p12-to-pem

#!/usr/bin/env ruby
# frozen_string_literal: true

# Copyright (c) 2011 The University of Manchester, UK.
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#    software without specific prior written permission.
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# Author: Robert Haines

require 'rubygems'
require 'openssl'
require 'optparse'
require 'io/console'

options = { cipher: 'des3' }
opts = OptionParser.new do |opt|
  opt.banner = 'Usage: p12-to-pem [options] p12-file'
  opt.separator '  Convert the supplied p12 file into pem format where ' \
    '[options] can be:'
  opt.on('-p PASSWORD', '--password=PASSWORD', 'The import password for the ' \
    'p12 file. If not specified it will be asked for.') do |val|
    options[:password] = val.chomp
  end
  opt.on('-R', '--reuse-password', 'Use the same password for pem export as ' \
    'was used for the p12 import.') do
    options[:reuse] = true
  end
  opt.on('-c CIPHER', '--cipher=CIPHER', 'Set the cipher to be used for ' \
    "encrypting the output. Use 'none' for no encryption. Default " \
    "'#{options[:cipher]}'.") do |val|
    options[:cipher] = val.chomp
  end
  opt.on('-l', '--list-ciphers', 'List available ciphers for output.') do
    list = OpenSSL::Cipher.ciphers
    puts list[(list.length / 2)..-1]
    exit
  end
  opt.on_tail('-h', '-?', '--help', 'Show this help message.') do
    puts opts
    exit
  end
  opt.on_tail('-v', '--version', 'Show the version.') do
    puts '2.0'
    exit
  end
end

opts.parse!

infile = ARGV.shift
if infile.nil?
  warn opts
  exit(1)
else
  data = File.read(infile.chomp)
end

password = options[:password]
begin
  p12 = OpenSSL::PKCS12.new(data, password)
rescue StandardError
  password = $stdin.getpass('Enter Import Password:')
  retry
end

password = nil unless options[:reuse]

cert = OpenSSL::X509::Certificate.new(p12.certificate)
key = OpenSSL::PKey::RSA.new(p12.key)

if options[:cipher] == 'none'
  cipher = nil
  password = nil
else
  cipher = OpenSSL::Cipher.new(options[:cipher])
end

puts cert
puts key.to_pem(cipher, password)