Class: AesBridge::RandomGenerator

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

Overview

A class for generating cryptographically secure random bytes using a nonce.

Constant Summary collapse

@@nonce =

Class variable to store the nonce.

nil
@@nonce_mutex =

Mutex for safe access to nonce in a multi-threaded environment.

Mutex.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.update_nonce ⇒ Object

Updates the nonce



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# File 'lib/aes_bridge/common.rb', line 26

def self.update_nonce
  @@nonce_mutex.synchronize do
    if @@nonce.nil?
      # Generate a random starting value for the nonce.
      nonce = OpenSSL::Random.random_bytes(8)
      @@nonce = nonce.unpack('Q>').first
    end
    @@nonce += 1
  end
end

Instance Method Details

#generate_random_bytes(size) ⇒ String

Generates cryptographically secure random bytes.

Parameters:

  • size (Integer) —

    The length of the random byte string to generate.

Returns:

  • (String) —

    A cryptographically secure random byte string of length ‘size`.



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# File 'lib/aes_bridge/common.rb', line 41

def generate_random_bytes(size)
  self.class.update_nonce

  nonce_value = nil
  @@nonce_mutex.synchronize do
    nonce_value = @@nonce
  end

  nonce_bytes = [nonce_value].pack('Q>')

  # Generate random bytes before and after the nonce to increase entropy.
  data = OpenSSL::Random.random_bytes(13) + nonce_bytes + OpenSSL::Random.random_bytes(13)
  OpenSSL::Digest::SHA256.digest(data)[0, size]
end