Module: SymmetricEncryption

Defined in:
lib/symmetric_encryption/railtie.rb,
lib/symmetric_encryption/cipher.rb,
lib/symmetric_encryption/reader.rb,
lib/symmetric_encryption/writer.rb,
lib/symmetric_encryption/version.rb,
lib/symmetric_encryption/symmetric_encryption.rb

Overview

Encrypt using 256 Bit AES CBC symmetric key and initialization vector The symmetric key is protected using the private key below and must be distributed separately from the application

Defined Under Namespace

Classes: Cipher, Railtie, Reader, Writer

Constant Summary collapse

VERSION = 
"0.7.1"
MAGIC_HEADER = 
'@EnC'
MAGIC_HEADER_SIZE = 
MAGIC_HEADER.size
MAGIC_HEADER_UNPACK = 
"a#{MAGIC_HEADER_SIZE}v"
@@cipher =

Defaults

nil
@@secondary_ciphers = 
[]

Class Method Summary collapse

Class Method Details

.cipher(version = 0) ⇒ Object

Returns the Primary Symmetric Cipher being used If a version is supplied, then the cipher matching that version will be returned or nil if no match was found



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 32

def self.cipher(version = 0)
  raise "Call SymmetricEncryption.load! or SymmetricEncryption.cipher= prior to encrypting or decrypting data" unless @@cipher
  return @@cipher if version.nil? || (version == 0) || (@@cipher.version == version)
  secondary_ciphers.find {|c| c.version == version}
end

.cipher=(cipher) ⇒ Object

Set the Primary Symmetric Cipher to be used

Example: For testing purposes the following test cipher can be used:

SymmetricEncryption.cipher = SymmetricEncryption::Cipher.new(
  :key    => '1234567890ABCDEF1234567890ABCDEF',
  :iv     => '1234567890ABCDEF',
  :cipher => 'aes-128-cbc'
)



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 24

def self.cipher=(cipher)
  raise "Cipher must be similar to SymmetricEncryption::Ciphers" unless cipher.respond_to?(:encrypt) && cipher.respond_to?(:decrypt)
  @@cipher = cipher
end

.decrypt(str) ⇒ Object

AES Symmetric Decryption of supplied string

Returns decrypted string
Returns nil if the supplied str is nil
Returns "" if it is a string and it is empty

Note: If secondary ciphers are supplied in the configuration file the

first key will be used to decrypt 'str'. If it fails each cipher in the
order supplied will be tried.
It is slow to try each cipher in turn, so should be used during migrations
only

Raises: OpenSSL::Cipher::CipherError when ‘str’ was not encrypted using the supplied key and iv



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 66

def self.decrypt(str)
  raise "Call SymmetricEncryption.load! or SymmetricEncryption.cipher= prior to encrypting or decrypting data" unless @@cipher
  binary = ::Base64.decode64(str) if str
  begin
    @@cipher.decrypt(binary)
  rescue OpenSSL::Cipher::CipherError => exc
    @@secondary_ciphers.each do |cipher|
      begin
        return cipher.decrypt(binary)
      rescue OpenSSL::Cipher::CipherError
      end
    end
    raise exc
  end
end

.encrypt(str) ⇒ Object

AES Symmetric Encryption of supplied string

Returns result as a Base64 encoded string
Returns nil if the supplied str is nil
Returns "" if it is a string and it is empty



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 86

def self.encrypt(str)
  raise "Call SymmetricEncryption.load! or SymmetricEncryption.cipher= prior to encrypting or decrypting data" unless @@cipher

  # Encrypt data as a binary string
  result = @@cipher.encrypt(str)

  # Base 64 Encoding of binary data
  result = ::Base64.encode64(result) if result
  result
end

.encrypted?(encrypted_data) ⇒ Boolean

Returns [true|false] as to whether the data could be decrypted

Parameters:
  encrypted_data: Encrypted string

Returns:

  • (Boolean) 


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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 117

def self.encrypted?(encrypted_data)
  raise "Call SymmetricEncryption.load! or SymmetricEncryption.cipher= prior to encrypting or decrypting data" unless @@cipher

  # First make sure Base64 encoded data still ends with "\n" since it could be used in a key field somewhere
  return false unless encrypted_data.end_with?("\n")

