ca.info

Let’s break down what this script does in detail. The script is named ca.sh, authored by GJS (homelab-alpha), and its purpose is to facilitate the setup and management of an Intermediate Certificate Authority (CA). The script defines directory paths, renews database serial numbers, generates ECDSA keys, creates Certificate Signing Requests (CSRs), issues the intermediate certificate, and verifies the intermediate CA chain bundle. It ensures the validity and integrity of the generated keys, CSRs, and certificates.

Here’s a detailed explanation:

Script Metadata link

• Filename: ca.sh
• Author: GJS (homelab-alpha)
• Date: June 9, 2024
• Version: 1.0.1
• Description: This script manages an Intermediate Certificate Authority, handling key generation, CSR creation, certificate issuance, and verification processes.
• RAW Script: ca.sh

Detailed Explanation link

Functions link

1. print_cyan: This function is used to print text in cyan color for better readability in the terminal.

   print_cyan() {
     echo -e "\e[36m$1\e[0m" # \e[36m sets text color to cyan, \e[0m resets it
   }
   

   
   

2. generate_random_hex: This function generates a random hexadecimal value, which is used for serial numbers and CRL numbers.

   generate_random_hex() {
     openssl rand -hex 16
   }
   

   
   

3. print_section_header: This function prints section headers in cyan to clearly delineate different parts of the script.

   print_section_header() {
     echo ""
     echo ""
     echo -e "$(print_cyan "=== $1 === ")"
   }
   

Main Script Execution link

Define Directory Paths link

The script sets up necessary directory paths for the root and intermediate CA.

print_section_header "Define directory paths"
ssl_dir="$HOME/ssl"
root_dir="$ssl_dir/root"
intermediate_dir="$ssl_dir/intermediate"

Renew Database Serial Numbers link

It renews database serial numbers by generating random hex values and writing them to the respective serial files for the root, intermediate, and TSA directories.

print_section_header "Renew db serial numbers"
for dir in "$ssl_dir/root/db" "$intermediate_dir/db" "$ssl_dir/tsa/db"; do
  generate_random_hex >"$dir/serial"
done
generate_random_hex >"$ssl_dir/root/db/crlnumber"
generate_random_hex >"$intermediate_dir/db/crlnumber"

Generate ECDSA Key link

The script generates an ECDSA key using the secp384r1 curve and saves it to the private directory of the intermediate CA.

print_section_header "Generate ECDSA key"
openssl ecparam -name secp384r1 -genkey -out "$intermediate_dir/private/ca.pem"

Generate Certificate Signing Request (CSR) link

It creates a CSR for the intermediate CA using the generated ECDSA key and the configuration file.

print_section_header "Generate Certificate Signing Request (CSR)"
openssl req -new -sha384 -config "$intermediate_dir/ca.cnf" -key "$intermediate_dir/private/ca.pem" -out "$intermediate_dir/csr/ca.pem"

Generate Intermediate Certificate Authority link

The script then issues the intermediate certificate, valid for 1826 days, based on the CSR.

print_section_header "Generate Intermediate Certificate Authority"
openssl ca -config "$intermediate_dir/ca.cnf" -extensions v3_intermediate_ca -notext -batch -in "$intermediate_dir/csr/ca.pem" -days 1826 -out "$intermediate_dir/certs/ca.pem"

Create Intermediate Certificate Authority Chain Bundle link

It creates a chain bundle by concatenating the intermediate certificate and the root CA chain bundle.

print_section_header "Create Intermediate Certificate Authority Chain Bundle"
cat "$intermediate_dir/certs/ca.pem" "$root_dir/certs/root_ca_chain_bundle.pem" >"$intermediate_dir/certs/ca_chain_bundle.pem"

Verification Steps link

The script performs several verification steps to ensure the integrity and correctness of the certificates and keys.

1. Verify Intermediate CA against the Intermediate CA Chain Bundle

   print_section_header "Verify Intermediate Certificate Authority against the Intermediate Certificate Authority Chain Bundle"
   openssl verify -CAfile "$intermediate_dir/certs/ca_chain_bundle.pem" "$intermediate_dir/certs/ca.pem"
   

   
   

2. Verify Intermediate CA against Root CA Chain Bundle

   print_section_header "Verify Intermediate Certificate Authority against Root Certificate Authority Chain Bundle"
   openssl verify -CAfile "$root_dir/certs/root_ca_chain_bundle.pem" "$intermediate_dir/certs/ca.pem"
   

   
   

3. Verify Intermediate CA Chain Bundle against Root CA Chain Bundle

   print_section_header "Verify Intermediate Certificate Authority Chain Bundle against Root Certificate Authority Chain Bundle"
   openssl verify -CAfile "$root_dir/certs/root_ca_chain_bundle.pem" "$intermediate_dir/certs/ca_chain_bundle.pem"
   

Check Generated Files link

The script also includes steps to check the private key, CSR, intermediate CA certificate, and the CA chain bundle to verify their contents.

1. Check Private Key

   print_section_header "Check Private Key"
   openssl ecparam -in "$intermediate_dir/private/ca.pem" -text -noout
   

   
   

2. Check CSR

   print_section_header "Check Certificate Signing Request (CSR)"
   openssl req -text -noout -verify -in "$intermediate_dir/csr/ca.pem"
   

   
   

3. Check Intermediate CA

   print_section_header "Check Intermediate Certificate Authority"
   openssl x509 -in "$intermediate_dir/certs/ca.pem" -text -noout
   

   
   

4. Check CA Chain Bundle

   print_section_header "Check Intermediate Certificate Authority Chain Bundle"
   openssl x509 -in "$intermediate_dir/certs/ca_chain_bundle.pem" -text -noout
   

Conclusion link

This comprehensive script ensures that every step in setting up and managing an Intermediate Certificate Authority is performed correctly and securely, from key generation to certificate verification.