Longfellow ZK 0290cb32

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bogorng.h
1// Copyright 2025 Google LLC.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#ifndef PRIVACY_PROOFS_ZK_LIB_ALGEBRA_BOGORNG_H_
16#define PRIVACY_PROOFS_ZK_LIB_ALGEBRA_BOGORNG_H_
17
18 namespace proofs {
19// Totally bogus "random" number generator, used only for testing.
20// There is no guarantee that it will cycle over all elements in the
21// field, but this keeps dependencies internal to this directory.
22// The public and internal functions of this class all take a const Field&
23// parameter to produce random elements in the Field. It is the caller's
24// responsibility to ensure the object remains valid during execution.
25 template <class Field>
26 class Bogorng {
27 using Elt = typename Field::Elt;
28
29 public:
30 explicit Bogorng(const Field* F)
31 : f_(F), next_(F->of_scalar_field(123456789u)) {}
32
33 Elt next() {
34 // really old-school
35 f_->mul(next_, f_->of_scalar_field(1103515245u));
36 f_->add(next_, f_->of_scalar_field(12345u));
37 return next_;
38 }
39
40 Elt nonzero() {
41 Elt x;
42 do {
43 x = next();
44 } while (x == f_->zero());
45 return x;
46 }
47
48 private:
49 const Field* f_;
50 Elt next_;
51};
52} // namespace proofs
53
54#endif // PRIVACY_PROOFS_ZK_LIB_ALGEBRA_BOGORNG_H_
proofs::GF2_128::Elt
Definition gf2_128.h:63