From 1b8da6b12d6f7813817aeb498031e861758fe463 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Tue, 10 Jul 2018 23:58:06 +0100
Subject: [PATCH] ZIP 32 structures

---
 Cargo.toml |  5 +++++
 src/lib.rs | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index 16375d037..f97aee520 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,3 +12,8 @@ homepage = "https://github.com/zcash-hackworks/zip32"
 repository = "https://github.com/zcash-hackworks/zip32"
 
 [dependencies]
+pairing = "0.14.2"
+
+[dependencies.sapling-crypto]
+git = "https://github.com/zcash-hackworks/sapling-crypto"
+rev = "21084bde2019c04bd34208e63c3560fe2c02fb0e"
diff --git a/src/lib.rs b/src/lib.rs
index 31e1bb209..e696dd37a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,67 @@
+extern crate pairing;
+extern crate sapling_crypto;
+
+use pairing::bls12_381::Bls12;
+use sapling_crypto::{jubjub::JubjubEngine, primitives::ViewingKey};
+
+// Sapling key components
+
+/// An outgoing viewing key
+struct OutgoingViewingKey([u8; 32]);
+
+/// A Sapling expanded spending key
+struct ExpandedSpendingKey<E: JubjubEngine> {
+    ask: E::Fs,
+    nsk: E::Fs,
+    ovk: OutgoingViewingKey,
+}
+
+/// A Sapling full viewing key
+struct FullViewingKey<E: JubjubEngine> {
+    vk: ViewingKey<E>,
+    ovk: OutgoingViewingKey,
+}
+
+// ZIP 32 structures
+
+/// A Sapling full viewing key fingerprint
+struct FVKFingerprint([u8; 32]);
+
+/// A Sapling full viewing key tag
+struct FVKTag([u8; 4]);
+
+/// A child index for a derived key
+pub enum ChildIndex {
+    NonHardened(u32),
+    Hardened(u32), // Hardened(n) == n + (1 << 31) == n' in path notation
+}
+
+/// A chain code
+struct ChainCode([u8; 32]);
+
+/// A key used to derive diversifiers for a particular child key
+struct DiversifierKey([u8; 32]);
+
+/// A Sapling extended spending key
+pub struct ExtendedSpendingKey {
+    depth: u8,
+    parent_fvk_tag: FVKTag,
+    child_index: ChildIndex,
+    chain_code: ChainCode,
+    xsk: ExpandedSpendingKey<Bls12>,
+    dk: DiversifierKey,
+}
+
+// A Sapling extended full viewing key
+pub struct ExtendedFullViewingKey {
+    depth: u8,
+    parent_fvk_tag: FVKTag,
+    child_index: ChildIndex,
+    chain_code: ChainCode,
+    fvk: FullViewingKey<Bls12>,
+    dk: DiversifierKey,
+}
+
 #[cfg(test)]
 mod tests {
     #[test]