Class: Redwood::CryptoManager

Inherits:
Object
  • Object
show all
Includes:
Singleton
Defined in:
lib/sup/crypto.rb

Defined Under Namespace

Classes: Error

Constant Summary collapse

OUTGOING_MESSAGE_OPERATIONS = 
OrderedHash.new(
  [:sign, "Sign"],
  [:sign_and_encrypt, "Sign and encrypt"],
  [:encrypt, "Encrypt only"]
)

Instance Method Summary collapse

Methods included from Singleton

included

Constructor Details

#initialize ⇒ CryptoManager

Returns a new instance of CryptoManager.



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# File 'lib/sup/crypto.rb', line 58

def initialize
  @mutex = Mutex.new

  @not_working_reason = nil

  # test if the gpgme gem is available
  @gpgme_present =
    begin
      begin
        GPGME.check_version({:protocol => GPGME::PROTOCOL_OpenPGP})
        true
      rescue GPGME::Error
        false
      end
    rescue NameError
      false
    end

  unless @gpgme_present
    @not_working_reason = ['gpgme gem not present', 
      'Install the gpgme gem in order to use signed and encrypted emails']
    return
  end

  # if gpg2 is available, it will start gpg-agent if required
  if (bin = `which gpg2`.chomp) =~ /\S/
    GPGME.set_engine_info GPGME::PROTOCOL_OpenPGP, bin, nil
  else
    # check if the gpg-options hook uses the passphrase_callback
    # if it doesn't then check if gpg agent is present
    gpg_opts = HookManager.run("gpg-options", 
                             {:operation => "sign", :options => {}}) || {}
    if gpg_opts[:passphrase_callback].nil?
      if ENV['GPG_AGENT_INFO'].nil?
        @not_working_reason = ["Environment variable 'GPG_AGENT_INFO' not set, is gpg-agent running?",
                           "If gpg-agent is running, try $ export `cat ~/.gpg-agent-info`"]
        return
      end

      gpg_agent_socket_file = ENV['GPG_AGENT_INFO'].split(':')[0]
      unless File.exist?(gpg_agent_socket_file)
        @not_working_reason = ["gpg-agent socket file #{gpg_agent_socket_file} does not exist"]
        return
      end

      s = File.stat(gpg_agent_socket_file)
      unless s.socket?
        @not_working_reason = ["gpg-agent socket file #{gpg_agent_socket_file} is not a socket"]
        return
      end
    end
  end
end

Instance Method Details

#decrypt(payload, armor = false) ⇒ Object

returns decrypted_message, status, desc, lines



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# File 'lib/sup/crypto.rb', line 257

def decrypt payload, armor=false # a RubyMail::Message object
  return unknown_status(@not_working_reason) unless @not_working_reason.nil?

  gpg_opts = {:protocol => GPGME::PROTOCOL_OpenPGP}
  gpg_opts = HookManager.run("gpg-options",
                             {:operation => "decrypt", :options => gpg_opts}) || gpg_opts
  ctx = GPGME::Ctx.new(gpg_opts)
  cipher_data = GPGME::Data.from_str(format_payload(payload))
  plain_data = GPGME::Data.empty
  begin
    ctx.decrypt_verify(cipher_data, plain_data)
  rescue GPGME::Error => exc
    return Chunk::CryptoNotice.new(:invalid, "This message could not be decrypted", gpgme_exc_msg(exc.message))
  end
  begin
    sig = self.verified_ok? ctx.verify_result
  rescue ArgumentError => exc
    sig = unknown_status [gpgme_exc_msg(exc.message)]
  end
  plain_data.seek(0, IO::SEEK_SET)
  output = plain_data.read
  output.force_encoding Encoding::ASCII_8BIT if output.respond_to? :force_encoding

  ## TODO: test to see if it is still necessary to do a 2nd run if verify
  ## fails.
  #
  ## check for a valid signature in an extra run because gpg aborts if the
  ## signature cannot be verified (but it is still able to decrypt)
  #sigoutput = run_gpg "#{payload_fn.path}"
  #sig = self.old_verified_ok? sigoutput, $?

