canary.rb

# https://blog.spideroak.com/20140814060007-status-reports-transparency-overall-safety
# https://spideroak.com/canary
# https://en.wikipedia.org/wiki/Warrant_canary
# https://www.eff.org/deeplinks/2014/04/warrant-canary-faq
# https://en.wikipedia.org/wiki/National_security_letter
#
# SpiderOak now maintains a warrant canary so they can passively let their users know
# if they have been served a National Security Letter or other legal tool which
# prevents them from actively disclosing to their users that they are being coerced
# or forced into compromising the security or privacy of their userbase.
#
# If the canary has not been killed and you can still trust their service then you will
# be able to verify 3 valid PGP signatures against their canary.
#
# The signatures will be made every six months between:
# August 10 - August 15
# February 10 - February 15
#
# The default signing keys are listed below however they may be replaced or updated
# if one of the default signers goes rogue or leaves SpiderOak.
#
# Key ID: 0x1712D3E36F2F0403
# Primary key fingerprint: 0DAB 1518 36A3 CBBA 0362  FC17 1712 D3E3 6F2F 0403
#
# Key ID: 0xE435F15CA6B145F8
# Primary key fingerprint: B411 3438 B56B D51C D208  E17E E435 F15C A6B1 45F8
#
# Key ID: 0x132B9F2251131E5C
# Primary key fingerprint: DC1E FB15 4444 E4B5 2726  8430 132B 9F22 5113 1E5C
#
# Example output:
#
# Chip Black (SpiderOak Canary) <[email protected]> signed canary on August 11 2014 with key: 0DAB 1518 36A3 CBBA 0362  FC17 1712 D3E3 6F2F 0403
# Frank Sievertsen <[email protected]> signed canary on August 12 2014 with key: B411 3438 B56B D51C D208  E17E E435 F15C A6B1 45F8
# Tomas Touceda (SpiderOak canary) <[email protected]> signed canary on August 13 2014 with key: DC1E FB15 4444 E4B5 2726  8430 132B 9F22 5113 1E5C
# SpiderOak's Canary is alive and well!
#
# NOTE: This needs to have error handling added in various places, communicating with the network
# running GPG commands, handling if you actually do trust the signing keys, and the date ranges
# for the signature checking needs to be made more generic and the code should be refactored
# but its a start.

require 'open3'
require 'open-uri'
require 'tempfile'

class SpiderOakCanary
  CANARY_URL = 'https://spideroak.com/canary'
  DELIMITER = "-----BEGIN PGP SIGNATURE-----\n"
  DEFAULT_KEYS = [
    '0DAB 1518 36A3 CBBA 0362  FC17 1712 D3E3 6F2F 0403',
    'B411 3438 B56B D51C D208  E17E E435 F15C A6B1 45F8',
    'DC1E FB15 4444 E4B5 2726  8430 132B 9F22 5113 1E5C'
  ]

  def verify(out_stream)
    lines = open(CANARY_URL).readlines
    chunk_idx = 0
    chunks = lines.chunk { |line|
      DELIMITER == line ? chunk_idx+=1 : chunk_idx
    }.map { |chunk|
      chunk.last.join
    }
    canary, signatures = chunks.shift, chunks
    expected_signatures = {}

    canary_file = Tempfile.new('')
    canary_file.write(canary)
    canary_file.close

    signatures.each do |signature|
      command = "gpg --verify - #{canary_file.to_path}"
      stdin, stdout, stderr = Open3.popen3(command)
      stdin.puts signature
      stdin.close
      output = stderr.readlines

      signature_date = DateTime.parse(output[0][/made (.*) using/, 1])
      signer = output[1][/Good signature from \"(.*)\"/, 1]
      primary_key = output.select { |line| line.include?('Primary key') }.first
      key_fingerprint = primary_key[/fingerprint: (.*)/, 1]

      expected_signatures[key_fingerprint] = signature_date

      out_stream.puts "#{signer} signed canary on #{signature_date.strftime('%B %d %Y')} " +
        "with key: #{key_fingerprint}"
    end

    valid_signatures = DEFAULT_KEYS.select do |key|
      signature_date = expected_signatures[key]
      #
      # TODO: Automatically determine the appropriate date range of signatures
      # to check based on the current date or a passed in date.
      # Remove hardcoded date range below.
      #
      #current_month = Date.today.month
      #current_year = Date.today.year
      #start_date = DateTime.parse("10-#{current_month}-#{current_year}")
      #start_date = DateTime.parse("16-#{current_month}-#{current_year}")
      start_date = DateTime.parse("August 10, 2014")
      end_date = DateTime.parse("August 16, 2014")
      (start_date...end_date).cover? signature_date
    end.count

    if valid_signatures == 3
      out_stream.puts "SpiderOak's Canary is alive and well!"
    else
      out_stream.puts "Hrmmm SpiderOak's Canary seems to have died, consider your options."
    end

    canary_file.unlink
  end
end

# Run program if this file was executed,
# but not if file was just required
if $0 == __FILE__
  SpiderOakCanary.new.verify(STDOUT)
end

canary_spec.rb

require 'stringio'
require 'vcr'
require_relative 'canary'

VCR.configure do |c|
  c.cassette_library_dir = '.'
  c.hook_into :webmock
end

describe SpiderOakCanary, '#verify' do
  let(:output) { <<-OUTPUT }
Chip Black (SpiderOak Canary) <[email protected]> signed canary on August 11 2014 with key: 0DAB 1518 36A3 CBBA 0362  FC17 1712 D3E3 6F2F 0403
Frank Sievertsen <[email protected]> signed canary on August 12 2014 with key: B411 3438 B56B D51C D208  E17E E435 F15C A6B1 45F8
Tomas Touceda (SpiderOak canary) <[email protected]> signed canary on August 13 2014 with key: DC1E FB15 4444 E4B5 2726  8430 132B 9F22 5113 1E5C
SpiderOak's Canary is alive and well!
OUTPUT

  it 'writes output' do
    strio = StringIO.new
    VCR.use_cassette('spideroak') { described_class.new.verify(strio) }
    expect(strio.string).to eq output
  end
end

spideroak.yml

---
http_interactions:
- request:
    method: get
    uri: https://spideroak.com/canary
    body:
      encoding: US-ASCII
      string: ''
    headers:
      Accept-Encoding:
      - gzip;q=1.0,deflate;q=0.6,identity;q=0.3
      Accept:
      - "*/*"
      User-Agent:
      - Ruby
  response:
    status:
      code: 200
      message: OK
    headers:
      Server:
      - nginx
      Date:
      - Wed, 10 Sep 2014 06:37:46 GMT
      Content-Type:
      - text/plain; charset=utf8
      Content-Length:
      - '2376'
      Last-Modified:
      - Sun, 07 Sep 2014 19:58:37 GMT
      Connection:
      - keep-alive
      Expires:
      - Wed, 24 Sep 2014 06:37:46 GMT
      Cache-Control:
      - max-age=1209600
      Set-Cookie:
      - uid=AAAAKlQP8bqZBDEMEIazAg==; expires=Thu, 10-Sep-15 06:37:46 GMT; path=/
      Accept-Ranges:
      - bytes
    body:
      encoding: ASCII-8BIT
      string: !binary |-
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    http_version: 
  recorded_at: Wed, 10 Sep 2014 06:37:46 GMT
recorded_with: VCR 2.9.2