Use SHA512 as encryption in Multicraft panel (which you can change the settings for MD5), but I need to use an older version of the same database. This old version did not have the option to encrypt with SHA512, but only with MD5. Thus, all passwords are invalid with MD5.
It's possible convert all SHA512 passwords in MySQL database to MD5?
SHA512 and MD5 are hashes, not encryption algorithms. By design, they are not reversible.
The only way to convert these values is to wait for each user to log in, validate their password against the existing SHA512 hash, and rehash¹ their input with MD5. This is the reverse of how password hashes are updated to more secure standards.
But please, please, don't do this. MD5 is hopelessly broken. You would be doing your users a huge disservice to revert from SHA512 to MD5. Find a way to use the newer version of your software.
¹As noted by zaph in a comment, "rehashing" is an oversimplification, and depending on how your panel is actually implemented it might be using insecure password storage today.
To provide reasonable security each password must also have a unique random salt (which protects against things like rainbow tables) and each hash must be iterated enough times to make brute forcing impractical. As computers get more powerful the number of iterations must be increased. Today it is common to iterate tens or hundreds of thousands of times.
Cryptography is shockingly difficult to get right. Instead of trying to follow all the best practices manually, use libraries and functions that operate at the right level of abstraction and have been audited for security. An algorithm like bcrypt (via PHP's built-in password_hash function, where it is currently the default algorithm) would be a good choice.
Short answer: No.
Long answer:
By design, both MD5 and SHA512 are one-way hashes. In order to convert SHA512 to MD5, you would need to know both the original password for every password your are trying to convert, and also the salt that was used to encrypt them. You almost certainly wouldn't know every password for every one of your users.
One-way hashes work by actually casting the same algorithm every time a user logs in. The user types in their password, the algorithm is applied to it, and if it perfectly matches the copy in the database that has already been hashed, then the user is logged in. You can't use any sort of algorithm to work out what the original password was, only to compare if the output of applying a specific password would be to a password that is already encrypted.
MD5 is also a far weaker hashing algorithm than SHA512. Converting to MD5 would make your password far less secure, and this would be something that you probably wouldn't want to do. Instead, you should be looking at a way to incorporate the new database system.
Related
I understand that bcrypt is more secure than other methods but still puts you the same situation where you need to salt passwords!
If the salt is included in the hash string it's not needed to store it separately in the DB. Everytime I need to create a new hash, meaning a new salt as well, do I have to get all the passwords, extract the salts and check the new one doesn't exist already against my DB passwords?
Wouldn't be easier to store directly the salts separately for easy compare? If yes then I don't get:
the point of storing the salt in plain text
why bcrypt is more secure than manually use sha256 with salted passwords
I'm actually going to disagree with Curtis Mattoon's answer on a couple of things.
When you hash using bcrypt, the salt is stored directly inside the hash, so you don't need to store it separately. I'm not sure what he means by not having to store it at all, because the hash without the salt is completely useless. The salt is needed to verify the password against the hash.
I agree on this point. If you are updating one password, you don't need to update them all. In fact, it would be impossible because you (hopefully) don't know the passwords for any other users.
You don't need to go through pains to get a unique salt. If that were the case, you could use uniqid, but the problem with that is its output is predictable. Predictability is a bad thing in cryptography. Instead, what you want to do is use a pseudo random salt as close to random as possible (i.e. using /dev/random instead of /dev/urandom). If you have a billion users, you may get one or two that have exactly the same salt, but seriously, is this such a big problem? All it does is doubles someone's chance of brute forcing the password for those two particular passwords out of a billion, and I doubt it's even that high of a chance of a collision occurring. Don't strain yourself over this. Make the salts random, not unique. Using things like last login time or IP address is only going to take away from randomness.
As for a comparison between SHA512 and Blowfish, see here SHA512 vs. Blowfish and Bcrypt
This site seems to do a decent job at a brief explanation: http://michaelwright.me/php-password-storage
Quick answer:
1) You don't need to store the salt.
2) You don't need to update all the hashes, if you use a unique salt for each password.
3) I'm no crypto expert, but when you're using a unique salt for each user/password, an attacker would have to use a different set of rainbow tables for EACH user. Using the same salt value across the site means that every user's password would be susceptible to the same hash tables. In the past (for better or worse), I've used a function of the user's last login time and/or last IP as the for their password's salt.
e.g. (pseudocode) $password = hash(hash($_POST['password']) . hash($row['last_login']));
4) I'll defer the "Why is bcrypt better?" question to someone more knowledgeable about such things. This answer may help: How do you use bcrypt for hashing passwords in PHP?
