kesire

kesire is a simple shell script (~200 lines of code) designed to simplify the process of generating a private key and a Certificate Signing Request (CSR) using OpenSSL. The script's name is derived from key signing request, as that is its primary purpose.

By simply running the script, users can quickly generate a private key and a CSR with minimal input, making it easy to request a certificate from a Certificate Authority.

The script is compatible with both Linux and macOS operating systems and requires OpenSSL to be installed on the user's machine.

usage

Running kesire is as simple as typing ./kesire.sh in a shell.

The script can be used in both interactive and non-interactive modes. After running kesire, two (or three) files with the chosen Common Name (CN) as a prefix will be produced. It is important to note that if other files with the same name prefix already exist in the same directory where the script is run, they will be overwritten by the newly generated files.

Therefore, it is recommended to either run kesire in an empty directory or use a unique CN for each new private key and certificate signing request.

interactive mode

In interactive mode, the script prompts you for the necessary information, such as the Common Name (CN), Organization (O), and Country (C) for the certificate. After you enter the information, kesire creates the key and CSR files for you.

Here it is shown how to get and use kesire for generating a key and a CSR for the example domain example.xyz:

mkdir example.xyz && cd example.xyz && \
wget https://raw.githubusercontent.com/filippolauria/kesire/main/kesire.sh && \
chmod +x kesire.sh && ./kesire.sh

non-interactive mode

In non-interactive mode, you can customize the certificate request by editing the script's variables section. This section, located at the beginning of the script (lines 45 through 80), includes variables such as the key length, the common name, organization name, and others.

By using a text editor you can modify these variables and customize the certificate request according to your needs without having to interact with the script during its execution. This feature makes kesire a useful tool for automating the generation of certificate requests.

Alternatively, you can use the sed tool to modify the script in place and automate the editing process. For example, you can use the following command to download, modify and execute the script for generating a key and a CSR for the example domain example.xyz:

mkdir example.xyz && cd example.xyz && \
wget https://raw.githubusercontent.com/filippolauria/kesire/main/kesire.sh && \
export S=45 E=80 && \
sed -Ei "${S},${E}s/^ACCEPT_DISCLAIMER=.*/ACCEPT_DISCLAIMER='yes'/" kesire.sh && \
sed -Ei "${S},${E}s/^COUNTRY_CODE=.*/COUNTRY_CODE='IT'/" kesire.sh && \
sed -Ei "${S},${E}s/^STATE_OR_PROVINCE=.*/STATE_OR_PROVINCE='Lazio'/" kesire.sh && \
sed -Ei "${S},${E}s/^LOCALITY=.*/LOCALITY='Rome'/" kesire.sh && \
sed -Ei "${S},${E}s/^ORGANIZATION=.*/ORGANIZATION='My Organization'/" kesire.sh && \
sed -Ei "${S},${E}s/^ORGANIZATIONAL_UNIT=.*/ORGANIZATIONAL_UNIT='ICT Unit'/" kesire.sh && \
sed -Ei "${S},${E}s/^EMAIL=.*/EMAIL='myemail@example.xyz'/" kesire.sh && \
sed -Ei "${S},${E}s/^CN=.*/CN='example.xyz'/" kesire.sh && \
sed -Ei "${S},${E}s/^USE_ALT_NAMES=.*/USE_ALT_NAMES='yes'/" kesire.sh && \
sed -Ei "${S},${E}s/^ALT_NAMES=.*/ALT_NAMES='fqdn1.example.xyz, fqdn2.example.xyz, fqdn3.example.xyz'/" kesire.sh && \
sed -Ei "${S},${E}s/^ENCRYPT_KEY=.*/ENCRYPT_KEY='no'/" kesire.sh && \
unset S E && \
chmod +x kesire.sh && ./kesire.sh

Keep in mind that, since the script is modified in place, it's important to use a new copy of the script for every new private key and CSR you generate.