我脑子里只有一个简单的社区问题。曾几何时，当我开始编程时，我使用 md5 来散列密码，后来发现 md5 很容易被破解，我应该使用 salt 来确保它的安全。

我对 md5 没有信心，想使用 sha1、sha256、sha512 加密。但问题是现在我有加密形式的密码

md5("password"+"salt")

当时我不知道用户的密码，所以我做了什么

sha1(md5("password"+"salt"))

现在，在这个领域工作了几次之后，我发现 sha1 也不太安全并且已经损坏，我应该做的是使用 bcrypt() 来确保密码安全。

所以从现在开始我将使用

 crypt(sha1(md5("password"+"salt")))

密码现在非常安全，但主要问题仍然是它用于创建哈希值的时间总是大于使用 bcrypt("password")

现在我想说的是假设如果 bcrypt 被黑客入侵并被发现已损坏，并且将来会出现更安全的新加密功能。与此相比，从旧值创建密码总是很耗时。

解决这个问题的方法是什么。据我所知，邮寄用户更改密码并不总是 100% 成功。 另一件事是在数据库中添加一个新字段来存储新的散列值，如果所有字段都已填充而不是从 db 中删除 md5 值。但是这样以前的散列值仍然可见。

所以这件事会不会继续下去，或者你们有一些解决办法。 :)

最佳答案

PHP 5.5 introduces the Password API解决了这个问题:

The new Secure Password Hashing API in PHP 5.5

The RFC for a new simple to use password hashing API has just been accepted for PHP 5.5. As the RFC itself is rather technical and most of the sample codes are something you should not use, I want to give a very quick overview of the new API:

Why do we need a new API?

Everybody knows that you should be hashing their passwords using bcrypt, but still a surprising number of developers uses insecure md5 or sha1 hashes (just look at the recent password leaks). One of the reasons for this is that the crypt() API is ridiculously hard to use and very prone to programming mistakes.

By adding a new, very simple to use API we hope to move more developers towards bcrypt.

How to hash passwords

Creating password hashes can't be any simpler than this:

  $hash = password_hash($password, PASSWORD_DEFAULT);

This will create a password hash using the default algorithm (currently bcrypt), the default load factor (currently 10) and an automatically generated salt. The used algorithm and salt will also be part of the resulting hash, so you don't need to worry about them at all ;)

If you don't want to stick with the defaults (which might change in the future), you can also provide algorithm and load factor yourself:

$hash = password_hash($password, PASSWORD_BCRYPT, ['cost' => 12]);

Verifying passwords

Verifying passwords is just as easy:

<?php
// $password from user, $hash from database
if (password_verify($password, $hash)) {
    // password valid!
} else {
    // wrong password :(
}

Remember: The salt and algorithm are part of the hash, so you don't need to provide them separately.

Rehashing passwords

As time goes by you might want to change the password hashing algorithm or load factor, or PHP may change the defaults to be more secure. In this case new accounts should be created using the new options and existing passwords rehashed on login (you can do this only on login because you need the original password to do a rehash).

Doing this is also very simple:

<?php
function password_verify_with_rehash($password, $hash) {
    if (!password_verify($password, $hash)) {
        return false;
    }

    if (password_needs_rehash($hash, PASSWORD_DEFAULT)) {
        $hash = password_hash($password, PASSWORD_DEFAULT);

        // update hash in database
    }

    return true;
}

The above snippet will keep your hashes up to date with the PHP default. But once again you can also specify custom options, e.g. password_needs_rehash($hash, PASSWORD_BCRYPT, ['cost' => 12']).

Compatibility layer for older PHP versions

The new API will only be introduced in PHP 5.5, but you can already use a PHP implementation of the same API now! The compatibility implementation will automatically disable itself once you upgrade to 5.5.

关于php - 散列密码，从 splinter 的方法到现在最安全的方法，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15933462/