Security & convenience

Last week I needed to change my defective French SIM card, from Free (who as an aside are an awesome ISP and equally good mobile provider). I happened to be in Paris so I decided to go to the Free shop, as I thought it’d be easier then getting a new SIM card send to my address on file (my parent’s address in France) given I now live in the UK.

When I got to the counter, I was met by a friendly enough Free guy (let’s call him A.) who told me it was no problem, I just needed my Free login and password and we’d be on our way. Cool! Adhering to password Best Practice™, I store all my credentials in Lastpass, so I just had to login into Lastpass to get my stuff and go.

Now, being also mindful that having one big repo of passwords is valuable and high-risk, I have 2FA on this account with a Yubikey, so I can’t access it from e.g. my phone.

I didn’t have my laptop on me, but my fiancé did, so we tried to use hers to access Lastpass, tethered to her phone. Being secure and all, Lastpass realised this attempt came from a “new location” and asked me to confirm it was me by sending a code by email. Email which I couldn’t access from my phone, because, hey, SIM card’s broken.

Now thankfully, I keep my email password separate from Lastpass and do remember it, so I could just log into Gmail on the laptop and get that code!

But email is also a very valuable target, the backdoor to your systems used by password recovery mechanisms, so I have 2FA there as well! Instead of my Yubikey, I use Google Authenticator to provide TOTP (more factors, more good, right?). TOTP which sadly failed mysteriously — I realised later on that removing the battery to take the SIM card out had reset the date and time to factory settings, which breaks the Time in Time-based One-Time Password.

Thankfully, at this point A. took pity of me and told me he shouldn’t, but he could let me use the employee wifi to get the email from my phone (already authenticated = no 2FA), which could get the lastpass code, which could get the Free credentials. Success! My random 30-chars password was finally here.

When seeing the password, A. went a bit blank. “Oh… You’ve changed it”, he said – well yes, why? Because this password needs to be entered through a clunky touch-based interface on the kiosk. Five minutes and three tries later, and my new SIM card was finally here.

Next time, I’ll do it online.

OVH: Database quota exceeded

OVH emailed me a few weeks back telling me that my shared database for the plan that powers was approaching its (huge!) quota of 25MB, and then again last week to tell me that this time, the quota was reached.

Once you reach the quota, the DB is placed in read-only mode, although SQL `DELETE` commands do go through correctly, as we’ll see later.

So my first instinct was to see what was wrong, by going into the PhpMyAdmin that OVH gives to each shared DB owner. It confirmed that the database was too big, mainly because of two tables: the main culprit at 9MB was wp_comments, the comments on this blog, and the second one at 5MB was its related sibling wp_commentmeta. The root cause being, of course, spam: all these comments were properly intercepted and classified as spam by Akismet, but as long as I didn’t purge them, they were still taking valuable disk space.

So I thought I could just delete the comments that Akismet marked as spam (as that info is available directly in the table) and go on with my day, but unfortunately no – the deletion went through, but the table was still marked as being 9MB, including about 7MB of “overhead“. How do we reclaim this overhead? By running OPTIMIZE TABLE… Which we cannot do as we’re in read-only mode.

At this point, I took a dump of the database, and deleted it through the OVH admin interface, recreated a new database and reimported that dump: solved! The new DB clocked at about 14MB, enough for the foreseeable future.

Lesson learned: clean your spam.

(PS: in the few days that passed between the db clean and me writing this article, I got another 355 spam comments. Yay.)

“They use some weird padding…”

A few days ago, a colleague was telling me about a project where she needs to implement a crypto scheme from an external vendor in order to talk to their API over HTTP. For complicated (and probably wrong) reasons, they decided to eschew TLS and develop their own system instead, relying on DES –not even triple DES! Basic DES, the one from the ’70s that is horribly insecure today– and RC4, which isn’t great either.

The whole scheme was bad, but my colleague added “and they also use that strange padding scheme – because the plaintext length needs to be a multiple of 8 bytes, at the end of every message, they put seven “Bell” characters!”.

