nthcommunity 1.0.0

Example: Secure Intersection Size

A secure, privacy-preserving data collaboration begins when a recipient party is created. This party is responsible for defining the collaboration data workflow, distributing contribution keys to contributors, and performing the computation on the encrypted data contributions in concert with the nth.community service platform:

>>> from nthcommunity import *
>>> r = recipient()

Individual contributor objects encapsulate individual contributors. Two contributors are defined below:

>>> c_a = contributor()
>>> c_b = contributor()

Each contributor is assigned a unique identifier when the contributor object is created:

>>> c_a.identifier()
'57728767-55bf-4833-ab36-d3733a0e8448'

A collaboration is a tree-like data structure that defines how the overall result of a collaborative data workflow is computed. Every leaf node in the data structure must indicate which contributor must supply the encrypted data corresponding to that node. The internal, non-leaf nodes represent data operations such as count, intersection, and summation. The collaboration workflow defined below computes the size of the intersection between two tables (one from each contributor):

>>> w = count(intersection(table(contributor=c_a), table(contributor=c_b)))

The recipient can (by leveraging the nth.community service platform API) generate a dictionary that maps each of the contributor identifiers to their respective contribution key:

>>> id_to_key = r.generate(w)

Each of these individual keys id_to_key[c_a.identifier()] and id_to_key[c_b.identifier()] can be delivered to their corresponding contributor. Note that the collaboration class is derived from dict, making conversion to JSON straightforward (using either the built-in json library or the wrapper method used below):

>>> print(id_to_key[c_a.identifier()].to_json(indent=2))
{
  "type": "operation",
  "value": "count",
  "arguments": [
    {
      "type": "operation",
      "value": "intersection",
      "arguments": [
        {
          "type": "table",
          "contributor": {
            "type": "contributor",
            "identifier": "6a8dd844-6003-4475-aea7-b4182400bb90"
          },
          "public": "tdeJzrPIEpsFcykqnlN4M/hiP8gnNAJiSBRysLIutwo="
        }
      ]
    }
  ],
  "material": {
    "public": "F/RIe6jQ38Uk1CUdW7JKwd7Q9b+J+HlnOARSM70zERg=",
    "scalar": "A4f8MRxKsxZnKiScaJPw/O6uPzqBfREeNaPAaOdlnAU="
  },
  "certificate": "U4HFZcQ1hCplmec50gEDYnMxHn/ILclPmR6KC04uz1i5sJBwpEq0HB+tMlRPzWZu6dpPNuAjOzlIOshSgw7EXA=="
}

Each contributor can then encrypt their data contribution using their key:

>>> table_a = [['a'], ['b'], ['c'], ['d']]
>>> enc_a = c_a.encrypt(id_to_key[c_a.identifier()], table_a)
>>> table_b = [['b'], ['c'], ['d'], ['e']]
>>> enc_b = c_b.encrypt(id_to_key[c_b.identifier()], table_b)

As with contributor keys, encrypted contributions can be converted to and from JSON in a straightforward way:

>>> payload = enc_a.to_json(indent=2)
>>> print(payload)
{
  "type": "operation",
  "value": "count",
  "arguments": [
    {
      "type": "operation",
      "value": "intersection",
      "arguments": [
        {
          "type": "table",
          "contributor": {
            "type": "contributor",
            "identifier": "6a8dd844-6003-4475-aea7-b4182400bb90"
          },
          "public": "tdeJzrPIEpsFcykqnlN4M/hiP8gnNAJiSBRysLIutwo=",
          "value": [
            [
              "0Ch4F9+RVGu+e0dmK+ydFvOZSLld/xMk4xcXX8U2TGY5/CUiwCtPb0bM6nwJrbZPVBIAWa5tgVCGR2Tu8LdfalxDwpGqyNuWPcUtQP8T6P8=",
              "F1CZ5kRyYpEoZhlwTLu1gShLsH1HDZxQnQnypgDncyG+HGCrHn+UtKb9B4bvDaxbb8Nl92TV+U5ouE8MePbnFkslfwZyD6g5hWh4SOv1UhWl4uOuW4fSX8rnLsVg5VKc2Q=="
            ],
            [
              "4noLjc9aSpY1owBlSHv9IYZr6bvxkQUhhKOhV9Ty2kZTJP7UbXgSyxjsqEr1qbEWXQ1vP1uWS+JMN+rWqtpblcitqcg/epuPYWvJi6vr9vE=",
              "JC1L0t4JeVDr/+40c/JAsnpTqQUZLELZ5hJukDlX1Uxxf5MqZXglNc1aR9p+A5fvIZPj1P3YHOMS1Cbjpy1R3iZNUMsTOkn7pjhkZdkGE+XzHVRKz9TQdmkQZ2hk+13INQ=="
            ],
            [
              "TmQcw0iFgnnUofuJj4hhof6oqNp1iQ94E+jqNCdQT3i8kcL4D7I33lJdLyiUwAQHm1BE6SrU+ZS+jOrfle5mfY91PuuxFsB6UBlcc8MP+Do=",
              "puSkEfdRdNiIO668GG5jwV/zp84OhFN9rs5UjOoYNEUHif1BzrNDMq8huDJxFW8k78GbjMPZ/D4Yn5S3bjg/CwmGFPb99o4p7OwBYP1pGuds8smzUaVqcPt5FCCJxZWGYQ=="
            ],
            [
              "PcBEJUe6IjiJ5EKUBTfeebzlLo2s291sAEdi9UnSQ3O1yg+ttOVxQQNN2QVvc4V8Swj6J+FBbC+S3+av1yV/57yW88J8YJYBTLlK0awWYqw=",
              "ubwDp7Up8bRvznbOSmKlTDJ4MlC1JIz8zFaOHQIdfiCK1LPCKeyqIOaX/BPRbmNUkGQA9raLdsgUvWH9TQzGd3c7nvmbjltL9e4WWofM72+fBdj+/Dgg16+YAdEY6fXoog=="
            ]
          ]
        }
      ]
    }
  ]
}
>>> collaboration.from_json(payload) is not None
True

Once all the encrypted contributions are received, the recipient can (by again leveraging the nth.community service platform API) execute the workflow on the encrypted contributions to obtain a result:

>>> result = r.evaluate({c_a.identifier(): enc_a, c_b.identifier(): enc_b})
>>> result["value"]
3