README

Modern secret encryption library with authenticated encryption support.

Overview

Horde_Secret provides a dual-stack API for encrypting and decrypting small pieces of data:

• PSR-4 Modern API (Horde\Secret\SecretManager) - Authenticated encryption with Libsodium/AES-GCM
• PSR-0 Legacy API (Horde_Secret) - Backward-compatible Blowfish encryption

Installation

composer require horde/secret

Quick Start

Modern API (Recommended for new projects)

use Horde\Secret\SecretManager;

// Automatic cipher selection (prefers Sodium)
$secret = SecretManager::create($key);

// Encrypt
$encrypted = $secret->encrypt('sensitive data');

// Decrypt
$decrypted = $secret->decrypt($encrypted);

Legacy API (Backward compatible)

$secret = new Horde_Secret();

// Encrypt
$encrypted = $secret->write($key, 'sensitive data');

// Decrypt
$decrypted = $secret->read($key, $encrypted);

Features

Modern API (PSR-4)

✅ Authenticated Encryption (AEAD)

• Prevents tampering and forgery attacks
• Automatic integrity verification

✅ Multiple Cipher Support

• Libsodium XSalsa20-Poly1305 (primary, version 0x02)
• AES-256-GCM (fallback, version 0x03)
• Blowfish ECB (legacy compatibility, version 0x01)

✅ Type Safety

• PHP 8.1+ strict types
• Immutable value objects
• Full type declarations

✅ Automatic Legacy Detection

• Decrypts old PSR-0 data seamlessly
• Migration helpers included

Legacy API (PSR-0)

• 100% backward compatible with Horde_Secret 2.x
• No breaking changes
• Drop-in upgrade
• Cookie/session key management

Usage Examples

Cipher Selection

use Horde\Secret\SecretManager;

// Automatic selection (recommended)
$secret = SecretManager::create($key);

// Explicit cipher selection
$sodium = SecretManager::withSodium($key);    // XSalsa20-Poly1305
$aes = SecretManager::withAesGcm($key);       // AES-256-GCM
$blowfish = SecretManager::withBlowfish($key); // Legacy only

// Check current cipher
echo $secret->getCipherName();     // "XSalsa20-Poly1305"
echo $secret->getCipherVersion();  // 0x02

Working with Encrypted Data

use Horde\Secret\SecretManager;

$secret = SecretManager::create($key);

// Encrypt returns an EncryptedData object
$encrypted = $secret->encrypt('my secret');

// Get Base64-encoded string for storage
$storedValue = $encrypted->toBase64();

// Decrypt from string or object
$decrypted = $secret->decrypt($storedValue);

Migration from Legacy Format

use Horde\Secret\SecretManager;

$secret = SecretManager::create($key);

// Decrypt legacy PSR-0 data (automatic detection)
$decrypted = $secret->decrypt($oldCiphertext);

// Check if needs re-encryption
if ($secret->needsReEncryption($oldCiphertext)) {
    // Upgrade to modern format
    $newCiphertext = $secret->encrypt($decrypted);

    // Update database
    $db->update('table', [
        'encrypted_field' => $newCiphertext->toString()
    ], ['id' => $recordId]);
}

Lazy Migration Pattern

use Horde\Secret\SecretManager;

function getData($key, $ciphertext, $db, $recordId) {
    $secret = SecretManager::create($key);

    // Decrypt (works with any format)
    $data = $secret->decrypt($ciphertext);

    // Opportunistically upgrade
    if ($secret->needsReEncryption($ciphertext)) {
        $newCiphertext = $secret->encrypt($data);
        $db->update('table', ['field' => $newCiphertext->toString()], ['id' => $recordId]);
    }

    return $data;
}

Error Handling

use Horde\Secret\SecretManager;
use Horde\Secret\Exception\DecryptionException;
use Horde\Secret\Exception\InvalidKeyException;
use Horde\Secret\Exception\UnsupportedCipherException;

try {
    $secret = SecretManager::create($key);
    $decrypted = $secret->decrypt($ciphertext);
} catch (DecryptionException $e) {
    // Wrong key or corrupted/tampered data
    error_log("Decryption failed: " . $e->getMessage());
} catch (InvalidKeyException $e) {
    // Invalid key provided
    error_log("Invalid key: " . $e->getMessage());
} catch (UnsupportedCipherException $e) {
    // Required cipher not available
    error_log("Cipher not supported: " . $e->getMessage());
}

