feat(demo): add story 1 — Sorano: Rock and Time

2026-06-20 21:19:57 +02:00
parent 42ed59a6b3
commit 8f87155c1d
5508 changed files with 1595740 additions and 124 deletions
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TrilbyMedia\Cap;
+
+/**
+ * Deterministic PRNG that must be bit-exact with the upstream cap.js
+ * implementation in server/index.js. Used to regenerate the salt/target
+ * pairs for each sub-challenge from the challenge token.
+ *
+ * JS uses 32-bit unsigned/int32 semantics. In PHP (64-bit) we emulate
+ * that with explicit `& 0xFFFFFFFF` masks after every arithmetic op.
+ */
+final class Prng
+{
+    private const UINT32_MASK = 0xFFFFFFFF;
+    private const FNV_OFFSET  = 0x811C9DC5; // 2166136261
+
+    public static function generate(string $seed, int $length): string
+    {
+        if ($length <= 0) {
+            return '';
+        }
+
+        $state  = self::fnv1a($seed);
+        $result = '';
+
+        while (strlen($result) < $length) {
+            $state = self::next($state);
+            $result .= str_pad(dechex($state), 8, '0', STR_PAD_LEFT);
+        }
+
+        return substr($result, 0, $length);
+    }
+
+    private static function fnv1a(string $str): int
+    {
+        $hash = self::FNV_OFFSET;
+        $len  = strlen($str);
+
+        for ($i = 0; $i < $len; $i++) {
+            $hash = ($hash ^ ord($str[$i])) & self::UINT32_MASK;
+
+            $s1  = ($hash << 1)  & self::UINT32_MASK;
+            $s4  = ($hash << 4)  & self::UINT32_MASK;
+            $s7  = ($hash << 7)  & self::UINT32_MASK;
+            $s8  = ($hash << 8)  & self::UINT32_MASK;
+            $s24 = ($hash << 24) & self::UINT32_MASK;
+
+            $hash = ($hash + $s1 + $s4 + $s7 + $s8 + $s24) & self::UINT32_MASK;
+        }
+
+        return $hash;
+    }
+
+    private static function next(int $state): int
+    {
+        $state = ($state ^ (($state << 13) & self::UINT32_MASK)) & self::UINT32_MASK;
+        $state = ($state ^ ($state >> 17)) & self::UINT32_MASK;
+        $state = ($state ^ (($state << 5) & self::UINT32_MASK)) & self::UINT32_MASK;
+
+        return $state;
+    }
+}