How can this be extended to add more columns to sum?

[dougwatson]

Where in the code should I look to extend functionality to sum more than one column?

One value to sum:
"MbeI4RGJhnYcqk91Xap3NBhVtJ5vlxrn",610
"M9S1ih1nkN1EWDJG4V6e1a3MxkF9SESc",654
"pDrMne6gHAgdQVjlG0mihiHbf7qmbCpd",214

Two values to sum:
"MbeI4RGJhnYcqk91Xap3NBhVtJ5vlxrn",610,12
"M9S1ih1nkN1EWDJG4V6e1a3MxkF9SESc",654,41
"pDrMne6gHAgdQVjlG0mihiHbf7qmbCpd",214,321

[karnseth]

Hey Doug,
There's a couple of ways you could do this:

Currently the protocol sends along a single Paillier ciphertext that encrypts just one associated value. You could change this to allow multiple associated ciphertexts. This would involve changing EncryptedElement in match.proto to include multiple associated values. Additionally, you would have to change the server and client to populate the multiple fields, and also to homomorphically sum them.

The other way is to continue to use a single field, but to encode the two associated values as a single integer value. You could do this by reserving the higher order 32 bits as the first value and the lower order 32 bits as the second value. It's easy to implement this version by shifting and adding the two associated values together. You would have to be careful that the values don't overflow 32 bits after summing, though. Otherwise the lower order sum could corrupt the higher order sum or viceversa.