  if armor
    msg = RMail::Message.new
    # Look for Charset, they are put before the base64 crypted part
    charsets = payload.body.split("\n").grep(/^Charset:/)
    if !charsets.empty? and charsets[0] =~ /^Charset: (.+)$/
      output = Iconv.easy_decode($encoding, $1, output)
    end
    msg.body = output
  else
    # It appears that some clients use Windows new lines - CRLF - but RMail
    # splits the body and header on "\n\n". So to allow the parse below to
    # succeed, we will convert the newlines to what RMail expects
    output = output.gsub(/\r\n/, "\n")
    # This is gross. This decrypted payload could very well be a multipart
    # element itself, as opposed to a simple payload. For example, a
    # multipart/signed element, like those generated by Mutt when encrypting
    # and signing a message (instead of just clearsigning the body).
    # Supposedly, decrypted_payload being a multipart element ought to work
    # out nicely because Message::multipart_encrypted_to_chunks() runs the
    # decrypted message through message_to_chunks() again to get any
    # children. However, it does not work as intended because these inner
    # payloads need not carry a MIME-Version header, yet they are fed to
    # RMail as a top-level message, for which the MIME-Version header is
    # required. This causes for the part not to be detected as multipart,
    # hence being shown as an attachment. If we detect this is happening,
    # we force the decrypted payload to be interpreted as MIME.
    msg = RMail::Parser.read output
    if msg.header.content_type =~ %r{^multipart/} && !msg.multipart?
      output = "MIME-Version: 1.0\n" + output
      output.force_encoding Encoding::ASCII_8BIT if output.respond_to? :force_encoding
      msg = RMail::Parser.read output
    end
  end
  notice = Chunk::CryptoNotice.new :valid, "This message has been decrypted for display"
  [notice, sig, msg]
end

#encrypt(from, to, payload, sign = false) ⇒ Object 



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# File 'lib/sup/crypto.rb', line 143

def encrypt from, to, payload, sign=false
  return unknown_status(@not_working_reason) unless @not_working_reason.nil?

  gpg_opts = {:protocol => GPGME::PROTOCOL_OpenPGP, :armor => true, :textmode => true}
  if sign
    gpg_opts.merge!(gen_sign_user_opts(from)) 
    gpg_opts.merge!({:sign => true})
  end
  gpg_opts = HookManager.run("gpg-options",
                             {:operation => "encrypt", :options => gpg_opts}) || gpg_opts
  recipients = to + [from]
  recipients = HookManager.run("gpg-expand-keys", { :recipients => recipients }) || recipients
  begin
    cipher = GPGME.encrypt(recipients, format_payload(payload), gpg_opts)
  rescue GPGME::Error => exc
    raise Error, gpgme_exc_msg(exc.message)
  end

  # if the key (or gpg-agent) is not available GPGME does not complain 
  # but just returns a zero length string. Let's catch that
  if cipher.length == 0
    raise Error, gpgme_exc_msg("GPG failed to generate cipher text: check that gpg-agent is running and your key is available.")
  end

  encrypted_payload = RMail::Message.new
  encrypted_payload.header["Content-Type"] = "application/octet-stream"
  encrypted_payload.header["Content-Disposition"] = 'inline; filename="msg.asc"'
  encrypted_payload.body = cipher

  control = RMail::Message.new
  control.header["Content-Type"] = "application/pgp-encrypted"
  control.header["Content-Disposition"] = "attachment"
  control.body = "Version: 1\n"

  envelope = RMail::Message.new
  envelope.header["Content-Type"] = 'multipart/encrypted; protocol=application/pgp-encrypted'

  envelope.add_part control
  envelope.add_part encrypted_payload
  envelope
end

#have_crypto? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sup/crypto.rb', line 112

def have_crypto?; @not_working_reason.nil? end

#sign(from, to, payload) ⇒ Object 



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# File 'lib/sup/crypto.rb', line 114

def sign from, to, payload
  return unknown_status(@not_working_reason) unless @not_working_reason.nil?