  # For now have to decrypt it fully
  !try_decrypt(encrypted_data).nil?
end

.generate_symmetric_key_files(filename = nil, environment = nil) ⇒ Object

Generate new random symmetric keys for use with this Encryption library

Note: Only the current Encryption key settings are used

Creates Symmetric Key .key

and initilization vector .iv
    which is encrypted with the above Public key

Warning: Existing files will be overwritten



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 168

def self.generate_symmetric_key_files(filename=nil, environment=nil)
  config = read_config(filename, environment)
  cipher_cfg = config[:ciphers].first
  key_filename = cipher_cfg[:key_filename]
  iv_filename = cipher_cfg[:iv_filename]
  cipher = cipher_cfg[:cipher]

  raise "The configuration file must contain a 'private_rsa_key' parameter to generate symmetric keys" unless config[:private_rsa_key]
  rsa_key = OpenSSL::PKey::RSA.new(config[:private_rsa_key])

  # Generate a new Symmetric Key pair
  key_pair = SymmetricEncryption::Cipher.random_key_pair(cipher || 'aes-256-cbc', !iv_filename.nil?)

  # Save symmetric key after encrypting it with the private RSA key, backing up existing files if present
  File.rename(key_filename, "#{key_filename}.#{Time.now.to_i}") if File.exist?(key_filename)
  File.open(key_filename, 'wb') {|file| file.write( rsa_key.public_encrypt(key_pair[:key]) ) }

  if iv_filename
    File.rename(iv_filename, "#{iv_filename}.#{Time.now.to_i}") if File.exist?(iv_filename)
    File.open(iv_filename, 'wb') {|file| file.write( rsa_key.public_encrypt(key_pair[:iv]) ) }
  end
  puts("Generated new Symmetric Key for encryption. Please copy #{key_filename} and #{iv_filename} to the other web servers in #{environment}.")
end

.load!(filename = nil, environment = nil) ⇒ Object

Load the Encryption Configuration from a YAML file

filename:
  Name of file to read.
      Mandatory for non-Rails apps
      Default: Rails.root/config/symmetric-encryption.yml
environment:
  Which environments config to load. Usually: production, development, etc.
  Default: Rails.env



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 135

def self.load!(filename=nil, environment=nil)
  config = read_config(filename, environment)

  # Check for hard coded key, iv and cipher
  if config[:key]
    @@cipher = Cipher.new(config)
    @@secondary_ciphers = []
  else
    private_rsa_key = config[:private_rsa_key]
    @@cipher, *@@secondary_ciphers = config[:ciphers].collect do |cipher_conf|
      cipher_from_encrypted_files(
        private_rsa_key,
        cipher_conf[:cipher],
        cipher_conf[:key_filename],
        cipher_conf[:iv_filename])
    end
  end

  true
end

.random_password ⇒ Object

Generate a 22 character random password



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 193

def self.random_password
  Base64.encode64(OpenSSL::Cipher.new('aes-128-cbc').random_key)[0..-4]
end

.secondary_ciphers ⇒ Object

Returns the Primary Symmetric Cipher being used



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 48

def self.secondary_ciphers
  @@secondary_ciphers
end

.secondary_ciphers=(secondary_ciphers) ⇒ Object

Set the Secondary Symmetric Ciphers Array to be used



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 39

def self.secondary_ciphers=(secondary_ciphers)
  raise "secondary_ciphers must be a collection" unless secondary_ciphers.respond_to? :each
  secondary_ciphers.each do |cipher|
    raise "secondary_ciphers can only consist of SymmetricEncryption::Ciphers" unless cipher.respond_to?(:encrypt) && cipher.respond_to?(:decrypt)
  end
  @@secondary_ciphers = secondary_ciphers
end

.try_decrypt(str) ⇒ Object

Invokes decrypt

Returns decrypted String
Return nil if it fails to decrypt a String

Useful for example when decoding passwords encrypted using a key from a different environment. I.e. We cannot decode production passwords in the test or development environments but still need to be able to load YAML config files that contain encrypted development and production passwords



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# File 'lib/symmetric_encryption/symmetric_encryption.rb', line 105

def self.try_decrypt(str)
  raise "Call SymmetricEncryption.load! or SymmetricEncryption.cipher= prior to encrypting or decrypting data" unless @@cipher
  begin
    decrypt(str)
  rescue OpenSSL::Cipher::CipherError
    nil
  end
end