6 ms·

What would you use this for?

by pogue 2y ago

77pt77 2y ago
Compressing images into jpeg without anyone else ever seeing them. I personally would prefer something like Homomorphic encryption for say sql queries on a database that the server can never read.
- tgv 2y ago
  There's no information in the repo, but I suppose this means jpeg compression of an encrypted image without decryption, right?
  - mystified5016 2y ago
    Yes. Homomorphic encryption means that you can do math to the encrypted file to produce a new encrypted file. The operator doing the math cannot read either version, but the owner of the original file can.
- pogue 2y ago
  Without anyone ever seeing them?
- hot_gril 2y ago
  About the encrypted DB: https://people.csail.mit.edu/nickolai/papers/popa-cryptdb-tr.pdf https://people.csail.mit.edu/nickolai/papers/popa-cryptdb-tr... All I remember is that this didn't end up becoming practical because of some limitations, which were maybe discussed in the paper. Something about leaking row counts.
- dzidol 2y ago
  There's such thing, at least in prototype stage. Like cryptDB, which, afaik is homomorphic with a nice property of preserving the order of encrypted keys. It leaks some information, but you can apply predicates different than equality, like `where a between 100 and 200`. In that case, the query passed to server will look like `where a between encrypted(100) and encrypted(200)` and server will be able to apply it, without knowing real values of the range limits or data stored in `a` column. With encryption function which don't preserve order, the data would need to be filtered client-side, so whole projection would be dumped to client and it would be the client who first decrypts the data, and then filters-out unnecessary rows.
perching_aix 2y ago
As a technological demonstration of homomorphic encryption and its benefit.
- cogman10 2y ago
  I'm having a hard time wrapping my head around how you'd do homomorphic encryption securely (particularly FHE). Like, for example, let's say I want to farm out word counts to the cloud. Wouldn't the information required to identify what a "word" is require the running software to be able to see breaks/periods/etc? Doesn't that leak information about the cyphertext? How does it stop someone from writing software that, for example, maps out the position of all the a's, then b's, then c's, etc in a cyphertext and MITMing it?
  - perching_aix 2y ago
    I think the idea is that you would never get to know the answer to those individual questions, or any questions really; you'd be producing an encrypted blob of a response that supposedly has the answer and then just pass that onward. Unfortunately the mathematical details escape me as well. Maybe one day I'll set aside some time to look into it.
  - fragmede 2y ago
    That wouldn't be FHE, for the reason you identified. Outside of a tiny number of algorithms, homomorphic encryption doesn't usefully generalize to something as generic as word counting of arbitrary text like that. Production use of FHE is really limited. Probably the most well known application is by Apple for phone number lookup, where they're able to get the caller id for a phone number without knowing the phone number, basically.
  - uniq7 2y ago
    I have only read Craig Gentry, 2009 [1] (the first proposed FHE scheme), but the main idea is that an untrusted agent can perform operations on the encrypted data (i.e., addition and multiplication) and obtain an encrypted result. The untrusted agent cannot understand the result, but they can send it to the user, and the user can decrypt it. Since the scheme is asymmetric, the untrusted agent can also encrypt new data with the public key, meaning that they can do things like: `return encrypt(x) + encrypted_data_from_user * encrypt(y)` This alone doesn't let the untrusted agent evaluate a boolean condition or run an algorithm like the one you proposed, but they can at least run encrypted data through a neural network and send the encrypted output to the user. [1] https://www.cs.cmu.edu/~odonnell/hits09/gentry-homomorphic-encryption.pdf https://www.cs.cmu.edu/~odonnell/hits09/gentry-homomorphic-e...

What would you use this for?

by pogue 2y ago

What would you use this for?

Compressing images into jpeg without anyone else ever seeing them. I personally would prefer something like Homomorphic encryption for say sql queries on a database that the server can never read.

tgv 2y ago
There's no information in the repo, but I suppose this means jpeg compression of an encrypted image without decryption, right?
- mystified5016 2y ago
  Yes. Homomorphic encryption means that you can do math to the encrypted file to produce a new encrypted file. The operator doing the math cannot read either version, but the owner of the original file can.
pogue 2y ago
Without anyone ever seeing them?
hot_gril 2y ago
About the encrypted DB: https://people.csail.mit.edu/nickolai/papers/popa-cryptdb-tr.pdf https://people.csail.mit.edu/nickolai/papers/popa-cryptdb-tr... All I remember is that this didn't end up becoming practical because of some limitations, which were maybe discussed in the paper. Something about leaking row counts.
dzidol 2y ago
There's such thing, at least in prototype stage. Like cryptDB, which, afaik is homomorphic with a nice property of preserving the order of encrypted keys. It leaks some information, but you can apply predicates different than equality, like `where a between 100 and 200`. In that case, the query passed to server will look like `where a between encrypted(100) and encrypted(200)` and server will be able to apply it, without knowing real values of the range limits or data stored in `a` column. With encryption function which don't preserve order, the data would need to be filtered client-side, so whole projection would be dumped to client and it would be the client who first decrypts the data, and then filters-out unnecessary rows.

perching_aix 2y ago

As a technological demonstration of homomorphic encryption and its benefit.

cogman10 2y ago
I'm having a hard time wrapping my head around how you'd do homomorphic encryption securely (particularly FHE). Like, for example, let's say I want to farm out word counts to the cloud. Wouldn't the information required to identify what a "word" is require the running software to be able to see breaks/periods/etc? Doesn't that leak information about the cyphertext? How does it stop someone from writing software that, for example, maps out the position of all the a's, then b's, then c's, etc in a cyphertext and MITMing it?
- perching_aix 2y ago
  I think the idea is that you would never get to know the answer to those individual questions, or any questions really; you'd be producing an encrypted blob of a response that supposedly has the answer and then just pass that onward. Unfortunately the mathematical details escape me as well. Maybe one day I'll set aside some time to look into it.
- fragmede 2y ago
  That wouldn't be FHE, for the reason you identified. Outside of a tiny number of algorithms, homomorphic encryption doesn't usefully generalize to something as generic as word counting of arbitrary text like that. Production use of FHE is really limited. Probably the most well known application is by Apple for phone number lookup, where they're able to get the caller id for a phone number without knowing the phone number, basically.
- uniq7 2y ago
  I have only read Craig Gentry, 2009 [1] (the first proposed FHE scheme), but the main idea is that an untrusted agent can perform operations on the encrypted data (i.e., addition and multiplication) and obtain an encrypted result. The untrusted agent cannot understand the result, but they can send it to the user, and the user can decrypt it. Since the scheme is asymmetric, the untrusted agent can also encrypt new data with the public key, meaning that they can do things like: `return encrypt(x) + encrypted_data_from_user * encrypt(y)` This alone doesn't let the untrusted agent evaluate a boolean condition or run an algorithm like the one you proposed, but they can at least run encrypted data through a neural network and send the encrypted output to the user. [1] https://www.cs.cmu.edu/~odonnell/hits09/gentry-homomorphic-encryption.pdf https://www.cs.cmu.edu/~odonnell/hits09/gentry-homomorphic-e...