Ginkelsoft Laravel Encrypted Search Index

Overview

Modern applications that handle sensitive user data—such as healthcare, financial, or membership systems—must ensure that all personally identifiable information (PII) is properly encrypted at rest. However, standard encryption creates a practical challenge: once data is encrypted, it can no longer be searched efficiently.

Laravel's built-in Crypt system offers strong encryption (AES-256-CBC) but provides no mechanism for searching encrypted values. Some systems attempt to address this by storing partial plaintext or using blind indexes, which can leak statistical patterns and increase the risk of correlation attacks.

The Laravel Encrypted Search Index package provides a clean, secure, and scalable alternative. It allows encrypted model fields to be searched using deterministic hashed tokens, without ever exposing plaintext data.

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Problem Statement

The traditional trade-off

When data is fully encrypted, you lose the ability to perform meaningful queries. Developers must choose between:

1. Strong security (no search): Encrypt every value with a random IV; searches become impossible.
2. Weak security (searchable): Store hashed or partially-encrypted values that can be compared, leaking patterns.

This package removes that trade-off by introducing a detached searchable index that maps encrypted records to deterministic tokens.

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Key Features

• Searchable encryption — Enables exact and prefix-based searches over encrypted data.
• Detached search index — Tokens are stored separately from the main data, reducing exposure risk.
• Deterministic hashing with peppering — Each token is derived from normalized text combined with a secret pepper.
• No blind indexes in primary tables — Encrypted fields remain opaque; only hashed references are stored elsewhere.
• High scalability — Efficient for millions of records through database indexing or Elasticsearch.
• Elasticsearch integration — Optionally store and query search tokens directly in an Elasticsearch index.
• Laravel-native integration — Works directly with Eloquent models, query scopes, and model events.
• Automatic field detection — Automatically indexes fields that use an encrypted cast when enabled.
• Fine-grained configuration — Supports attributes (#[EncryptedSearch]) and $encryptedSearch arrays for per-field behavior.

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How It Works

Each model can declare specific fields as searchable. When the model is saved, the system normalizes the field value, generates one or more hashed tokens, and stores them in a separate table named encrypted_search_index or in an Elasticsearch index if configured.

When you search, the package hashes your input using the same process and retrieves matching model IDs from the index.

1. Token Generation

For each configured field:

• Exact match token: A SHA-256 hash of the normalized value + secret pepper.
• Prefix tokens: Multiple SHA-256 hashes representing progressive prefixes of the normalized text (e.g. w, wi, wie).

2. Token Storage

By default, all tokens are stored in the database table encrypted_search_index. When Elasticsearch is enabled, they are stored in the configured Elasticsearch index instead.

Example structure:

model_type	model_id	field	type	token
App\Models\Client	42	last_names	exact	[hash]
App\Models\Client	42	last_names	prefix	[hash]

3. Querying

The package provides two Eloquent scopes:

Client::encryptedExact('last_names', 'Vermeer')->get();
Client::encryptedPrefix('first_names', 'Wie')->get();

These use indexed lookups (DB or Elasticsearch) and remain performant even at scale.

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Elasticsearch Integration

Enabling Elasticsearch

To enable Elasticsearch as the storage and query backend for encrypted tokens, set the following in your .env file:

ENCRYPTED_SEARCH_DRIVER=elasticsearch
ELASTICSEARCH_HOST=http://localhost:9200
ELASTICSEARCH_INDEX=encrypted_search

In config/encrypted-search.php:

return [
    'search_pepper' => env('SEARCH_PEPPER', ''),
    'max_prefix_depth' => 6,

    'elasticsearch' => [
        'enabled' => env('ENCRYPTED_SEARCH_DRIVER', 'database') === 'elasticsearch',
        'host' => env('ELASTICSEARCH_HOST', 'http://localhost:9200'),
        'index' => env('ELASTICSEARCH_INDEX', 'encrypted_search'),
    ],
];

When enabled, the package will skip database writes to encrypted_search_index and instead sync tokens directly to Elasticsearch via the ElasticsearchService.

Searching via Elasticsearch

To manually query Elasticsearch for a specific token:

curl -X GET "http://localhost:9200/encrypted_search/_search?pretty" \
-H 'Content-Type: application/json' \
-d '{
  "query": {
    "term": {
      "token.keyword": "<your-token-here>"
    }
  }
}'

Both the database and Elasticsearch drivers use the same search scopes — your application code remains identical regardless of which backend is active.

