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require 'openssl'
require 'encryptor/version'
# A simple wrapper for the standard OpenSSL library
module Encryptor
extend self
# The default options to use when calling the <tt>encrypt</tt> and <tt>decrypt</tt> methods
#
# Defaults to { algorithm: 'aes-256-gcm',
# auth_data: '',
# insecure_mode: false,
# hmac_iterations: 2000,
# v2_gcm_iv: false }
#
# Run 'openssl list-cipher-commands' in your terminal to view a list all cipher algorithms that are supported on your platform
def default_options
@default_options ||= { algorithm: 'aes-256-gcm',
auth_data: '',
insecure_mode: false,
hmac_iterations: 2000,
v2_gcm_iv: false }
end
# Encrypts a <tt>:value</tt> with a specified <tt>:key</tt> and <tt>:iv</tt>.
#
# Optionally accepts <tt>:salt</tt>, <tt>:auth_data</tt>, <tt>:algorithm</tt>, <tt>:hmac_iterations</tt>, and <tt>:insecure_mode</tt> options.
#
# Example
#
# encrypted_value = Encryptor.encrypt(value: 'some string to encrypt', key: 'some secret key', iv: 'some unique value', salt: 'another unique value')
# # or
# encrypted_value = Encryptor.encrypt('some string to encrypt', key: 'some secret key', iv: 'some unique value', salt: 'another unique value')
def encrypt(*args, &block)
crypt :encrypt, *args, &block
end
# Decrypts a <tt>:value</tt> with a specified <tt>:key</tt> and <tt>:iv</tt>.
#
# Optionally accepts <tt>:salt</tt>, <tt>:auth_data</tt>, <tt>:algorithm</tt>, <tt>:hmac_iterations</tt>, and <tt>:insecure_mode</tt> options.
#
# Example
#
# decrypted_value = Encryptor.decrypt(value: 'some encrypted string', key: 'some secret key', iv: 'some unique value', salt: 'another unique value')
# # or
# decrypted_value = Encryptor.decrypt('some encrypted string', key: 'some secret key', iv: 'some unique value', salt: 'another unique value')
def decrypt(*args, &block)
crypt :decrypt, *args, &block
end
protected
def crypt(cipher_method, *args) #:nodoc:
options = default_options.merge(value: args.first).merge(args.last.is_a?(Hash) ? args.last : {})
raise ArgumentError.new('must specify a key') if options[:key].to_s.empty?
cipher = OpenSSL::Cipher.new(options[:algorithm])
cipher.send(cipher_method)
unless options[:insecure_mode]
raise ArgumentError.new("key must be #{cipher.key_len} bytes or longer") if options[:key].bytesize < cipher.key_len
raise ArgumentError.new('must specify an iv') if options[:iv].to_s.empty?
raise ArgumentError.new("iv must be #{cipher.iv_len} bytes or longer") if options[:iv].bytesize < cipher.iv_len
end
if options[:iv]
# This is here for backwards compatibility for Encryptor v2.0.0.
cipher.iv = options[:iv] if options[:v2_gcm_iv]
if options[:salt].nil?
# Use a non-salted cipher.
# This behaviour is retained for backwards compatibility. This mode
# is not secure and new deployments should use the :salt options
# wherever possible.
cipher.key = options[:key]
else
# Use an explicit salt (which can be persisted into a database on a
# per-column basis, for example). This is the preferred (and more
# secure) mode of operation.
cipher.key = OpenSSL::PKCS5.pbkdf2_hmac_sha1(options[:key], options[:salt], options[:hmac_iterations], cipher.key_len)
end
cipher.iv = options[:iv] unless options[:v2_gcm_iv]
else
# This is deprecated and needs to be changed.
cipher.pkcs5_keyivgen(options[:key])
end
yield cipher, options if block_given?
value = options[:value]
if cipher.authenticated?
if encryption?(cipher_method)
cipher.auth_data = options[:auth_data]
else
value = extract_cipher_text(options[:value])
cipher.auth_tag = extract_auth_tag(options[:value])
# auth_data must be set after auth_tag has been set when decrypting
# See http://ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL/Cipher.html#method-i-auth_data-3D
cipher.auth_data = options[:auth_data]
end
end
result = cipher.update(value)
result << cipher.final
result << cipher.auth_tag if cipher.authenticated? && encryption?(cipher_method)
result
end
def encryption?(cipher_method)
cipher_method == :encrypt
end
def extract_cipher_text(value)
value[0..-17]
end
def extract_auth_tag(value)
value[-16..-1]
end
end