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  • Is it a good idea to use only a key to encrypt an entire (small) filesystem?

    - by Fernando Miguélez
    This question comes as part of my doubts presented on a broader question about ideas implementing a small encrypted filesystem on Java Mobile phones (J2ME, BlackBerry, Android). Provided the litte feedback received, considering the density of the question, I decided to divide those doubts into small questions. So to sum up I plan to "create" an encrypted filesystem for for mobile phones (with the help of BoucyCastle or a subset of JCE), providing an API that let access to them in a transparent way. Encryption would be carried out on a file basis (not blocks). My question is this: Is it a good idea to use only a simmetric key (maybe AES-256) to encrypt all the files (they wouldn't be that many, maybe tens of them) and store this key in a keystore (protected by a pin) or would you rather encrypt each file with an on-the-fly generated key stored alongside each file, encrypting that key with the "master" key stored on the keystore? What are the benefits/drawbacks of each approach?

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  • Cross-Origin Resource Sharing (CORS) - am I missing something here?

    - by David Semeria
    I was reading about CORS (https://developer.mozilla.org/en/HTTP_access_control) and I think the implementation is both simple and effective. However, unless I'm missing something, I think there's a big part missing from the spec. As I understand, it's the foreign site that decides, based on the origin of the request (and optionally including credentials), whether to allow access to its resources. This is fine. But what if malicious code on the page wants to POST a user's sensitive information to a foreign site? The foreign site is obviously going to authenticate the request. Hence, again if I'm not missing something, CORS actually makes it easier to steal sensitive information. I think it would have made much more sense if the original site could also supply an immutable list of servers its page is allowed to access. So the expanded sequence would be: 1) Supply a page with list of acceptable CORS servers (abc.com, xyz.com, etc) 2) Page wants to make an XHR request to abc.com - the browser allows this because it's in the allowed list and authentication proceeds as normal 3) Page wants to make an XHR request to malicious.com - request rejected locally (ie by the browser) because the server is not in the list. I know that malicious code could still use JSONP to do its dirty work, but I would have thought that a complete implementation of CORS would imply the closing of the script tag multi-site loophole. I also checked out the official CORS spec (http://www.w3.org/TR/cors) and could not find any mention of this issue.

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  • What's the state of support for SHA-2 in various platforms?

    - by Cheeso
    I read that SHA-1 is being retired from the FIPS 180-2 standard. Apparently there are weaknesses in SHA-1 that led to this decision. Can anyone elaborate on the basis for that decision? Are there implications for the use of SHA-1 in commercial applications? My real questions are: What is the state of SHA-2 support in various class libraries and platforms? Should I attempt to move to SHA-2? Interested in mainstream platforms: .NET, Java, C/C++, Python, Javascript, etc.

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  • PHP 2-way encryption: I need to store passwords that can be retrieved

    - by gAMBOOKa
    I am creating an application that will store passwords, which the user can retrieve and see. The passwords are for a hardware device, so checking against hashes are out of the question. What I need to know is: How do I encrypt and decrypt a password in PHP? What is the safest algorithm to encrypt the passwords with? Where do I store the private key? Instead of storing the private key, is it a good idea to require users to enter the private key any time they need a password decrypted? (Users of this application can be trusted) In what ways can the password be stolen and decrypted? What do I need to be aware of?

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  • Claims-based Authentication: Are strings the essence of claims?

    - by Rising Star
    I've been programming with claims-based authentication for some time now with Windows Identity Foundation. It appears to me that in Windows Identity Foundation, once a user is logged in, the claims are basically strings of information that describe the user. With the old role-based authentication, I could say that a user is or is not a member of a given group, but with claims-based authentication, I can now have strings of information that describe a user. "This user is female". This user was born on "July 6, 1975". "This user logged in using a USB key". Is it the essence of claims-based authentication,that I have strings of information about the user given to the application by the framework?

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  • Cross-Application User Authentication

    - by Chris Lieb
    We have a webapp written in .NET that uses NTLM for SSO. We are writing a new webapp in Java that will tightly integrate with the original application. Unfortunately, Java has no support for performing the server portion of NTLM authentication and the only library that I can find requires too much setup to be allowed by IT. To work around this, I came up with a remote authentication scheme to work across applications and would like your opinions on it. It does not need to be extremely secure, but at the same time not easily be broken. User is authenticated into .NET application using NTLM User clicks link that leaves .NET application .NET application generates random number and stores it in the user table along with the user's full username (domain\username) Insecure token is formed as random number:username Insecure token is run through secure cipher (likely AES-256) using pre-shared key stored within the application to produce a secure token The secure token is passed as part of the query string to the Java application The Java application decrypts the secure key using the same pre-shared key stored within its own code to get the insecure token The random number and username are split apart The username is used to retrieve the user's information from the user table and the stored random number is checked against the one pulled from the insecure token If the numbers match, the username is put into the session for the user and they are now authenticated If the numbers do not match, the user is redirected to the .NET application's home page The random number is removed from the database

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  • Bruteforcing Blackberry PersistentStore?