  gpg_opts = {:protocol => GPGME::PROTOCOL_OpenPGP, :armor => true, :textmode => true}
  gpg_opts.merge!(gen_sign_user_opts(from))
  gpg_opts = HookManager.run("gpg-options", 
                             {:operation => "sign", :options => gpg_opts}) || gpg_opts

  begin
    sig = GPGME.detach_sign(format_payload(payload), gpg_opts)
  rescue GPGME::Error => exc
    raise Error, gpgme_exc_msg(exc.message)
  end

  # if the key (or gpg-agent) is not available GPGME does not complain 
  # but just returns a zero length string. Let's catch that
  if sig.length == 0
    raise Error, gpgme_exc_msg("GPG failed to generate signature: check that gpg-agent is running and your key is available.")
  end

  envelope = RMail::Message.new
  envelope.header["Content-Type"] = 'multipart/signed; protocol=application/pgp-signature'

  envelope.add_part payload
  signature = RMail::Message.make_attachment sig, "application/pgp-signature", nil, "signature.asc"
  envelope.add_part signature
  envelope
end

#sign_and_encrypt(from, to, payload) ⇒ Object 



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# File 'lib/sup/crypto.rb', line 185

def sign_and_encrypt from, to, payload
  encrypt from, to, payload, true
end

#verified_ok?(verify_result) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sup/crypto.rb', line 189

def verified_ok? verify_result
  valid = true
  unknown = false
  all_output_lines = []
  all_trusted = true

  verify_result.signatures.each do |signature|
    output_lines, trusted = sig_output_lines signature
    all_output_lines << output_lines
    all_output_lines.flatten!
    all_trusted &&= trusted

    err_code = GPGME::gpgme_err_code(signature.status)
    if err_code == GPGME::GPG_ERR_BAD_SIGNATURE
      valid = false
    elsif err_code != GPGME::GPG_ERR_NO_ERROR
      valid = false
      unknown = true
    end
  end

  if valid || !unknown
    summary_line = simplify_sig_line(verify_result.signatures[0].to_s, all_trusted)
  end

  if all_output_lines.length == 0
    Chunk::CryptoNotice.new :valid, "Encrypted message wasn't signed", all_output_lines
  elsif valid
    if all_trusted
      Chunk::CryptoNotice.new(:valid, summary_line, all_output_lines)
    else
      Chunk::CryptoNotice.new(:valid_untrusted, summary_line, all_output_lines)
    end
  elsif !unknown
    Chunk::CryptoNotice.new(:invalid, summary_line, all_output_lines)
  else
    unknown_status all_output_lines
  end
end

#verify(payload, signature, detached = true) ⇒ Object

both RubyMail::Message objects



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# File 'lib/sup/crypto.rb', line 229

def verify payload, signature, detached=true # both RubyMail::Message objects
  return unknown_status(@not_working_reason) unless @not_working_reason.nil?

  gpg_opts = {:protocol => GPGME::PROTOCOL_OpenPGP}
  gpg_opts = HookManager.run("gpg-options",
                             {:operation => "verify", :options => gpg_opts}) || gpg_opts
  ctx = GPGME::Ctx.new(gpg_opts)
  sig_data = GPGME::Data.from_str signature.decode
  if detached
    signed_text_data = GPGME::Data.from_str(format_payload(payload))
    plain_data = nil
  else
    signed_text_data = nil
    plain_data = GPGME::Data.empty
  end
  begin
    ctx.verify(sig_data, signed_text_data, plain_data)
  rescue GPGME::Error => exc
    return unknown_status [gpgme_exc_msg(exc.message)]
  end
  begin
    self.verified_ok? ctx.verify_result
  rescue ArgumentError => exc
    return unknown_status [gpgme_exc_msg(exc.message)]
  end
end