feat: implemented Aes256Gcm

README.md

@@ -61,6 +61,23 @@ echo $pullStream->pull($ciphertextChunk2);
 $xChaCha20Poly1305->eraseData($key);
 ```
 
+### Symmetric block encryption with additional data
+
+```php
+use PetrKnap\CryptoSodium\Aead\Aes256Gcm;
+
+$aes256Gcm = new Aes256Gcm();
+$message = 'Hello World!';
+$purpose = 'example';
+$key = $aes256Gcm->generateKey();
+
+$ciphertext = $aes256Gcm->encrypt($message, $key, additionalData: $purpose);
+
+echo $aes256Gcm->decrypt($ciphertext, $key, additionalData: $purpose);
+
+$aes256Gcm->eraseData($key);
+```
+
 
 ---
 

composer.json

@@ -23,13 +23,17 @@
   ],
   "homepage": "https://github.com/petrknap/php-crypto-sodium",
   "keywords": [
+    "AEAD",
+    "AES-256",
     "ChaCha20",
     "Curve25519",
     "Poly1305",
     "Sodium",
     "X25519",
     "XChaCha20",
     "asymmetric cryptography",
+    "authenticated encryption with associated data",
+    "authenticated encryption",
     "block cipher",
     "cryptography",
     "decryption",

src/Aead/Aes256Gcm.php

@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PetrKnap\CryptoSodium\Aead;
+
+use PetrKnap\CryptoSodium\CiphertextWithNonce;
+use PetrKnap\CryptoSodium\CryptoSodiumTrait;
+use PetrKnap\CryptoSodium\DataEraser;
+use PetrKnap\CryptoSodium\Exception;
+use PetrKnap\CryptoSodium\KeyGenerator;
+use PetrKnap\Shorts\Exception\MissingRequirement;
+use SensitiveParameter;
+
+/**
+ * @see sodium_crypto_aead_aes256gcm_encrypt()
+ */
+class Aes256Gcm implements KeyGenerator, DataEraser
+{
+    use CryptoSodiumTrait;
+
+    public const HEADER_BYTES = SODIUM_CRYPTO_AEAD_AES256GCM_NPUBBYTES;
+
+    public function __construct()
+    {
+        if (!sodium_crypto_aead_aes256gcm_is_available()) {
+            throw new MissingRequirement(self::class, 'available', 'aes256gcm');
+        }
+    }
+
+    public function generateKey(): string
+    {
+        return sodium_crypto_aead_aes256gcm_keygen();
+    }
+
+    /**
+     * @throws Exception\CouldNotEncryptData
+     */
+    public function encrypt(
+        string $message,
+        #[SensitiveParameter]
+        string &$key,
+        ?string $nonce = null,
+        ?string $additionalData = null,
+    ): CiphertextWithNonce {
+        return $this->wrapEncryption(static function (string $message, string $nonce) use (&$key, $additionalData): string {
+            $additionalData ??= '';
+            return sodium_crypto_aead_aes256gcm_encrypt($message, $additionalData, $nonce, $key);
+        }, $message, $nonce, self::HEADER_BYTES);
+    }
+
+    /**
+     * @throws Exception\CouldNotDecryptData
+     */
+    public function decrypt(
+        CiphertextWithNonce|string $ciphertext,
+        #[SensitiveParameter]
+        string &$key,
+        ?string $nonce = null,
+        ?string $additionalData = null,
+    ): string {
+        return $this->wrapDecryption(static function (string $ciphertext, string $nonce) use (&$key, $additionalData): string {
+            $additionalData ??= '';
+            $message = sodium_crypto_aead_aes256gcm_decrypt($ciphertext, $additionalData, $nonce, $key);
+            if ($message === false) {
+                throw new Exception\CouldNotDecryptData('sodium_crypto_aead_aes256gcm_decrypt', $ciphertext);
+            }
+            return $message;
+        }, $ciphertext, $nonce, self::HEADER_BYTES);
+    }
+}

tests/Aead/Aes256GcmTest.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PetrKnap\CryptoSodium\Aead;
+
+use PetrKnap\CryptoSodium\CiphertextWithNonce;
+use PetrKnap\CryptoSodium\CryptoSodiumTestCase;
+
+final class Aes256GcmTest extends CryptoSodiumTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->instance = new Aes256Gcm();
+        $key = base64_decode('9+PiVpFGyLSks1UJlpgGL6VuxJ86zzaizKB5e0C3IE8=');
+        $additionalData = 'AD';
+        $this->ciphertextWithNonce = new CiphertextWithNonce(
+            ciphertext: base64_decode('sycH81OWv2uCxygkUDpBq+Jy7SBl6zSuWjh4zTQ='),
+            nonce: base64_decode('FJbSk+jybJUfvxrn'),
+        );
+        $this->encryptArgsSet = [
+            [self::MESSAGE, $key, $this->ciphertextWithNonce->nonce, $additionalData],
+        ];
+        $this->decryptArgsSet = [
+            [$this->ciphertextWithNonce, $key, null, $additionalData],
+            [$this->ciphertextWithNonce->toString(), $key, null, $additionalData],
+            [$this->ciphertextWithNonce->ciphertext, $key, $this->ciphertextWithNonce->nonce, $additionalData],
+        ];
+    }
+}

tests/CryptoSodiumInterfaceTest.php

@@ -29,6 +29,7 @@ public function testIsImplementedByClass(string $className): void
     public static function dataIsImplementedByClass(): array
     {
         return [
+            Aead\Aes256Gcm::class => [Aead\Aes256Gcm::class],
             Box::class => [Box::class],
             SecretBox::class => [SecretBox::class],
             SecretStream\XChaCha20Poly1305::class => [SecretStream\XChaCha20Poly1305::class],

tests/ReadmeTest.php

@@ -23,6 +23,7 @@ public static function getExpectedOutputsOfPhpExamples(): iterable
             SecretBox::class => 'Hello World!',
             Box::class => 'Hello World!',
             SecretStream\XChaCha20Poly1305::class => 'Hello World!',
+            Aead\Aes256Gcm::class => 'Hello World!',
         ];
     }
 }