在 PHP 中生成盐
在 PHP 中生成加密安全的 32 字节盐而不依赖于典型 PHP 安装中很少包含的库的最佳方法是什么？
经过一番谷歌搜索后，我发现 mt_rand 被认为不够安全，但我还没有找到替代的建议。一篇文章建议从 /dev/random 读取，但这不仅在 Windows 上不起作用；它也非常慢。
我想要安全性和速度之间的合理平衡（即，生成 512 字节不应该花费 20 秒，就像 /dev/random 通常那样）
What's the best way to generate a cryptographically secure 32 bytes salt in PHP, without depending on libraries seldom included in typical PHP installations?
After some googling I discovered that mt_rand is not considered secure enough, but I haven't found a suggestion for a replacement. One article suggested reading from /dev/random but not only this won't work on windows; it is also very slow.
I want a reasonable balance between security and speed (ie, it shouldn't take 20 seconds to generate 512 bytes, like /dev/random usually does)
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这在 PHP 7 中更容易：
只需使用
$salt = random_bytes($numberOfDesiredBytes);生成盐。无论如何，你需要盐做什么？如果是密码，只需使用
password_hash()和password_verify()。This is easier in PHP 7:
Just use
$salt = random_bytes($numberOfDesiredBytes);to generate a salt.What do you need a salt for, anyway? If it's for passwords, just use
password_hash()andpassword_verify().您可能想查看
mcrypt_create_iv()。You might want to take a look at the documentation (and comments) for
mcrypt_create_iv().您可以使用函数
mycrypt_create_iv()，从 PHP 版本 5.3 开始，它还使用 Windows 服务器上的随机源（不仅在 Unix 上）。在使用它之前，您应该检查常量MCRYPT_DEV_URANDOM是否已定义。与随机不同，如果没有足够的可用熵，urandom 不会阻塞服务器。由于密码盐应该是唯一的（不一定是随机的），urandom 对我来说似乎是一个不错的选择。
You can use the function
mycrypt_create_iv(), since PHP Version 5.3 it also uses the random source on a Windows server (not only on Unix). Before using it, you should check if the constantMCRYPT_DEV_URANDOMis defined.Unlike random, urandom does not block the server, if there is not enough entropy available. Since the password salt should be unique (not necessarily random), urandom seems to be a good choice to me.
uniqueid不太适合生成随机字符串，因为它也是基于microtime的。CPU 周期通常比微时间周期短得多，这可能导致循环内给定变量可能保持不变。
将第二个参数“entropy”设置为 true，
将提供增加的随机性。
为了获得与大多数字符集良好兼容的随机字符串，可以将base64编码应用于mcrypt初始化向量函数
mcrypt_create_iv：将字符字母减少到2^ 6Bit增加了大小，上面已经说明了。
uniqueidis not well suited for generating a random string as it too ismicrotimebased.A CPU Cycle is generally much shorter than a microtime-tick, which may lead to possible constancy for a given variable within loops.
Setting the second parameter "entropy" to true,
will provide increased randomness.
To get a random string that is well compatible with most character-sets,one may apply base64 encoding to the mcrypt initilization vector function
mcrypt_create_iv:Reducing the character-alphabet to 2^6Bit increases the size, which is accounted for above.
从
/dev/urandom读取，或使用openssl_random_pseudo_bytes()。Read from
/dev/urandom, or useopenssl_random_pseudo_bytes().看起来这个问题有一个公认的答案，但我只是想在经过一些研究和阅读这篇文章后额外声明，如果你不把所有鸡蛋放在一个篮子里，你可能会增加一些安全性。
我可能建议不要仅仅依赖 PHP 来创建盐并对密码进行哈希处理。如果让数据库完成部分工作，您可以进一步混淆您的解决方案。
有人建议只使用password_hash()和password_verify()。虽然这些都是很好的方法，但我强烈建议坚持除这些方法之外还加入盐的想法。
为了回答这个问题，盐可以是任何真正随机的东西，并且对用户来说是唯一的。只要遵守这两条规则，从技术上讲，您可以随心所欲地生成它。
一些很好的资源：
https://www. codeproject.com/Articles/704865/Salted-Password-Hashing-Doing-it-Right
https://auth0.com /blog/将盐添加到散列-存储密码的更好方式/
Looks like this question has an accepted answer but I just want to additionally state after a bit of research and reading this thread that you might add some security if you don't put all your eggs in one basket.
I might suggest not relying solely on PHP to create your salts and hashing your passwords. You can obfuscate your solution a little more if you let the database do part of the work.
Someone suggested just using password_hash() and password_verify(). While those are great methods, I strongly recommend sticking to the idea of incorporating a salt in addition to these.
To answer the question, a salt can be anything that is truly random and enforced as unique to the user. You can technically generate it however you wish as long as you adhere to those 2 rules.
a couple of good resources:
https://www.codeproject.com/Articles/704865/Salted-Password-Hashing-Doing-it-Right
https://auth0.com/blog/adding-salt-to-hashing-a-better-way-to-store-passwords/
uniqid() 应该可以满足此目的。
uniqid() should be fine for this purpose.
我认为
microtime()就足够了。奇怪的是，但我仍然对这个答案投反对票。
尽管我得到的唯一解释是微时间是可以预测的。
这对我来说听起来很奇怪，因为盐总是被认为是公开已知的 - 所以，预测根本没有用处。
I think
microtime()is enough.Strangely, but I am still getting downvotes for this answer.
Though the only explanation I get is that microtime is predictable.
It sounds strange to me as salt always assumed as openly known - so, there is no use for prediction at all.