File: README_ACTIVE_CRYPTO [ezcrypto-0.7.2 Documentation]

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# ActiveCrypto - Easy to use Crypto for Ruby on Rails

ActiveCrypto is based on EzCrypto and provides application oriented crypto support for Ruby on Rails applications.

## Features

- Transparent encryption/decryption

- Ruby on Rails like domain language

## Installation

Download it from here:

rubyforge.org/frs/?group_id=755

or install it via Ruby Gems:

    gem install ezruby

## Simple examples

#### A simple encrypted class

You specify in your class which fields are encrypted:

    class Document < ActiveRecord::Base
            encrypt :title,:body
    end

Two encrypt it you need to enter a key. For ease of use there is a method called enter_password which sets the key based on a password of your choice.

    doc=Document.new
    doc.enter_password "This stuff is secret man!!!"
    doc.title="Plan to take over the world"
    doc.body="Write apps in Rails"
    doc.save

This needs to be done as well if you want to read your document:

    doc=Document.find 1
    doc.enter_password "This stuff is secret man!!!"
    puts doc.name

If you don't remember to set a key it will through a MissingKeyError.

#### More realistic example with KeyHolder

It probably isn't much use if each record needs its own key. The solution to this is the KeyHolder. A KeyHolder is an object that holds keys for use by other objects. A typical example would be a user.

    class User < ActiveRecord::Base
            has_many :documents
            keyholder
    end

We use standard ActiveRecord associations to associate the User with his documents. We also need to specify that he is a keyholder. We now modify our Document class as follows:

    class Document < ActiveRecord::Base
            belongs_to :user
            encrypt :title,:body,:key=>:user
    end

We have the standard associations going on here, but we have also added the option :key=>:user to the encrypt statement. Now we could do this:

    @user=User.new
    @user.enter_password "This stuff is secret man!!!"
    @user.save

    @doc=Document.new
    @doc.user=@user
    @doc.title="Plan to take over the world"
    @doc.body="Write apps in Rails"
    @doc.save

You could also do ordinary rails like stuf such as:

    @user.documents.each do |doc|
            puts doc.name
    end

Decryption is done transparently.

When doing this within a rails application, active_crypto automatically maintains a list of keys for each user session. Besides the 2 steps below you don't need to do anything special within your controller.

1. When a user logs on with a password enter his password like this:

       @user.enter_password @params['password']

2. When a user logs off call the following

       clear_session_keys

## Usage as a Rails plugin

Just unpack it into your $MY_RAILS_PROJECTS/vendor/plugins folder to use it as a self contained plugin. Otherwise you can install it as a gem using:

    $ gem install ezcrypto

Then make sure to require "active_crypto.rb" at the end of your environment.rb file.

## Database Schema issues

ActiveCrypto doesn't really care about the schema, but that said you do need a schema that will accept and not mangle it's output. On MySQL I normally use TINYBLOB instead of VARCHAR and BLOB instead of TEXT.

## License

EzCrypto and ActionCrypto is released under the MIT license.

## Support

To contact the author, send mail to pelleb@gmail.com

Also see my blogs at: stakeventures.com and neubia.com

This project was based on code used in my projects WideWord where you can securely share documents and StakeItOut, where you can securely share web services with your partners. wideword.net stakeitout.com

(C) 2005 Pelle Braendgaard

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