I'm the developer of a new website built in PHP and I'm wondering what exactly is the best
thing to use for hashing. I've looked at md5 and sha1 but is there anything more secure.
I'm sorry if this is a nooby question but I'm new to PHP Security and I'm trying to make my
site as secure as possible. Also what is a salt?
Thanks,
Waseem
First off md5 and sha1 have been proven to be vunrable to collision attacks and can be rainbow
tabled easily (When they see if you hash is the same in their database of common passwords).
There are currently two things that are secure enough for passwords, that you can use.
The first being sha512. sha512 is a sub-version of SHA2. SHA2 has not yet been proven to be
vunrable to collision attacks and sha512 will generate a 512 bit hash. Here is an example of
how to use sha512:
<?php
hash('sha512',$password);
The other option is called bcrypt. bcrypt is famous for its secure hashes. Its
probably the most secure one out there and most customizable one too.
Before you want to start using bcrypt you need to check if your sever has it enabled, Enter
this code:
<?php
if (defined("CRYPT_BLOWFISH") && CRYPT_BLOWFISH) {
echo "CRYPT_BLOWFISH is enabled!";
}else {
echo "CRYPT_BLOWFISH is not available";
}
If it returns that it is enabled then the next step is easy, All you need to do to bcrypt a
password is (Note for more customizability you need to see this How do you use bcrypt for hashing passwords in PHP?):
crypt($password, $salt);
Now to answer your second question. A salt is usally a random string that you add at the end of
all you passwords when you hash them. Using a salt means if some one gets your database
they can not check the hashes for common passwords. Checking the database is called using a rainbow table. You should always use a salt when hashing!!
Here are my proofs for the SHA1 and MD5 collision attack vulnerabilities:
http://www.schneier.com/blog/archives/2012/10/when_will_we_se.html, http://eprint.iacr.org/2010/413.pdf, http://people.csail.mit.edu/yiqun/SHA1AttackProceedingVersion.pdf, http://conf.isi.qut.edu.au/auscert/proceedings/2006/gauravaram06collision.pdf and Understanding sha-1 collision weakness
The whole purpose of the salt is to slow down an attacker from comparing a list of pre-generated hashes against the target hash.
Instead of needing to pre-compute one "hashed" value for each plaintext password, an attacker needs to precompute 16384 "hashed" values for each plaintext password (2^7 * 2^7).
That kinda pales today but was pretty big when the crypt function was first developed - the computational power to pre-compute that many passwords times the number of plaintext password you suspect (dictionary) was pretty high.
Not so much today which is why we have things like shadow passwords, other core password functions besides crypt and every sysad wanting you to pick a password that would not show up in a dictionary.
If the hashes you want to generate are for passwords this is a well accepted method of implementing it.
http://www.openwall.com/phpass/
If you're planning to do this for passwords, then do not use MD5 or SHA1. They are known to be weak and insecure, even with salt.
If you're using them for other purposes (eg providing a hash of a file to confirm its authenticity, or a random hash database column to provide a pseudo-random sort order) then they are fine (up to a point), but not for passwords or anything else that you would consider needing to be kept secure.
The current best-practice algorithm for password hasing is BCrypt, with suitable salting.
And the best way to implement BCrypt password hashing in PHP is to use PHP's new password API. This API will be featured as a set of built-in functions in the next version of PHP, v5.5, due for release in the next few months. The good news is that they have also released a backward-compatibility version for users of current versions of PHP (5.3 and 5.4), so even though PHP 5.5 isn't released yet, you can start using the new API immediately.
You can download the compatibility library from here: https://github.com/ircmaxell/password_compat
Also: You asked what "salt" is. Since I've mentioned it a couple of times in this answer, I should address that part of the question too.
Salt is basically an additional string added to the password when hashing it, in order to make it harder to crack.
For example, an attacker may know in advance what the hashed value is for a given password string, or even a whole lot of given password strings. If he can get hold of your hashed data and you haven't used a salt, then he can just compare your hashes against his list of known passwords, and if any of your users are using an easy to guess password, they'll be cracked in seconds, regardless of what hashing method was used.
However, if you've added a secret extra string to the password when you hash it, then the hashed value won't match the standard hash for the original password, thus making it harder for the attacker to find the value.
