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2

Lastpass uses a preconfigured and extensible set of site aliases to make two or more domains equivalent. Here is a snapshot from my account settings page. YMMV.


1

If we assume that the content of the input files is random, we can view your proposal as using MD5 as a PRNG algorithm and using the input files as the seed to the PRNG function. So your question becomes: Is it secure to use a PRNG algorithm, whose seeds are stored on my disk, as a password generator? The answer to that is clearly no because all of the ...


1

Advantages over a password manager: Little to none. Security problems: Your password generation technique would be logged in command history. Any file access mechanisms would record access to these files every time you log in. Your password would be visible on screen every time you needed to use it. If any files change without your knowledge, your ...


0

You could generate a cryptographically secure 128-bit key and store it in HTML5 storage on the browser. This would encrypt data without any input from the user. However, the user would have to use the same browser and computer all the time. You could add the option to export the value - e.g. a browser extension that extracts the key in HTML5 storage and ...


2

The answers so far are good but it's important to note that from a profiling point of view- I don't care if I don't get in to their account but the knowledge they're using a service is enough to social engineer a situation/monitor their social feeds for potential passwords (pets, kids, cars etc). That being said, during user signup it would be a bad UX ...


1

Your point about trying to register and getting a 'this email address is already in use, or unavailable' message is interesting and seems to be a more important point to consider than whether or not to let people know the forgot password email was sent. They seem to go hand in hand. If you are willing to display the fact that an email is already in use and ...


1

So I guess as a primer we need to consider what an attacker can actually do if you confirm / deny existence of an email on your system in some easily accessible way. This is a possible scenario: An attacker has gained access to a database of compromised email addresses + passwords. (i.e. they can log into any of these user's emails) They want to gain ...


3

There is sometimes a trade-off between security and usability. If it's important to you or your users that other people don't know they're using the site, then your second choice is the best one. You can always send an email to an address that doesn't exist in your system, like "Someone requested a password reset for this address, but it's not in our ...


3

While the currently accepted answer is correct and the number of iterations is usually stored where the hashes themselves are, even if this was not the case: By Kerckhoff's principle, you should assume the attacker can find out. In practice they could find out for example by creating their own login with a known password or timing a login attempt. Even if ...


1

It is worth considering that revealing the information of whether the holder of a specific email address has an account at your site may be illegal in some jurisdictions. For instance, here in the UK, you should obtain the user's consent before revealing this information. One work around would be to ask for some lower security information, eg date of birth, ...


1

Depending how easy it is to sign up to your site you may not be leaking info by telling whether email was sent or not. If anyone can create an account it will probably tell if email is in use or not. So at the end of the day the extra annoyance isn't buying you any extra security. What you should not leak is the emails if users can supply either username ...


1

Sites where the privacy of the users are more important, If a user tries login with the email and a wrong password, its better not let him know whether the email exist or not.just let him know its wrong and could ask to enter password with mobile number/username. Answer It is to respect the privacy of the already existing users. Else others will be able to ...


2

I think this is generally on the wrong side of being unhelpful to legitimate users of legitimate sites - but if your site was promoting anonymity, telling a random web user if a particular email address was valid would be a leak.


12

How does a hacker know how many times a password was hashed? The same way you do. The goal of hashing a password is to make it impossible (in practice very difficult) to determine the password, even with full access to all the data. The other requirement for hashing is that the server must be able to determine if an entered password is correct. This means ...


1

In general, storing passwords in a reversible format is a bad idea. That said, you could use AES, with the user's password as key (enforce a strong password policy). That way, users wouldn't be able to view each other's encrypted data, and a compromise of the server won't reveal the key to everyone's data without cracking the user password hashes first. ...


34

Number of rounds is often stored with the password and hash. For example, using bcrypt: $2a$10$oEuthjiY8HJp/NaBCJg.bu76Nt4eY4jG/S3sChJhZjqsCvhRXGztm The 10 indicates the work factor, effectively adding 10 bits of entropy in terms of hashing time to brute force. 2^10 = 1024 rounds. It is stored with the hash in case of the need to up the work factor due ...


8

The number of iterations and the salt are stored in the same database, usually in the same field as the password hash itself. Because the site needs to know those things just as much as a potential attacker does, and so they have to be easily available. For example, bcrypt hashed passwords contain the (log base 2 of the) number of iterations separated by $ ...


