From 7af9b80f3be7cf17e40f2dc64a956177b690fa70 Mon Sep 17 00:00:00 2001
From: Deirdre Connolly <deirdre@zfnd.org>
Date: Fri, 13 Mar 2020 18:58:02 -0400
Subject: [PATCH] Add the beginnings of Sprout and Sapling key types

---
 zebra-chain/src/addresses.rs    |  2 ++
 zebra-chain/src/keys/sapling.rs |  7 +++++++
 zebra-chain/src/keys/sprout.rs  | 20 ++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/zebra-chain/src/addresses.rs b/zebra-chain/src/addresses.rs
index 7e200d1b..13b47325 100644
--- a/zebra-chain/src/addresses.rs
+++ b/zebra-chain/src/addresses.rs
@@ -1,3 +1,5 @@
 //! Address types.
 
+pub mod sapling;
+pub mod sprout;
 pub mod transparent;
diff --git a/zebra-chain/src/keys/sapling.rs b/zebra-chain/src/keys/sapling.rs
index 0605a25e..486dc8d0 100644
--- a/zebra-chain/src/keys/sapling.rs
+++ b/zebra-chain/src/keys/sapling.rs
@@ -1,4 +1,11 @@
 //! Sapling key types
+//!
+//! "The spend authorizing key ask, proof authorizing key (ak, nsk),
+//! full viewing key (ak, nk, ovk), incoming viewing key ivk, and each
+//! diversied payment address addr_d = (d, pk_d ) are derived from sk,
+//! as described in [Sapling Key Components][ps]."
+//!
+//! [ps]: https://zips.z.cash/protocol/protocol.pdf#saplingkeycomponents
 
 use std::{
     fmt,
diff --git a/zebra-chain/src/keys/sprout.rs b/zebra-chain/src/keys/sprout.rs
index 583d00fe..d910e602 100644
--- a/zebra-chain/src/keys/sprout.rs
+++ b/zebra-chain/src/keys/sprout.rs
@@ -1,4 +1,10 @@
 //! Sprout key types
+//!
+//! "The receiving key sk_enc, the incoming viewing key ivk = (apk,
+//! sk_enc), and the shielded payment address addr_pk = (a_pk, pk_enc) are
+//! derived from a_sk, as described in [‘Sprout Key Components’][ps]
+//!
+//! [ps]: https://zips.z.cash/protocol/protocol.pdf#sproutkeycomponents
 
 use std::{
     fmt,
@@ -12,6 +18,20 @@ use proptest_derive::Arbitrary;
 
 use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize};
 
+/// All other Sprout key types derive from the SpendingKey value.
+pub struct SpendingKey;
+
+pub struct ReceivingKey;
+
+pub struct PayingKey;
+
+pub struct TransmissionKey;
+
+pub struct IncomingViewingKey {
+    paying_key: PayingKey,
+    receiving_key: ReceivingKey,
+}
+
 #[cfg(test)]
 proptest! {