Underlock

Underlock makes it dead simple to encrypt and decrypt your data and files. It comes with little to no dependencies and has a very small API surface.

Installation

Add this line to your application’s Gemfile:

gem 'underlock'

And then execute:

$ bundle

Or install it yourself as:

$ gem install underlock

Initialization

Underlock::Base.configure do |config|
  config.public_key  = File.read('./key.pub')
  config.private_key = File.read('./key.priv')
  config.cipher      = OpenSSL::Cipher.new('aes-256-gcm')
end

For the config.cipher value, all algorithms available in OpenSSL::Cipher.ciphers are supported.

Important Note: Choose your algorithm carefully and stick to it. It’ll kind of suck to be not able to decrypt your encrypted data.

Generating Public/Private keypair

key = OpenSSL::PKey::RSA.new 4096
puts key.to_pem
puts key.public_key.to_pem

Usage

Encrypting Strings/Text

irb> Underlock::Base.encrypt("super secret message")
=> #<Underlock::EncryptedEntity:0x007fef2e4b8320>

Underlock::EncryptedEntity has the following 3 methods

encrypted_entity.value
encrypted_entity.key
encrypted_entity.iv # iv stands for initialization vector

You should persist or store the key and iv in order to be able to decrypt the encrypted value.

Decrypting Strings/Text

• Create an instance of Underlock::EncryptedEntity, use the key and iv collected in the previous steps.

irb> encrypted_entity = Underlock::EncryptedEntity.new(value: value, key: key, iv: iv)

• Decrypt using one of the following methods:

irb> encrypted_entity.decrypt

irb> Underlock::Base.decrypt(encrypted_entity)

Encrypting Files

To encrypt files, instead of passing a String object, pass a File object to Underlock::Base.encrypt

irb> file = File.open('/path/to/your/secret/file.txt')
irb> Underlock::Base.encrypt(file)
=> #<Underlock::EncryptedEntity:0x007fef2e4b8320>

The return value is an instance of Underlock::EncryptedEntity and has the following methods:

encrypted_entity.encrypted_file
encrypted_entity.key
encrypted_entity.iv # iv stands for initialization vector here

#encrypted_file returns a File object. This file is saved in the same directory as your original file.

Decrypting Files

• Create an instance of Underlock::EncryptedEntity, use the key and iv collected in the previous steps.

irb> file = File.open('/path/to/your/secret/file.txt.enc')
irb> encrypted_entity = Underlock::EncryptedEntity.new(encrypted_file: file, key: key, iv: iv)

• Decrypt using one of the following methods:

irb> encrypted_entity.decrypt

irb> Underlock::Base.decrypt(encrypted_entity)

Following naming scheme is followed when encrypting/decrypting files:

original file name	encrypted file name	decrypted file name
file.pdf	file.pdf.enc	file.decrypted.pdf

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/metaware/underlock.

License

The gem is available as open source under the terms of the MIT License.