The only your concern should be password complexity.

Question

md5($password.md5($password))

这对口号的 has弄是否好? 我并不要求将这一点与像加密这样的东西相比较。

如果情况不可靠,我就告诉我为什么。

Answer 1

每一用户口号使用不同的盐类的原因是,攻击者可以拿到所有破旧的口号清单,看看看其中任何一种口号是否与“密码”或“12345”等容易混淆。如果你将密码本身用作盐类,那么攻击者可计算<代码>md5("12345'md5(“12345”),并看其是否与任何条目相符。

根据我的理解,在密码表中可使用四级洗 has器:

None - store the password as plain text. If someone gets a copy of your database, they have access to all accounts. Plain text is bad, mkay?
Hash the password - store the hash of the password, and throw away the real password. If someone gets a copy of your database, they can t see any passwords, only hashes. However, if any users have used weak passwords, then their hashes will appear in rainbow tables. For example, if a user has the password "password", then an md5 hash stored in the database would be "5f4dcc3b5aa765d61d8327deb882cf99". If I look up that hash in a rainbow table like the one at gromweb.com, it spits out "password".
Use a salt value - choose a large random string like a GUID and store it in your configuration file. Append that string to every password before calculating a hash. Now the rainbow table is far less likely to work because it probably won t have an entry for "password59fJepLkm6Gu5dDV" or "picard59fJepLkm6Gu5dDV". Although precalculated rainbow tables are not as effective anymore, you can still be susceptible if the attacker knows your salt value. The attacker can calculate the hash of a weak password plus your salt and see if any user in your database uses that weak password. If you ve got several thousand users, then each hash calculation lets the attacker make several thousand comparisons. How you actually use the salt may depend on the encryption algorithm you re using. For simplicity, just imagine it as appending the salt and the password together.
Use a distinct salt value - now you take something distinct like the user name, e-mail address, or even user id, and combine that with the password and the large random string from your configuration file before you calculate the hash. Now an attacker who knows your salt still has to recalculate the hash for every user to see if they have used a weak password like "password".

详情请见Coding Horror员额,“。

Answer 2

Although it seems quite enough to me, it will be in danger in case if someone precomputed a rainbow table based on the same algorithm (what is quite possible). So, I d rather use an email for the salt which seems pretty secure yet usable. Paranoids may add some constant site-wide salt.

人们往往过多地去掉口食盐(理论上),而在应用中,他们允许简单密码,并在简单案文中将其转移至实际上不安全的吉大港山区。

Every freakin day I see questions regarding salt or hash.
And not a single one regarding password complexity. While

The only your concern should be password complexity.

为什么? 让我向你表示。

极好的盐加弱的密码 = 秒钟()。

It is always assumed that salt is known to attacker. So, by using some dictionary of most used passwords and adding [whatever extra-random-super-long] salt to them, a weak password can be discovered in seconds. Same goes for brute-forcing short passwords.

just sensible Salt + Robword = unbreakable

某些独特的盐类使 pre食表变得无用和好的口号,使dict和二恶英的攻击毫无结果。

Answer 3

它对口腔攻击没有多大作用,只有两倍难以计算出字典和单一<代码>md5<>/code>,而<代码>md5<>>则这些天基本便宜。

Answer 4

计量吸入器5本身并不可靠,因为它部分被打碎(col),太小。如果有人不想在加密、加密或 PBK2DF上使用适当的密码衍生功能,那么你至少应当使用SHA-256新设计(计划一旦完成,将计划转移到SHA-3,这样可以肯定地储存你用来将密码与结果混在一起的计划,那么这两种办法就能够共存,因为当人们改变口号时,你可以使用新的散装程序。

如果你打算以任何身份出售MD5方案,就可以成为大多数政府销售的显示器(例如,美国计算法中所用的FPS 140-2必须获得批准,而且许多其他国家也满足同样的要求)。

Answer 5

随机密码盐之所以被推荐用于洗衣口,是因为知道密码的攻击者可以将其与以下网址进行比较:http://en.wikipedia.org/wiki/Rainbow_table”rel=“nofollow”>rainbow table, 事先计算出的口 ha。

If you re using password as salt, attacker can pre-calculate hashes of $word.md5($word) first from their dictionary

Answer 6

有了你的解决办法,你就大打败了用盐对付预谋的独裁袭击的目的。

有了预先判断的字典,正如名称所暗示的那样,有人已经为特定词预先设定了一张海螺表(计算结果:<代码>md5<>>>>)。

审议本表<编码> (带有想象力的斜体,仅供参考)

word | hash
------------
foo  | 54a64
bar  | 3dhc5
baz  | efef3

Testing these values against your table, could be as simple as:

SELECT h.word
FROM hashtable h, yourtable y
WHERE y.password = MD5( CONCAT( h.word, h.hash ) );

顺便说一句,你有密码。

However, if you did NOT hash the password, before concatenating it again with the password and hashing it once more, it would be more difficult to attack it with a pre-computed dictionary. Because then the password would be for instance md5( testtest ) which makes the precomputed table worthless, if the precomputed table has only taken into account single instances of the word.

如果你不使用口号作为盐类,而是使用另一种随机体格作为盐类,那么你就很容易看到它变得更加困难。而且,当你为每个口号创造独特的盐类时,它变得更加困难。当然,如果你每口打上独一无二的盐类,你就必须在单列一栏中节省食盐量,同时在数据库中添加密码。

因此,我的建议是:

md5(  uniquesalt  .  password  );

或者实际上,不使用<代码>md5,而是使用最完善的<代码>sha1,sha256(或更高)洗 algorithm算法。

The only your concern should be password complexity.

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