26,285 reputation
22661
bio website
location Troy, NY
age 30
visits member for 1 year, 11 months
seen 6 hours ago

Jul
23
comment PHP web application security
are communicating securely via some other trusted means, such as SSL being used to verify the server to the client.
Jul
23
comment PHP web application security
@DaGhostmanDimitrov - your method of approaching encryption is still fundamentally broken. You don't use asymmetric crypto for encryption at rest. You use either a derived or client cert protected data key and use that for encryption. You can either use a password that derives a key which is used to encrypt/decrypt the symmetric data key or you can encrypt the symmetric data key with a client cert public key so that it can only be decrypted by the user. You would then have to submit the decryption key as part of a challenge to the user to get the decryption key once the client and server..
Jul
22
comment Can a VPN avoid the Prism Surveillance Programme?
@Ke. - the idea that the government could get information from private parties that agree to work with them isn't really new either, and the idea that they would work with a lot of the big companies to reduce costs of requesting information by putting in an automated system isn't surprising, it's good business (as long as it doesn't become a public scandal.) Why pay for a team of dedicated customer support staff to process government requests when you can just give the government access? (from the businesses perspective) I'm not at all shocked.
Jul
20
comment Download a data file, add it to the database only when certain it's clean
@Edwardo - yes, your article isn't news to me. that's using a format that supports arbitrary extension. That's why I suggested to use a) a combination of signatures and b) a format that does not support arbitrary extension without detection. It makes the problem much more complicated. Arbitrary extension collision generation against MD5 is trivial, but non-arbitrary multiple hash algorithm attacks are much more complicated.
Jul
19
comment Is using a numbers station to transmit a one-time-pad as key actually insecure?
@TomLeek - ok, that's fair I suppose, thanks for the further explanation.
Jul
19
comment Is using a numbers station to transmit a one-time-pad as key actually insecure?
@TomLeek - For the pseudo randoms, the sequence of numbers is apparently random, but you still only get the security of the complexity of the initialization value. The problem isn't attacking the sequence of numbers, it is attacking the initialization of the sequence of numbers, which is a great deal less complex than apparently random phenomena. I guess if you can feed a very long initialization in, it may be practically indistinguishable since the foreseeable future will lack the processing power to test the entire space of initialization values, but it is still the key weakness.
Jul
19
comment Infection risk downloading one’s own file from Gmail
It would be far easier to simply use Firefox's sync functionality. This would allow you to store your bookmarks in the cloud and have Firefox simply import them whenever you start the thumb drive. It's effectively the same as what you are doing now, but with less steps.
Jul
19
comment Download a data file, add it to the database only when certain it's clean
@Edwardo - Yes, but unless you are higher value than other people, it is far too elaborate of an attack to put the resources in to. The majority of non-targeted criminal hacking is very basic and those that are doing custom exploits are looking for big payoffs, not going after individuals. Forging a thumbprint for multiple hashes in a structured file is quite complex and computationally pricey. It isn't something joe blow scriptkiddie is gonna do to try and get in to random bloke's computer.
Jul
19
comment Download a data file, add it to the database only when certain it's clean
@Edwardo - are you sure you are a high value target, unless you have LARGE amounts of data that would be of high value to either governments, law enforcement or the black market then you are not likely worth the effort to generate a targeted compromised file. Your best bet is still thumbprint verification, though you could use one or more cryptographically secure hashes and use a file format with a predictable structure that would put further limits, such as compressing the data prior to upload so that alterations have to decompress validly.
Jul
19
comment Is using a numbers station to transmit a one-time-pad as key actually insecure?
From a practical standpoint, the mathematical "non-random" matters. It reduces the bits of complexity from infinite to the number of possible initialization values for the random number generator. That's a very large reduction in complexity. OTP is also the only thing perfectly forward secure, though it does rely on physical security of the keys so in some ways it can be practically less secure, which is worth mentioning, but as far as security of the data transmitted, it is the most verifiable security out there.
Jul
19
comment Download a data file, add it to the database only when certain it's clean
@Edwardo - if you are uploading the file and simply want to make sure it isn't modified, generate a SHA-1 or MD5 hash of the file. There are some ways to make a collision attack against it, but it's pretty unlikely someone would go through the effort just to get to you unless you are a high value target. I updated my answer with more info.
Jul
18
comment Why do most cars use physical keys and no PIN?
This question appears to be off-topic because it is about general security, not IT security.
Jul
18
comment Encrypted disk at risk if laptop stolen while turned on but locked
Cold boot is less bad if only because it isn't guaranteed to work. Data degrades pretty quick once power is removed and they only get one shot. It is a real possibility, but far less simple to implement than the firewire based attack, which has an open source and public implementation available and doesn't require any special treatment and is non-destructive.
Jul
18
comment Am I covered with GPL If I want to share open source code of project developed in my company?
This question appears to be off-topic because it is about programming and legal. It is definitely not security related.
Jul
16
comment Building a web app with encrypted MySQL database entries?
@JoeyO - note that good selection of a key derivation function is still important as well, just like good hash selection is. You don't want someone to be able to brute force the keygen easily, so salts are still advisable.
Jul
16
comment Building a web app with encrypted MySQL database entries?
It also allows account recovery since if the password is lost, the user key may still be recoverable if it is encrypted to another derived key. (Since the user's data key can be shared without needing the user's password.) So the net effect is that it is more versatile and potentially more secure against particular types of attacks.
Jul
16
comment Building a web app with encrypted MySQL database entries?
It has to do with the methods of trying to crack a key. Derived keys by definition are less secure than a random key because they have less entropy and the key itself has to follow certain rules on how it is derived. It is more likely that an attack could be found that could use statistical analysis to reveal portions of the key due to the added complexity. If you limit the data encrypted and decrypted with it, you also limit the surface area for statistical analysis. It might or might not actually be a gain (since such attacks might not exist) but it's a fairly cheap step.
Jul
16
comment Building a web app with encrypted MySQL database entries?
Oh, one other thought, if you use a derived key, you don't have to actually store a hash of the password either. Just have it derive the key, then use the user key that it decrypts to encrypt a login string of some type. If it encrypts properly, they were able to decrypt the user key which means they have the derived key and thus the password is valid.
Jul
16
comment Intercepting and reading SSL traffic generated by Android
I don't know your particular proxy, but if it doesn't include the proper site name in the certificate, it is going to still error. That may be the problem. It is also possible the application is running off it's own trusted root certificate in which case you might not be able to do anything.
Jul
15
comment Can you make a digital signature using the receiver's public key?
@Matthew - see my update, it does make sense when looking at their flowcharts later on, it just is a really REALLY badly worded summary steps.