    - by Haoest
    Hello, I am experimenting with Blackberry's Persistent Store, but I have gotten nowhere so far, which is good, I guess. So I have written a a short program that attempts iterator through 0 to a specific upper bound to search for persisted objects. Blackberry seems to intentionally slow the loop. Check this out: String result = "result: \n"; int ub = 3000; Date start = Calendar.getInstance().getTime(); for(int i=0; i<ub; i++){ PersistentObject o = PersistentStore.getPersistentObject(i); if (o.getContents() != null){ result += (String) o.getContents() + "\n"; } } result += "end result\n"; result += "from 0 to " + ub + " took " + (Calendar.getInstance().getTime().getTime() - start.getTime()) / 1000 + " seconds"; From 0 to 3000 took 20 seconds. Is this enough to conclude that brute-forcing is not a practical method to breach the Blackberry? In general, how secure is BB Persistent Store?

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  • Authenticate User manually

    - by Sergey
    I am trying to authenticate the user after I got credentials using oAuth (with Twitter if that makes a difference). As far as I could understand it, I can directly put the Authentication object into SecurityContextHolder. Here is how I do it: Authentication auth = new TwitterOAuthAuthentication(member, userDetailsService.loadUserByUsername(member.getUsername()).getAuthorities()); SecurityContextHolder.getContext().setAuthentication(auth); This for some reason does absolutely nothing. What am I missing and what should I do to accomplish what need?

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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  • Preventing dictionary attacks on a web application

    - by Kevin Pang
    What's the best way to prevent a dictionary attack? I've thought up several implementations but they all seem to have some flaw in them: Lock out a user after X failed login attempts. Problem: easy to turn into a denial of service attack, locking out many users in a short amount of time. Incrementally increase response time per failed login attempt on a username. Problem: dictionary attacks might use the same password but different usernames. Incrementally increase response time per failed login attempt from an IP address. Problem: easy to get around by spoofing IP address. Incrementally increase response time per failed login attempt within a session. Problem: easy to get around by creating a dictionary attack that fires up a new session on each attempt.

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  • Session Fixation in ASP.NET

    - by AJM
    I'm wondering how to prevent Session fixation in ASP.NET My approach would to this would normally be to generate and issue a new session id whenever someone logs in. But is this level of control possible in ASP.NET land?

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  • HTTPS-Compliant Sharepoint Web Parts

    - by bporter
    We are planning to create a new sub-site within our company's intranet site. The intranet is built on SharePoint 2007. My question is this: Suppose I want to add a 3rd-party weather web part to the home page of my new intranet site. Since the new site uses HTTPS, do I need to make sure to find an HTTPS-compliant web part? If I use a standard web part, will users get a "This page contains both secure and non-secure items" error message when they load the page? Thanks in advance!

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  • Persisting sensitve data in asp.net, odd implementation

    - by rawsonstreet
    For reasons not in scope of this question I have implemented a .net project in an iframe which runs from a classic asp page. The classic asp site persisted a few sensitive values by hitting the db on each page. I have passed there variables as xml to the aspx page, now I need to make these values available on any page of this .net site. I've looked into the cache object but we are on a web farm so I am not sure it would work. Is there a way I can can instantiate an object in a base page class and have other pages inherit from the base page to access these values? What is the best way to persist these values? A few more points to consider the site runs in https mode and I cannot use session variables, and I would like to avoid cookies if possible..

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  • How do I validate that my the openid.op_endpoint when a request is completed.

    - by Sam Saffron
    I have an Open ID based authentication system on my site. Occasionally users will have an account registered under [email protected] and they will attempt to login using the google open id provider https://www.google.com/accounts/o8/id, in this case I would like to automatically associate the account and log them in. When the process is done I get a payload from somewhere claiming that openid.op_endpoint=https://www.google.com/accounts/o8/id. My question: Can I trust openid.op_endpoint to be correct? Can this be spoofed somehow by a malicious openid provider? For illustration, lets say someone types in http://evil.org as their openid provider, can I somehow end up getting a request back that claims openid.op_endpoint is google? Do I need to store extra information against the nonce to validate? The spec is kind of tricky to understand

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  • Single Sign On with 3 applications

    - by John H.
    I'm building three web applications in .NET that will all share a users database and login information. Lets pretend that application 1 is the "parent" application and applications "A" and "B" are the "child" applications. All users have to be logged into application 1 to have access to applications A and B. Authorization, Authentication, and MachineKey sections of all web configs are present and work correctly. I have the correct web.config settings in all applications to achieve Single Sign On except one problem remains: what do I put in the "loginUrl" attribute of the forms tag in Applications A and B. Assume that the url for the login to application 1 is "www.johnsapp.com/login.aspx" How can I get applications A and B to send the user back to application 1 for authentication using only settings in web.config?

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  • What is this hacker trying to do?

    - by JW
    If you do a search for: http://www.google.co.uk/search?q=0x57414954464F522044454C4159202730303A30303A313527&hl=en&start=30&sa=N you will see a lot of examples of an attempted hack along the lines of: 1) declare @q varchar(8000) select @q = 0x57414954464F522044454C4159202730303A30303A313527 exec(@q) -- What is exactly is it trying to do? Which db is it trying to work on? Do you know of any advisories about this?

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