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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How does Windows 8's Microsoft Account authentication work?

One of the new features to Windows 8 is the ability to log in to your PC using your credentials from a Microsoft Account. How is this implemented, and what steps are taken to prevent hijacking of ...
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7answers
8k views

Forgotten password or reset link, which is more secure to email?

I originally posted this as a reply here in this thread but didn't get much feedback on it, and now I'm curious as to what others think is the best approach, or if there is any difference between the ...
13
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9answers
814 views

Anybody have additional information on the EMC RSA SecurID compromise?

The Security Advisory Press Release here doesn't have much information, the email that alerted me to this didn't help much more, and unfortunately I heard about the two Thursday evening conference ...
13
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2answers
4k 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 ...
13
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3answers
608 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 ...
13
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3answers
12k views

Choosing a session ID algorithm for a client-server relationship

I am developing an application which has a client-server relationship, and I am having trouble deciding on the algorithm by which the session identifier is determined. My goal is to restrict ...
13
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2answers
21k views

How does ssh public key authentication work?

My basic understanding is this: The (connected to) server's sshd uses the public key to encrypt some message The client's ssh or ssh-agent decrypts it and sends something back (the message's ...
13
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5answers
1k views

Is there any reason to show the same message for invalid username as password?

I've seen a security question/requirement that a website login return the same error message for invalid password as for non-existent user. The idea being that this it makes it impossible to discover ...
13
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5answers
1k views

Is there a digital “safety deposit box” equivalent?

Digital safety deposit boxes: do they exist? if yes, are (any|they) trustworthy? There are many bricks and mortar financial institutions where one can rent a locked box in a locked room and be ...
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4answers
4k views

How to protect against login CSRF?

http://seclab.stanford.edu/websec/csrf/csrf.pdf points out that most CSRF protection mechanisms fail to protect login forms. As http://stackoverflow.com/a/15350123/14731 explains: The ...
13
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5answers
438 views

I need ideas for blocking a single malevolent user

Let me throw out this problem I'm having to some of my technical peeps and see if you guys have any new suggestions: We have a website that sends text messages and voice mails for our clients. ...
13
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2answers
463 views

Why should one avoid chains of SSH sessions?

In this document on Security on NSC computing resources, there are several obvious pieces of advice (use a strong password, don't repeat passwords, etc.). One piece of advice I have not seen before, ...
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1answer
1k views

When authenticating ciphertexts, what should be HMACed?

Some have argued for using AES-256-CTR with HMAC-SHA-256 for authenticated encryption over AEAD-specific modes like EAX and GCM. However, when doing, this, what should be HMAC'd? And how? ...
13
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2answers
614 views

How do I prevent my twin sister's “pulled from public record” information from being used when I try to answer security questions?

Several times in the past months, I have been asked security questions that are "pulled from public record" to verify my identity, either over the phone or on a website (Chase Bank, Walgreens ...
12
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5answers
2k views

What is the best way to transmit password hash over unreliable TLS?

I have TLS connection between my server and client. I have no certificate, so the connection is susceptible to the Man-in-the-middle attack. I fear that attacker could intercept the password hash ...
12
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7answers
26k views

Can my email account be accessed without the password? How secure is it?

Can my email account be accessed without the password, and how secure is email if I store my personal documents on it? And how come Yahoo Mail asks me to tell them my friends and folders names to ...
12
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4answers
19k views

What is the difference between authenticity and non-repudiation

I'm new to infosec and doing some reading. Not surprisingly one starting point was wikipedia. In this article, authenticity and non-repudiation are listed as 2 separate 'Basic concepts'. My ...
12
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4answers
7k views

avoid hitting DB to authenticate a user on EVERY request in stateless web app architecture?

Summary Once a user logs into a web site and his username/password credentials are verified and an active session is established, is it possible to avoid hitting the DB for each and every request ...
12
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1answer
710 views

Why is the truncate function for HMAC one time passwords so complicated?

I've been reading through RFC4226 as part of some research and I was wondering why the function to truncate the HMAC was so complicated. As far as I understand it, the last 4 bits of the HMAC define ...
12
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6answers
15k views

Securing an API for mobile access

I've built a nice REST/JSON API that is used by other companies (our clients) as a B2B service. Each of our clients has a username/password pair, and we also do HTTPS and validate the source IP of ...
12
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3answers
403 views

Verifying server software integrity?

I'm trying to brainstorm a security scheme for the problem of verifying server software integrity. The domain of this problem is Game Servers built on Valve's Source Dedicated Servers. These servers ...
12
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2answers
1k views

Does having 2-factor authentication help with HeartBleed?

I was talking with a friend about HeartBleed, and he mentioned that he had 2-factor authentication enabled on all the sites that supported it, so even with his username and passwords, nobody would be ...
12
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4answers
4k views

How do the STS token formats compare to each other SAML vs SWT vs JWT?

I'm configuring an Azure ACS STS and would like to know if there is any impact on security based on the following token formats or how they are used. The answers to this questions should apply to ...
12
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3answers
7k views

How does deauthing work in aireplay-ng?

I have a question of how aireplay-ng works when it deauths. I mean, it is really easy to disconnect another client from an AP: you just need to run the deauth command (in aireplay-ng) once, specifying ...
12
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3answers
510 views

Is it inconsistent to tell users to “not click on password links in email”, and requiring clicks on “forgot password” links?

On one hand, IT Security shops have been telling users to not click on links in email because they can do damage to your computer, or phish your personal information. Many of those issues are ...
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4answers
3k views

Authenticating without a database

I've been inspired by a question over on Code Review, which boils down to: What is the proper way to authenticate a user without a database? Would it be the exact same process if you stored ...
11
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9answers
2k views

Why do we authenticate by prompting a user to enter both username and password? Does prompting the password only suffice?