The good news is that if you're using the API I mentioned above, then you don't need to worry too much about the details of this, as the API handles the salting for you.
Hope that helps.
I know that there are more than a dozen questions about this. But I want to know if it would be better to encrypt passwords for a login system with hash methods like sha1, sha512 etc or would it be better to use Mcrypt ciphers for this ?
I know that decrypting after encrypting with hash methods like sha it's impossible, and if encrypting using mcrypt it's possible. But is it safe to use mcrypt since you can also decrypt ?
Passwords must not be recoverable. The point of hashing them is to make sure that if the database is compromised, the attacker can't get access to every password and thus every user's account (and every account on other services where the password has been reused).
For a password storage that you don't need the plaintext passwords lateron you always should use a Hash-Function. That way you can check the passwords, but a potential attacker cannot find out the plain-text passwords (This is relevant when users always use the same password)
Passwords must NOT be recoverable. As such, you need to use hash algorithms. The most popular are MD5 and SHA1. I won't suggest using MD5 because it can be easily attacked and there are many pregenerated hashes. SHA1 is better, but it has some, too. The most secure is SHA256/SHA512 (part of SHA2 family) based on this. Although, the problem with the SHA2 family is that it is very much based on SHA1. It is not yet broken, but it can be broken soon. If you have time, you may port one of the algorithms made for the SHA3 competition or a less known algorithm. If you can install extensions, then the SHA3 competitors already have PHP extensions.
A good table for the security level is at the Wikipedia. And if you have chosen, you should google "collision attack on [algorithm]" and [preimage attack on [algorithm]" to see whether is there an attack (Wikipedia might be outdated).
Also, don't forget to salt. That means that you hash the $string+"Whatever" instead of $string.
I have a user table in my mysql database that has a password column. Currently, I use the MD5 algorithm to hash the users' password for storage in the database. Now I like to think that I am a security conscience person. I noticed while reading the MySQL docs that they don't recommend MD5 or the SHA/SHA1 hashing methods, but don't offer an alternative.
What would be the best way to hash my passwords in MySQL? A function that is natively supported in both PHP and MySQL would be ideal and necessary with my current implementation.
Thanks!
It's not necessarily that you shouldn't use MD5, as much it's that you shouldn't use just MD5, as this leaves you vulnerable to rainbow-table attacks (a rainbow table is a table of precomputed hash values - if your password is even remotely common or simple, the attacker needs merely to look up the hash and he knows your plaintext password.)
At the very least you should add a salt to every password so that any existing rainbow table is useless, forcing the attacker to generate an entire new rainbow table just for your database of passwords.
Better still is to use a different salt for every password in your database, say the username it's associated with, so that an attacker can't even generate a rainbow table for your whole database and has to crack each entry separately.
MD5 is also a very fast algorithm. Speed is the enemy when it comes to cracking - the longer it takes to generate a hash, the longer it takes for each attempt a hacker makes. Something simple like hashing the plaintext 100 times with a new additional salt each time would be barely perceptible (if at all) to a user logging in to your site, but it would increase the time it takes to brute-force a password by the same 100 times.
Far, far more detail here: http://www.codinghorror.com/blog/archives/000953.html
MD5 is considered to be weak by today's standards. It would still take some work to crack a hash made with MD5, but it's several times easier than guessing the password by brute-force. Ideally, cracking a hash should not be easier than brute-force.
SHA1 is also considered easier to crack than guessing the password by brute-force.
I actually contributed a patch to MySQL to surface the SHA224, SHA256, SHA384, and SHA512 functions from OpenSSL. These are recommended by NIST for password hashing (actually SHA256 and higher).
My patch was finished by MySQL engineers, and is included in MySQL 6.0.5 and later, if I recall.
If you use an earlier version of MySQL (and who doesn't), then you can probably use an implementation of strong hashing functions in your host language. PHP has the hash() function for example. You can do the hashing in your application and save the resulting message string to the database.
Don't forget to do salting, too!
This question is 7 years old. In that time we have progressed in computing to where MD5 and SHA1 are now easily broken by modern computers. These should be avoided now.
With PHP 5.5 came the introduction of password_hash, which uses the far more secure bcrypt algorithm. While MySQL can encrypt/decrypt bcrypt, it's a terrible solution because you're not only adding a potentially large computation load to your database layer, but the unhashed password could be stored in your logs
Under no circumstances should a plain text password hit MySQL, even if at the query level. Otherwise you risk writing the passwords to log (query log, general log, slow query log, etc). Which is horrific. So no, don't even bother...
