From 6ed5592d22e31054b2bc8dfa92d827251ff8237f Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Sat, 14 Jan 2023 02:59:43 -0500
Subject: [PATCH] Stub code for #222

---
 Cargo.lock                          |  7 ++++
 Cargo.toml                          |  1 +
 crypto/dynamic-generator/Cargo.toml | 16 ++++++++
 crypto/dynamic-generator/LICENSE    | 21 ++++++++++
 crypto/dynamic-generator/src/lib.rs | 62 +++++++++++++++++++++++++++++
 5 files changed, 107 insertions(+)
 create mode 100644 crypto/dynamic-generator/Cargo.toml
 create mode 100644 crypto/dynamic-generator/LICENSE
 create mode 100644 crypto/dynamic-generator/src/lib.rs

diff --git a/Cargo.lock b/Cargo.lock
index 16bdcacb..683212f2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1707,6 +1707,13 @@ version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c9b0705efd4599c15a38151f4721f7bc388306f61084d3bfd50bd07fbca5cb60"
 
+[[package]]
+name = "dynamic-generator"
+version = "0.1.0"
+dependencies = [
+ "group",
+]
+
 [[package]]
 name = "ecdsa"
 version = "0.14.8"
diff --git a/Cargo.toml b/Cargo.toml
index 7cdec0c1..75616bd2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,6 +7,7 @@ members = [
   "crypto/ff-group-tests",
   "crypto/dalek-ff-group",
   "crypto/ed448",
+  "crypto/dynamic-generator",
   "crypto/ciphersuite",
 
   "crypto/multiexp",
diff --git a/crypto/dynamic-generator/Cargo.toml b/crypto/dynamic-generator/Cargo.toml
new file mode 100644
index 00000000..27884ba0
--- /dev/null
+++ b/crypto/dynamic-generator/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "dynamic-generator"
+version = "0.1.0"
+description = "Provide dynamic generators for curves implementing the Group API"
+license = "MIT"
+repository = "https://github.com/serai-dex/serai/tree/develop/crypto/custom-generator"
+authors = ["Luke Parker <lukeparker5132@gmail.com>"]
+keywords = ["ff", "group", "generator"]
+edition = "2021"
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[dependencies]
+group = "0.12"
diff --git a/crypto/dynamic-generator/LICENSE b/crypto/dynamic-generator/LICENSE
new file mode 100644
index 00000000..e6bff13c
--- /dev/null
+++ b/crypto/dynamic-generator/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Luke Parker
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/crypto/dynamic-generator/src/lib.rs b/crypto/dynamic-generator/src/lib.rs
new file mode 100644
index 00000000..3e7fad4f
--- /dev/null
+++ b/crypto/dynamic-generator/src/lib.rs
@@ -0,0 +1,62 @@
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+
+use core::any::{TypeId, Any};
+
+use std::{
+  thread::{self, ThreadId},
+  sync::RwLock,
+  collections::HashMap,
+};
+
+use group::Group;
+
+type Stack = Option<HashMap<ThreadId, HashMap<TypeId, Vec<Box<dyn Any>>>>>;
+static mut GENERATORS: RwLock<Stack> = RwLock::new(None);
+
+fn stack<G: Group>(map: &mut Stack) -> &mut Vec<Box<dyn Any>> {
+  map
+    .get_or_insert_with(HashMap::new)
+    .entry(thread::current().id())
+    .or_insert(HashMap::new())
+    .entry(TypeId::of::<G>())
+    .or_insert(Vec::new())
+}
+
+#[doc(hidden)]
+pub fn push<G: Group>(generator: G) {
+  stack::<G>(&mut unsafe { GENERATORS.write() }.unwrap()).push(Box::new(generator));
+}
+
+#[doc(hidden)]
+pub fn pop<G: Group>() {
+  stack::<G>(&mut unsafe { GENERATORS.write() }.unwrap()).pop().unwrap();
+}
+
+#[doc(hidden)]
+fn get<G: Group>() {
+  stack::<G>(&mut unsafe { GENERATORS.write() }.unwrap()).get(0).unwrap_or(G::generator());
+}
+
+macro_rules! dynamic_generator {
+  ($Name: ident, $Base: ident, $generator: expr) => {
+    #[derive(Clone, Copy, PartialEq, Eq, Debug)]
+    struct $Name($Base);
+  }
+}
+
+// type G: Group<Scalar = Self::F> + GroupOps + PrimeGroup + Zeroize + ConstantTimeEq;
+macro_rules! complete_dynamic_generator {
+  ($Name: ident, $Base: ident, $generator: expr) => {
+    #[derive(Clone, Copy, PartialEq, Eq, Debug, ConstantTimeEq, Zeroize)]
+    struct $Name($Base);
+    impl Group for DynamicGenerator {}
+    impl GroupEncoding for DynamicGenerator {}
+    impl PrimeGroup for DynamicGenerator {}
+  }
+}
+
+/*
+struct DynamicGenerator<G: Group> { _phantom: PhantomData<G> }
+impl DynamicGenerator {}
+*/