Openssl encrypt private key file

For example, a SAN certificate can include the domain www. Wildcard certificates can be used for a domain, including all of its subdomains. The main difference is that instead of it being issued for a specific FQDN, wildcard certificates are used for a wide range of subdomains. CAs have diversified certificate validation levels in response to a growing demand for certificates.

Some organizations use SSL just for encryption, while others want to show their customers that they are a trusted company. Different needs have resulted in different certificate validation levels. This type of SSL certificate is ideal for securing blogs, social media apps, and personal websites. The certificate authority does not guarantee for an organization's identity, and only domain ownership is verified. The certificate authority verifies domain ownership and conducts a thorough investigation of the organization associated with the EV certificate.

Strict rules are followed when reviewing an extended validation request, and the CA has to verify the following:. How to generate a certificate signing request solely depends on the platform you're using and the particular tool of choice.

Red Hat release 7. To read more about this, see OpenSSL's documentation. To check whether OpenSSL is installed on a yum server e. If your output format differs, it means that OpenSSL is not installed on your server.

Run the following command to install OpenSSL:. A certificate signing request CSR contains the most vital information about your organization and domain. However, that is not a strict rule. You can generate a CSR and key pair on one server and install the certificate on another. However, that makes things more complicated. We shall cover that scenario as well.

Note : A certificate signing request CSR is an encrypted block of text that includes your organization's information, such as country, email address, fully qualified domain name, etc. Secure Socket Layer SSL uses two long strings of randomly generated numbers, which are known as private and public keys. A public key is available to the public domain as it is a part of your SSL certificate and is made known to your server.

The private key must correspond to the CSR it was generated with and, ultimately, it needs to match the certificate created from the CSR. If the private key is missing, it could mean that the SSL certificate is not installed on the same server which generated the Certificate Signing Request. Please note there are certain naming conventions to be considered. Certificate signing requests CSR are generated with a pair of keys — a public and private key.

Only the public key is sent to a Certificate Authority and included in the SSL certificate, and it works together with your private key to encrypt the connection. Anyone can have access to your public key, and it verifies that the SSL certificate is authentic. A private key is a block of encoded text which, together with the certificate, verifies the secure connection between two machines.

It must not be publicly accessed, and it shouldn't be sent to the CA. The integrity of a certificate relies on the fact that only you know the private key. If ever compromised or lost, re-key your certificate with a new private key as soon as possible. Most CAs do not charge you for this service. Note : Most key pairs are bits. Even though bits key pairs are more secure, they slow down SSL handshakes and put a strain on server processors.

Due to this, most websites still use bit key pairs. The first thing to do would be to generate a bit RSA key pair locally. This pair will contain both your private and public key. Once you have generated a CSR with a key pair, it is challenging to see what information it contains as it will not be in a human-readable format.

It is advised to decode the CSR and verify that it contains the right information about your organization before it's sent off to a certificate authority. There are a lot of CSR decoders on the web that can help you do the same just by copy-pasting the content of your CSR file.

It is recommended to issue a new private key whenever you are generating a CSR. If, for any reason, you need to generate a certificate signing request for an existing private key, use the following OpenSSL command:. One unlikely scenario in which this may come in handy is if you need to renew your existing certificate, but neither you nor your certificate authority have the original CSR. This will extract information about your domain and organization from the SSL certificate and use it to create a new CSR, thus saving you time.

A self-signed certificate is usually used for test and development environments and on an intranet. Transfer file. Transfer the public key as well presumably inside the application bundle. To extract the original text and verify the signature, run. If it's more convenient, you can transfer file itself, and produce a separate signature file which is called a detached signature. To produce the detached signature:. You can additionally encrypt the file with the -e option. Of course this means that you need a separate key pair, where the recipient specified with the -r option has the private key and the producer has the public key.

You're speaking of an app. That means you probably want to use a library, not a command line. I'm sure there are more, these are just the most popular solutions. Most of these libraries have bindings for other languages, too, in case you're not using C. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How to encrypt a file with private key Ask Question. Asked 5 years, 6 months ago. Active 3 months ago. Viewed 27k times. Improve this question. Gilles 'SO- stop being evil' k gold badges silver badges bronze badges. NoTrust NoTrust 1 1 gold badge 1 1 silver badge 7 7 bronze badges. What you're describing sounds like signing making sure the file was created by somebody who knows the private key , not encrypting making sure only somebody with the private key can read it?

PHP also has a function for encrypting with a private key. I have not used it myself, but did want to share it here. Add a comment. Active Oldest Votes. Use OpenSSL to do that. Improve this answer. Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs. Because of how the RSA algorithm works it is not possible to encrypt large files.

If you create a key of n bits, then the file you want to encrypt must not larger than n minus 11 bits. The most effective use of RSA crypto is to encrypt a random generated password, then encrypt the file with the password using symmetric crypto. If the file is larger then the key size the encryption command will fail:. We generate a random file and use that as the key to encrypt the large file with symmetric crypto. That random file acts as the password so to say. We encrypt the large file with the small password file as password.

Then we send the encrypted file and the encrypted key to the other party and then can decrypt the key with their public key, the use that key to decrypt the large file. The key is just a string of random bytes.