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A simple wrapper for the standard ruby OpenSSL library
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Encryptor

Build Status Code Climate Coverage Gem Version security

A simple wrapper for the standard Ruby OpenSSL library

Upgrading from v2.0.0 to v3.0.0

A bug was discovered in Encryptor 2.0.0 wherein the IV was not being used when using an AES-*-GCM algorithm. Unfornately fixing this major security issue results in the inability to decrypt records encrypted using an AES-*-GCM algorithm from Encryptor v2.0.0. While the behavior change is minimal between v2.0.0 and v3.0.0, the change has a significant impact on users that used v2.0.0 and encrypted data using an AES-*-GCM algorithm, which is the default algorithm for v2.0.0. Consequently, we decided to increment the version with a major bump to help people avoid a confusing situation where some of their data will not decrypt. A new option is available in Encryptor 3.0.0 that allows decryption of data encrypted using an AES-*-GCM algorithm from Encryptor v2.0.0.

Installation

gem install encryptor

Usage

Basic

Encryptor uses the AES-256-GCM algorithm by default to encrypt strings securely.

The best example is:

cipher = OpenSSL::Cipher.new('aes-256-gcm')
cipher.encrypt # Required before '#random_key' or '#random_iv' can be called. http://ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL/Cipher.html#method-i-encrypt
secret_key = cipher.random_key # Insures that the key is the correct length respective to the algorithm used.
iv = cipher.random_iv # Insures that the IV is the correct length respective to the algorithm used.
salt = SecureRandom.random_bytes(16)
encrypted_value = Encryptor.encrypt(value: 'some string to encrypt', key: secret_key, iv: iv, salt: salt)
decrypted_value = Encryptor.decrypt(value: encrypted_value, key: secret_key, iv: iv, salt: salt)

A slightly easier example is:

require 'securerandom'
secret_key = SecureRandom.random_bytes(32) # The length in bytes must be equal to or greater than the algorithm bit length.
iv = SecureRandom.random_bytes(12) # Recomended length for AES-###-GCM algorithm. https://tools.ietf.org/html/rfc5084#section-3.2
encrypted_value = Encryptor.encrypt(value: 'some string to encrypt', key: secret_key, iv: iv)
decrypted_value = Encryptor.decrypt(value: encrypted_value, key: secret_key, iv: iv)

NOTE: It is imperative that you use a unique IV per each string and encryption key combo; a nonce as the IV. See RFC 5084 for more details.

The value to encrypt or decrypt may also be passed as the first option if you'd prefer.

encrypted_value = Encryptor.encrypt('some string to encrypt', key: secret_key, iv: iv)
decrypted_value = Encryptor.decrypt(encrypted_value, key: secret_key, iv: iv)

Options

Defaults:

    { algorithm: 'aes-256-gcm',
      auth_data: '',
      insecure_mode: false,
      hmac_iterations: 2000,
      v2_gcm_iv: false }

Older versions of Encryptor allowed you to use it in a less secure way. Namely, you were allowed to run Encryptor without an IV, or with a key of insufficient length. Encryptor now requires a key and IV of the correct length respective to the algorithm that you use. However, to maintain backwards compatibility you can run Encryptor with the :insecure_mode option. Additionally, when using AES-*-GCM algorithms in Encryptor v2.0.0, the IV was set incorrectly and was not used. The :v2_gcm_iv option is available to allow Encryptor to set the IV as it was set in Encryptor v2.0.0. This is provided to assist with migrating data that unsafely encrypted using an AES-*-GCM algorithm from Encryptor v2.0.0.

You may also pass an :algorithm,:salt, and hmac_iterations option, however none of these options are required. If you pass the :salt option, a new unique key will be derived from the key that you passed in using PKCS5 with a default of 2000 iterations. You can change the number of PKCS5 iterations with the hmac_iterations option. As PKCS5 is slow, it is optional behavior, but it does provide more security to use a unique IV and key for every encryption operation.

Encryptor.default_options.merge!(algorithm: 'aes-256-cbc', key: 'some default secret key', iv: iv, salt: salt)

Strings

Older versions of Encryptor added encrypt and decrypt methods to String objects for your convenience. However, this behavior has been removed to avoid polluting Ruby's core String class. The Encryptor::String module remains within this gem to allow users of this feature to implement it themselves. These encrypt and decrypt methods accept the same arguments as the associated ones in the Encryptor module. They're nice when you set the default options in the Encryptor.default_options attribute. For example:

require 'encryptor/string'
String.include Encryptor::String
Encryptor.default_options.merge!(key: 'some default secret key', iv: iv)
credit_card = 'xxxx xxxx xxxx 1234'
encrypted_credit_card = credit_card.encrypt

There's also encrypt! and decrypt! methods that replace the contents of a string with the encrypted or decrypted version of itself.

