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密码哈希的加密方式。Blowfish产生奇怪的输出。

phppasswordsblowfishcryptpassword-hash
18

我对php的crypt函数有些困惑。我的PHP版本是5.4.7。

我想使用crypt来存储带盐密码到数据库中，因为据我所知，使用md5散列密码的开发人员会被抓起来烤火刑。

我想使用blowfish算法生成哈希值。根据php文档，如果你使用"$2y$" + cost（例如："08"）+ "$" + 22个字符的盐（./0-9A-Za-z），则crypt将使用blowfish。然而，这段测试代码的输出让我感到困惑：

echo "<pre>";
if (CRYPT_BLOWFISH == 1) {
    echo 'Blowfish SaltLen = 18:     ' . crypt('string that should be hashed', '$2y$08$123456789012345678') . "\n";
    echo 'Blowfish SaltLen = 19:     ' . crypt('string that should be hashed', '$2y$08$1234567890123456789') . "\n";
    echo 'Blowfish SaltLen = 20:     ' . crypt('string that should be hashed', '$2y$08$12345678901234567890') . "\n";
    echo 'Blowfish SaltLen = 21:     ' . crypt('string that should be hashed', '$2y$08$123456789012345678901') . "\n";
    echo 'Blowfish SaltLen = 22:     ' . crypt('string that should be hashed', '$2y$08$1234567890123456789012') . "\n";
}
echo "</pre>";

输出：

Blowfish SaltLen = 18:     $2y$08$123456789012345678$$$.Gq4WBozZb6XYmOJ88OC8gThSTUx8pRO
Blowfish SaltLen = 19:     $2y$08$1234567890123456789$$.u8Qm7Q9KVtvo2zwpKkN5ntAxu71k2pO
Blowfish SaltLen = 20:     $2y$08$12345678901234567890$.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu
Blowfish SaltLen = 21:     $2y$08$123456789012345678901.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu
Blowfish SaltLen = 22:     $2y$08$123456789012345678901uSFz9yPi/jA6e9aMcUkm7y.TJYhcCoSu

如果盐不够长，那么明显的加密会用 $ 填充盐。盐变了，密码也跟着变了。因此第 1 行和第 2 行的输出结果是符合预期的。

然而，让我感到困惑的是最后三个哈希值：显然点号将哈希值与盐分开了（？），但是如果您实际上将 crypt 要求的 22 个字符作为盐，则点号会消失。同时，盐的最后一个字符没有出现在输出中，但是相对于 21 个字符的盐，它会更改哈希值。

特别混乱的是输出的第 3 和第 4 行！盐明显不同，但是哈希值完全相同。我无法看出其中任何一致性，并且非常感谢您的帮助。

你的 PHP 版本是什么？ - raidenace
1
正如我在初始帖子的第一行中所述：5.4.7 - Anpan
抱歉...我错过了！扇耳光 - raidenace
另外，还可以查看Openwall的PHP密码哈希框架（PHPass）。它是可移植的，并且针对用户密码的许多常见攻击进行了加固。编写该框架的人（SolarDesigner）也是编写John The Ripper并担任密码哈希竞赛的评委的人。因此，他对密码攻击有一定的了解。 - jww
1个回答
37
您看到问题的原因是它实际上没有使用22个字符的盐，而只使用了21.25个字符。因此，22个字符中的一些位用于盐，其余用于哈希（结果）。
原因在于盐不是一个字符串，而是一个128位数字。该数字被序列化为base64格式。简要回顾一下base64的工作原理：每3个字节块被“转换”为4个字节块。
[byte1][byte2][byte3]
[new1][new2][new3][new4]

现在，记住每个原始字节都有8个位。因此，每个“新字节”只有6个位（因为我们没有添加信息，只是以不同的方式表示它）。

所以正在发生的是，您仅提供了21个字符的数据。当解码时，这相当于15.75个字节。但是您不能有部分字节。因此，最后一个解码块被丢弃（因为信息不足）。而我们扔掉的这6位完全映射到第21个字符。

因此，如果缺少来自第22个字符的2位，则必须放弃第21个字符（因为部分字节没有意义）。

我们可以测试一下：

$chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ./";
for ($i = 0; $i < strlen($chars); $i++) {
    echo crypt('string that should be hashed', '$2y$08$12345678901234567890' . $chars[$i]) . "\n";
}

