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}"

  if File.exist?()
    # 1a) if alice's account file exists load the pickle from the file
    @account = SelfCrypto::Account.from_pickle(File.read(), @storage_key)
  else
    # 1b-i) if create a new account for alice if one doesn't exist already
    @account = SelfCrypto::Account.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
    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 74

def decrypt(message, sender, sender_device)
  ::SelfSDK.logger.debug("decrypting a message")
  session_file_name = session_path(sender, sender_device)

  ::SelfSDK.logger.debug("loading sessions")
  session_with_bob = get_inbound_session_with_bob(message, session_file_name)

  # 8) create a group session and set the identity of the account you're using
  ::SelfSDK.logger.debug("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("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("decrypt the message ciphertext")
  pt = gs.decrypt("#{sender}:#{sender_device}", message).to_s

  # 11) store the session to a file
  ::SelfSDK.logger.debug("store the session to a file")
  File.write(session_file_name, session_with_bob.to_pickle(@storage_key))

  pt
end

#encrypt(message, recipients) ⇒ Object 



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# File 'lib/crypto.rb', line 35

def encrypt(message, recipients)
  ::SelfSDK.logger.debug('encrypting a message')

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

  sessions = {}
  ::SelfSDK.logger.debug('managing sessions with all recipients')
  recipients.each do |r|
    session_file_name = session_path(r[:id], r[:device_id])
    session_with_bob = nil

    begin
      session_with_bob = get_outbound_session_with_bob(r[:id], r[:device_id], session_file_name)
    rescue => e
      ::SelfSDK.logger.warn("  there is a problem adding group participant #{r[:id]}:#{r[:device_id]}, skipping...")
      ::SelfSDK.logger.warn(e)
      next
    end

    ::SelfSDK.logger.debug("  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("group encrypting message")
  ct = gs.encrypt(message).to_s

  # 6) store the session to a file
  ::SelfSDK.logger.debug("storing sessions")
  sessions.each do |session_file_name, session_with_bob|
    File.write(session_file_name, session_with_bob.to_pickle(@storage_key))
  end

  ct
end