Wallet spending key derivation path

zcash_client_backend/src/keys.rs

@@ -0,0 +1,24 @@
+//! Helper functions for managing light client key material.
+
+use zcash_primitives::zip32::{ChildIndex, ExtendedSpendingKey};
+
+/// Derives the ZIP 32 [`ExtendedSpendingKey`] for a given coin type and account from the
+/// given seed.
+///
+/// # Examples
+///
+/// ```
+/// use zcash_client_backend::{constants::testnet::COIN_TYPE, keys::spending_key};
+///
+/// let extsk = spending_key(&[0; 32][..], COIN_TYPE, 0);
+/// ```
+pub fn spending_key(seed: &[u8], coin_type: u32, account: u32) -> ExtendedSpendingKey {
+    ExtendedSpendingKey::from_path(
+        &ExtendedSpendingKey::master(&seed),
+        &[
+            ChildIndex::Hardened(32),
+            ChildIndex::Hardened(coin_type),
+            ChildIndex::Hardened(account),
+        ],
+    )
+}