keystore: use xpubs instead of xprvs where possible

Functionally the same, but for clarity it is better to use xpubs where
only pubkeys are involved. This will also make it easier to add xpub
caching to increase performance if needed (for example, xpubs are
derived anew for each BTC transaction input and change).

The extra keystore_is_locked check is not needed getting a xprv/xpub
already does that check.

Author: benma

src/keystore.c

@@ -574,14 +574,11 @@ bool keystore_secp256k1_pubkey_hash160(
     size_t keypath_len,
     uint8_t* hash160_out)
 {
-    if (keystore_is_locked()) {
-        return false;
-    }
-    struct ext_key xprv __attribute__((__cleanup__(keystore_zero_xkey))) = {0};
-    if (!_get_xprv_twice(keypath, keypath_len, &xprv)) {
+    struct ext_key xpub __attribute__((__cleanup__(keystore_zero_xkey))) = {0};
+    if (!keystore_get_xpub(keypath, keypath_len, &xpub)) {
         return false;
     }
-    memcpy(hash160_out, xprv.hash160, sizeof(xprv.hash160));
+    memcpy(hash160_out, xpub.hash160, sizeof(xpub.hash160));
     return true;
 }
 
@@ -590,14 +587,11 @@ bool keystore_secp256k1_pubkey_uncompressed(
     size_t keypath_len,
     uint8_t* pubkey_out)
 {
-    if (keystore_is_locked()) {
-        return false;
-    }
-    struct ext_key xprv __attribute__((__cleanup__(keystore_zero_xkey))) = {0};
-    if (!_get_xprv_twice(keypath, keypath_len, &xprv)) {
+    struct ext_key xpub __attribute__((__cleanup__(keystore_zero_xkey))) = {0};
+    if (!keystore_get_xpub(keypath, keypath_len, &xpub)) {
         return false;
     }
-    return _compressed_to_uncompressed(xprv.pub_key, pubkey_out);
+    return _compressed_to_uncompressed(xpub.pub_key, pubkey_out);
 }
 
 bool keystore_secp256k1_nonce_commit(