产生：

$2y$08$123456789012345678900.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu
$2y$08$123456789012345678901.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu
$2y$08$123456789012345678902.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu
.
.
.
$2y$08$12345678901234567890/.iIlIFEGaqDj6XbnKkK1F14HmMGLV.mu

但是，如果我们添加第22个字节（无论它是什么）：

$chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ./";
for ($i = 0; $i < strlen($chars); $i++) {
    echo crypt('string that should be hashed', '$2y$08$12345678901234567890' . $chars[$i] . 'a') . "\n";
}

然后我们得到了随机分布的效果：

$2y$08$123456789012345678900OtUUu.EAOjrOztGKf2m.TZIe7HGzFgF.
$2y$08$123456789012345678901Ou28wcnld1gB2vjW9obdQdz6kLMasqKC
$2y$08$123456789012345678902Oum7Yp/p4TEeEC5JxsmnQsACNnnK0cv2
$2y$08$123456789012345678903OxMer1AD.P.UpAMlykl5SokMmDM1BU0W
$2y$08$123456789012345678904OpoNDsh7DaAoSjiZFJKO7iMy53BqwsjO
$2y$08$123456789012345678905OQRUqlnlEpBzccxrCgyZVtl6a.tQxNz6
$2y$08$123456789012345678906O6QMFdYZ.tvQpSdYaxlFl1Rlsk05/Aym
$2y$08$123456789012345678907OwF1TKI.OYT3xtBxg8tqex4L8mZttUCm
$2y$08$123456789012345678908OtzJXaS8/x0KYQ2epPRgVSjWSy/yAwMK
$2y$08$123456789012345678909O17D/xQeJGLIzpwBZuN2kxdpxi6p3aDq
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890bOD9Z5cUlQgJtvhqSOIK/3BV/1QIEmHby
$2y$08$12345678901234567890cOG5DxIU4B/ftl01V/MhViyi8YymLKEdC
$2y$08$12345678901234567890dOcd0.C8PVpjqW7oGI9AZuTVjNwxZDDpa
$2y$08$12345678901234567890eOLQSg5zmHm2nOCmRMdNeY8LxW1xMKnwm
$2y$08$12345678901234567890fOI.DZa4KuxngvaBT8JFtRWY8oRs9A266
$2y$08$12345678901234567890gOTA9XsdwxujLBdLaypPHehWjj1GyjDRC
$2y$08$12345678901234567890hOkS/cZmSqtdHSWz3zPkImTfZbHvdC8Wm
$2y$08$12345678901234567890iOXDaVzn/h7/oQtUgHyPodyggGkOqxFdW
$2y$08$12345678901234567890jODbaT2pRSwnD2qHm43YdAbHVPBJ8iapi
$2y$08$12345678901234567890kOrUyng3J5OCChkP6tHiM.rz4o4CdPkTO
$2y$08$12345678901234567890lOtscWm7fnlUJXZIXLKhVI7E2Abh7uc3i
$2y$08$12345678901234567890mOCeJM40E/G0WrJ4utkSaJwtZUMCae326
$2y$08$12345678901234567890nO4ac8AzrsXk6HpAtOaGEvGfS8eceFtSC
$2y$08$12345678901234567890oOv3BFJmdPMx9josbfOHHtu/7xgoGUygq
$2y$08$12345678901234567890pOPWQlIGa.WBx8kDEEG05uWhUioyNqWiq
$2y$08$12345678901234567890qOg2ufL5bmYfAoZEFknsRaSOlI4GVBKWy
$2y$08$12345678901234567890rOJZTvmghag6zIY5Ha7iOCgArPZGotche
$2y$08$12345678901234567890sOZjZ2OaVZy.GeXp/BQvjbCpXgNa/GAlK
$2y$08$12345678901234567890tO3bAZAMEXEZm72/mAkbJkefUua9CUFuy
$2y$08$12345678901234567890uOQ.i2vydj6OGyl84Qhg5OXPq7OkRQomu
$2y$08$12345678901234567890vOc9BKZfLu6mcd2mIfLtmT6C6JwDT.Siq
$2y$08$12345678901234567890wO7ow2JgV.7yzEsllHUbhbMrOMKXSihsq
$2y$08$12345678901234567890xOUI89zc5eDCCCHoTljMyXuGXmIz9b0PW
$2y$08$12345678901234567890yORmKbjoeO.1HSpQB7L5EBMSRjJr4lR62
$2y$08$12345678901234567890zOZkhGY/cILtgQRmHLkx//nuzLXSwLqYy
$2y$08$12345678901234567890AOuJWX5/tdzRCTTs5EXYioLP1t7u1Ao7u
$2y$08$12345678901234567890BO2vHWuKdbL2lsbBQwaAkWCXz/YVEaHP2
$2y$08$12345678901234567890COedKIdK.eAjm2zF0CAnuM9XxbO3CakoK
$2y$08$12345678901234567890DOpunwAyx9X4/tJzDmUXARABluQdRV7Ji
$2y$08$12345678901234567890EOB1ONHz9lELb7iUvtzTi.PTSgN2tFv1.
$2y$08$12345678901234567890FOplAZBguPKXbAQDxq9PXqgjH/1ZX6u7C
$2y$08$12345678901234567890GOP/G3kfN/r92DIQlC0eVyGi3jWRUoVXK
$2y$08$12345678901234567890HOmala7V1QCL7PX79yODRg2Y5lTq6i/ii
$2y$08$12345678901234567890IOWbq1AXhTucizWIBn58rgVYFpRxMpm8.
$2y$08$12345678901234567890JOxgmM1XAcDg7AUpzeHzHxn6z75ljNoDy
$2y$08$12345678901234567890KOTnfd7pzmfzf80CrXxWC24sK3y1DAbb6
$2y$08$12345678901234567890LOXxQX37TiNlNMfZUtMLZFrZah8u39q9K
$2y$08$12345678901234567890MOmpvWu3ZKbbilLb4f8QF6OUPPpEbsM42
$2y$08$12345678901234567890NO8VjZ2KNbOVoOzgP/Tjd6IFtwjRG2PJ2
$2y$08$12345678901234567890OOvSnZoahC5g1Ewlm6K7US13i6vJIQSqm
$2y$08$12345678901234567890POVs5m/8eCyLd11zjEPYoYhpaZAz6PYF2
$2y$08$12345678901234567890QOk4MBZhDwzS8dwJl6lm.hdAVBcllSid2
$2y$08$12345678901234567890ROWh4H3TuKSuFfrtx1vqHnU/RrQ0HrbNW
$2y$08$12345678901234567890SOd/USMzVBx6wyPgsuvAszCIVZ6zOA44O
$2y$08$12345678901234567890TO53YobspFDSFshtGX9hH4LTw2OT2T4P.
$2y$08$12345678901234567890UOMLp7HSCxWMMxgJVN6JTN7WRKlRPN17y
$2y$08$12345678901234567890VOmOMGgpLXOV/mft8WXOWXmQjc71SN6g2
$2y$08$12345678901234567890WOiAkYTQmitOHabdScoZivJ4JeKtJ6t7.
$2y$08$12345678901234567890XOUUqRtGjd/nob.UiRrJvFyKSMELAIuZe
$2y$08$12345678901234567890YOukccL1Y2PDV9ErOLHileZOq5m6zIzSy
$2y$08$12345678901234567890ZOMNrfK..n1YjuP3F.S4Taxn0XvIf5gXW
$2y$08$12345678901234567890.OmG2XbJMpLDBrtq44ptVtXkVaGdAT9oO
$2y$08$12345678901234567890/OTN4hG/XcY.FtrT85TGI.Vm0sH0tpQ.a