Algorithms

To view a list of all cipher algorithms that are supported on your platform, run the following code in your favorite Ruby REPL:

require 'openssl'
puts OpenSSL::Cipher.ciphers

The supported ciphers will vary depending on the version of OpenSSL that was used to compile your version of Ruby. However, the following ciphers are typically supported:

Cipher Name Key size in bytes IV size in bytes
aes-128-cbc 16 16
aes-128-cbc-hmac-sha1 16 16
aes-128-cbc-hmac-sha256 16 16
aes-128-ccm 16 12
aes-128-cfb 16 16
aes-128-cfb1 16 16
aes-128-cfb8 16 16
aes-128-ctr 16 16
aes-128-ecb 16 0
aes-128-gcm 16 12
aes-128-ofb 16 16
aes-128-xts 32 16
aes-192-cbc 24 16
aes-192-ccm 24 12
aes-192-cfb 24 16
aes-192-cfb1 24 16
aes-192-cfb8 24 16
aes-192-ctr 24 16
aes-192-ecb 24 0
aes-192-gcm 24 12
aes-192-ofb 24 16
aes-256-cbc 32 16
aes-256-cbc-hmac-sha1 32 16
aes-256-cbc-hmac-sha256 32 16
aes-256-ccm 32 12
aes-256-cfb 32 16
aes-256-cfb1 32 16
aes-256-cfb8 32 16
aes-256-ctr 32 16
aes-256-ecb 32 0
aes-256-gcm 32 12
aes-256-ofb 32 16
aes-256-xts 64 16
aes128 16 16
aes192 24 16
aes256 32 16
bf 16 8
bf-cbc 16 8
bf-cfb 16 8
bf-ecb 16 0
bf-ofb 16 8
blowfish 16 8
camellia-128-cbc 16 16
camellia-128-cfb 16 16
camellia-128-cfb1 16 16
camellia-128-cfb8 16 16
camellia-128-ecb 16 0
camellia-128-ofb 16 16
camellia-192-cbc 24 16
camellia-192-cfb 24 16
camellia-192-cfb1 24 16
camellia-192-cfb8 24 16
camellia-192-ecb 24 0
camellia-192-ofb 24 16
camellia-256-cbc 32 16
camellia-256-cfb 32 16
camellia-256-cfb1 32 16
camellia-256-cfb8 32 16
camellia-256-ecb 32 0
camellia-256-ofb 32 16
camellia128 16 16
camellia192 24 16
camellia256 32 16
cast 16 8
cast-cbc 16 8
cast5-cbc 16 8
cast5-cfb 16 8
cast5-ecb 16 0
cast5-ofb 16 8
des 8 8
des-cbc 8 8
des-cfb 8 8
des-cfb1 8 8
des-cfb8 8 8
des-ecb 8 0
des-ede 16 0
des-ede-cbc 16 8
des-ede-cfb 16 8
des-ede-ofb 16 8
des-ede3 24 0
des-ede3-cbc 24 8
des-ede3-cfb 24 8
des-ede3-cfb1 24 8
des-ede3-cfb8 24 8
des-ede3-ofb 24 8
des-ofb 8 8
des3 24 8
desx 24 8
desx-cbc 24 8
idea 16 8
idea-cbc 16 8
idea-cfb 16 8
idea-ecb 16 0
idea-ofb 16 8
rc2 16 8
rc2-40-cbc 5 8
rc2-64-cbc 8 8
rc2-cbc 16 8
rc2-cfb 16 8
rc2-ecb 16 0
rc2-ofb 16 8
rc4 16 0
rc4-40 5 0
rc4-hmac-md5 16 0
seed 16 16
seed-cbc 16 16
seed-cfb 16 16
seed-ecb 16 0
seed-ofb 16 16

NOTE: Some ciphers may not be supported by Ruby. Additionally, Ruby compiled with OpenSSL >= v1.0.1 will include AEAD ciphers, ie., aes-256-gcm.

Notes on patches/pull requests

  • Fork the project.
  • Make your feature addition or bug fix.
  • Add tests for it: this is important so I don't break it in a future version unintentionally.
  • Commit, do not mess with Rakefile, version, or history: if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull).
  • Send me a pull request: bonus points for topic branches.
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