143 reputation
4
bio website blog.physionconsulting.com
location Boston, MA
age 34
visits member for 2 years, 9 months
seen Jan 19 at 21:34

Founder and CEO of Physion


Dec
28
comment What are the practical differences between 256-bit, 192-bit, and 128-bit AES encryption?
Awesome answer. As a "user" (not a professional cryptographer), it's awesome to get more details on the algorithms I'm using everyday. Thanks, Paŭlo.
Dec
28
comment Can I determine if a user has the wrong symmetric encryption key?
Great suggestion. We do control key generation and using a checksum sounds like a great idea.
Dec
21
awarded  Scholar
Dec
21
accepted Can I determine if a user has the wrong symmetric encryption key?
Dec
21
comment Can I determine if a user has the wrong symmetric encryption key?
great comments. We do use PKCS5/PBKDF2 to generate a key + IV from the users' secret key and a salt derived from the record ID. You (and @poncho) are definitely right that we're limited by the data size restriction, and we just have to accept that we can't authenticate the data...
Dec
21
comment Can I determine if a user has the wrong symmetric encryption key?
Great comments. Unfortunately, the core dump bubbles up from the database engine (which, I agree, should have better error handling). I'm trying to mitigate the otherwise disastrous UX. We do use an IV, derived (along with the encryption key) via PKCS5 from the password and a salt calculated from the record ID. The salt is not random, but is unique per record. The major issue—brought up by your last point—is that we can't do authenticated encryption (i.e. using a MAC). Doing so would let us authenticate the data, as well as detect decryption errors. Sigh.
Dec
19
awarded  Supporter
Dec
19
comment Can I determine if a user has the wrong symmetric encryption key?
Unfortunately, no. The Objectivity/DB storage manager + encryption system doesn't allow us to append any data to MSG. We get exactly size(MSG) bytes for our encrypted data.
Dec
19
awarded  Student
Dec
19
awarded  Autobiographer
Dec
19
asked Can I determine if a user has the wrong symmetric encryption key?