{"id":591,"date":"2022-03-18T01:27:54","date_gmt":"2022-03-17T16:27:54","guid":{"rendered":"https:\/\/derrylab.com\/?p=591"},"modified":"2022-03-18T01:27:54","modified_gmt":"2022-03-17T16:27:54","slug":"now-i-understand-what-is-oblivious-ram","status":"publish","type":"post","link":"https:\/\/blog.derrylab.com\/index.php\/2022\/03\/18\/now-i-understand-what-is-oblivious-ram\/","title":{"rendered":"Now I Understand: What is Oblivious RAM?"},"content":{"rendered":"\n

ORAM is the acronym of an Oblivious Random-Access Machine.<\/p>\n\n\n\n

The main idea is to hide the access patterns from attackers.<\/p>\n\n\n\n

For example, when a client tries to access data stored in the server, the server cannot gain any information about the user access pattern.<\/p>\n\n\n\n

Imagine data storage, where each data is inside a block, and that block is inside a node (or bucket.)<\/p>\n\n\n\n

Each node (or bucket) may have multiple blocks inside or even none.<\/p>\n\n\n\n

\"\"
ORAM Storage Structure <\/figcaption><\/figure>\n\n\n\n\n\n\n\n

Now to access a block, there is a path.<\/p>\n\n\n\n

And the client (who wants to access it) has a map for it, called Position Map.<\/p>\n\n\n\n

The position map has information about the block’s position. Each block has its block’s position information.<\/p>\n\n\n\n

So when a client wants to access, say block 7, then it will look into the position map where is the location of block 7.<\/p>\n\n\n\n

Then how does it traverse the path? There are two principles.<\/p>\n\n\n\n