Module: SecurizeString::CipherMethods::InstanceMethods

Defined in:
lib/securize_string/cipher_methods.rb

Overview

Adds instance methods for OpenSSL::Cipher support, including AES encryption, via inclusion of SecurizeString::CipherMethods into a class.

Instance Method Summary collapse

Instance Method Details

#from_aes(key, iv) ⇒ Object

Given an AES key and init vector, AES-CBC decode the data.



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# File 'lib/securize_string/cipher_methods.rb', line 114

def from_aes(key, iv)
  key_len = (key.bytesize * 8)
  return self.class.new( from_cipher("aes-#{key_len}-cbc", key, iv) )
end

#from_cipher(cipher_name, key, iv) ⇒ Object

Given an OpenSSL cipher name, a key, and an init vector, decrypt the data.



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# File 'lib/securize_string/cipher_methods.rb', line 94

def from_cipher(cipher_name, key, iv)
  cipher = OpenSSL::Cipher.new(cipher_name)
  cipher.decrypt # MUST set the mode BEFORE setting the key and iv!
  cipher.key = key
  cipher.iv = iv
  msg = cipher.update(self.to_s)
  msg << cipher.final
  return self.class.new(msg)
end

#to_aes(key, iv) ⇒ Object

Given an AES key and initialization vector, AES-CBC encode the data.

Note that one normally never wants to use the same key and iv combination on two different messages as this weakens the security.



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# File 'lib/securize_string/cipher_methods.rb', line 108

def to_aes(key, iv)
  key_len = (key.bytesize * 8)
  return self.class.new( to_cipher("aes-#{key_len}-cbc", key, iv) )
end

#to_cipher(cipher_name, key, iv) ⇒ Object

Given an OpenSSL cipher name, a key, and initialization vector, encrypt the data.

Use OpenSSL::Cipher.ciphers to get a list of available cipher names.

To generate a new key and iv, do the following:

cipher = OpenSSL::Cipher::Cipher.new(cipher_name)
cipher.encrypt
key = cipher.random_key
iv = cipher.random_iv



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# File 'lib/securize_string/cipher_methods.rb', line 82

def to_cipher(cipher_name, key, iv)
  cipher = OpenSSL::Cipher.new(cipher_name)
  cipher.encrypt # MUST set the mode BEFORE setting the key and iv!
  cipher.key = key
  cipher.iv = iv
  msg = cipher.update(self.to_s)
  msg << cipher.final
  return self.class.new(msg)
end