Fehlende ALTCHA-Bibliotheksdateien ergaenzt

2026-09-21 18:08:42 +02:00
parent a8a44631c7
commit bfb998f7ce
1 changed files with 64 additions and 0 deletions
@@ -0,0 +1,64 @@
+<?php
+
+namespace AltchaOrg\Altcha\V1;
+
+use AltchaOrg\Altcha\V1\Hasher\Algorithm;
+use AltchaOrg\Altcha\V1\Hasher\Hasher;
+use AltchaOrg\Altcha\V1\Hasher\HasherInterface;
+
+class Obfuscator
+{
+    public const DEFAULT_MAX_NUMBER = 10_000;
+
+    /**
+     * @param int $maxNumber Maximum number for the random number generator (default: 10,000)
+     */
+    public function __construct(
+        private readonly int $maxNumber = self::DEFAULT_MAX_NUMBER,
+        private readonly HasherInterface $hasher = new Hasher(),
+    ) {
+    }
+
+    /**
+     * Encrypts a payload for PoW-based reveal using AES-GCM.
+     *
+     * @param string   $raw     Plaintext payload to encrypt.
+     * @param string   $key     Symmetric key used to encrypt/decrypt the payload. Defaults to empty string, ie. no key.
+     * @param null|int $counter Optional fixed PoW counter used to derive the IV. If null, a random integer in [0, $this->maxNumber] inclusive is chosen.
+     *
+     * @return string Base64-encoded bytes of ciphertext followed by the 16‑byte GCM authentication tag ($ciphertext . $tag).
+     */
+    public function obfuscateData(string $raw, string $key = '', ?int $counter = null): string
+    {
+        $cipher = 'AES-256-GCM';
+        $keyHash = $this->hasher->hash(Algorithm::SHA256, $key);
+
+        $ivLength = openssl_cipher_iv_length($cipher);
+
+        if (false === $ivLength) {
+            throw new \RuntimeException('Getting cipher iv length failed.');
+        }
+
+        $iv = ''; // AES‑GCM initialization vector (IV), typically 12 bytes for AES-256-GCM
+        $num = $counter ?? $this->randomInt();
+
+        // Fill IV from the counter, one byte at a time (little‑endian)
+        for ($i = 0; $i < $ivLength; $i++) {
+            $iv .= \chr(abs($num % 256));
+            $num = intdiv($num, 256);
+        }
+
+        $encryptedData = openssl_encrypt($raw, $cipher, $keyHash, \OPENSSL_RAW_DATA, $iv, $tag);
+
+        if (!$encryptedData) {
+            throw new \RuntimeException('Data encryption failed.');
+        }
+
+        return base64_encode($encryptedData . $tag);
+    }
+
+    private function randomInt(): int
+    {
+        return random_int(0, $this->maxNumber);
+    }
+}