Misha

1,224 reputation

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	1,224 reputation	bio	website		visits	member for	1 year, 10 months
315 badges		location			seen	May 20 '12 at 21:36

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Sep 22	comment	How to properly encrypt a communication channel between a client and a server (without SSL)? Why are you trying to create your own protocol, rather than using an existing one? Is the "no SSL" constraint just to encourage "novel" answers, or are there particular aspects of an SSL/TLS-based approach which make it unacceptable to you?
Sep 19	awarded	Enlightened
Sep 19	awarded	Nice Answer
Sep 14	comment	when is it safe to click through an SSL warning message? For the "name doesn't match" case it often suffices to change the URL to the one specified in the certificate; the admin did test it, just not from every URL/domain name that can be used to reach that server.
Sep 14	comment	when is it safe to click through an SSL warning message? Isn't an HTTPS-with-broken-cert website is also theoretically worse than a plain HTTP website if you have visited it before (even if your use this time is non-confidential browsing, say), because it will have access to HTTPS-only cookies for that domain? (And it could be part of an active attack, as you note.)
Sep 14	comment	Online backup : how could encryption and de-duplication be compatible? Your edit beat my answer to it :-)
Sep 14	answered	Online backup : how could encryption and de-duplication be compatible?
Sep 12	comment	Most secure password hash algorithm(s)? You could implement "pick #iters based on time taken" using a library-provided bcrypt -- just time the bcrypt call and if it's "too quick" increase the workload factor and re-try. But are you sure you want that? What if someone deploys your code onto a slow machine (e.g. a small VM) -- you don't want to get too-small work factors as a result. What if your system is left on a "2011" spec machine through to 2019 when all the attackers have 128-way 20GHz boxes? What if the attacker can use a DoS to increase the time your hashing takes? You will at least want a secure-for-now initial work factor.
Sep 1	revised	XKCD #936: Short complex password, or long dictionary passphrase? split out edited-in parts of answer
Sep 1	answered	XKCD #936: Short complex password, or long dictionary passphrase?
Sep 1	suggested	suggested edit on XKCD #936: Short complex password, or long dictionary passphrase?
Sep 1	revised	Flaw in encryption through pseudorandom number stream (from gpg documentation) linkify eSTREAM
Sep 1	comment	Flaw in encryption through pseudorandom number stream (from gpg documentation) Done. The statement was a too-aggressive interpretation of min("computational complexity of the best known attack", "effective key length") from the columns in the table on the wikipedia page (and removing VEST based on eSTREAM phase 2 finding a practical attack). But you are right, there are too many explicit and implicit question marks over those figures for them to be reliable, and one of the eSTREAM ciphers (MICKEY) isn't even listed. I kept in the references to the specific ciphers to keep the concreteness of the answer, but e.g. HC256, Pike, SEAL and SNOW2 are also contenders.
Sep 1	revised	Flaw in encryption through pseudorandom number stream (from gpg documentation) removed "strongest" claim
Sep 1	comment	Can a survey website viewed in Firefox trick the user into sending stored passwords? (With sufficient rep - 75 points) you can set a bounty on a question (to encourage answers) but not on the act of physical harm to another person (or on any other action outside of stackexchange, for that matter) :-)
Sep 1	comment	How to best set up public WiFi without giving access to the rest of my network? OK. I thought that the OP didn't currently have a public WLAN set up, but did already have the mentioned AP ("wireless router that I've disabled DHCP on and have effectively made into a wireless-wired bridge"), so assumed he'd still need that AP for whatever he was using it for before (e.g. private WLAN, LAN bridging via WLAN, etc.)
Aug 31	comment	Flaw in encryption through pseudorandom number stream (from gpg documentation) Just having to have seen 624 of the random words (19937 bits) would be bad enough. I suspect that if you know that the MT19937 state had been initialised from a 256-bit seed just prior to use then it could reduce the difficulty even further.
Aug 31	answered	Flaw in encryption through pseudorandom number stream (from gpg documentation)
Aug 31	comment	What is the difference between authenticity and non-repudiation Another example: OTR (cypherpunks.ca/otr) is designed specifically to provide authentication but no repudiation -- deniability is an explicit design goal.
Aug 31	comment	How would you store a 4 digit pin code securely in the database? Your analysis in para 1 seems to assume that an attacker who "gets a dump the database" has access to everything on the server which is used to verify the PIN. SQL injection and priv-escalation vulns are quite distinct (and its probably rare for SQL injection to be bad enough to provide a platform for OS-level priv escalation), which makes this untrue in general, I think.