Change measurement type of Prio3MultihotCountVec

draft-irtf-cfrg-vdaf.md

@@ -4156,18 +4156,18 @@ class Histogram(Valid[int, list[int], F]):
 | `PROOFS`          | `1`                                                                       |
 {: title="Parameters for Prio3MultihotCountVec."}
 
-For this instance of Prio3, each measurement is a vector of ones and zeros,
-where the number of ones is bounded. This provides a functionality similar to
-Prio3Histogram except that more than one entry (or none at all) may be
-non-zero. This allows Prio3MultihotCountVec to be composed with a randomized
-response mechanism, like {{EPK14}}, for providing differential privacy. (For
-example, each Client would set each entry to one with some small probability.)
+For this instance of Prio3, each measurement is a vector of true and false
+values, where the number of true values is bounded. This provides a
+functionality similar to Prio3Histogram except that more than one entry (or none
+at all) may be non-zero. This allows Prio3MultihotCountVec to be composed with a
+randomized response mechanism, like {{EPK14}}, for providing differential
+privacy. (For example, each Client would set each entry with some small
+probability.)
 
 The validity circuit is denoted `MultihotCountVec` and has three parameters:
-`length`, the number of entries in the count vector; `max_weight`, the
-maximum number of non-zero entries (i.e., the weight must be at most
-`max_weight`); and `chunk_length`, used the same way as in {{prio3sumvec}} and
-{{prio3histogram}}.
+`length`, the number of entries in the count vector; `max_weight`, the maximum
+number of true entries (i.e., the weight must be at most `max_weight`); and
+`chunk_length`, used the same way as in {{prio3sumvec}} and {{prio3histogram}}.
 
