Using Openssl To Create Keys For Mac

Enter file in which to save the key (/home/youruser/.ssh/id rsa): Leave this empty to create the key in the default location, which is /home/youruser/.ssh/ idrsa. The public key file will be created in the very same location, and with the same name, but with the.PUB extension. Afterwards you will be prompted to choose a password. Create a hashed MAC using 'key'. Create MAC (keyed Message Authentication Code). The most popular MAC algorithm is HMAC (hash-based MAC), but there are other MAC algorithms which are not based on hash, for instance gost-mac algorithm, supported by ccgost engine. MAC keys and other options should be set via -macopt parameter. The examples below use the new EVPDigestSign. and EVPDigestVerify. functions to demonstarte signing and verification. The first example uses an HMAC, and the second example uses RSA key pairs. Additionally, the code for the examples are available for download. Note: CMAC is only supported since the version 1.1.0 of OpenSSL. The first step to obtaining an SSL certificate is using OpenSSL to create a certificate signing request (CSR) that can be sent to a Certificate Authority (CA) (e.g., DigiCert). The CSR contains the common name (s) you want your certificate to secure, information about your company, and your public key.

If you want to convert your website from HTTP to HTTPS, you need to get a SSL certificate from a valid organization like Verisign or Thawte. You can also generate self signed SSL certificate for testing purpose.

In this article, let us review how to generate private key file (server.key), certificate signing request file (server.csr) and webserver certificate file (server.crt) that can be used on Apache server with mod_ssl.

Key, CSR and CRT File Naming Convention

I typically like to name the files with the domain name of the HTTPS URL that will be using this certificate. This makes it easier to identify and maintain.

Instead of server.key, I use www.thegeekstuff.com.key
Instead of server.csr, I use www.thegeekstuff.com.csr
Instead of server.crt, I use www.thegeekstuff.com.crt

1. Generate Private Key on the Server Running Apache + mod_ssl

Openssl Create Public Key From Private Key

First, generate a private key on the Linux server that runs Apache webserver using openssl command as shown below.

The generated private key looks like the following.

2. Generate a Certificate Signing Request (CSR)

Using the key generate above, you should generate a certificate request file (csr) using openssl as shown below.

3. Generate a Self-Signed SSL Certificate

For testing purpose, you can generate a self-signed SSL certificate that is valid for 1 year using openssl command as shown below.

You can use this method to generate Apache SSL Key, CSR and CRT file in most of the Linux, Unix systems including Ubuntu, Debian, CentOS, Fedora and Red Hat.

4. Get a Valid Trial SSL Certificate (Optional)

Instead of signing it youself, you can also generate a valid trial SSL certificate from thawte. i.e Before spending the money on purchasing a certificate, you can also get a valid fully functional 21 day trial SSL certificates from Thawte. Once this valid certificate works, you can either decide to purchase it from Thawte or any other SSL signing organization.

This step is optional and not really required. For testing purpose, you can always use the self-signed certificate that was generated from the above step.

Go to Thwate trial certificate request page and do the following:

Select “SSL Web Server Certificate (All servers)” under the “select your trial certificate”.
Do not check the PKCS #7 check-box under the “configure certificate”
Copy/Paste the *.csr file that you generate above in the textbox under “certificate signing request (CSR)”
Click on next at the bottom, which will give you a 21-day free trial certificate.

Copy/Paste the trial certificate to the www.thegeekstuff.com.crt file as shown below.

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< Cryptography

Download and install the OpenSSL runtimes. If you are running Windows, grab the Cygwin package.

OpenSSL can generate several kinds of public/private keypairs.RSA is the most common kind of keypair generation.^[1]

Other popular ways of generating RSA public key / private key pairs include PuTTYgen and ssh-keygen.^[2]^[3]

Generate an RSA keypair with a 2048 bit private key[edit]

Execute command: 'openssl genpkey -algorithm RSA -out private_key.pem -pkeyopt rsa_keygen_bits:2048'^[4] (previously “openssl genrsa -out private_key.pem 2048”)

e.g.

Make sure to prevent other users from reading your key by executing chmod go-r private_key.pem afterward.

Extracting the public key from an RSA keypair[edit]

Openssl Create Key Pair

Execute command: 'openssl rsa -pubout -in private_key.pem -out public_key.pem'

e.g.

A new file is created, public_key.pem, with the public key.

It is relatively easy to do some cryptographic calculations to calculate the public key from the prime1 and prime2 values in the public key file.However, OpenSSL has already pre-calculated the public key and stored it in the private key file.So this command doesn't actually do any cryptographic calculation -- it merely copies the public key bytes out of the file and writes the Base64 PEM encoded version of those bytes into the output public key file.^[5]

Viewing the key elements[edit]

Execute command: 'openssl rsa -text -in private_key.pem'

All parts of private_key.pem are printed to the screen. This includes the modulus (also referred to as public key and n), public exponent (also referred to as e and exponent; default value is 0x010001), private exponent, and primes used to create keys (prime1, also called p, and prime2, also called q), a few other variables used to perform RSA operations faster, and the Base64 PEM encoded version of all that data.^[6](The Base64 PEM encoded version of all that data is identical to the private_key.pem file).

Password-less login[edit]

Often a person will set up an automated backup process that periodically backs up all the content on one 'working' computer onto some other 'backup' computer.

Because that person wants this process to run every night, even if no human is anywhere near either one of these computers, using a 'password-protected' private key won't work -- that person wants the backup to proceed right away, not wait until some human walks by and types in the password to unlock the private key.Many of these people generate 'a private key with no password'.^[7]Some of these people, instead, generate a private key with a password,and then somehow type in that password to 'unlock' the private key every time the server reboots so that automated toolscan make use of the password-protected keys.^[8]^[3]

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