Encrypted But Searchable Online Storage?

An anonymous reader asks "Is there a solution for online storage of encrypted data providing encrypted search and similar functions over the encrypted data? Is there an API/software/solution or even some online storage company providing this? I don't like Google understanding all my unencrypted data, but I like that Google can search them when they are unencrypted. So I would like to have both: the online storage provider does not understand my data, but he can still help me with searching in them, and doing other useful stuff. I mean: I send to the remote server encrypted data and later an encrypted query (the server cannot decipher them), and the server sends me back a chunk of my encrypted data stored there — the result of my encrypted query. Or I ask for the directory structure of my encrypted data (somehow stored in my data too — like in a tar archive), and the server sends it back, without knowing that this encrypted chunk is the directory structure. I googled for this and found some papers, however no software and no online service providing this yet." Can anyone point to an available implementation?

Comments

Re:It's not possible even in theory

[TheRaven64]

It is possible. When you upload the data, you also upload an index. When you connect again, you download the index (which is much smaller than the data) and search that on the local machine. Neither the index, nor the data, is ever unencrypted on the server.

As for frequency analysis, I don't think any encryption algorithms published in the last 40 years have been vulnerable to this sort of attack...