Ubuntu Generate Public Key From Private
One of the most common forms of cryptography today is public-key cryptography. Public-key cryptography utilizes a public key and a private key. The system works by encrypting information using the public key. The information can then only be decrypted using the private key.
A common use for public-key cryptography is encrypting application traffic using a Secure Socket Layer (SSL) or Transport Layer Security (TLS) connection. One example: configuring Apache to provide HTTPS, the HTTP protocol over SSL/TLS. This allows a way to encrypt traffic using a protocol that does not itself provide encryption.
Oct 06, 2017 This article shows how to configure a SSH connection for authentication by using the public-key method. To do this, a key pair is created at the client, the public part of the key is transferred to the server, and afterwards the server is set up for key authentication. The user can log on to the server without a login password, only the password is required to protect the private key. Jun 22, 2012 The private key (identification) is now located in /home/ demo /.ssh/idrsa. Step Three—Copy the Public Key. Once the key pair is generated, it’s time to place the public key on the server that we want to use. You can copy the public key into the new machine’s authorizedkeys file with the ssh-copy-id command. Manually generating your SSH key in Windows ›. For Type of key to generate, select SSH-2 RSA. Click the Generate button. Move your mouse in the area below the progress bar. When the progress bar is full, PuTTYgen generates your key pair. Ssh-keygen.exe Generating public/private rsa key pair. Enter file in which to save the key (/c. Oct 24, 2018 Ubuntu 18.04 Setup SSH Public Key Authentication. The procedure to set up secure ssh keys on Ubuntu 18.04: Create the key pair using ssh-keygen command. Copy and install the public key using ssh-copy-id command. Add yourself to sudo admin account on Ubuntu 18.04 server. Disable the password login for root account on Ubuntu 18.04.
- SSH public key can be of different bit but to work on Acquia Cloud you require SSH key of 4096 bites. Below is the method to generate SSH private/public key pair using the ssh-keygen command. Step 1: Open Terminal and Run this commands to check you do not have public key saved on your system.
- Creating a private/public key pair on Ubuntu Last updated: 04 Jun 2012. There are many reasons you might want to create a key pair on Linux, more specifically on Ubuntu. For more information about key pairs, see this. If your server is an Amazon EC2 Server Instance, you might want to.
- Dec 18, 2019 In this tutorial, we will walk through how to generate SSH keys on Ubuntu 18.04 machines. We will also show you how to set up an SSH key-based authentication and connect to your remote Linux servers without entering a password.
A certificate is a method used to distribute a public key and other information about a server and the organization who is responsible for it. Certificates can be digitally signed by a Certification Authority, or CA. A CA is a trusted third party that has confirmed that the information contained in the certificate is accurate.
Types of Certificates
To set up a secure server using public-key cryptography, in most cases, you send your certificate request (including your public key), proof of your company’s identity, and payment to a CA. The CA verifies the certificate request and your identity, and then sends back a certificate for your secure server. Alternatively, you can create your own self-signed certificate.
Note
Note that self-signed certificates should not be used in most production environments.
Continuing the HTTPS example, a CA-signed certificate provides two important capabilities that a self-signed certificate does not:
Browsers (usually) automatically recognize the CA signature and allow a secure connection to be made without prompting the user.
When a CA issues a signed certificate, it is guaranteeing the identity of the organization that is providing the web pages to the browser.
Most of the software supporting SSL/TLS have a list of CAs whose certificates they automatically accept. If a browser encounters a certificate whose authorizing CA is not in the list, the browser asks the user to either accept or decline the connection. Also, other applications may generate an error message when using a self-signed certificate.
The process of getting a certificate from a CA is fairly easy. A quick overview is as follows:
Create a private and public encryption key pair.
Create a certificate signing request based on the public key. The certificate request contains information about your server and the company hosting it.
Send the certificate request, along with documents proving your identity, to a CA. We cannot tell you which certificate authority to choose. Your decision may be based on your past experiences, or on the experiences of your friends or colleagues, or purely on monetary factors.
Once you have decided upon a CA, you need to follow the instructions they provide on how to obtain a certificate from them. Making a key generator for spn.
When the CA is satisfied that you are indeed who you claim to be, they send you a digital certificate.
Install this certificate on your secure server, and configure the appropriate applications to use the certificate.
Generating a Certificate Signing Request (CSR)
Whether you are getting a certificate from a CA or generating your own self-signed certificate, the first step is to generate a key.
