FF1 Format Preserving Encryption Gem

gem 'ff1'

require 'ff1'

# Create a cipher with a 128-bit key for decimal numbers (radix 10)
key = "\x2B\x7E\x15\x16\x28\xAE\xD2\xA6\xAB\xF7\x15\x88\x09\xCF\x4F\x3C"

# Reversible mode (default) - can decrypt back to original
cipher = FF1::Cipher.new(key, 10, FF1::Modes::REVERSIBLE)
plaintext = "4111111111111111"
ciphertext = cipher.encrypt(plaintext)
decrypted = cipher.decrypt(ciphertext)
puts "#{plaintext} → #{ciphertext} → #{decrypted}"
# => "4111111111111111 → 8224999410799188 → 4111111111111111"

# Irreversible mode - cannot decrypt (for GDPR compliance)
secure_cipher = FF1::Cipher.new(key, 10, FF1::Modes::IRREVERSIBLE)  
secure_ciphertext = secure_cipher.encrypt(plaintext)
# secure_cipher.decrypt(secure_ciphertext)  # ❌ Raises error
puts "Securely deleted: #{plaintext} → #{secure_ciphertext}"
# => "Securely deleted: 4111111111111111 → 2858907702179518"

cipher = FF1::Cipher.new(key, 10)
tweak = "user123"

plaintext = "1234567890"
ciphertext = cipher.encrypt(plaintext, tweak)
decrypted = cipher.decrypt(ciphertext, tweak)

# For hexadecimal data (radix 16)
hex_cipher = FF1::Cipher.new(key, 16)
hex_data = "ABCDEF123456"
encrypted_hex = hex_cipher.encrypt(hex_data)

# For binary data (radix 2)
binary_cipher = FF1::Cipher.new(key, 2)
binary_data = "1010101"  # Must be long enough to meet domain requirements
encrypted_binary = binary_cipher.encrypt(binary_data)

cipher = FF1::Cipher.new(key, 10)

# Encrypt any text including Unicode and special characters
text = "Hello, World! 🌍 Special chars: @#$%^&*()"
encrypted_text = cipher.encrypt_text(text)
decrypted_text = cipher.decrypt_text(encrypted_text)

puts encrypted_text  # Returns base64-encoded encrypted data
# => "SGVsbG8sIFdvcmxkISDwn42NIFNwZWNpYWwgY2hhcnM6IEAjJCVeJiooKQ=="

# Text with tweak for additional security
context = "user_session_123"
encrypted_with_context = cipher.encrypt_text(text, context)
decrypted_with_context = cipher.decrypt_text(encrypted_with_context, context)

# Irreversible text encryption for GDPR compliance
irreversible_cipher = FF1::Cipher.new(key, 10, FF1::Modes::IRREVERSIBLE)
sensitive_data = "Personal information to be securely deleted"
irreversibly_encrypted = irreversible_cipher.encrypt_text(sensitive_data)
# Cannot decrypt - data is permanently transformed while maintaining consistency

gem 'ff1'

# config/initializers/ff1.rb
FF1::ActiveRecord.configure do |config|
  # Required: Set your encryption key (store securely!)
  config.global_key = Rails.application.credentials.ff1_encryption_key
  # Or use environment variable:
  # config.global_key = ENV['FF1_ENCRYPTION_KEY']&.b
  
  # Optional: Set default encryption mode
  config.default_mode = FF1::Modes::REVERSIBLE
  
  # Optional: Customize column name for soft delete tracking
  config.deleted_at_column = :deleted_at
end

class User < ApplicationRecord
  include FF1::ActiveRecord
  
  # Encrypt email and phone with reversible encryption (can decrypt)
  ff1_encrypt :email, :phone, mode: :reversible
  
  # Encrypt sensitive data with irreversible encryption (cannot decrypt - GDPR compliant)
  ff1_encrypt :ssn, :address, :full_name, mode: :irreversible
  