The bell character? That’s odd. I mean, it’s in ASCII, and not usually part of any plaintext, so it’s probably safe to use as padding, but… Wait a second – padding with strange characters, all the same? That rings a bell!

And indeed it does – it’s PKCS#7!

PKCS#7 is meant to pad a message until it reaches the next block boundary, to use with block ciphers. It works by appending n characters of ASCII value 0xn, and of course the ASCII codepoint of the bell character is 0x07!

“Oh, that explains a lot. Now I won’t have to add blank spaces until it reaches (x mod 8) + 1 bytes and pad with bell characters”, my colleague said. I guess that’s the danger when you’re given a bad scheme to implement: it’s harder to realise when they actually do something right.

(Hat’s up to the Matasano crypto challenges: despite doing only level 1 and 2 if the memory serves –it was a while back–, they’re super useful for these sort of cryptography basics.) is back!

So, had been in a pretty sorry state for a couple of months now, and I kept thinking I should go have a look into it and get to the bottom of the issue.

And the bottom of the issue was the 6000 spam emails sitting in the inbox, making the server crash at startup.

They’re now deleted, and everything is back up and happy. I’m currently thinking about different monitoring options, but given it’s all email-based, no solution that I know of seem overly practical to me. Any idea would be appreciated. :)

Large-scale, automated whimsy — A journey into blog spam

As you may have noticed if you write a blog, however modest it might be (such as yours truly), you’ll receive spam comments. A lot. Things like that:

spam 1


Spam like this is usually obvious. Thankfully, some spammers go out of their ways to create engaging messages to fool your filters, both automated (like Akismet, who dutifully collected all the ones exposed in this post) and human. I’ve been collecting the best of breed (I know, I live a very sheltered life), such as…


The Ones Sucking Up


Aaaah, the day-to-day of spam. “Magnificent”, nothing less!



“Famous”! Money! Girls! Bling! Bring it on!




“Amazing”, yay! Although I hope you realized you are trying to advertise train horns on a tech blog. Train horns.


The Confused Identities


Why thank you, Sabine — I mean Dave. Hmm, wait.


The Sarcastic


The colors on this post are amazing? Are you on drugs?


great risk


Ah, yes. Writing about SICP almost got me killed by M.I.T.’s own Secret Service. As a matter of fact, I’m hiding in Kazakhstan right now.

(On a serious note, I emailed Hal Abelson about a typo in the online version of SICP and received a very nice answer by him personally the very next day — hats off to you, sir!)


The Keyword Bingo

keywordbingoGotta unlock ’em all!


The Compliment That Wasn’t


This starts well… Grow, trendy, extremely amazing, attractive… Yeah, classical spam. But at closer look, this is actually a poorly translated troll insinuating that my post is unworthy. Darn!


The Cringe-Worthy


It is very telling whether you consider “incite full” or the concept of high-waist shorts to be the worst part of this spam. I can’t really pick, they’re both frightening.


The Big-In-Japan

A slight variation on plain sucking up is doing so in different languages.




Google translating that last one gives:

Hello interesting post, I liked a lot, maybe we could become blog palls:) lol!
Aside from the jokes call me Navid and look like you publish on the Internet although the theme of my room … this is very different.
I study the pages on poker free bonus without risking your cash … …
Greatly enjoyed what I saw written on this second visit
I shall return:)
Ps: I have a bad Portuguese

Thumbs up for the politeness and the disclaimer at the end. That’s top quality spam. Not so much to say for the reading skills though, because I don’t remember discussing online poker strategies together with ncurses.


The Philosopher


Wow! That turns out to be an (unsourced) citation of the late John Enoch Powell, a conservative English MP who’s also quoted as saying “reading one’s diary is like returning to one’s own vomit”, which may or may not be a more appropriate metaphor for blogs. And spam. Oh well.


The Prescient


Apart from the fact that they fscked up the URL bbtag — HOW DO THEY KNOW ABOUT MY SECRET PASSION!?

pity the lolcatpity the lolcat, by tizzie on flickr


What were your best ones?