From e91aabd2d4235e35f7cddae7f86a8d197f91bd06 Mon Sep 17 00:00:00 2001
From: Murisi Tarusenga <murisit@gmail.com>
Date: Fri, 30 Aug 2024 10:37:05 +0200
Subject: [PATCH] Consolidate the view key components into one object.

---
 app/src/crypto.c | 19 ++++++++++---------
 rs/src/lib.rs    | 15 ++-------------
 rs/src/params.rs |  2 ++
 rs/src/utils.rs  |  9 ++-------
 4 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/app/src/crypto.c b/app/src/crypto.c
index 38a6c52..540c6e4 100644
--- a/app/src/crypto.c
+++ b/app/src/crypto.c
@@ -528,16 +528,17 @@ __Z_INLINE zxerr_t copyKeys(keys_t *saplingKeys, key_kind_e requestedKeys, uint8
             break;
 
         case ViewKeys:
-            if (outputLen < 6 * KEY_LENGTH + TAG_LENGTH) {
+            if (outputLen < 5 * KEY_LENGTH + 2 * TAG_LENGTH + 1) {
                 return zxerr_buffer_too_small;
             }
-            memcpy(output, saplingKeys->ak, KEY_LENGTH);
-            memcpy(output + KEY_LENGTH, saplingKeys->nk, KEY_LENGTH);
-            memcpy(output + 2 * KEY_LENGTH, saplingKeys->ovk, KEY_LENGTH);
-            memcpy(output + 3 * KEY_LENGTH, saplingKeys->ivk, KEY_LENGTH);
-            memcpy(output + 4 * KEY_LENGTH, saplingKeys->dk, KEY_LENGTH);
-            memcpy(output + 5 * KEY_LENGTH, saplingKeys->chain_code, KEY_LENGTH);
-            memcpy(output + 6 * KEY_LENGTH, saplingKeys->parent_fvk_tag, TAG_LENGTH);
+            memcpy(output, &hdPathLen, 1);
+            memcpy(output + 1, saplingKeys->parent_fvk_tag, TAG_LENGTH);
+            memcpy(output + 5, &hdPath[hdPathLen - 1], TAG_LENGTH);
+            memcpy(output + 9, saplingKeys->chain_code, KEY_LENGTH);
+            memcpy(output + 41, saplingKeys->ak, KEY_LENGTH);
+            memcpy(output + 73, saplingKeys->nk, KEY_LENGTH);
+            memcpy(output + 105, saplingKeys->ovk, KEY_LENGTH);
+            memcpy(output + 137, saplingKeys->dk, KEY_LENGTH);
             break;
 
         case ProofGenerationKey:
@@ -616,7 +617,7 @@ zxerr_t crypto_fillMASP(uint8_t *buffer, uint16_t bufferLen, uint16_t *cmdRespon
             break;
 
         case ViewKeys:
-            *cmdResponseLen = 6 * KEY_LENGTH + TAG_LENGTH;
+            *cmdResponseLen = 5 * KEY_LENGTH + 2 * TAG_LENGTH + 1;
             break;
 
         case ProofGenerationKey:
diff --git a/rs/src/lib.rs b/rs/src/lib.rs
index 7896d70..d4d56b2 100644
--- a/rs/src/lib.rs
+++ b/rs/src/lib.rs
@@ -34,7 +34,7 @@ pub use params::{
     InstructionCode, KeyResponse, NamadaKeys, ADDRESS_LEN, CLA, ED25519_PUBKEY_LEN,
     PK_LEN_PLUS_TAG, SIG_LEN_PLUS_TAG,
 };
-use params::{KEY_LEN, SALT_LEN, TAG_LEN};
+use params::{KEY_LEN, SALT_LEN, XFVK_LEN};
 use utils::{
     ResponseAddress, ResponseGetConvertRandomness, ResponseGetOutputRandomness,
     ResponseGetSpendRandomness, ResponseMaspSign, ResponseProofGenKey, ResponsePubAddress,
@@ -369,19 +369,8 @@ where
                 public_address: response_data[..KEY_LEN].try_into().unwrap(),
             })),
             NamadaKeys::ViewKey => {
-                let (view_key, rest) = response_data.split_at(2 * KEY_LEN);
-                let (ovk, rest) = rest.split_at(KEY_LEN);
-                let (ivk, rest) = rest.split_at(KEY_LEN);
-                let (dk, rest) = rest.split_at(KEY_LEN);
-                let (chain_code, rest) = rest.split_at(KEY_LEN);
-                let (parent_fvk_tag, _) = rest.split_at(TAG_LEN);
                 Ok(KeyResponse::ViewKey(ResponseViewKey {
-                    view_key: view_key.try_into().unwrap(),
-                    ovk: ovk.try_into().unwrap(),
-                    ivk: ivk.try_into().unwrap(),
-                    dk: dk.try_into().unwrap(),
-                    chain_code: chain_code.try_into().unwrap(),
-                    parent_fvk_tag: parent_fvk_tag.try_into().unwrap(),
+                    xfvk: response_data[..XFVK_LEN].try_into().unwrap(),
                 }))
             }
             NamadaKeys::ProofGenerationKey => {
diff --git a/rs/src/params.rs b/rs/src/params.rs
index c4c8358..5ea101f 100644
--- a/rs/src/params.rs
+++ b/rs/src/params.rs
@@ -26,6 +26,8 @@ pub const CLA: u8 = 0x57;
 pub const KEY_LEN: usize = 32;
 /// MASP tag length
 pub const TAG_LEN: usize = 4;
+/// MASP extended full viewing key length
+pub const XFVK_LEN: usize = 1 + 2*TAG_LEN + 5*KEY_LEN;
 /// Public Key Length
 pub const ED25519_PUBKEY_LEN: usize = 32;
 /// Public Key + Tag Length
diff --git a/rs/src/utils.rs b/rs/src/utils.rs
index f9036d6..f5aa539 100644
--- a/rs/src/utils.rs
+++ b/rs/src/utils.rs
@@ -22,7 +22,7 @@ use std::error::Error;
 const HARDENED: u32 = 0x80000000;
 
 use crate::params::{
-    ADDRESS_LEN, ED25519_PUBKEY_LEN, KEY_LEN, PK_LEN_PLUS_TAG, SALT_LEN, SIG_LEN_PLUS_TAG, TAG_LEN,
+    ADDRESS_LEN, ED25519_PUBKEY_LEN, KEY_LEN, PK_LEN_PLUS_TAG, SALT_LEN, SIG_LEN_PLUS_TAG, XFVK_LEN,
 };
 use byteorder::{LittleEndian, WriteBytesExt};
 
@@ -48,12 +48,7 @@ pub struct ResponsePubAddress {
 }
 
 pub struct ResponseViewKey {
-    pub view_key: [u8; 2 * KEY_LEN],
-    pub ivk: [u8; KEY_LEN],
-    pub ovk: [u8; KEY_LEN],
-    pub dk: [u8; KEY_LEN],
-    pub chain_code: [u8; KEY_LEN],
-    pub parent_fvk_tag: [u8; TAG_LEN],
+    pub xfvk: [u8; XFVK_LEN],
 }
 
 pub struct ResponseProofGenKey {