Authentication - establishing the authenticity of a person or other entity. Not to be confused with authorization - defining access rights to resources.

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19
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12answers
3k views

Why do we even use passwords / passphrases next to biometrics?

In the last couple of days there were a lot of talking about passwords and passphrases, not only here, but on several blogs and forums I follow (especially after XKCD #936 saw the light of this ...
17
votes
3answers
3k views

Should I have a maximum password length?

I'm creating a webapp, and part of my authentication method is password length. Should I put one in place? (say, 50 characters?) Or should I just put a minimum length (Currently at 6). Are there ...
15
votes
5answers
835 views

Safe way to authenticate (multi-factor authentication?) while being monitored?

(I'm trying for a bit more precise answer, particularly with regard to multi-factor authentication, than I received for "Safe way to use a computer that has spyware/keylogger installed?" on SU.) ...
13
votes
3answers
544 views

Does signing out of a website ensure no-one can cookie hack?

If I click the signout link of a website, does this mean it is not possible for someone to hijack my cookie and sign in with it? While I'm logged in, is it possible for someone who has access to my ...
8
votes
5answers
307 views

How to verify new accounts against a known persons database?

I need to (try to) solve the problem of new account creation for a patient portal for a medical records system (electronic health record). That is, a way to activate a patient online and match her ...
10
votes
4answers
2k views

How can an access point spoof me into connecting?

I was reading through the answers of the question "How can I ensure that I connect to the right wireless Access Point?" and was wondering how it is possible for an access point to imitate another wifi ...
5
votes
2answers
1k views

Frameworks or any Solutions for authentications/security/ login management in Java Web Applications

I am looking for a framework/solution for authentication/ user-login management/ security in java web application that can make the naive developer's job easier/faster and make the application ...
7
votes
8answers
828 views

Is the following authentication scheme secure?

I was trying to design an authentication system that would make it much harder to guess a password via brute force, and reduce the risk to a user if the hashed password was stolen through a snooping ...
5
votes
3answers
363 views

DHE exchange and client authentication

If a server has a known public key and a Diffie-Helman exchange is performed and signed by that key, is there any benefit to authenticating the client before establishing a secure channel instead of ...
33
votes
3answers
2k views

Am I wrong to believe that passwords should never be recoverable (one way hash)?

I recently forgot my password for our cable provider online account, only to discover that they sent it to us via plain text in an email. I quickly sent an email to customer support asking them if ...
0
votes
0answers
79 views

Pages restricted to certain IPs, safe? [duplicate]

Possible Duplicate: In what scenarios is relying on source IP address as a security control acceptable/unacceptable? If a website has a page which only renders for certain IPs, is there ...
6
votes
2answers
2k views

Is Access Control Through MAC ADDRESS a practical/secure solution

I run a small local gaming website with a custom admin panel I coded to let trusted members do administrative tasks through the software's API. Since their IP Address is dynamic, can I authenticate ...
8
votes
7answers
340 views

Aren't permanantly logged in accounts inherently insecure?

The basic premise behind a "keep me logged in until I log out" feature is a cookie is stored with some identifier that is used to log the user in again when returning to the site. While these ...
5
votes
1answer
235 views

Using AD authentication in a publicly accessible webapp

I am sys admin working with a development team who is extending a publically accessible .net web app that currently uses forms authentication with usernames/passwords (hashed) stored in a sql ...
4
votes
3answers
363 views

Locking down web-based admin areas with personal SSL certificates

I've been tasked to setup a secure platform, where I've been asked to assign personal SSL certificates to administrators, and have the server only allow persons into the administration areas that have ...
5
votes
6answers
753 views

How do I secure my login page?

The login page is the starting point to any web site and the most important thing to authenticate the user. When I begin to build any web application, I take a lot of time to think about how to ...
15
votes
5answers
907 views

Does two factor authentication prevent social engineering attacks

After reading this article from symantec I got to think how much all these social engineering techniques rely on the authentication system of users, a password. Considering three different additional ...
14
votes
2answers
2k views

What are the most common password salting methods?

I learned that the Sun guys used the login name as salt for password hashing. Is this a common approach? What are the most common salt values?
20
votes
3answers
5k views

What are the main advantages and disadvantages of webid compared to browserid?

What are the main advantages and disadvantages of webid compared to browserid? This question is inspired by this answer which got a number of upvotes despite being very vague on the topic of that ...
40
votes
5answers
7k views

What are the downsides of BrowserID/Persona compared to OpenID/OAuth/Facebook?

Mozilla went live with a new service called BrowserID/Persona (announcement, background). It is intended to replace current single-sign-on solutions such as OpenID, OAuth and Facebook. One advantage ...
19
votes
9answers
876 views

What's a good way to trigger a hidden 'distress signal' in instant messaging?

Here's the scenario: Alice and bob use Off-the-record messaging to communicate over IM. The have: Encryption Authentication Deniability Perfect forward secrecy They communicate after ...
6
votes
2answers
504 views

Cellular phone cloning

It is known that certain methods of authentication are used to tie a particular device to a particular phone number, so that cloning can be prevented. What are these authentication mechanisms? ...
3
votes
2answers
817 views

OAuth User revoke token

I haven't read it myself but a colleague told me that the end-user can revoke his/her OAuth token. I searched but I couldn't find enough docs on: is this true / is the end-user the one to revoke the ...
6
votes
3answers
941 views

chosen plaintext attacks against MD5 and SHA1

According to http://tools.ietf.org/html/rfc2617#section-4.9, having the server chose a nonce but not having the client chose a nonce opens up Digest Access authentication to chosen plaintext attacks. ...
10
votes
4answers
1k views

Can .htaccess and .htpasswd really protect me?

