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visits member for 3 years, 6 months
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19m
comment Why use a Smartcard for (Two Factor) Auth instead of another medium?
"change it periodically based on your level of paranoia"; How does changing your password every 90 days increase security?
43m
comment Pattern to allow multiple persons to decrypt a document, without sharing the encryption key?
The best publicly known semi-practical attack against AES-256 appears to be a related-key attack with a complexity of about 2^99.5. The best known full key recovery attack again on AES-256 is 2^254.4 complexity. The former can probably be avoided in the key selection, and the latter is more of an academic curiosity than anything else, given that we can't even realistically count to a trivial 2^192 and are hard pressed for 2^128. Wikipedia: publicly known AES attacks.
49m
comment Pattern to allow multiple persons to decrypt a document, without sharing the encryption key?
This was a pretty good answer until the last two bullet points. Using untested algorithms in favor of well known, thoroughly examined ones that have been found to be quite secure in practice is a bad idea, for reasons that have been discussed over and over again. Edward Snowden was confident in using GnuPG to communicate securely, and has stated that "Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on.", with a strong caveat of endpoint security.
1h
comment Pattern to allow multiple persons to decrypt a document, without sharing the encryption key?
Possibly related: SuperUser: Encrypting a document with multiple keys, and making people accountable for those keys
Oct
25
comment Is using TrueCrypt in OSX secure?
Secure against what? (Note that the linked article is general, and not specific to the "activist or protester" category of people.)
Oct
25
comment How can I use Windows 10 unattended, without getting keylogged and sending everything to Microsoft?
Unplug the network cable, and don't join any wireless network?
Oct
15
revised SSL3 “POODLE” Vulnerability
Also two-exponents
Oct
15
suggested suggested edit on SSL3 “POODLE” Vulnerability
Oct
13
comment What is the difference between a key algorithm and the encryption algorithm?
Also, don't forget that often encryption and signing is used together. Since signing uses the (encrypted, password-protected) private key, the software would need to prompt for the private key's passphrase, even though the private key is not used for the encryption process per se.
Sep
29
comment Mapping of plaintext and ciphertext in DES
@Mark Fair enough point. How about now?
Sep
29
revised Mapping of plaintext and ciphertext in DES
added 585 characters in body
Sep
28
answered Mapping of plaintext and ciphertext in DES
Sep
28
answered HTTPS self signed certficiate for personal website
Sep
26
comment Four-factor authentication
While this answer may be true, I don't really see how it answers the question of whether there exists a fourth class of authentication factors. Care to edit to elaborate on that part?
Sep
17
comment Is SHA1 weak for SSL?
This answer effectively says "X is, because Y does Z because X". The answer to "why does Entity X say Y is Z?" can't be simply "Entity A is Act B because C", where C = Z (Qualys are saying SHA-1 based certs are weak because Google is going to warn about them because they are weak). The answer would be C' = Z' where those are the reason entities A and X are stating C and Z, respectively.
Sep
2
suggested suggested edit on Unix execute permission can be easily bypassed. Is it superfluous, or what's the intention behind it?
Sep
2
comment Why is security through obscurity not a good option for encryption?
Actually, this is not correct. A basic underlying assumption of any symmetric crypto is that the sender and recipient (whether different entities, or the same entity separated in time or space) shares a secret. (In the case of most modern algorithms, that secret being the key.) How to establish such a shared secret is a separate problem, and it can be done using techniques like public-key cryptography, pre-shared secrets, and so on.
Sep
2
comment How valuable is secrecy of an algorithm?
Now, designing something such that it can be made public without severly impacting security, and actually making it public, are two different things. Look at today: I have little doubt that the vast majority of the security in military encryption rests in the key (and key distribution), but that doesn't mean that every military encryption algorithm is made public as due course, only that if that were to happen security would not be greatly adversely affected. Particularly in such situations, there is no need to make things easier for your adversary than you need to.
Sep
2
comment How valuable is secrecy of an algorithm?
@FelixDombek If the Enigma had been designed from the ground up to be a published design, and for its security to lie in the key, the efforts to crack it would have had to focus on the key rather than the machine. In that case, even having access to Enigmas would have removed the need to build any, but it would not fundamentally have changed much: you'd still have needed to break the key, and with a good algorithm, that basically means trying every possible key. Make the key long enough and that simply is not feasible. Keys are also in some ways easier to safeguard.
Sep
2
comment How valuable is secrecy of an algorithm?
Changing the internals of the Windows password hashing scheme (if that is done; I don't know) also prevents software vendors from relying on a particular scheme being used. That might actually be quite worthwhile in itself, even if the exact algorithm was public. Note that anything officially documented is generally considered by contract from the vendor who documents it, and thus cannot easily be changed in the future if there is ever a problem with that design.