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# frozen_string_literal: true
require "pathname"
require "active_support/message_encryptor"
module ActiveSupport
class EncryptedFile
class MissingContentError < RuntimeError
def initialize(content_path)
super "Missing encrypted content file in #{content_path}."
end
end
class MissingKeyError < RuntimeError
def initialize(key_path:, env_key:)
super \
"Missing encryption key to decrypt file with. " +
"Ask your team for your master key and write it to #{key_path} or put it in the ENV['#{env_key}']."
end
end
CIPHER = "aes-128-gcm"
def self.generate_key
SecureRandom.hex(ActiveSupport::MessageEncryptor.key_len(CIPHER))
end
attr_reader :content_path, :key_path, :env_key, :raise_if_missing_key
def initialize(content_path:, key_path:, env_key:, raise_if_missing_key:)
@content_path, @key_path = Pathname.new(content_path), Pathname.new(key_path)
@env_key, @raise_if_missing_key = env_key, raise_if_missing_key
end
def key
read_env_key || read_key_file || handle_missing_key
end
def read
if !key.nil? && content_path.exist?
decrypt content_path.binread
else
raise MissingContentError, content_path
end
end
def write(contents)
IO.binwrite "#{content_path}.tmp", encrypt(contents)
FileUtils.mv "#{content_path}.tmp", content_path
end
def change(&block)
writing read, &block
end
private
def writing(contents)
tmp_file = "#{Process.pid}.#{content_path.basename.to_s.chomp('.enc')}"
tmp_path = Pathname.new File.join(Dir.tmpdir, tmp_file)
tmp_path.binwrite contents
yield tmp_path
updated_contents = tmp_path.binread
write(updated_contents) if updated_contents != contents
ensure
FileUtils.rm(tmp_path) if tmp_path.exist?
end
def encrypt(contents)
encryptor.encrypt_and_sign contents
end
def decrypt(contents)
encryptor.decrypt_and_verify contents
end
def encryptor
@encryptor ||= ActiveSupport::MessageEncryptor.new([ key ].pack("H*"), cipher: CIPHER)
end
def read_env_key
ENV[env_key]
end
def read_key_file
key_path.binread.strip if key_path.exist?
end
def handle_missing_key
raise MissingKeyError, key_path: key_path, env_key: env_key if raise_if_missing_key
end
end
end
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