I don't know why do we authenticate by prompting the user to enter both username and password. In my mental model, prompting password only suffices. The reason is as follows: Assume there are x ...
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7answers
2k views

Prevent denial of service attacks against slow hashing functions?

I've been thinking about bcrypt recently, and what I wonder is if there's a way to deal with the inherent (D)DoS problems with slow hashing functions. Namely, if I set up bcrypt so my machine takes ...
11
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5answers
2k views

CSRF protection with Session Id

To protect against CSRF, couldn't my page javascript just dynamically insert the session id from the cookie into the body of each HTTP request right before it's sent? The server would then just ...
11
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1answer
583 views

Fell for phishing scam. Is my gmail account with 2-step verification vulnerable?

I can't believe it happened to me but I entered Gmail account's user-name and password into a website as part of a phishing scam. I use Gmail's 2-step verification and have changed my password. Is ...
11
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3answers
7k views

Is HTTPS and Basic Authentication secure enough for banking webservices (RESTful)?

I have been reading about SSL/TLS for the last few days and looks like it has never been practically cracked. Given SSL/TLS is used for all communications between client application and the server, ...
11
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3answers
2k views

Is SiteKey a valid defense against Phishing?

As described here, some banks use a SiteKey mechanism in an attempt to provide a defense against phishing. (This is a scheme where the user is shown a personalized image (each user has their own ...
11
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2answers
1k views

BCrypt's 72-character limit and using it as a general digest algorithm

Goal: have token/cookie-based authentication that doesn't require keeping sessions on the server TL;DR: What, if any, is the accepted mechanism to work around the 72-character limitation of BCrypt? ...
11
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6answers
409 views

How to protect against adversaries snatching booted laptops to defeat full disk encryption?

I read an article describing how FBI agents snatched Ross Ulbricht's laptop while it was running to defeat full-disk encryption: Two plainclothes FBI agents, one male and one female, walked up ...
11
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3answers
1k views

What is the risk and mitigation of accidentally typing a YubiKey password in an open forum?

I have a YubiKey in my laptop (for testing) and accidentally broadcast my YubiKey password out to the Internet. Since this is only a test key, and has no access to anything of value, here are some ...
11
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3answers
8k views

How to set up OpenSSH to use x509 PKI for authentication?

I do not mean simply putting the public RSA key of a x.509 certificate into ~/.ssh/authorized_keys - I'm looking for a way to set up a ssh such that x.509 certificates signed by a pre-defined CA will ...
11
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2answers
292 views

Preventing Voter Fraud on a Social Media Contest

I'm creating a contest that will allow users to login using their Facebook & Twitter accounts and submit votes on videos. My clients concern is that users will game the system by logging into ...
11
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1answer
585 views

Is Postgres's uuid_generate_v4 securely random?

I'm using Postgres's uuid_generate_v4 in a uuid primary key column to generate secure one-time authentication tokens. Is this okay? Does Postgres use a secure random number source for generating these ...
11
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3answers
12k views

How secure is Android's facial recognition?

Android supports using facial recognition for unlocking your phone. How secure is that mechanism? For instance, if someone has a good quality picture of your face, can they defeat the facial ...
11
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3answers
955 views

How much information about the reason for an unsuccessful login should a web application give?

After an unsuccessful login attempt, should I inform the user about its reason? Or more generally, how much information about the reason for an unsuccessful login attempt should a web application ...
11
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4answers
2k views

Multiple CAs signing a single Cert/CSR?

Just saw this suggested on Slashdot So I've seen quite a few people wanting a switch to self-signed certs (who IMO mostly don't understand what making that secure actually involves), and an idea ...
11
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3answers
3k views

OAuth2 - Resource Owner Password Credentials grant

The OAuth2 spec describes the Resource Owner Password Credentials grant type and authorisation flow here. I understand that only 'trusted' client applications would be allowed to use this grant, for ...
11
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1answer
5k views

Ways to sign gpg public key so it is trusted?

I have a service through SSL which gives the user a code for a specific reason. I want to sign the code with the web server's private key (gpg --clearsign) and send the signed code along so that they ...
11
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3answers
357 views

What email addresses are treated as trusted?

Windows Live recently suffered a security incident because they didn't realize that email addresses like administrator@live.fi are considered "trusted": some certificate authorities will consider ...
11
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4answers
589 views

NFC contactless payment security

This is really bugging me. Up until recently debit cards with an electronic chip were the most popular electronic form of payment available in Poland (I'd wager that in other European countries as ...
11
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1answer
279 views

Is TLS in Tor useless?

I am trying to optimize the Orchid Tor client library for my needs and noticed that every connection with every node uses TLS with turned off certificate verification. Actually there are no TLS ...
11
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3answers
2k views

API message verification without storing private key?

I'm in the process of implementing a public API for my web service. Security is a key concern as money is involved. It seems the current common practice for "authenticating" users in API requests is ...
11
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5answers
933 views

Non-OEM Biometric Software?

Most of us with fingerprint readers and such devices probably use the software provided by the vendor, to enable biometric OS login or single sign-on functionality. However, I've recently wondered if ...
11
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1answer
968 views

MPPE-Send and Receive key derivation from MS-CHAPv2

I am trying to get the MS-MPPE-Send-key and MS-MPPE-Recv-key from the MS-CHAPv2 challenge material. I am able to follow the RFCs 2548 3078 and 3079 to the step of getting the GetNewKeyFromSHA() it is ...
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4answers
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Is Facebook Connect or Twitter OAuth PCI Compliant?

We have a system that stores credit cards securely on file. We'd love to allow users to sign up using Facebook Connect or Twitter. Obviously this wouldn't be secure if we were trusting just any old ...