0

I would use HTTPS with certificates signed by a CA you create, if you don't want the cost/hassle of using a trusted CA. Then merely verify your keys against your own CA. For example see this guide for how to create your own CA, and sign your own certificates with this CA, though for your purpose, you do not need to install your root certificate into ...


2

I will try to address this at network/protocol level an leave the method you send them (IE email's) up to you. If you have thought on the transfer medium that we can address that as well. Base on your post, I am guessing these are internal use only and no external access is required. If this is not the case, buy a third part cert. Internal only, your ...


2

You can use the Internet Protocol Security (IPSec). This way your LAN communications are both authenticated and encrypted for each IP packet of a communication session. It is not a problem whether your machines are running Windows or Linux based operating systems. Note that you can also use it in conjunction with Layer 2 Tunneling Protocol (L2TP) that ...


2

First, don't store the SHA256 of your master password! See this answer for how to store the hash of the master password. Onto your question... Salt is used to prevent the attacker precomputing the hashes for many/all possible inputs. In the specific case of storing the hash of the master password, a sufficiently large and random salt will prevent an ...


3

A shim or polyfill does not get installed into a browser but gets delivered as part of a web page to provide functionality for this page. It is just normal active content (JavaScript, Flash...) which only gets named as shim or polyfill because it serves the specific purpose described by these names. It has no special permissions or restrictions compared to ...


2

Honestly "password security with short passwords" is an oxymoron. On balance, if this is a site/service that you simply must use, I would just make the password as random as you reasonably can, possibly rely on a password manager app to use a random password you can't remember easily, and most importantly make the password different from any other passwords ...


3

A developer chooses to write a polyfill because it fulfills his personal need. From this personal aspect may come all problems you may imagine, namely malicious JavaScript code. Can a shim be installed in IE, FF, or Chrome without user knowledge? Surely. Drive-by download attacks which consist in malware delivery without the knownledge/consent of the ...


9

With eight characters you're extremely limited. My advice - forget the memorisation part. Generate an eight character string using a cryptographically secure pseudo random number generator, using letters (both cases), numbers and symbols. This will give your password 52 bits of entropy, which is the maximum you can achieve using this scheme. The ...


0

When a web application limits passwords to short lengths, the user has almost nothing left in his control. The main problem of short passwords is what you already know: password guessing and password cracking. But you never know: may be the website is hashing your password (How to securely hash passwords?), salting it (How to store salt?), using a pepper ...


1

A shim or polyfill isn't anything particularly special. It's just javascript code - the name is used to describe the task that it performs (i.e backfilling expected behaviour into older or incompatible browsers) To answer your questions: Can a shim be installed in IE, FF, or Chrome without user knowledge? As shims and polyfills are just Javascript ...


0

In both examples, it became significantly stronger. However, the original was almost assuredly strong enough And by adding the randomness you generally blow up the "easy to remember/type" value in the diceware/xkcd style password if you need more entropy,either add more words, or use a password manager with a completely gibberish password. Silverlight ...


1

Use enough entropy then there's nothing to worry about. For an 80 bit password just choose 8 random words. Using your correct $58j#O1, battery staple technique with CSPRNG, assuming your password section is over the full character range (96 chars) then you have 10 bits + 6.5 * 7 + 10 + 10 = 75.5 bits. These are both under the assumption the attacker ...


2

The BIOS or equivalent firmware is the first thing that runs when the computer is booted, so it could easily start a lightweight hypervisor before loading the OS that will present a clean firmware image if the OS ever asks for it, while still being compromised. So from the actual machine, there is no reliable way to check if the firmware is malicious. You ...


-4

I'd run these programs (http://pastebin.com/BeKzci9A). I'd highly suggest trying to find out what rootkit, if any, has been installed on your system and researching how to specifically remove it on top of everything else. Also it is highly suggested that you always boot your operating system that you know is compromised with a LiveCD, mount your infected ...


1

Offline attacks are slightly different than online attacks. In an online attack, rate limiting and the overhead of network transmission means that extremely fast password attempts are not practical. In an offline attack, when you have a hashed password, you can get much much faster attack rates typically. And you can scale it up (by using cloud computing) ...


0

The biggest problem I see is that it doesn't help against offline attacks, or it hurts them. You had better be salting and hashing the password, or else you're dramatically weakening the password security. And if you're doing that, then this has to be done by an external call, and all that remains is security by obscurity.