If the certificate will be used by service daemons, such as Apache, Postfix, Dovecot, etc., a key without a passphrase is often appropriate. Not having a passphrase allows the services to start without manual intervention, usually the preferred way to start a daemon.
This section will cover generating a key with a passphrase, and one without. The non-passphrase key will then be used to generate a certificate that can be used with various service daemons.
Warning
Running your secure service without a passphrase is convenient because you will not need to enter the passphrase every time you start your secure service. But it is insecure and a compromise of the key means a compromise of the server as well.
To generate the keys for the Certificate Signing Request (CSR) run the following command from a terminal prompt:
You can now enter your passphrase. For best security, it should at least contain eight characters. The minimum length when specifying -des3 is four characters. As a best practice it should include numbers and/or punctuation and not be a word in a dictionary. Also remember that your passphrase is case-sensitive.
Re-type the passphrase to verify. Once you have re-typed it correctly, the server key is generated and stored in the server.key file.
Now create the insecure key, the one without a passphrase, and shuffle the key names:
The insecure key is now named server.key Cryptographic key generation from fingerprint. , and you can use this file to generate the CSR without passphrase.
To create the CSR, run the following command at a terminal prompt:
It will prompt you enter the passphrase. If you enter the correct passphrase, it will prompt you to enter Company Name, Site Name, Email Id, etc. Once you enter all these details, your CSR will be created and it will be stored in the server.csr file.
You can now submit this CSR file to a CA for processing. The CA will use this CSR file and issue the certificate. On the other hand, you can create self-signed certificate using this CSR.
Creating a Self-Signed Certificate
To create the self-signed certificate, run the following command at a terminal prompt:
The above command will prompt you to enter the passphrase. Once you enter the correct passphrase, your certificate will be created and it will be stored in the server.crt file.
Warning
Ubuntu 18.04 Create Private Key
If your secure server is to be used in a production environment, you probably need a CA-signed certificate. It is not recommended to use self-signed certificate.
Installing the Certificate
You can install the key file server.key and certificate file server.crt, or the certificate file issued by your CA, by running following commands at a terminal prompt:
Now simply configure any applications, with the ability to use public-key cryptography, to use the certificate and key files. For example, Apache can provide HTTPS, Dovecot can provide IMAPS and POP3S, etc.
Certification Authority
If the services on your network require more than a few self-signed certificates it may be worth the additional effort to setup your own internal Certification Authority (CA). Using certificates signed by your own CA, allows the various services using the certificates to easily trust other services using certificates issued from the same CA.
First, create the directories to hold the CA certificate and related files:
The CA needs a few additional files to operate, one to keep track of the last serial number used by the CA, each certificate must have a unique serial number, and another file to record which certificates have been issued:
The third file is a CA configuration file. Though not strictly necessary, it is very convenient when issuing multiple certificates. Edit /etc/ssl/openssl.cnf, and in the [ CA_default ] change:
Next, create the self-signed root certificate:
You will then be asked to enter the details about the certificate.
Now install the root certificate and key:
You are now ready to start signing certificates. The first item needed is a Certificate Signing Request (CSR), see Generating a Certificate Signing Request (CSR) for details. Once you have a CSR, enter the following to generate a certificate signed by the CA:
After entering the password for the CA key, you will be prompted to sign the certificate, and again to commit the new certificate. You should then see a somewhat large amount of output related to the certificate creation.
There should now be a new file, /etc/ssl/newcerts/01.pem, containing the same output. Copy and paste everything beginning with the line: -----BEGIN CERTIFICATE----- and continuing through the line: ----END CERTIFICATE----- lines to a file named after the hostname of the server where the certificate will be installed. For example mail.example.com.crt, is a nice descriptive name.
Subsequent certificates will be named 02.pem, 03.pem, etc.
Ubuntu Generate Public Key From Private Bank
Note
Replace mail.example.com.crt with your own descriptive name.
Finally, copy the new certificate to the host that needs it, and configure the appropriate applications to use it. The default location to install certificates is /etc/ssl/certs. This enables multiple services to use the same certificate without overly complicated file permissions.
For applications that can be configured to use a CA certificate, you should also copy the /etc/ssl/certs/cacert.pem file to the /etc/ssl/certs/ directory on each server.
References
The Wikipedia HTTPS page has more information regarding HTTPS.
For more information on OpenSSL see the OpenSSL Home Page.
Also, O’Reilly’s Network Security with OpenSSL is a good in-depth reference.