Class: SharedSecret

Inherits:
Object
  • Object
show all
Defined in:
lib/shared_secret.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ SharedSecret

Returns a new instance of SharedSecret.



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# File 'lib/shared_secret.rb', line 14

def initialize(io)
  if ARGV.size == 0
    STDERR.puts "Please enter the message to be processed followd by ^D:"
  end
  @input = io.read
  @mode = encrypted_input? ? :decrypt : :encrypt
end

Instance Attribute Details

#mode ⇒ Object (readonly)

Returns the value of attribute mode.



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# File 'lib/shared_secret.rb', line 3

def mode
  @mode
end

Class Method Details

.run ⇒ Object 



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# File 'lib/shared_secret.rb', line 5

def self.run
  app = SharedSecret.new(ARGF)
  output = app.process
  label = "--- OUTPUT (#{app.mode}) ---"
  STDERR.puts label
  puts output
  STDERR.puts "-" * label.size
end

Instance Method Details

#decrypt(cypher) ⇒ Object 



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# File 'lib/shared_secret.rb', line 31

def decrypt(cypher)
  message = JSON.parse(@input.unpack('m')[0])['shared-secret']
  cipher = OpenSSL::Cipher::Cipher.new(message['cipher'])
  digest = OpenSSL::Digest::Digest.new(message['digest'])
  digest << prompt('secret key?')
  cipher.key = expand_key(digest.digest)
  if message['iv']
    cipher.iv = message['iv'].unpack('m')[0]
  else
    cipher.iv = expand_key(digest.digest)
  end
  cipher.decrypt
  cipher.update(message['message'].unpack('m')[0]) + cipher.final
end

#encrypt(text) ⇒ Object 



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# File 'lib/shared_secret.rb', line 46

def encrypt(text)
  cipher_algorithm = select_cipher
  cipher = OpenSSL::Cipher::Cipher.new(cipher_algorithm)
  # TODO: support more digest types including SHA256 and
  # cipher texts.
  digest = OpenSSL::Digest::Digest.new('sha1')
  digest << prompt('secret key?')
  cipher.key = expand_key(digest.digest)
  cipher.iv = expand_key(digest.digest)
  cipher.encrypt
  message = cipher.update(text) + cipher.final
  [{'shared-secret' => {
    'cipher' => cipher_algorithm,
    'digest' => 'sha1',
    'message' => [message].pack('m')
  }}.to_json].pack('m')
end

#process ⇒ Object 



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# File 'lib/shared_secret.rb', line 22

def process
  case @mode
  when :decrypt
    decrypt(@input)
  when :encrypt
    encrypt(@input)
  end
end

#select_cipher ⇒ Object 



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# File 'lib/shared_secret.rb', line 64

def select_cipher
  loop do
    algo = prompt('cipher algorithm (l to list)?', :string, 'bf')
    if algo == 'l'
      puts OpenSSL::Cipher.ciphers
      next
    end
    break algo
  end
end