Description
The current PSI implementation supports 2 operations:
- Get intersection elements.
- Get Intersection size.
In order to finish the PSI integration, we need:
On completion, it should be straightforward to integrate PIR in https://github.com/OpenMined/PSI
The current PSI flow:
1. Setup phase
The server encrypts all its elements x under a commutative encryption scheme, computing H(x)^s where s is its secret key. The encrypted elements are then inserted in a Bloom filter, which is sent to the client encoded as JSON. The message has the following form:
{
"num_hash_functions": <int>,
"bits": <string>
}
Here, bits is a Base64-encoded string.
2. Client request
The client encrypts all their elements x using the commutative encryption scheme, computing H(x)^c, where c is the client's secret key. The encoded elements are sent to the server as a JSON array of Base64 strings, together with a boolean reveal_intersection that indicates whether the client wants to learn the elements in the intersection or only its size.
{
"reveal_intersection": <bool>,
"encrypted_elements": [ Base64(H(x_1)^c), Base64(H(x_2)^c), ... ]
}
3. Server response
For each encrypted element H(x)^c received from the client, the server encrypts it again under the commutative encryption scheme with its secret key s, computing (H(x)^c)^s = H(x)^(cs). The result is sent back to the client as a JSON array of strings:
{
"encrypted_elements": [ Base64(H(x_1)^c), Base64(H(x_2)^c), ... ]
}
If reveal_intersection is false, the array is sorted to hide the order of entries from the client.
4. Client computes intersection
The client decrypts each element received from the server's response using its secret key c, computing (H(x)^(cs))^(1/c) = H(x)^s. It then checks if each element is present in the Bloom filter, and reports the number of matches as the intersection size.
Description
The current PSI implementation supports 2 operations:
In order to finish the PSI integration, we need:
On completion, it should be straightforward to integrate PIR in https://github.com/OpenMined/PSI
The current PSI flow:
1. Setup phase
The server encrypts all its elements x under a commutative encryption scheme, computing H(x)^s where s is its secret key. The encrypted elements are then inserted in a Bloom filter, which is sent to the client encoded as JSON. The message has the following form:
Here,
bitsis a Base64-encoded string.2. Client request
The client encrypts all their elements x using the commutative encryption scheme, computing H(x)^c, where c is the client's secret key. The encoded elements are sent to the server as a JSON array of Base64 strings, together with a boolean reveal_intersection that indicates whether the client wants to learn the elements in the intersection or only its size.
3. Server response
For each encrypted element H(x)^c received from the client, the server encrypts it again under the commutative encryption scheme with its secret key s, computing (H(x)^c)^s = H(x)^(cs). The result is sent back to the client as a JSON array of strings:
If reveal_intersection is false, the array is sorted to hide the order of entries from the client.
4. Client computes intersection
The client decrypts each element received from the server's response using its secret key c, computing (H(x)^(cs))^(1/c) = H(x)^s. It then checks if each element is present in the Bloom filter, and reports the number of matches as the intersection size.