从PHP 5.5开始，PHP就有了简单安全的散列和验证密码的函数password_hash()和password_verify()

$password = 'anna';
$hash = password_hash($password, PASSWORD_DEFAULT);
$expensiveHash = password_hash($password, PASSWORD_DEFAULT, array('cost' => 20));

password_verify('anna', $hash); //Returns true
password_verify('anna', $expensiveHash); //Also returns true
password_verify('elsa', $hash); //Returns false

当使用password_hash()时，它生成一个随机的盐并将其包含在输出的哈希中(以及使用的代价和算法)。password_verify()然后读取该哈希并确定使用的盐和加密方法，并根据提供的明文密码验证它。

提供PASSWORD_DEFAULT指示PHP使用已安装的PHP版本的默认哈希算法。具体哪种算法在未来的版本中会随着时间的推移而改变，因此它将始终是可用的最强算法之一。

不断增加的成本(默认为10)使得哈希更难使用暴力，但也意味着生成哈希并根据它们验证密码将为服务器的CPU带来更多的工作。

请注意，即使默认的哈希算法可能会改变，旧的哈希将继续进行验证，因为所使用的算法存储在哈希中，password_verify()会捕获它。

好吧 在fitsy，我们需要盐 盐必须是独一无二的 我们来生成它

   /**
     * Generating string
     * @param $size
     * @return string
     */
    function Uniwur_string($size){
        $text = md5(uniqid(rand(), TRUE));
        RETURN substr($text, 0, $size);
    }

我们还需要哈希值 我使用sha512 它是最好的，而且是用PHP编写的

   /**
     * Hashing string
     * @param $string
     * @return string
     */
    function hash($string){
        return hash('sha512', $string);
    }

所以现在我们可以使用这个函数来生成安全的密码

// generating unique password
$password = Uniwur_string(20); // or you can add manual password
// generating 32 character salt
$salt = Uniwur_string(32);
// now we can manipulate this informations

// hashin salt for safe
$hash_salt = hash($salt);
// hashing password
$hash_psw = hash($password.$hash_salt);

现在我们需要在数据库中保存$hash_psw变量值和$salt变量

对于授权，我们将使用相同的步骤…

这是保护客户密码的最好方法……

另外，最后两个步骤你可以使用自己的算法… 但是要确保将来可以生成这个散列密码 当您需要授权用户…

我通常使用SHA1和salt和用户ID(或其他特定于用户的信息)，有时我还使用常数salt(因此我有2部分salt)。

SHA1 is now also considered somewhat compromised, but to a far lesser degree than MD5. By using a salt (any salt), you're preventing the use of a generic rainbow table to attack your hashes (some people have even had success using Google as a sort of rainbow table by searching for the hash). An attacker could conceivably generate a rainbow table using your salt, so that's why you should include a user-specific salt. That way, they will have to generate a rainbow table for each and every record in your system, not just one for your entire system! With that type of salting, even MD5 is decently secure.

我不会以两种不同的方式存储哈希密码，因为这样的话，系统至少和正在使用的最弱的哈希算法一样弱。

虽然问题已经回答了，但我只是想重申，用于哈希的盐应该是随机的，而不是像第一个答案中建议的电子邮件地址那样。

更多的解释可以在(archive.org的副本)http://www.pivotalsecurity.com/blog/password-hashing-salt-should-it-be-random/上找到

Recently I had a discussion whether password hashes salted with random bits are more secure than the one salted with guessable or known salts. Let’s see: If the system storing password is compromised as well as the system which stores the random salt, the attacker will have access to hash as well as salt, so whether the salt is random or not, doesn’t matter. The attacker will can generate pre-computed rainbow tables to crack the hash. Here comes the interesting part- it is not so trivial to generate pre-computed tables. Let us take example of WPA security model. Your WPA password is actually never sent to Wireless Access Point. Instead, it is hashed with your SSID (the network name- like Linksys, Dlink etc). A very good explanation of how this works is here. In order to retrieve password from hash, you will need to know the password as well as salt (network name). Church of Wifi has already pre-computed hash tables which has top 1000 SSIDs and about 1 million passwords. The size is of all tables is about 40 GB. As you can read on their site, someone used 15 FGPA arrays for 3 days to generate these tables. Assuming victim is using the SSID as “a387csf3″ and password as “123456″, will it be cracked by those tables? No! .. it cannot. Even if the password is weak, the tables don’t have hashes for SSID a387csf3. This is the beauty of having random salt. It will deter crackers who thrive upon pre-computed tables. Can it stop a determined hacker? Probably not. But using random salts does provide additional layer of defense. While we are on this topic, let us discuss additional advantage of storing random salts on a separate system. Scenario #1 : Password hashes are stored on system X and salt values used for hashing are stored on system Y. These salt values are guessable or known (e.g. username) Scenario#2 : Password hashes are stored on system X and salt values used for hashing are stored on system Y. These salt values are random. In case system X has been compromised, as you can guess, there is a huge advantage of using random salt on a separate system (Scenario #2) . The attacker will need to guess addition values to be able to crack hashes. If a 32 bit salt is used, 2^32= 4,294,967,296 (about 4.2 billion) iterations will can be required for each password guessed.

从PHP 5.5开始，PHP就有了简单安全的散列和验证密码的函数password_hash()和password_verify()

$password = 'anna';
$hash = password_hash($password, PASSWORD_DEFAULT);
$expensiveHash = password_hash($password, PASSWORD_DEFAULT, array('cost' => 20));

password_verify('anna', $hash); //Returns true
password_verify('anna', $expensiveHash); //Also returns true
password_verify('elsa', $hash); //Returns false

当使用password_hash()时，它生成一个随机的盐并将其包含在输出的哈希中(以及使用的代价和算法)。password_verify()然后读取该哈希并确定使用的盐和加密方法，并根据提供的明文密码验证它。

提供PASSWORD_DEFAULT指示PHP使用已安装的PHP版本的默认哈希算法。具体哪种算法在未来的版本中会随着时间的推移而改变，因此它将始终是可用的最强算法之一。

不断增加的成本(默认为10)使得哈希更难使用暴力，但也意味着生成哈希并根据它们验证密码将为服务器的CPU带来更多的工作。

请注意，即使默认的哈希算法可能会改变，旧的哈希将继续进行验证，因为所使用的算法存储在哈希中，password_verify()会捕获它。