Building Searchable Encrypted Databases with PHP and SQL
1–10 of 33 posts
Re: Building Searchable Encrypted Databases with PHP and SQL
#2I know this is a I'm going quest and for that reason it annoys me when i see my companies competitors say they encrypt all their users searchable data and I know what they are really doing is using Amazon disk level encryption that's not really helpful if your live database gets dumped.
Re: Building Searchable Encrypted Databases with PHP and SQL
#3Why not just use AES-SIV instead of separate encrypted and HMAC fields?
Re: Building Searchable Encrypted Databases with PHP and SQL
#4Why not just use AES-SIV instead of separate encrypted and HMAC fields?
The practical reason: https://3v4l.org/LEar1 (No SIV in that list.) It's also not present in libsodium or (shudder) mcrypt.
What property are you hoping to extract out of AES-SIV in particular? (And would AEZ, HS1-SIV, AES-SIV-GCM, etc. solve your problem?)
From what I understand, SIV mode still uses a nonce, but it doesn't explode if you reuse it for different messages. Are you aiming for nonce-less encryption?
The end goal that was being worked towards in the article (Argon2-derived Bloom filters for partial searching) is a little more useful than nonce-less encryption.
Re: Building Searchable Encrypted Databases with PHP and SQL
#5I disagree with the dishonorable mention as you've only considered the naive case which you can build upon to avoid the issues mentioned. Consider a design where everything is AES-256 encrypted in the application and the database just receives an encrypted binary. You can build an in-memory cache for situations where you need to search sensitive information (first name, last name, ssn) by using a tokenizer and using a technology like Erlang term storage. It will be eventually consistent which should be fine for our use case since that type of information does not change that often and the cache recompute can be done asynchronously.
From a security standpoint you don't change the threat model for the application. If someone gets unauthorized access to the server you are already screwed since your application can get access to the plain text data in order to serve requests.
If you threw away that computation for every request I would agree that it is wasteful but we don't need to do that if we rethink the role of the database in our application.
Re: Building Searchable Encrypted Databases with PHP and SQL
#6I disagree with the dishonorable mention as you've only considered the naive case which you can build upon to avoid the issues mentioned. Consider a design where everything is AES-256 encrypted in the application and the database just receives an encrypted binary. You can build an in-memory cache for situations where you need to search sensitive information (first name, last name, ssn) by using a tokenizer and using…
> I disagree with the dishonorable mention as you've only considered the naive case which you can build upon to avoid the issues mentioned. Consider a design where everything is AES-256 encrypted in the application and the database just receives an encrypted binary. You can build an in-memory cache for situations where you need to search sensitive information (first name, last name, ssn) by using a tokenizer and using a technology like Erlang term storage. It will be eventually consistent which should be fine for our use case since that type of information does not change that often and the cache recompute can be done asynchronously.
https://tonyarcieri.com/all-the-crypto-code-youve-ever-writt...
https://blog.filippo.io/the-ecb-penguin/
There are defensible positions for which ECB mode is acceptable. I wouldn't classify the scenario you described as one of them.
> If someone gets unauthorized access to the server you are already screwed since your application can get access to the plain text data in order to serve requests.
If someone gets unauthorized access to the webserver, yes, it's game over.
If someone gets unauthorized access to the database server, and it's a separate machine from the webserver, then your analysis here isn't applicable.
That's the threat model alluded to in the beginning of the article, but if it's not your threat model, then you may reach different conclusions about the best way to protect data. (You may not even use encryption, for example.)
Re: Building Searchable Encrypted Databases with PHP and SQL
#7Why not just use AES-SIV instead of separate encrypted and HMAC fields?
The practical reason: https://3v4l.org/LEar1 (No SIV in that list.) It's also not present in libsodium or ( shudder ) mcrypt. What property are you hoping to extract out of AES-SIV in particular? (And would AEZ, HS1-SIV, AES-SIV-GCM, etc. solve your problem?) From what I understand, SIV mode still uses a nonce, but it doesn't explode if you reuse it for different messages. Are you aiming for nonce-less encryption? Th…
I was specifically after a deterministic encryption scheme that would allow for exact-match comparisons and whose deployment was fairly foolproof (so a non-expert couldn't screw it up too badly), which AES-SIV appears to provide nicely. Another benefit in my case is that I'm using a NoSQL database where separating the encrypted value from its indexed value is not always practical, so having a single value that serves both purposes is highly desirable.
I'm not familiar with the other schemes you mentioned, but the practical reason for using AES-SIV is the converse of yours for not using it: there's an implementation for JavaScript. :) It's unlikely there are implementations for the other schemes you listed.
I agree that the Bloom filters are a nice natural outcome of your approach, though it would also be possible to combine AES-SIV for primary encryption with a truncated HMAC for partial match Bloom filters.
Re: Building Searchable Encrypted Databases with PHP and SQL
#8Earlier quoted context omitted.
The practical reason: https://3v4l.org/LEar1 (No SIV in that list.) It's also not present in libsodium or ( shudder ) mcrypt. What property are you hoping to extract out of AES-SIV in particular? (And would AEZ, HS1-SIV, AES-SIV-GCM, etc. solve your problem?) From what I understand, SIV mode still uses a nonce, but it doesn't explode if you reuse it for different messages. Are you aiming for nonce-less encryption? Th…
I was specifically after a deterministic encryption scheme that would allow for exact-match comparisons and whose deployment was fairly foolproof (so a non-expert couldn't screw it up too badly), which AES-SIV appears to provide nicely. Another benefit in my case is that I'm using a NoSQL database where separating the encrypted value from its indexed value is not always practical, so having a single value that serves…
Here's the killer feature of my approach: Each filter has its own HMAC/Argon2 key, so it becomes less useful for what I like to call crossword puzzle attacks. (I hope that's easier to understand than a wordy explanation of how such an attack would work.)
Re: Building Searchable Encrypted Databases with PHP and SQL
#9If I understand this correctly, you basically store HMAC or password hash as a separate field and index on it? That may work for SSNs (which are unique), but it won't work for other things you commonly need to encrypt, such as personally identifiable data (in healthcare scenarios).
If you (for example) encrypt first names of people (or any other data point that is not unique per entry) using this scheme, then HMAC will reveal all the rows that have the same first name. You can then use frequency analysis to determine with high probablity what the encrypted names are.
Re: Building Searchable Encrypted Databases with PHP and SQL
#10How is this different than CryptDB?