 Validation works as follows. Let
 
@@ -4185,7 +4185,7 @@ zero if and only if the reported weight is equal to the true weight. The
 complete circuit is defined below.
 
 ~~~ python
-class MultihotCountVec(Valid[list[int], list[int], F]):
+class MultihotCountVec(Valid[list[bool], list[int], F]):
     EVAL_OUTPUT_LEN = 2
     field: type[F]
 
@@ -4232,12 +4232,12 @@ class MultihotCountVec(Valid[list[int], list[int], F]):
         self.OUTPUT_LEN = self.length
         self.JOINT_RAND_LEN = self.GADGET_CALLS[0]
 
-    def encode(self, measurement: list[int]) -> list[F]:
+    def encode(self, measurement: list[bool]) -> list[F]:
         if len(measurement) != self.length:
             raise ValueError('invalid Client measurement length')
 
         # The first part is the vector of counters.
-        count_vec = list(map(self.field, measurement))
+        count_vec = [self.field(int(x)) for x in measurement]
 
         # The second part is the reported weight.
         weight_reported = sum(count_vec, self.field(0))

poc/gen_test_vec.py

@@ -212,15 +212,15 @@ def gen_test_vec_for_xof(cls: type[Xof]) -> None:
         vdaf_prio3.Prio3MultihotCountVec(2, 4, 2, 2),
         None,
         ctx,
-        [[0, 1, 1, 0]],
+        [[False, True, True, False]],
         0,
     )
     gen_test_vec_for_vdaf(
         vdaf_test_vec_path,
         vdaf_prio3.Prio3MultihotCountVec(4, 10, 2, 3),
         None,
         ctx,
-        [[0, 1, 0, 0, 0, 0, 0, 0, 0, 1]],
+        [[False, True, False, False, False, False, False, False, False, True]],
         1,
     )
     gen_test_vec_for_vdaf(
@@ -229,11 +229,11 @@ def gen_test_vec_for_xof(cls: type[Xof]) -> None:
         None,
         ctx,
         [
-            [0, 1, 1, 0],
-            [0, 0, 1, 0],
-            [0, 0, 0, 0],
-            [1, 1, 1, 0],
-            [1, 1, 1, 1],
+            [False, True, True, False],
+            [False, False, True, False],
+            [False, False, False, False],
+            [True, True, True, False],
+            [True, True, True, True],
         ],
         2,
     )

poc/tests/test_flp_bbcggi19.py

@@ -97,10 +97,10 @@ def test(self) -> None:
 
         # Successful cases:
         cases = [
-            (flp.encode([0, 0, 0, 0]), True),
-            (flp.encode([0, 1, 0, 0]), True),
-            (flp.encode([0, 1, 1, 0]), True),
-            (flp.encode([1, 1, 0, 0]), True),
+            (flp.encode([False, False, False, False]), True),
+            (flp.encode([False, True, False, False]), True),
+            (flp.encode([False, True, True, False]), True),
+            (flp.encode([True, True, False, False]), True),
         ]
         # Failure cases: too many number of 1s, should fail weight check.
         cases += [
@@ -114,15 +114,26 @@ def test(self) -> None:
             for i in range(valid.max_weight + 1, valid.length + 1)
         ]
         # Failure case: pass count check but fail bit check.
-        cases += [(flp.encode([flp.field.MODULUS - 1, 1, 0, 0]), False)]
+        cases += [
+            (
+                [
+                    flp.field(flp.field.MODULUS - 1),
+                    flp.field(1),
+                    flp.field(0),
+                    flp.field(0),
+                ]
+                + [flp.field(0)] * valid.bits_for_weight,
+                False
+            )
+        ]
         self.run_flp_test(flp, cases)
 
     def test_small(self) -> None:
         flp = FlpBBCGGI19(MultihotCountVec(Field128, 1, 1, 1))
 
         self.run_flp_test(flp, [
-            (flp.encode([0]), True),
-            (flp.encode([1]), True),
+            (flp.encode([False]), True),
+            (flp.encode([True]), True),
             ([flp.field(0), flp.field(1337)], False),
             ([flp.field(1), flp.field(0)], False),
         ])

poc/tests/test_vdaf_prio3.py

@@ -135,12 +135,30 @@ def test(self) -> None:
         # chunk_length = 2.
         prio3 = Prio3MultihotCountVec(2, 4, 2, 2)
         self.assertEqual(prio3.ID, 0x00000005)
-        self.run_vdaf_test(prio3, None, [[0, 0, 0, 0]], [0, 0, 0, 0])
-        self.run_vdaf_test(prio3, None, [[0, 1, 0, 0]], [0, 1, 0, 0])
-        self.run_vdaf_test(prio3, None, [[0, 1, 1, 0]], [0, 1, 1, 0])
         self.run_vdaf_test(
-            prio3, None, [[0, 1, 1, 0], [0, 1, 0, 1]], [0, 2, 1, 1])
-        self.run_vdaf_test(prio3, None, [[0, 1, 1, 0]], [0, 1, 1, 0])
+            prio3,
+            None,
+            [[False, False, False, False]],
+            [0, 0, 0, 0],
+        )
+        self.run_vdaf_test(
+            prio3,
+            None,
+            [[False, True, False, False]],
+            [0, 1, 0, 0],
+        )
+        self.run_vdaf_test(
+            prio3,
+            None,
+            [[False, True, True, False]],
+            [0, 1, 1, 0],
+        )
+        self.run_vdaf_test(
+            prio3,
+            None,
+            [[False, True, True, False], [False, True, False, True]],
+            [0, 2, 1, 1],
+        )
 
     def test_3_shares(self) -> None:
         # Prio3MultihotCountVec with length = 11, max_weight = 5,
@@ -149,7 +167,7 @@ def test_3_shares(self) -> None:
         self.run_vdaf_test(
             prio3,
             None,
-            [[1] * 5 + [0] * 6],
+            [[True] * 5 + [False] * 6],
             [1] * 5 + [0] * 6,
         )
 

poc/vdaf_poc/flp_bbcggi19.py

@@ -738,12 +738,12 @@ def test_vec_set_type_param(self, test_vec: dict[str, Any]) -> list[str]:
 # NOTE: This class is excerpted in the document. Its width should be
 # limited to 69 columns to avoid warnings from xml2rfc.
 # ===================================================================
-class MultihotCountVec(Valid[list[int], list[int], F]):
+class MultihotCountVec(Valid[list[bool], list[int], F]):
     # REMOVE ME
     """
     A validity circuit that checks each Client's measurement is a bit
-    vector with at most `max_weight` number of 1s. We call the number
-    of 1s in the vector the vector's "weight".
+    vector with at most `max_weight` number of true values. We call
+    the number of true values in the vector the vector's "weight".
 
     The circuit determines whether the weight of the vector is at most
     `max_weight` as follows. First, it computes the weight of the
@@ -818,12 +818,12 @@ def __init__(self,
         self.OUTPUT_LEN = self.length
         self.JOINT_RAND_LEN = self.GADGET_CALLS[0]
 
-    def encode(self, measurement: list[int]) -> list[F]:
+    def encode(self, measurement: list[bool]) -> list[F]:
         if len(measurement) != self.length:
             raise ValueError('invalid Client measurement length')
 
         # The first part is the vector of counters.
-        count_vec = list(map(self.field, measurement))
+        count_vec = [self.field(int(x)) for x in measurement]
 
         # The second part is the reported weight.
         weight_reported = sum(count_vec, self.field(0))

poc/vdaf_poc/vdaf_prio3.py

@@ -653,7 +653,7 @@ def __init__(
         )
 
 
-class Prio3MultihotCountVec(Prio3[list[int], list[int], Field128]):
+class Prio3MultihotCountVec(Prio3[list[bool], list[int], Field128]):
     ID = 0x00000005
     xof = XofTurboShake128
     VERIFY_KEY_SIZE = xof.SEED_SIZE

test_vec/vdaf/Prio3MultihotCountVec_0.json

@@ -21,10 +21,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                0,
-                1,
-                1,
-                0
+                false,
+                true,
+                true,
+                false
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [

test_vec/vdaf/Prio3MultihotCountVec_1.json

@@ -31,16 +31,16 @@
                 "808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
             ],
             "measurement": [
-                0,
-                1,
-                0,
-                0,
-                0,
-                0,
-                0,
-                0,
-                0,
-                1
+                false,
+                true,
+                false,
+                false,
+                false,
+                false,
+                false,
+                false,
+                false,
+                true
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [

test_vec/vdaf/Prio3MultihotCountVec_2.json

@@ -21,10 +21,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                0,
-                1,
-                1,
-                0
+                false,
+                true,
+                true,
+                false
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [
@@ -59,10 +59,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                0,
-                0,
-                1,
-                0
+                false,
+                false,
+                true,
+                false
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [
@@ -97,10 +97,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                0,
-                0,
-                0,
-                0
+                false,
+                false,
+                false,
+                false
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [
@@ -135,10 +135,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                1,
-                1,
-                1,
-                0
+                true,
+                true,
+                true,
+                false
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [
@@ -173,10 +173,10 @@
                 "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"
             ],
             "measurement": [
-                1,
-                1,
-                1,
-                1
+                true,
+                true,
+                true,
+                true
             ],
             "nonce": "000102030405060708090a0b0c0d0e0f",
             "out_shares": [