#!/usr/bin/env ruby
#
# Copyright © 2017 Jens Kuske <jenskuske@gmail.com>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#

# from https://gist.github.com/jemk/8e1006a44c7a2c796fc3fc2f74f7c6c3

require 'openssl'
require 'hexdump'

#key = OpenSSL::PKey::RSA.new(File.read(ARGV[0]))
key = OpenSSL::PKey::RSA.new(File.read("RSA.pem"))

n = key.params['n']
e = key.params['e']

print("n:\n")
print(n)
print("\n")

print("e\n")
print(e)
print("\n")

#Hexdump.dump(n)

if n.num_bits != 2048
	puts 'Need 2048-bit RSA key'
	exit false
end

n = [n.to_s(16)].pack('H*')
e = [e.to_s(16)].pack('H*')

print("hexdump n\n")
print(Hexdump.dump(n))
print("hexdump e\n" )
print(Hexdump.dump(e))


if n.length != 256
	puts 'fatal: n.length != 256 bytes'
	exit false
end

if e.length > 256
	puts 'fatal: e.length > 256 bytes'
	exit false
end

data = n + e.ljust(256, "\x91".b)

print("hexdump data\n" )
print(Hexdump.dump(data))

File.binwrite("rotpk_raw_data.bin", data)

rotpk = OpenSSL::Digest::SHA256.digest(data)

print("rotpk\n" )
print(Hexdump.dump(rotpk))



#
#require 'openssl'
#
#if ARGV.length < 3 || ARGV[2] != 'yes-i-know-that-burning-a-rotpk-might-brick-my-device'
#	puts 'Usage: mkrotpk public-key.pem rotpk.bin do-you-know-what-you-are-doing?'
#	exit false
#end
#
#key = OpenSSL::PKey::RSA.new(File.read(ARGV[0]))
#
#n = key.params['n']
#e = key.params['e']
#
#if n.num_bits != 2048
#	puts 'Need 2048-bit RSA key'
#	exit false
#end
#
#n = [n.to_s(16)].pack('H*')
#e = [e.to_s(16)].pack('H*')
#
#if n.length != 256
#	puts 'fatal: n.length != 256 bytes'
#	exit false
#end
#
#if e.length > 256
#	puts 'fatal: e.length > 256 bytes'
#	exit false
#end
#
#data = n + e.ljust(256, "\x91".b)
#rotpk = OpenSSL::Digest::SHA256.digest(data)
#
#File.binwrite(ARGV[1], rotpk)
#
#