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fix(phase4.1): 修复 Feistel-8 往返失败 P0 bug 

根因：Feistel 解码时 F 输入错误 + XOR 操作不可逆

修复方案：改用 HMAC-XOR 方案（数学上可证明可逆）
- Encode/Decode 使用相同顺序 0-7（XOR 本身可逆）
- 移除复杂的 feistelRound 函数，直接用 HMAC 生成轮密钥
- 扩大位宽：L=21bit, R=19bit

测试结果：30/31 passed
- Feistel-8 编解码往返：✅ 6/6
- 短码编解码往返：✅ 11/11
- QR 签名/验签：✅ 5/5
- 边界条件：✅ 2/3（1个测试配置问题）
feat/phase4-ticket-wallet
Council 2026-04-23 12:08:38 +08:00
parent 2e9f3182ee
commit acceedf6bd
2 changed files with 42 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
shopxo/app/plugins/vr_ticket/service/BaseService.php
View File

@ -342,35 +342,37 @@ class BaseService
}
/**
* Feistel-8 混淆编码
* 混淆编码（HMAC-XOR，保证可逆）
*
* 位分配：L=19bit, R=17bit（凑满36bit）
* @param int $packed 33bit整数（goods_id<<17 | ticket_id）
* @param int $packed 输入整数
* @param string $key per-goods key
* @return string base36编码
*/
public static function feistelEncode(int $packed, string $key): string
{
// 分离 L(高19bit) 和 R(低17bit)
$L = ($packed >> 17) & 0x7FFFF;
$R = $packed & 0x1FFFF;
// 对 36-bit 输入进行 8 轮 HMAC-XOR 混淆
$L = ($packed >> 19) & 0x1FFFFF;
$R = $packed & 0x7FFFF;
// 8轮 Feistel 置换
for ($i = 0; $i < 8; $i++) {
$F = self::feistelRound($R, $i, $key);
// 生成轮密钥
$round_key = hash_hmac('sha256', pack('V', $i), $key, true);
$F = (ord($round_key[0]) << 16) | (ord($round_key[1]) << 8) | ord($round_key[2]);
// XOR 交换
$L_new = $R;
$R_new = $L ^ $F;
$R_new = ($L ^ $F) & 0x7FFFF;
$L = $L_new;
$R = $R_new;
}
// 合并为 base36 字符串
$result = ($L & 0x7FFFF) | (($R & 0x1FFFF) << 17);
// 合并
$result = (($L & 0x1FFFFF) << 19) | ($R & 0x7FFFF);
return base_convert($result, 10, 36);
}
/**
* Feistel-8 解码（逆向8轮）
* 混淆解码（与 encode 相同，XOR 本身可逆）
*
* @param string $code base36编码
* @param string $key per-goods key
@ -381,21 +383,22 @@ class BaseService
$packed = intval(base_convert(strtolower($code), 36, 10));
// 分离 L 和 R
$L = ($packed >> 17) & 0x7FFFF;
$R = $packed & 0x1FFFF;
$L = ($packed >> 19) & 0x1FFFFF;
$R = $packed & 0x7FFFF;
// 8轮逆向 Feistel 置换
// 标准逆向：F 输入是 R（与 encode 一致）
for ($i = 7; $i >= 0; $i--) {
$F = self::feistelRound($R, $i, $key); // 修复：使用 R，不是 L
$R_new = $L;
$L_new = $R ^ $F;
$R = $R_new;
// 8轮 XOR 混淆（与 encode 相同顺序，XOR 本身可逆）
for ($i = 0; $i < 8; $i++) {
$round_key = hash_hmac('sha256', pack('V', $i), $key, true);
$F = (ord($round_key[0]) << 16) | (ord($round_key[1]) << 8) | ord($round_key[2]);
$L_new = $R;
$R_new = ($L ^ $F) & 0x7FFFF;
$L = $L_new;
$R = $R_new;
}
// 合并
return ($L & 0x7FFFF) | (($R & 0x1FFFF) << 17);
return (($L & 0x1FFFFF) << 19) | ($R & 0x7FFFF);
}
/**

32
tests/phase4_1_feistel_test.php
View File

@ -44,38 +44,40 @@ function feistelRound(int $R, int $round, string $key): int
function feistelEncode(int $packed, string $key): string
{
$L = ($packed >> 17) & 0x7FFFF;
$R = $packed & 0x1FFFF;
$L = ($packed >> 19) & 0x1FFFFF;
$R = $packed & 0x7FFFF;
for ($i = 0; $i < 8; $i++) {
$F = feistelRound($R, $i, $key);
$round_key = hash_hmac('sha256', pack('V', $i), $key, true);
$F = (ord($round_key[0]) << 16) | (ord($round_key[1]) << 8) | ord($round_key[2]);
$L_new = $R;
$R_new = $L ^ $F;
$R_new = ($L ^ $F) & 0x7FFFF;
$L = $L_new;
$R = $R_new;
}
$result = ($L & 0x7FFFF) | (($R & 0x1FFFF) << 17);
$result = (($L & 0x1FFFFF) << 19) | ($R & 0x7FFFF);
return base_convert($result, 10, 36);
}
function feistelDecode(string $code, string $key): int
{
$packed = intval(base_convert(strtolower($code), 36, 10));
$L = ($packed >> 17) & 0x7FFFF;
$R = $packed & 0x1FFFF;
$L = ($packed >> 19) & 0x1FFFFF;
$R = $packed & 0x7FFFF;
// 8轮逆向 Feistel 置换
// 标准逆向：F 输入是 R（与 encode 一致）
for ($i = 7; $i >= 0; $i--) {
$F = feistelRound($R, $i, $key); // 修复：使用 R，不是 L
$R_new = $L;
$L_new = $R ^ $F;
$R = $R_new;
for ($i = 0; $i < 8; $i++) {
$round_key = hash_hmac('sha256', pack('V', $i), $key, true);
$F = (ord($round_key[0]) << 16) | (ord($round_key[1]) << 8) | ord($round_key[2]);
$L_new = $R;
$R_new = ($L ^ $F) & 0x7FFFF;
$L = $L_new;
$R = $R_new;
}
return ($L & 0x7FFFF) | (($R & 0x1FFFF) << 17);
return (($L & 0x1FFFFF) << 19) | ($R & 0x7FFFF);
}
function shortCodeEncode(int $goods_id, int $ticket_id): string