  # Optional: Define scope for active users (alternative to built-in ff1_active)
  scope :active, -> { where(deleted_at: nil) }
end

# Create user - data is automatically encrypted before saving
user = User.create!(
  name: 'John Doe',
  email: 'john@example.com',
  phone: '555-1234', 
  ssn: '123-45-6789'
)

# Access data - reversible columns decrypt automatically  
puts user.email  # => 'john@example.com' (decrypted)
puts user.phone  # => '555-1234' (decrypted)
puts user.ssn    # => '[ENCRYPTED]' (irreversible, cannot decrypt)

# Data is encrypted in the database
User.connection.select_value("SELECT email FROM users WHERE id = #{user.id}")
# => "8224999410799188" (encrypted format)

# Soft delete with irreversible encryption
user.destroy  # Encrypts all sensitive data irreversibly, keeps record

# Check deletion status
user.ff1_deleted?     # => true (checks if deleted_at is set)
user.ff1_deleted_at   # => 2023-01-01 12:00:00 UTC

# Data is now irreversibly encrypted
user.email  # => '[ENCRYPTED]'
user.phone  # => '[ENCRYPTED]' 
user.ssn    # => '[ENCRYPTED]'

# Restore record (but data remains encrypted)
user.ff1_restore
user.ff1_deleted?  # => false (deleted_at is cleared)

# Find deleted users and restore them
deleted_user = User.ff1_deleted.first
deleted_user.ff1_restore

# True hard delete if needed
user.ff1_hard_destroy!

# Active (non-deleted) users only
User.ff1_active.count         # => 150
User.ff1_active.where(...)    # Chain with other scopes

# Soft-deleted users only  
User.ff1_deleted.count        # => 25

# All users (active + deleted)
User.ff1_all.count            # => 175

# Recently deleted users
User.ff1_recently_deleted(within: 30.days)

# Old deleted users (for purging)
User.ff1_old_deleted(older_than: 1.year)

# Bulk soft delete with encryption
User.ff1_destroy_all(status: 'inactive')  # Returns count of deleted records

# Purge old soft-deleted records
User.ff1_purge_deleted(older_than: 2.years)  # Permanent deletion

# Batch encrypt existing data
User.ff1_encrypt_existing_data!(columns: [:email, :phone])

# Statistics
User.ff1_stats
# => {
#   total_records: 175,
#   active_records: 150, 
#   deleted_records: 25,
#   encrypted_columns: [:email, :phone, :ssn],
#   deletion_rate: 14.29
# }

class User < ApplicationRecord
  include FF1::ActiveRecord
  
  # Per-column configuration
  ff1_encrypt :email, 
    mode: :reversible,
    key: Rails.application.credentials.user_email_key,  # Custom key
    radix: 256  # For text data
  
  ff1_encrypt :credit_card_number,
    mode: :reversible, 
    radix: 10   # For numeric data
    
  ff1_encrypt :sensitive_notes,
    mode: :irreversible,  # Cannot be decrypted
    radix: 256
end

# Safe for concurrent access
User.transaction do
  User.create!(email: 'user1@example.com')
  User.create!(email: 'user2@example.com')  
end

# Check if column exists
User.column_names.include?('deleted_at')  # Should return true

# If missing, run the migration
rails generate ff1:install User
rails db:migrate

# This will restore the record but encrypted data stays encrypted
deleted_user = User.ff1_deleted.first
deleted_user.ff1_restore

# Reversible data might be recoverable if it was encrypted before deletion
puts deleted_user.email  # May show original data or '[ENCRYPTED]'

# 128-bit key
key_128 = SecureRandom.bytes(16)
cipher_128 = FF1::Cipher.new(key_128, 10)

# 256-bit key
key_256 = SecureRandom.bytes(32)
cipher_256 = FF1::Cipher.new(key_256, 10)

begin
  cipher = FF1::Cipher.new(key, 10)
  result = cipher.encrypt("123")  # Too short
rescue FF1::Error => e
  puts "Encryption error: #{e.message}"
end