Module: SecurizeString::CipherMethods::ClassMethods

Defined in:
lib/securize_string/cipher_methods.rb

Overview

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

Instance Method Summary collapse

Instance Method Details

#aes_keygen(key_len = 256) ⇒ Object

A convenience method for generating a random key and init vector for AES encryption.

Defaults to a key length of 256.



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# File 'lib/securize_string/cipher_methods.rb', line 54

def aes_keygen(key_len=256)
  return cipher_keygen("aes-#{key_len.to_i}-cbc")
end

#aes_passphrase_keygen(key_len, passphrase, salt, iterations = 2048) ⇒ Object

A convenience method for generating a key and init vector from a passphrase for AES encryption.

Defaults to a key length of 256.



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# File 'lib/securize_string/cipher_methods.rb', line 62

def aes_passphrase_keygen(key_len, passphrase, salt, iterations=2048)
  return cipher_passphrase_keygen("aes-#{key_len.to_i}-cbc", passphrase, salt, iterations)
end

#cipher_keygen(cipher_name) ⇒ Object

A convenience method for generating random cipher keys and initialization vectors.



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# File 'lib/securize_string/cipher_methods.rb', line 25

def cipher_keygen(cipher_name)
  cipher = OpenSSL::Cipher.new(cipher_name)
  cipher.encrypt
  return [cipher.random_key, cipher.random_iv].map {|s| self.new(s)}
end

#cipher_passphrase_keygen(cipher_name, passphrase, salt, iterations = 2048) ⇒ Object

A convenience method for generating a cipher key from a passphrase using PKCS5 v2 standards. The key and the salt may be any string.

This also derives a predictable initialization vector from the given passphrase in a manor consistent with RFC2898, though it is better to generate a random IV with each encryption of the same data if possible.

Note that the OpenSSL::Cipher#pkcs5_keyivgen method is not PKCS5 v2 compliant, and therefore will not be implemented.



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# File 'lib/securize_string/cipher_methods.rb', line 40

def cipher_passphrase_keygen(cipher_name, passphrase, salt, iterations=2048)
  # The first pits of a PBKDF2 are the same wether I build the key and IV
  # at once, but when an IV is built in the RFC2898 standards, they do it
  # this way.
  cipher = OpenSSL::Cipher.new(cipher_name.to_s)
  cipher.encrypt
  key_and_iv = OpenSSL::PKCS5.pbkdf2_hmac_sha1(passphrase.to_s, salt.to_s, iterations.to_i, cipher.key_len+cipher.iv_len)
  return [key_and_iv[0,cipher.key_len], key_and_iv[cipher.key_len, cipher.iv_len]].map {|s| self.new(s)}
end

#supported_ciphers ⇒ Object

Returns a list of supported ciphers. These can be passed directly into the cipher methods.



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# File 'lib/securize_string/cipher_methods.rb', line 19

def supported_ciphers
  return OpenSSL::Cipher.ciphers
end