MD5 and SHA-1 probably aren't recommended anymore due to know attacks. But, they're still generally sufficient for most use cases.
If you're looking for more options, just use PHP's hash functions -- you've got plenty of options there.
I am using a combination. For example SHA1(MD5()) is working fine.
What is the fastest, yet secure way to encrypt passwords (in PHP preferably), and for whichever method you choose, is it portable?
In other words, if I later migrate my website to a different server, will my passwords continue to work?
The method I am using now, as I was told, is dependent on the exact versions of the libraries installed on the server.
If you are choosing an encryption method for your login system then speed is not your friend, Jeff had a to-and-frow with Thomas Ptacek about passwords and the conclusion was that you should use the slowest, most secure encryption method you can afford to.
From Thomas Ptacek's blog:
Speed is exactly what you don’t want in a password hash function.
Modern password schemes are attacked with incremental password crackers.
Incremental crackers don’t precalculate all possible cracked passwords. They consider each password hash individually, and they feed their dictionary through the password hash function the same way your PHP login page would. Rainbow table crackers like Ophcrack use space to attack passwords; incremental crackers like John the Ripper, Crack, and LC5 work with time: statistics and compute.
The password attack game is scored in time taken to crack password X. With rainbow tables, that time depends on how big your table needs to be and how fast you can search it. With incremental crackers, the time depends on how fast you can make the password hash function run.
The better you can optimize your password hash function, the faster your password hash function gets, the weaker your scheme is. MD5 and SHA1, even conventional block ciphers like DES, are designed to be fast. MD5, SHA1, and DES are weak password hashes. On modern CPUs, raw crypto building blocks like DES and MD5 can be bitsliced, vectorized, and parallelized to make password searches lightning fast. Game-over FPGA implementations cost only hundreds of dollars.
I'm with Peter. Developer don't seem to understand passwords. We all pick (and I'm guilty of this too) MD5 or SHA1 because they are fast. Thinking about it ('cuz someone recently pointed it out to me) that doesn't make any sense. We should be picking a hashing algorithm that's stupid slow. I mean, on the scale of things, a busy site will hash passwords what? every 1/2 minute? Who cares if it take 0.8 seconds vs 0.03 seconds server wise? But that extra slowness is huge to prevent all types of common brute-forcish attacks.
From my reading, bcrypt is specifically designed for secure password hashing. It's based on blowfish, and there are many implementation.
For PHP, check out PHP Pass
For anyone doing .NET, check out BCrypt.NET
It should be pointed out that you don't want to encrypt the password, you want to hash it.
Encrypted passwords can be decrypted, letting someone see the password. Hashing is a one-way operation so the user's original password is (cryptographically) gone.
As for which algorithm you should choose - use the currently accepted standard one:
SHA-256
And when you hash the user's password, be sure to also hash in some other junk with it. e.g.:
password: password1
salt: PasswordSaltDesignedForThisQuestion
Append the salt to the user's password:
String s = HashStringSHA256("password1PasswordSaltDesignedForThisQuestion");
Whatever you do, don't write your own encryption algorithm. Doing this will almost guarantee (unless you're a cryptographer) that there will be a flaw in the algorithm that will make it trivial to crack.
I'm not necessarily looking for the fastest but a nice balance, some of the server that this code is being developed for are fairly slow, the script that hashes and stores the password is taking 5-6 seconds to run, and I've narrowed it down to the hashing (if I comment the hashing out it runs, in 1-2 seconds).
It doesn't have to be the MOST secure, I'm not codding for a bank (right now) but I certainly WILL NOT store the passwords as plain-text.
Consider to use bcrypt it is used in many modern frameworks like laravel.
Use this function when inserting in database
Password_harsh($password,PASSWORD_DEFAULT);
And when selecting from the database you compare the password you are inserting with the one in the database using the function
if(password_verify($password,$databasePassword)){
}else{
echo "password not correct";
}
This will harsh the password in a secure format
password_hash ( string $password , int $algo [, array $options ] ). (PHP 5 >= 5.5.0, PHP 7)
password_hash() creates a new password hash using a strong one-way hashing algorithm. password_hash() is compatible with crypt(). Therefore, password hashes created by crypt() can be used with password_hash().