Class: Melos::Struct::PrivateMessage

Inherits:
Base
  • Object
show all
Defined in:
lib/melos/struct/structs.rb

Overview

6.3

Constant Summary collapse

STRUCT = 
[
  [:group_id, :vec],
  [:epoch, :uint64],
  [:content_type, :uint8],
  [:authenticated_data, :vec],
  [:encrypted_sender_data, :vec],
  [:ciphertext, :vec]
]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#deserialize_select_elem_with_context, #initialize, #raw

Constructor Details

This class inherits a constructor from Melos::Struct::Base

Instance Attribute Details

#authenticated_data ⇒ Object (readonly)

Returns the value of attribute authenticated_data.



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# File 'lib/melos/struct/structs.rb', line 811

def authenticated_data
  @authenticated_data
end

#ciphertext ⇒ Object (readonly)

Returns the value of attribute ciphertext.



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# File 'lib/melos/struct/structs.rb', line 811

def ciphertext
  @ciphertext
end

#content_type ⇒ Object (readonly)

Returns the value of attribute content_type.



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# File 'lib/melos/struct/structs.rb', line 811

def content_type
  @content_type
end

#encrypted_sender_data ⇒ Object (readonly)

Returns the value of attribute encrypted_sender_data.



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# File 'lib/melos/struct/structs.rb', line 811

def encrypted_sender_data
  @encrypted_sender_data
end

#epoch ⇒ Object (readonly)

Returns the value of attribute epoch.



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# File 'lib/melos/struct/structs.rb', line 811

def epoch
  @epoch
end

#group_id ⇒ Object (readonly)

Returns the value of attribute group_id.



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# File 'lib/melos/struct/structs.rb', line 811

def group_id
  @group_id
end

Class Method Details

.create(group_id:, epoch:, content_type:, authenticated_data:, encrypted_sender_data:, ciphertext:) ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 821

def self.create(group_id:, epoch:, content_type:, authenticated_data:, encrypted_sender_data:, ciphertext:)
  new_instance = self.allocate
  new_instance.instance_variable_set(:@group_id, group_id)
  new_instance.instance_variable_set(:@epoch, epoch)
  new_instance.instance_variable_set(:@content_type, content_type)
  new_instance.instance_variable_set(:@authenticated_data, authenticated_data)
  new_instance.instance_variable_set(:@encrypted_sender_data, encrypted_sender_data)
  new_instance.instance_variable_set(:@ciphertext, ciphertext)
  new_instance
end

.private_content_aad_impl(gid, ep, ct, ad) ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 844

def self.private_content_aad_impl(gid, ep, ct, ad)
  Melos::Vec.from_string(gid) + [ep].pack('Q>') + [ct].pack('C') + Melos::Vec.from_string(ad)
end

.protect(authenticated_content, suite, secret_tree, sender_data_secret, padding_size) ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 848

def self.protect(authenticated_content, suite, secret_tree, sender_data_secret, padding_size)
  leaf_index = authenticated_content.content.sender.leaf_index
  content_type = authenticated_content.content.content_type
  reuse_guard = SecureRandom.random_bytes(4)
  key, nonce, generation = Melos::SecretTree::ratchet_and_get(suite, content_type, secret_tree, leaf_index)
  new_nonce = apply_nonce_reuse_guard(nonce, reuse_guard)

  private_message_content_plain = serialize_private_message_content(authenticated_content.content, authenticated_content.auth, padding_size)
  aad = private_content_aad_impl(
    authenticated_content.content.group_id,
    authenticated_content.content.epoch,
    authenticated_content.content.content_type,
    authenticated_content.content.authenticated_data)
  private_message_content_ciphertext = Melos::Crypto.aead_encrypt(suite, key, new_nonce, aad, private_message_content_plain)

  sender_data_plain = Melos::Struct::SenderData.create(
    leaf_index: leaf_index,
    generation: generation,
    reuse_guard: reuse_guard
  )
  sd_aad = sender_data_aad_impl(
    authenticated_content.content.group_id,
    authenticated_content.content.epoch,
    authenticated_content.content.content_type)
  sender_data_key   = Melos::Crypto.sender_data_key(suite, sender_data_secret, private_message_content_ciphertext)
  sender_data_nonce = Melos::Crypto.sender_data_nonce(suite, sender_data_secret, private_message_content_ciphertext)
  sender_data_ciphertext = Melos::Crypto.aead_encrypt(suite, sender_data_key, sender_data_nonce, sd_aad, sender_data_plain.raw)

  create(
    group_id: authenticated_content.content.group_id,
    epoch: authenticated_content.content.epoch,
    content_type: authenticated_content.content.content_type,
    authenticated_data: authenticated_content.content.authenticated_data,
    encrypted_sender_data: sender_data_ciphertext,
    ciphertext: private_message_content_ciphertext
  )
end

.sender_data_aad_impl(gid, ep, ct) ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 836

def self.sender_data_aad_impl(gid, ep, ct)
  Melos::Vec.from_string(gid) + [ep].pack('Q>') + [ct].pack('C')
end

Instance Method Details

#private_content_aad ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 840

def private_content_aad
  self.class.private_content_aad_impl(group_id, epoch, content_type, authenticated_data)
end

#sender_data_aad ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 832

def sender_data_aad
  self.class.sender_data_aad_impl(group_id, epoch, content_type)
end

#unprotect(suite, secret_tree, sender_data_secret) ⇒ Object 



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# File 'lib/melos/struct/structs.rb', line 886

def unprotect(suite, secret_tree, sender_data_secret)
  sender_data = decrypt_sender_data(suite, sender_data_secret)
  key, nonce, _ = Melos::SecretTree.ratchet_until_and_get(suite, content_type, secret_tree, sender_data.leaf_index, sender_data.generation)
  new_nonce = self.class.apply_nonce_reuse_guard(nonce, sender_data.reuse_guard)
  stream = StringIO.new(Melos::Crypto.aead_decrypt(suite, key, new_nonce, private_content_aad, ciphertext))
  pmc = Melos::Struct::PrivateMessageContent.new_with_content_type(stream, content_type)

  fc = Melos::Struct::FramedContent.create(
    group_id: group_id,
    epoch: epoch,
    sender: Melos::Struct::Sender.create_member(sender_data.leaf_index),
    authenticated_data: authenticated_data,
    content_type: content_type,
    content: pmc.content
  )

  Melos::Struct::AuthenticatedContent.create(
    wire_format: Melos::Constants::WireFormat::MLS_PRIVATE_MESSAGE, # private_message
    content: fc,
    auth: pmc.auth
  )
end