3

This is not a good idea. I would also like to quote the question: I still feel like most people are probably using a password that is the required length or only 1 or 2 characters over the limit. Agree! Well, I don't actually assume people to create passwords of one or two characters if you set the minimum length to 0, but most of your unrestricted ...


1

This makes (somewhat) sure that you really are the user associated with the account, you should at least know what email address was used to create the account. Filling the email address automatically could already give an attacker the opportunity to get all the email addresses in the database, just request a new password for every account you can think of. ...


52

One related question that you missed in your list is this one: How critical is it to keep your password length secret? The accepted answer there (disclaimer: mine) shows that if you have a password scheme which allows all 95 printable ascii characters, then the key space ramps insanely quickly every time you increase the length of the password by 1. You ...


13

The answer is in your question. Assuming the use of only alphanumeric characters, requiring 8+ characters removes about 3.5 trillion password possibilities (most of them would just be random gibberish). This leaves ~13 quadrillion passwords that are 8-9 characters. Establishing a minimum length, or even an exact length, for passwords forces the user to ...


4

Not uniformly applying a password policy introduces unnecessary security risks and definitely does not improve security. Allowing weak passwords to exist just improves the likelihood that the attacker will crack a hash using a list of common passwords. This problem is made worse as the number of users increases. If 1/100 accounts have a password that ...


46

I wrote brainflayer and gave a talk about it at DEFCON. Neither Thomas Baekdal's article nor XKCD's comic apply well to modern offline attacks. I read Thomas's article and his FAQ about it, and it may have been marginally reasonable when he wrote it, it no longer is. A key point is that password cracking attacks have gotten much better since then. Q: If ...


1

SHA-256 and ECDSA are considered very strong currently, but they might be broken in the far future. If that happens, Bitcoin can shift to a stronger algorithm. (Block hashing algorithm) So the hashing algorithms used are not an issue. Adding to this, the computational capacities (Block hashing algorithm) required for cracking are not that easy; ...


8

Interesting question. @RoryMcCune nicely addressed the question about brainflyer, so I'd like to address your more open-ended question: are passwords such as "this is fun" really as safe as Thomas Baekdal claims? No, no it is not. My first thoughts are 1) that Thomas Baekdal doesn't explain how he's calculating his time estimates, which makes my inner ...


0

You simply avoid processing raw biometric data on your server at all cost. The way Apple does it on their iDevices is a good guide line. Let specialised and isolated hardware compute and store the sensitive biometric information for you. Then fetch the already hashed data from the hardware. If possible, you should not use pictures captured by the sensor.


15

The specific attack your talking about had, per the defcon talk, certain specific characteristics that mean that the same attack doesn't really apply to all passwords. First and most importantly, brainwallets effectively put the password hash in a public location. Usually the first defence against cracking of password hashes is to try and secure the hash ...


2

You should use a password, without any doubt. A 4-digit PIN is easily crackable via brute-force; for this reason it is only used in conjunction with other mechanisms that deny access after a limited number of tries, e.g. SIM cards and bank cards. Any other use is doomed to failure, as the hacking of Google Wallet showed a few years ago. Longer PINs are ...


2

As Martin suggested in the comments, I would highly suggest using TLS. Even if your audience is young teens, disclosing the salt to the client is not a good idea. For example, what would happen if the salt for the hashes is hard-coded into your web application and an attacker exploits a vulnerability to extract the bcrypt password hashes? If the attacker ...


2

No, this does not indicate whether they are storing your password in plain text or with reversible encryption. They might be, but this still leaves other possibilities open. All you know for certain is that they created a new password and emailed that new password to you. That password may well be hashed appropriately for storage in their system. However; ...


1

Not necessarily, I don't see an immediate correlation between the two. What is probably happening is that the application got your plain text password from the POST request and sent it to you as a reminder. It is likely that they are not retaining the plain text version and that they are keeping its hash instead. If, on the other hand, you haven't typed ...


0

I use insecure password for throwaway-accounts that have 0 value to them. Some sites generally have a low security standard and using a password like 123456 gives hackers of those sites less informations to your actual passwords. The other problem is that sites have arbitrary constrains on passwords. When passwords would have unlimited maximum length, ...


1

The one-time token offers much more security than the secret question simply because it implements 2-factor authentication; all things being equal, 2FA (password + code via SMS, password + RSA SecurID token, etc) is always safer than a simple password. On the other hand, the infamous "secret question" - so often offered by web services as a security ...



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