I want to set up a kind of personal wiki where I can store various sensitive information. However to make it 100% portable and and just plain convineant, I want to put it on the Internet. I'm sure at ...
5
votes
2answers
1k views

How does openid implement Single sign on?

I'm wondering which security model is behind the OpenID. Is it anything like kerberos?
211
votes
7answers
155k views

RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
1
vote
2answers
200 views

TCrypto - Comments about design decisions I made?

I have pushed some code to GitHub to demonstrate the usage of symmetric key encryption in PHP. It is a small key-value storage library and it (optionally) offers ability to encrypt the stored ...
3
votes
3answers
110 views

Question on information retrieved from systems that could potentially lead to exploits

Usually it is advised, when one wants to secure an application, to "provide" as little information, or better yet, no information at all to unauthorized (possibly malicious) users. I'm thinking of ...
14
votes
4answers
3k views

Three-Factor Authentication for Windows

This HowToGeek article... http://www.howtogeek.com/67556/how-to-unlock-your-pc-by-being-nearby-with-a-bluetooth-phone/ ...got me thinking. Is there any software (or combination of software) that ...
2
votes
1answer
797 views

iOS/Android authentication and security

Here is what I am trying to do and can anyone provide some best practice advice for authentication and security? Each user will have their own private database on the cloud. He will have his local ...
8
votes
4answers
1k views

How to protect ftp account information in the source code of a program

I wrote a game which stores high score information on an ftp server. In the the source code I need to write out the ftp link with the account name and password in it. For example: url = new ...
17
votes
4answers
958 views

Is it a bad idea for an information holder to e-mail a user their password?

A couple of websites with which I'm registered have, after a period of inactivity on my part, each sent me an e-mail to remind me that I'm still registered. In each case, that e-mail has included my ...
8
votes
3answers
684 views

zero knowledge proof and its protocol

In Zero-Knowledge Proof where we take the analogy of Peggy (Prover) and Victor (Verifier): In this story, Peggy has uncovered the secret word used to open a magic door in a cave. The cave is ...
6
votes
1answer
1k views

Deploying a campus WiFi network that authenticates against an AD LDAP

We are looking to deploy about 15-20 Cisco 1131ag access points on campus. I have been reading up on different authentication methods, but I don’t know what will be the best long term solution that ...
8
votes
2answers
578 views

Is a rand from glibc's rand secure for a login key?

Same question as Is a rand from /dev/urandom secure for a login key, but with glibc's rand function instead of /dev/urandom. And what would be a sufficiently secure seed generator?
-1
votes
1answer
2k views

How can I avoid sending passwords in plain text when logging into a website?

Suppose that I login to a website. When I type my personal data, aka, password and email, the password is sent in clear text to the server, correct? Then, a network card in promiscuous mode can ...
38
votes
5answers
5k views

How do some sites (e.g. online banks) only ask for specific characters from a password without storing it as plaintext?

I thought How can a system enforce a minimum number of changed characters... would answer my question, but it seems this is a different case. When I sign on to my online banking account, I'm prompted ...
3
votes
7answers
1k views

Sharing passwords and credentials between founders and employees

What's the best way to share passwords and credentials from the business's various accounts in a secure manner? For example, email doesn't work because if someone gets into one of your employee's ...
7
votes
1answer
264 views

Collision attacks on OCB?

I've been looking into the OCB cipher mode and everything I hear sounds good. I was planning on implementing it. Everything except for this lone voice, that is: Collision attacks on OCB: We ...
22
votes
5answers
2k views

Should usernames be kept secret?

Help me settle an discussion among colleagues and guide future design: Even in a high impact scenario: e.g. protecting payment application or government gateway but in an Internet accessible ...
300
votes
20answers
51k views

How does changing your password every 90 days increase security?

Where I work I'm forced to change my password every 90 days. This security measure has been in place in many organizations for as long as I can remember. Is there a specific security vulnerability ...
4
votes
3answers
230 views

Choosing an authenticated encryption cipher mode without associated data

In the application I'm writing there is need for a huge amount of private data transfer on the order of eighty gigabytes, but there is no public data. I'm looking especially to gain ...
6
votes
1answer
2k views

What is the purpose of AEAD?

I think I need to correct some misunderstandings I have about AEAD. What is associated data used for in authenticated encryption?
14
votes
6answers
1k views

Is This Login Security Enough?

I'm coming up with my next login system for admins of an ecommerce website to have login form is SSL secured password is converted to sha256 before being transmitted (bcrypt is too slow still for ...
8
votes
3answers
564 views

Which authentication at the end of the Secure Remote Password protocol?

For the the client and server to prove to each other that they have the same premaster shared key, the original author suggests this: M = H(A | B | K) --> <-- H(A | M | K) ...
7
votes
2answers
476 views

How does external authentication work?

For example, I can log in to stackexchange websites by logging in to external websites such as OpenID, Yahoo, etc. How does this work? How do the websites (SE and Yahoo!, for example) communicate? How ...
12
votes
2answers
3k views

Secure communication between applications using SSL Certificates

I am looking for a way how to secure communication between our applications. There is a "server" application listening on some TCP port and "client" application which is communicating with the ...
9
votes
1answer
361 views

Optimal variable sizes in the Secure Remote Password protocol

I am implementing the Secure Remote Password protocol: U = <username> --> <-- s = <salt from passwd file> a = random() A = g^a ...
6
votes
2answers
617 views

Implementing Secure Remote Password: Constructing the verifier

The SRP protocol as described in RFC 2945 generates the password verifier: x = SHA(<salt> | SHA(<username> | ":" | <raw password>))` v = g^x % N I have three questions: why use ...