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[liberationtech] WeChat partners with the Guardian Project?!

Nathan of Guardian nathan at guardianproject.info
Fri Dec 13 09:01:07 PST 2013


In a strange bedfellows revelation, it turns out that WeChat (the
China-originated mobile messaging app) is using the SQLCipher for
Android software that the Guardian Project developed with Team Zetetic.
This makes WeChat more secure in terms of protecting local message
storage than any other mainstream messaging solution. While their
implementation isn't perfect, I still consider this a win for
open-source mobile security software.

Perhaps a WeChat developer heard my talk at Google IO about how insecure
their software was, and decided to show me up a bit..... next up, OTR
and proxy support? Or is it time to convince WhatsApp to step up to the
plate?

Thanks to CitizenLab (Asia Chats FTW!) and Emaze.com for bringing this
fascinating development to our attention.

***
https://guardianproject.info/2013/12/10/sqlcipher-has-300-million-mobile-users-thanks-to-wechat/

SQLCipher has 100M+ Mobile Users (Thanks to WeChat!)
Posted on 2013/12/10 by n8fr8
(Note: Originally this post had a title claiming 300 Million WeChat
users… that would have included iOS and Android, and we don’t know if
the WeChat iOS app also includes SQLCipher encryption or not. That said,
there are 50-100M Google Play downloads of WeChat for Android, which
does not include all of the users inside China)

Through some of our own recent sluething, Citizen Lab’s research into
“Asia Chats” security, and now via this detailed look at WeChat security
from Emaze.com, it has been recently discovered that WeChat for Android
uses SQLCipher for local data encryption in its app. We co-developed
SQLCipher for Android with Zetetic, and have been working to promote its
adoption among Android developers who need to protect data stored
locally on a device. While many people would point to Android’s Full
Disk Encryption feature as a solution for that, only a small percentage
of users ever enable it, and even then, once a device is unlocked, then
all data is accessible by someone looking to extract it. With SQLCipher,
the application can ensure its own data is encrypted, and if the app is
closed, then the data is secured.

Now, as with most things WeChat, the actually implementation of
SQLCipher is not that ideal, utilizing a short key, generated in part
from the device’s ID, and some sort of server provided token. Still, at
least they tried, and SQLCipher is considered stable enough to be used
for the over 300 million WeChat users around the world. Who knows,
though, maybe the devs are on our developer list or the SQLCipher list,
and we can help them improve their implementation using CacheWord!

The biggest irony of this, is that I gave a lightning talk at Google IO
2013, highlighting the concern I had with the rapid growth of WeChat,
and their parent company’s and country’s poor record on human rights,
free speech, and generally defending their users. With the growth of
WeChat beyond the borders of China, it is the first major mobile service
to be exported and adopted outside of the Great Firewall, by non-Chinese
users.

So, for now, I raise a toast to the Android developers at
Tencent/WeChat, who at least took a shot at providing local message
encryption in their app, and may they continue to endeavor to defend
their users privacy and security, as best as they can, considering their
circumstances.

More from the emaze-ing post below…

WeChat locally stores application data in an encrypted SQLite database
named “EnMicroMsg.db”. This database is located in the “MicroMsg”
subfolder inside the application’s data directory (typically something
like “/data/data/com.tencent.mm”).

The database is encrypted using SQLCipher, an open source extension for
SQLite that provides full database encryption. The encryption password
is derived from the “uin” parameter (see previous sections) combined
with the device identifier through a custom function. More precisely,
the key generation function leverages the mangle() function shown in the
previous Python snippet. The actual database encryption key can be
generated through the following pseudo-code:

password = mangle(deviceid + uin)[:7]

Here deviceid is the value returned by the Android API function
TelephonyManager.getDeviceId(). Follows a sample SQLCipher console
session that demonstrate how the EnMicroMsg.db database can be decrypted.

$ sqlcipher EnMicroMsg.db
sqlite> PRAGMA key = ‘b60c8e4′;
sqlite> PRAGMA cipher_use_hmac = OFF;
sqlite> .schema
CREATE TABLE conversation (unReadCount INTEGER, status INT, …
CREATE TABLE bottleconversation (unReadCount INTEGER, status INT, …
CREATE TABLE tcontact (username text PRIMARY KEY, extupdateseq long, …
…

It is also worth pointing out that, as the key generation algorithm
truncates the password to 7 hex characters, it would be not so difficult
for motivated attackers who are able to get the encrypted database to
brute force the key, even without knowing the uin or the device identifier.



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