Class: Rack::Bacoo::Encryptor

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/bacoo/encryptor.rb

Constant Summary collapse

DecryptionError = 
Class.new(StandardError)
AUTH_TAG_LENGTH = 
16
CIPHER = 
"aes-256-gcm"
SALT = 
"entropy comes from the password"
SEPARATOR = 
"--"

Instance Method Summary collapse

Constructor Details

#initialize(password) ⇒ Encryptor

Returns a new instance of Encryptor.



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# File 'lib/rack/bacoo/encryptor.rb', line 16

def initialize(password)
  key_len = new_cipher.key_len
  digest = OpenSSL::Digest.new("SHA256")
  # Rationale on how the key is generated: https://github.com/rails/rails/pull/6952
  @key = OpenSSL::PKCS5.pbkdf2_hmac(password, SALT, 1000, key_len, digest)
end

Instance Method Details

#decrypt(encrypted_message) ⇒ Object

Raises:



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# File 'lib/rack/bacoo/encryptor.rb', line 34

def decrypt(encrypted_message)
  cipher = new_cipher
  encrypted_data, iv, auth_tag = extract_parts(encrypted_message)

  # Currently the OpenSSL bindings do not raise an error if auth_tag is
  # truncated, which would allow an attacker to easily forge it:
  # https://github.com/ruby/openssl/issues/63
  raise DecryptionError, "truncated auth_tag" if auth_tag.bytesize != AUTH_TAG_LENGTH

  cipher.decrypt
  cipher.key = @key
  cipher.iv  = iv
  cipher.auth_tag = auth_tag
  cipher.auth_data = ""
  cipher.update(encrypted_data) + cipher.final
end

#encrypt(data) ⇒ Object 



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# File 'lib/rack/bacoo/encryptor.rb', line 23

def encrypt(data)
  cipher = new_cipher
  cipher.encrypt
  cipher.key = @key
  iv = cipher.random_iv
  cipher.auth_data = ""
  encrypted_data = cipher.update(data) + cipher.final
  parts = [encrypted_data, iv, cipher.auth_tag(AUTH_TAG_LENGTH)]
  parts.map { ::Base64.strict_encode64(_1) }.join(SEPARATOR)
end