If it is possible at all? What you want is bcrypt, not blowfish. CodesInChaos, bcrypt is based on blowfish. Masoud With the same reasoning you could say "C" when you actually mean "C ". Blowfish is a blockcipher, bcrypt is a password hash based on the blowfish key setup.
Show 1 more comment. Active Oldest Votes. Regarding DoS attacks Yes, the extra processing your application performs upto login could be a target for an attacker to submit either really long passwords to your application, or to repeatedly hit it with login requests in order to consume CPU and memory resources on your server. These type of attacks can be mitigated in the following ways: Log the username and IP address of each login attempt. After say 6 failed attempts, introduce a delay in response from your application if that username or IP is repeated again.
This will also help mitigate password guessing attacks in general. For example you could artificially delay by 1 second, then 2 seconds then 4 and up to a reasonable value e. This has the advantage that an attacker can't lock out another account on purpose as the legitimate user only has to wait 16 seconds. An attacker could use a botnet and random usernames to bypass these checks, however they would need a huge number of IP addresses than they would without this control, and a more casual attacker would also not be aware that the delay in response was artificial.
Monitor the number of login attempts on your system. Once this is above a set threshold rate e. The threshold rate you choose very much depends on the user base and capacity of your system. Implement two factor authentication. Only proceed to validate password by hashing once the One Time Password has been validated. Improve this answer. SilverlightFox SilverlightFox SilverlightFox, In my opinion, an slow algorithm is not much secure. I have 2 reasons, one is explained in question DDOS Attacks and another is commented in martinstoeckli answer.
Can you please check these out and tell me if I'm wrong or not? With a 10 chars length password containing a-z, A-Z and chars we can break it in hours in average even with this software, and with a 12 chars passwords, it needs years in average just to break a single hash value. Isn't it enough? Also, thank you for these very good advices. I used all of them, but in different ways. I set a constant delay of 2 seconds for all login attempts and after this 2 seconds, I check connection status to see if user is waiting for response or connection is dropped.
Which your suggestions is much better than my way. Remember, password strength is not a real metric - it depends on the sources of entropy actually used.
Yes a keyspace attack on a 10 char password might take days, however if you know the user hasn't chosen a truly random password as human's are not random then practically it won't take days. You can't ever force a user to create a truly random password unless you specify it yourself - and that has its own problems. That's why we choose an algorithm with a configurable amount of iterations. As Moore's law takes hold, you increase the number of iterations. But nevertheless, everybody can buy some cheap GPUs and start the race But he can't match the hash of an existing file he didn't influence.
I don't know if the attacks applies to your application, but personally I'd start migrating even if you think it doesn't. It's far too easy to overlook something. Better safe than sorry. Once SHA-3 gets standardized it will be a good choice too. People who deal with databases are not the same people as those who deal with security. They often see no problem in using weak algorithms e.
Performance is much more often discussed than measured; and yet, logically, there cannot be a performance issue if there is nothing to measure.
Consequently, there is no performance issue relatively to hashing in databases. Don't do it. You should not use elementary cryptographic algorithms, but protocols which assemble several algorithms so that they collectively provide some security features e. Really, don't do it. For storing passwords more accurately, password verification tokens , don't make a custom mix of a hash function and salts; use a construction which has been studied specifically for such a use.
If a hash function is indeed what does the job, then use SHA Consider using any other function only if some serious problem with SHA most probably its performance has been duly detected and measured. If you are salting MD5 hashes, you definitely don't want to be using MD5.
I have worked with a lot of DBAs that are at least 5 years behind in general technology not using version control, unformatted perl scripts for everything, etc.
They might have been particularly bad DBAs, but I think it comes with the extremely conservative mindset of not changing things. Just to complement the answers already given most of which are excellent we now have a real world example of where a data breach Ashley Madison lead to the entire password table being leaked.
They used bcrypt with a random salt to hash the passwords. A security researcher decided to take those hashes and brute force them. This was the result. As a result of all this, bcrypt is putting Herculean demands on anyone trying to crack the Ashley Madison dump for at least two reasons.
First, 4, hashing iterations require huge amounts of computing power. In Pierce's case, bcrypt limited the speed of his four-GPU cracking rig to a paltry guesses per second. Second, because bcrypt hashes are salted, his rig must guess the plaintext of each hash one at a time, rather than all in unison. Pierce gave up once he passed the 4, mark.
To run all six million hashes in Pierce's limited pool against the RockYou passwords would have required a whopping 19, years, he estimated. With a total 36 million hashed passwords in the Ashley Madison dump, it would have taken , years to complete the job. At the end of the day, the only ones he was able to crack were ridiculously simple or common passwords like "".
Just make sure it is done properly. MD5 is a about 2. To put it short it is pretty insecure now because of rainbow tables, Rainbow table is a list of MD5 hashes and their matching strings. So basically i would consider other alternatives such as SHA1. You are all talking about insecurity, but none of you has given a straight anwser to the question. I have been working with MD5 and Sha, both of them where easy to crack once I had put my little hacker expert on it, until it both hit us like a thunder!
The most simple and effective way to stop "Mass Attacks" like the ones described above, is setting a limiter of login attemps, meaning :.
You get my point? The maximum amount of combinations the hacker wants to try, he is limited to 5 fails per 2 hours. You can even block the user after X attempts.
Sign up to join this community. The best answers are voted up and rise to the top. It is a part of the Message Digest Algorithm family which was created to verify the integrity of any message or file that is hashed.
MD5 is still used in a few cases ; however, MD5 is insecure and should not be used in any application. Hash functions are not reversible in general. Obviously if you run all strings of length, say, bits, some of them have to hash to the same value. The SHA algorithm returns hash value of bits, or 64 hexadecimal digits. While not quite perfect, current research indicates it is considerably more secure than either MD5 or SHA The hash size for the MD5 algorithm is bits.
The ComputeHash methods of the MD5 class return the hash as an array of 16 bytes. Note that some MD5 implementations produce a character, hexadecimal-formatted hash.
If the hashes match, you can be sure that the ISO was copied correctly and completely. Other options commonly used in practice are bcrypt , scrypt , among many others that you can find in this list of cryptographic algorithms. MD5 is 7. SHA is The concept behind these hashing algorithms is that these are used to generate a unique digital fingerprint of data or message which is known as a hash or digest.
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