Class: SelfSDK::Crypto

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

Instance Method Summary collapse

Constructor Details

#initialize(client, device, storage_folder, storage_key) ⇒ Crypto

Returns a new instance of Crypto.



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# File 'lib/crypto.rb', line 7

def initialize(client, device, storage_folder, storage_key)
  @client = client
  @device = device
  @storage_key = storage_key
  @storage_folder = "#{storage_folder}/#{@client.jwt.key_id}"
  @lock_strategy = true
  @mode = "r+"

  if File.exist?()
    # 1a) if alice's account file exists load the pickle from the file
    @account = SelfCrypto::.from_pickle(File.read(), @storage_key)
  else
    # 1b-i) if create a new account for alice if one doesn't exist already
    @account = SelfCrypto::.from_seed(@client.jwt.key)

    # 1b-ii) generate some keys for alice and publish them
    @account.gen_otk(100)

    # 1b-iii) convert those keys to json
    keys = @account.otk['curve25519'].map{|k,v| {id: k, key: v}}.to_json

    # 1b-iv) post those keys to POST /v1/identities/<selfid>/devices/1/pre_keys/
    res = @client.post("/v1/apps/#{@client.jwt.id}/devices/#{@device}/pre_keys", keys)
    raise 'unable to push prekeys, please try in a few minutes' if res.code != 200

    # 1b-v) store the account to a file
    FileUtils.mkdir_p(@storage_folder)
    File.write(, @account.to_pickle(storage_key))
  end
end

Instance Method Details

#decrypt(message, sender, sender_device) ⇒ Object 



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# File 'lib/crypto.rb', line 101

def decrypt(message, sender, sender_device)
  f = nil
  ::SelfSDK.logger.debug("- [crypto] decrypting a message")
  session_file_name = session_path(sender, sender_device)

  if File.exist?(session_file_name)
    # Lock the session file
    f = File.open(session_file_name, @mode)
    f.flock(File::LOCK_EX)
  end

  ::SelfSDK.logger.debug("- [crypto] loading sessions")
  session_with_bob = get_inbound_session_with_bob(f, message)

  # 8) create a group session and set the identity of the account you're using
  ::SelfSDK.logger.debug("- [crypto] create a group session and set the identity of the account #{@client.jwt.id}:#{@device}")
  gs = SelfCrypto::GroupSession.new("#{@client.jwt.id}:#{@device}")

  # 9) add all recipients and their sessions
  ::SelfSDK.logger.debug("- [crypto] add all recipients and their sessions #{@sender}:#{@sender_device}")
  gs.add_participant("#{sender}:#{sender_device}", session_with_bob)

  # 10) decrypt the message ciphertext
  ::SelfSDK.logger.debug("- [crypto] decrypt the message ciphertext")
  pt = gs.decrypt("#{sender}:#{sender_device}", message).to_s

  # 11) store the session to a file
  ::SelfSDK.logger.debug("- [crypto] store the session to a file")

  pickle = session_with_bob.to_pickle(@storage_key)
  if !f.nil?
    f.rewind
    f.write(pickle)
    f.truncate(f.pos)
  else
    File.write(session_file_name, pickle)
  end

  pt
ensure
  # Unlock the session file
  f&.flock(File::LOCK_UN)
  f&.close
end

#encrypt(message, recipients) ⇒ Object 



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# File 'lib/crypto.rb', line 38

def encrypt(message, recipients)
  ::SelfSDK.logger.debug('- [crypto] encrypting a message')

  # create a group session and set the identity of the account youre using
  ::SelfSDK.logger.debug('- [crypto] create a group session and set the identity of the account youre using')
  gs = SelfCrypto::GroupSession.new("#{@client.jwt.id}:#{@device}")

  sessions = {}
  locks = {}
  ::SelfSDK.logger.debug('- [crypto] managing sessions with all recipients')

  recipients.each do |r|
    f = nil
    next if r[:id] == @client.jwt.id && r[:device_id] == @device

    session_file_name = session_path(r[:id], r[:device_id])
    session_with_bob = nil

    begin
      if File.exist?(session_file_name)
        # Lock the session file
        locks[session_file_name] = File.open(session_file_name, @mode)
        locks[session_file_name].flock(File::LOCK_EX)
      end
      session_with_bob = get_outbound_session_with_bob(locks[session_file_name], r[:id], r[:device_id])
    rescue => e
      ::SelfSDK.logger.warn("- [crypto]   there is a problem adding group participant #{r[:id]}:#{r[:device_id]}, skipping...")
      ::SelfSDK.logger.warn("- [crypto] #{e}")
      next
    end

    ::SelfSDK.logger.debug("- [crypto]   adding group participant #{r[:id]}:#{r[:device_id]}")
    gs.add_participant("#{r[:id]}:#{r[:device_id]}", session_with_bob)
    sessions[session_file_name] = session_with_bob
  end

  # 5) encrypt a message
  ::SelfSDK.logger.debug("- [crypto] group encrypting message")
  ct = gs.encrypt(message).to_s

  # 6) store the session to a file
  ::SelfSDK.logger.debug("- [crypto] storing sessions")
  sessions.each do |session_file_name, session_with_bob|
    pickle = session_with_bob.to_pickle(@storage_key)
    if locks[session_file_name]
      locks[session_file_name].rewind
      locks[session_file_name].write(pickle)
      locks[session_file_name].truncate(locks[session_file_name].pos)
    else
      File.write(session_file_name, pickle)
    end
  end

  ct
ensure
  locks.each do |session_file_name, lock|
    # Unlock the file
    if lock
      lock.flock(File::LOCK_UN)
    end
  end
end