将密码哈希从md5升级到bcrypt [英] Upgrade password hash from md5 to bcrypt

问题描述

前面已经讨论过，但似乎没有任何结论。

理想情况下，不希望维护数据库中的状态（升级/未升级）等等，所以，这就是我的想法：

对MD5的密码进行加密，并使用username + something作为盐。

1. 这个方案有什么意义吗？


2. 另外，通常使用用户名作为salt的一部分是个好主意？我在某处读到，为每个散列添加不同的盐使其更安全。这是否正确（特别是在bcrypt的情况下）？

解决方案

当然，切换到更安全的散列算法是个好主意。您可以使用 password_hash（）功能来创建一个BCrypt哈希：

  //哈希存储在数据库中的新密码。 
 //该函数自动生成密码安全的盐。 
 $ hashToStoreInDb = password_hash（$ password，PASSWORD_DEFAULT）; 
 
 //检查输入的登录密码的哈希是否与存储的哈希匹配。 
 // salt和成本因子将从$ existingHashFromDb中提取。 
 $ isPasswordCorrect = password_verify（$ password，$ existingHashFromDb）; 
  

从你的回答中我猜你已经使用了一个无盐MD5值，所以双重散列可以是一个很好的解决方案这里。只需将MD5哈希值传递给password_hash（）函数，它就会自动生成一个安全salt。

  // //迁移旧的MD5散列到MD5-BCrypt 
 $ hashToStoreInDb = password_hash（$ existingMd5Hash，PASSWORD_DEFAULT）; 
  

先验证检查双重散列，然后相应地验证密码。

  if（checkIfDoubleHash（$ ）
 {
 $ isPasswordCorrect = password_verify（MD5（$ password），$ existingHashFromDb）; 
 
 //使用纯BCrypt散列更新数据库
 if（$ isPasswordCorrect）
 $ hashToStoreInDb = password_hash（$ password，PASSWORD_DEFAULT）; 
} 
 else 
 {
 $ isPasswordCorrect = password_verify（$ password，$ existingHashFromDb）
} 
  

存储的散列可以由前导$或单独的db字段来识别，例如BCrypt散列总是以$字符开始，MD5散列不会。 / p>

盐不应该从其他参数中剥离出来，它应该是每个密码唯一的。 password_hash（）函数将处理这个问题。由于必须在每个盐之前建立彩虹色表，攻击者必须为每个密码创建一个彩虹表。欲了解更多信息，你可以看看我的教程有关安全密码存储。

Its been discussed here before, but there seems to be no conclusion.

Ideally, don't want to maintain state (upgraded/not upgraded) in the database etc. so, here is what I'm thinking:

bcrypt the MD5'd password, and use "username + something else" as a salt.

1. Does this scheme make any sense?
2. Also, in general is it a good idea to use the username as a part of the salt? I read somewhere that adding a different salt to each hash makes it more secure. Is that correct (especially in context of bcrypt)?

解决方案

Surely it is a good idea to switch to a more secure hash algorithm. There is a function password_hash() you can use for creating a BCrypt hash:

// Hash a new password for storing in the database.
// The function automatically generates a cryptographically safe salt.
$hashToStoreInDb = password_hash($password, PASSWORD_DEFAULT);

// Check if the hash of the entered login password, matches the stored hash.
// The salt and the cost factor will be extracted from $existingHashFromDb.
$isPasswordCorrect = password_verify($password, $existingHashFromDb);

From your answer i guess that you used an unsalted MD5 value, so double hashing can be a good solution here. Just pass the MD5 hash to the password_hash() function, it will generate a safe salt on its own.

// Migrating the old MD5 hashes to MD5-BCrypt
$hashToStoreInDb = password_hash($existingMd5Hash, PASSWORD_DEFAULT);

For verification first check for a double hash, and then verify the password accordingly.

if (checkIfDoubleHash($existingHashFromDb))
{
  $isPasswordCorrect = password_verify(MD5($password), $existingHashFromDb);

  // Update database with pure BCrypt hash
  if ($isPasswordCorrect)
    $hashToStoreInDb = password_hash($password, PASSWORD_DEFAULT);
}
else
{
  $isPasswordCorrect = password_verify($password, $existingHashFromDb)
}

The stored hashes can be recognized by the leading $ or by a separate db field, a BCrypt hash for example always starts with a $ character, an MD5 hash does not.

A salt should not be derrived from other parameters and it should be unique per password. The password_hash() function will take care of this. Since a rainbowtable must be built fore each salt, an attacker would have to build a rainbowtable for each password. For more information you can have a look at my tutorial about secure password storing.

这篇关于将密码哈希从md5升级到bcrypt的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！