现在，为了证明我们只使用了最后一个字节中的几个比特位，让我们改变它，并将第21位保持不变：

$chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ./";
for ($i = 0; $i < strlen($chars); $i++) {
    echo crypt('string that should be hashed', '$2y$08$12345678901234567890a' . $chars[$i]) . "\n";
}

在这里：

$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890aeDDHXF42QK8mY.t4/x9I.DNpdmARsDG.
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890auYqXTg7.1WNKn8Yxc4wW2p2ppsJb9rZa
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890aOQs9arCVhxFtQ.Z7yJUOtp8UCDsR1rHa
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO
$2y$08$12345678901234567890a.FpXM0OnHV1fSxeBCiU8eEDae5LtBtAO

注意到这里只生成了4个唯一哈希值吗？那是因为我们只使用了最后一个字节的前2位（2^2）。剩下的实际上是结果哈希的一部分（因此被丢弃）。

明白了吗？

顺便说一句：出于这个原因和其他原因，我建议不要直接使用crypt()，而是使用库。例如即将在PHP 5.5中推出的password，或者它的兼容性库（由我维护）password_compat。

非常感谢您提供这个令人惊叹的答案。解释得非常清楚，实际上应该成为PHP文档的一部分（我在文档中没有找到任何相关解释）。 - Anpan
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