For prefix-based queries, you can match multiple tokens:

curl -X GET "http://localhost:9200/encrypted_search/_search?pretty" \
-H 'Content-Type: application/json' \
-d '{
  "query": {
    "bool": {
      "should": [
        { "terms": { "token.keyword": ["token1", "token2", "token3"] } }
      ]
    }
  }
}'

The same token-based hashing rules apply — plaintext values must first be converted into deterministic tokens.

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Security Model

Threat	Mitigation
Database dump or breach	Tokens cannot be reversed (salted + peppered SHA-256).
Statistical analysis	Tokens are detached; frequency analysis yields no correlation.
Insider access	No sensitive data in index table; encrypted fields remain opaque.
Leaked APP_KEY	Irrelevant for tokens; pepper is stored separately in .env.

This design follows a defense-in-depth model: encrypted data stays secure, while search operations remain practical.

---

Installation

composer require ginkelsoft/laravel-encrypted-search-index
php artisan vendor:publish --provider="Ginkelsoft\EncryptedSearch\EncryptedSearchServiceProvider" --tag=config
php artisan vendor:publish --provider="Ginkelsoft\EncryptedSearch\EncryptedSearchServiceProvider" --tag=migrations
php artisan migrate

If you plan to use the Elasticsearch integration, make sure an Elasticsearch instance (version 8.x or newer) is running and accessible at the host defined in your .env file.

Then add a unique pepper to your .env file:

SEARCH_PEPPER=your-random-secret-string

---

Configuration

config/encrypted-search.php:

return [
    'search_pepper' => env('SEARCH_PEPPER', ''),
    'max_prefix_depth' => 6,
    'elasticsearch' => [
        'enabled' => env('ENCRYPTED_SEARCH_DRIVER', 'database') === 'elasticsearch',
        'host' => env('ELASTICSEARCH_HOST', 'http://localhost:9200'),
        'index' => env('ELASTICSEARCH_INDEX', 'encrypted_search'),
    ],
];

---

Usage

Model Setup

If auto_index_encrypted_casts is enabled in the configuration (default: true), all model fields that use an encrypted: cast will be automatically indexed for exact search, even if they are not explicitly listed in $encryptedSearch.

You can also use PHP attributes to control search behavior per field:

use Ginkelsoft\EncryptedSearch\Attributes\EncryptedSearch;

class Client extends Model
{
    #[EncryptedSearch(exact: true, prefix: true)]
    public string $last_names;
}

When a record is saved, searchable tokens are automatically generated in `encrypted_search_index` or synced to Elasticsearch.

### Searching

```php
// Exact match
$clients = Client::encryptedExact('last_names', 'Vermeer')->get();

// Prefix match
$clients = Client::encryptedPrefix('first_names', 'Wie')->get();

Attributes always override global or $encryptedSearch configuration for the same field.

---

✅ 3. Configuration block (insert this before 'elasticsearch' => [...])

'auto_index_encrypted_casts' => true,

## Rebuilding or Syncing the Search Index
This command automatically detects whether you are using the database or Elasticsearch driver,
and rebuilds the appropriate index accordingly.

Rebuild indexes via Artisan:

```bash
php artisan encryption:index-rebuild "App\\Models\\Client"

If Elasticsearch is enabled, this will repopulate the Elasticsearch index instead of the database.

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Scalability and Performance

• Indexed database or Elasticsearch lookups for efficient token search.
• Chunked rebuilds for large datasets (--chunk option).
• Queue-compatible for asynchronous index rebuilds.
• Elasticsearch mode scales horizontally for enterprise use.

The detached index structure scales linearly and supports millions of records efficiently.

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Framework Compatibility

Laravel Version	Supported PHP Versions
8.x	8.0 – 8.1
9.x	8.1 – 8.2
10.x	8.1 – 8.3
11.x	8.2 – 8.3
12.x	8.3 and higher

The package is continuously tested across all supported combinations using GitHub Actions.

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Compliance

• GDPR — Encrypted and hashed separation ensures minimal data exposure.
• HIPAA — Meets encryption-at-rest requirements for ePHI.
• ISO 27001 — Aligns with confidentiality and cryptographic control standards.

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Troubleshooting

ConnectionException (cURL error 7)
Ensure your Elasticsearch container or service is running and reachable at the configured ELASTICSEARCH_HOST.

Missing index mappings
If you haven’t created the Elasticsearch index yet, initialize it manually:

curl -X PUT http://localhost:9200/encrypted_search

## License

MIT License
(c) 2025 Ginkelsoft