outform PEMThe 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. Export the RSA Public Key to a FileThis is a command that isopenssl rsa -in private.pem -outform PEM -pubout -out public.pemThe -pubout flag is really important.

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.

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.

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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General OpenSSL Commands

Openssl Generate Public Private Key

These commands allow you to generate CSRs, Certificates, Private Keys and do other miscellaneous tasks.

Generate a new private key and Certificate Signing Request
Generate a self-signed certificate (see How to Create and Install an Apache Self Signed Certificate for more info)
Generate a certificate signing request (CSR) for an existing private key
Generate a certificate signing request based on an existing certificate
Remove a passphrase from a private key

Checking Using OpenSSL

If you need to check the information within a Certificate, CSR or Private Key, use these commands. You can also check CSRs and check certificates using our online tools.

Check a Certificate Signing Request (CSR)
Check a private key
Check a certificate
Check a PKCS#12 file (.pfx or .p12)

Debugging Using OpenSSL

If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.

Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key
Check an SSL connection. All the certificates (including Intermediates) should be displayed

Converting Using OpenSSL

These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.