= Sentry lib - painless encryption library
 
Sentry is a simple wrapper around the mostly undocumented OpenSSL encryption classes.  
For now, look at the pseudo test cases in sentry.rb until I can get more examples written out.
 
== Resources
 
Install
 
* gem install sentry
 
Rubyforge project
 
* http://rubyforge.org/projects/sentry
 
RDocs
 
* http://sentry.rubyforge.org
 
Subversion
 
* http://techno-weenie.net/svn/projects/sentry
 
Collaboa
 
* http://collaboa.techno-weenie.net/repository/browse/sentry
 
== Using with ActiveRecord
 
I wrote this for the purpose of encrypting ActiveRecord attributes.  Just <tt>require 'sentry'</tt>, and some new 
class methods will be available to you:
 
=== generates_crypted
 
  generates_crypted :password, :mode => :sha | :symmetric | :asymmetric
  
This is the generic class method to use.  Default mode is :sha.  
 
=== generates_crypted_hash_of
 
  generates_crypted_hash_of :password
 
This is a shortcut for using SHA encryption.  No different than specifying <tt>generates_crypted :password</tt>.  In the above 
example, model.password is a virtual field, and the SHA hash is saved to model.crypted_password
 
=== asymmetrically_encrypts
  
  asymmetrically_encrypts :password
 
This is a shortcut for using an asymmetrical algorithm with a private/public key file.  To use this, generate a public and
private key with Sentry::AsymmetricalSentry.save_random_rsa_key(private_key_file, public_key_file).  If you want to encrypt the
private key file with a symmetrical algorithm, pass a secret key (neither the key nor the decrypted value will be stored).
 
  Sentry::AsymmetricSentry.save_random_rsa_key(private_key_file, public_key_file, :key => 'secret_password')
 
What that does, is requires you to pass in that same secret password when accesing the method.  
 
  class Model < ActiveRecord::Base
    generates_crypted :password, :mode => :asymmetric
  end
  
  model.password = '5234523453425'
  model.save   # password is encrypted and saved to crypted_password in the database, 
               # model.password is cleared and becomes a virtual field.
  model.password('secret_password')
  => '5234523453425'
 
The public and private key file names can be set in config/environment.rb
 
  Sentry::AsymmetricSentry.default_public_key_file = "#{RAILS_ROOT}/config/public.key"
  Sentry::AsymmetricSentry.default_private_key_file = "#{RAILS_ROOT}/config/private.key"
 
If the private key was encrypted with the Sentry::AsymmetricalSentry#save_random_rsa_key, you must provide that same key
when accessing the AR model.
 
=== symmetrically_encrypts
 
  symmetrically_encrypts :password
 
This is a shortcut for using a symmetrical algorithm with a secret password to encrypt the field.  
 
  class Model < ActiveRecord::Base
    generates_crypted :password, :mode => :symmetric
  end
  
  model.password = '5234523453425'
  model.save   # password is encrypted and saved to crypted_password in the database, 
               # model.password is cleared and becomes a virtual field.
  model.password
  => '5234523453425'
 
The secret password can be set in config/environment.rb
 
  Sentry::SymmetricSentry.default_key = "secret_password"