Let’s break down what this script does in detail. The script is named openssl_verify_certificates.sh, authored by GJS (homelab-alpha), and its purpose is to verify SSL/TLS certificates by checking them against their corresponding chain of trust. It performs various checks, including verification of root, intermediate, and individual certificates, with support for a verbose mode to provide detailed output during the verification process.

Here’s a detailed explanation:

Script Metadata

  • Filename: openssl_verify_certificates.sh
  • Author: GJS (homelab-alpha)
  • Date: June 9, 2024
  • Version: 1.0.1
  • Description: This script verifies SSL/TLS certificates by checking them against their corresponding chain of trust. It includes options for verbose output for detailed verification processes.
  • RAW Script: openssl_verify_certificates.sh

Detailed Explanation

Define Directories

The script sets the paths for the certificates, intermediate certificates, and root certificates:

# Define directories
certificates_dir="$HOME/ssl/certificates/certs"
intermediate_dir="$HOME/ssl/intermediate/certs"
root_dir="${HOME}/ssl/root/certs"

Default Settings and Helper Functions

The script initializes the verbose mode to false and defines helper functions to print section headers and usage information:

# Default to non-verbose mode
verbose=false

# Function to print section headers.
print_section_header() {
  echo ""
  echo ""
  echo -e "\e[38;2;102;204;204m=== $1 ===\e[0m"
}

# Function to print usage information
print_usage() {
  echo "Usage: $0 [-v|--verbose]"
  echo "  -v, --verbose    Enable verbose mode for detailed output during verification"
  exit 1
}

Certificate Verification Function

The main function for verifying certificates uses openssl to check the certificate against the chain of trust:

# Function to perform certificate verification
verify_certificate() {
  local cert_path="$1"
  local chain_path="$2"

  # Print verification header
  echo "Verifying $cert_path against $chain_path:"

  # Run openssl command and capture the result
  result=$(openssl verify -CAfile "$chain_path" "$cert_path" 2>&1)

  # Check the result and print in color
  if [[ "$result" == *"OK"* ]]; then
    ok_part=$(echo "$result" | grep -o "OK")
    result_colored="${result/OK/$'\e[32m'$ok_part$'\e[0m'}"
    echo -e "$result_colored"
  else
    echo -e "$result"
  fi
## Detailed Explanation

Command-Line Options Parsing

The script parses command-line options to enable verbose mode if specified:

# Parse command line options
while [[ $# -gt 0 ]]; do
  case "$1" in
  -v | --verbose)
    verbose=true
    shift
    ;;
  *)
    print_usage
    ;;
  esac
done

Prompt for Certificate Name

The script prompts the user for the name of the certificate to verify:

# Prompt user for the certificate name
read -r -p "Enter the name of the certificate to verify: " file_name

Certificate Verification Process

The script verifies various types of certificates, printing section headers for each step:

# Verify Trusted Identity against Trusted Identity.
print_section_header "Verify Trusted Identity against Trusted Identity"
verify_certificate "$root_dir/trusted-id.pem" "$root_dir/trusted-id.pem"

# Verify Root Certificate Authority against Trusted Identity.
print_section_header "Verify Root Certificate Authority against Trusted Identity"
verify_certificate "$root_dir/root_ca.pem" "$root_dir/trusted-id.pem"

# Verify Root Certificate Authority Chain against Trusted Identity.
print_section_header "Verify Root Certificate Authority Chain against Trusted Identity"
verify_certificate "$root_dir/root_ca_chain_bundle.pem" "$root_dir/trusted-id.pem"

# Verify Intermediate Certificate Authority against the Root Certificate Authority.
print_section_header "Verify Intermediate Certificate Authority against the Root Certificate Authority"
verify_certificate "$intermediate_dir/ca.pem" "$root_dir/root_ca_chain_bundle.pem"

# Verify Intermediate Certificate Authority Chain against the Root Certificate Authority Chain.
print_section_header "Verify Intermediate Certificate Authority Chain against the Root Certificate Authority Chain"
verify_certificate "$intermediate_dir/ca_chain_bundle.pem" "$root_dir/root_ca_chain_bundle.pem"

# Verify Certificate against the Certificate Chain.
print_section_header "Verify Certificate against the Certificate Chain"
verify_certificate "$certificates_dir/${file_name}.pem" "$certificates_dir/${file_name}_chain_bundle.pem"

# Verify Certificate against the Intermediate Certificate Chain.
print_section_header "Verify Certificate against the Intermediate Certificate Chain"
verify_certificate "$certificates_dir/${file_name}.pem" "$intermediate_dir/ca_chain_bundle.pem"

# Verify Certificate Chain against the Intermediate Certificate Chain.
print_section_header "Verify Certificate Chain against the Intermediate Certificate Chain"
verify_certificate "$certificates_dir/${file_name}_chain_bundle.pem" "$intermediate_dir/ca_chain_bundle.pem"

# Verify Haproxy Certificate Chain against the Intermediate Certificate Chain.
print_section_header "Verify Haproxy Certificate Chain against the Intermediate Certificate Chain"
verify_certificate "$certificates_dir/${file_name}_haproxy.pem" "$intermediate_dir/ca_chain_bundle.pem"

Exit the Script

Finally, the script exits successfully:

# Exit successfully
exit 0

Conclusion

This script is a robust tool for verifying SSL/TLS certificates, ensuring they are correctly chained to trusted root and intermediate certificates. The use of the openssl command ensures thorough verification, and the optional verbose mode provides additional detail for debugging or inspection purposes.

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Last updated 01 Sep 2024, 10:22 CEST . history