Checking Cipher Availability

use Horde\Secret\Cipher\SodiumCipher;
use Horde\Secret\Cipher\AesGcmCipher;
use Horde\Secret\Cipher\BlowfishCipher;

if (SodiumCipher::isSupported()) {
    echo "Sodium available (recommended)\n";
}

if (AesGcmCipher::isSupported()) {
    echo "AES-GCM available\n";
}

if (BlowfishCipher::isSupported()) {
    echo "Blowfish available (legacy)\n";
}

System Requirements

Modern API (PSR-4)

• PHP ^8.1
• One of:
  • ext-sodium (recommended, bundled with PHP 7.2+)
  • ext-openssl with AES-GCM support

Legacy API (PSR-0)

• PHP ^8.1
• horde/crypt_blowfish ^2

Migration Guide

See UPGRADING.md for detailed migration instructions.

Quick Migration Summary

1. No immediate action required - PSR-0 API remains fully functional
2. For new code - Use PSR-4 SecretManager::create()
3. When ready - Migrate existing data using lazy or batch migration patterns
4. PSR-4 can decrypt PSR-0 data - Seamless compatibility

Security Considerations

PSR-0 (Blowfish ECB)

• ❌ No authentication (vulnerable to tampering)
• ❌ ECB mode (pattern leakage)
• ❌ 56-byte key limit
• ⚠️ Use only for backward compatibility

PSR-4 (Sodium/AES-GCM)

• ✅ Authenticated encryption (AEAD)
• ✅ Modern stream ciphers
• ✅ 256-bit keys
• ✅ Unique nonces per message
• ✅ Constant-time operations (Sodium)

Recommendation: Use PSR-4 for all new and sensitive data.

Data Format

PSR-4 Format

[Magic: 'H']['S'][Version: 1 byte][Payload: variable]

• Magic header: HS (0x48 0x53) for format identification
• Version byte:
  • 0x01 - Blowfish ECB (legacy)
  • 0x02 - Sodium XSalsa20-Poly1305
  • 0x03 - AES-256-GCM
• Payload: Cipher-specific encrypted data

PSR-0 Format (Legacy)

[Payload: variable]

• No header, raw Blowfish ciphertext
• Detected by absence of magic header

Testing

# Run all tests
vendor/bin/phpunit

# Run PSR-0 tests only
vendor/bin/phpunit test/Unit/SecretTest.php

# Run PSR-4 tests only
vendor/bin/phpunit --testsuite psr4

# Run integration tests
vendor/bin/phpunit test/Unit/Psr0Psr4IntegrationTest.php

Contributing

Contributions are welcome! Please:

1. Follow PER-1 coding style
2. Add tests for new features
3. Use Conventional Commits format
4. Ensure all tests pass on PHP 8.1+

# Check coding style
vendor/bin/phpcs

# Run tests
vendor/bin/phpunit

Changelog

See doc/changelog.yml for version history.

License

LGPL-2.1-only - see LICENSE for details.

Links

• Homepage: https://www.horde.org/libraries/Horde_Secret
• Documentation: https://www.horde.org/libraries/Horde_Secret
• GitHub: https://github.com/horde/Secret
• Issues: https://github.com/horde/Secret/issues
• Packagist: https://packagist.org/packages/horde/secret

Support

• Mailing List: dev@lists.horde.org
• GitHub Issues: https://github.com/horde/Secret/issues

Credits

• Authors: Chuck Hagenbuch, Michael Slusarz
• Copyright: 1999-2026 Horde LLC
• License: LGPL-2.1-only