fix(import): recognize real DragonX key formats in the import gate

The client-side pre-check rejected legitimate keys before the daemon ever
saw them, surfacing "Unrecognized key format" / a cryptic daemon "Invalid"
error. Two concrete defects plus the brittle heuristic behind them:

- Viewing keys: isViewingKey looked for Zcash's "zxview" extended-FVK
  prefix, but DragonX's z_exportviewingkey emits a Sapling *incoming*
  viewing key (HRP "zivks"), which z_importviewingkey is the only form the
  daemon decodes. Every real DragonX viewing key was refused. (F1)
- Uncompressed transparent WIF: the length+first-char heuristic accepted
  {5,K,L,U} only, but a version-188 uncompressed key starts with '7'. (F2)

Replace the heuristic with structural validation using the existing
checksum validators (F3): add util::decodeBase58Check (checksum-stripped
payload) and util::bech32Hrp (HRP of a valid Bech32 string). Transparent
keys are now accepted by decoding Base58Check and checking the payload is a
33/34-byte secret key with a DragonX SECRET_KEY version byte (188 main/
regtest, 128 testnet) — covering compressed and uncompressed, rejecting
addresses/typos by real checksum. Viewing keys are matched by the real
incoming-VK HRPs (zivks / zivktestsapling / zivkregtestsapling).

The Sweep gate and the dialog's live type indicator run off the same
predicates, so they are fixed too (F4). Messaging now names the likely
cause and appends a wrong-coin/network hint to the daemon's raw "Invalid"
error (F5).

Adds testPrivateKeyImportRecognition plus decodeBase58Check/bech32Hrp
coverage; suite green (1/1).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app_network.cpp

@@ -3834,7 +3834,9 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
     // Reject anything that isn't a recognized Z/T private key or shielded viewing key before handing
     // it to the daemon (the dialog's indicator and this guard share isRecognizedImportKey).
     if (!services::WalletSecurityController::isRecognizedImportKey(key)) {
-        if (callback) callback(false, "Unrecognized key format.", "");
+        if (callback) callback(false,
+            "Not a recognized DragonX private key or viewing key. Check for missing or "
+            "mistyped characters, and that this is a DragonX key (not another coin).", "");
         return;
     }
 
@@ -3874,6 +3876,14 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
         }
         // Scrub the worker's copy of the key now that the request has been sent (all paths).
         if (!key.empty()) sodium_memzero(&key[0], key.size());
+        // A checksum-valid key the daemon still rejects is almost always the right *format* but the
+        // wrong network/coin (Komodo-family chains share version bytes) or a corrupted paste — say so,
+        // since the bare "Invalid …" text reads like a wallet bug (F5).
+        if (!err.empty() && err.find("Invalid") != std::string::npos &&
+            err.find("DragonX") == std::string::npos) {
+            err += " — check the key is for DragonX (not another coin or network) and has no missing "
+                   "or altered characters.";
+        }
         return [this, err, addr, callback]() {
             if (!err.empty()) {
                 if (callback) callback(false, err, "");

src/services/wallet_security_controller.cpp

@@ -1,9 +1,12 @@
 #include "wallet_security_controller.h"
 #include "../util/secure_vault.h"
+#include "../util/address_validation.h"
 
 #include <cctype>
+#include <cstdint>
 #include <cstdio>
 #include <utility>
+#include <vector>
 
 namespace dragonx {
 namespace services {
@@ -108,18 +111,35 @@ WalletSecurityController::KeyKind WalletSecurityController::classifyPrivateKey(c
 
 bool WalletSecurityController::isViewingKey(const std::string& key)
 {
-    // Sapling extended full viewing key (mainnet HRP "zxviews"; "zxview" also matches the prefix the
-    // lite backend recognizes). Watch-only: reveals the address's funds but cannot spend them.
-    return key.rfind("zxview", 0) == 0;
+    // DragonX's z_exportviewingkey returns a Sapling *incoming* viewing key (mainnet HRP "zivks");
+    // z_importviewingkey only decodes that form. Recognize it structurally — a valid Bech32 checksum
+    // plus a known HRP — instead of a bare prefix, and cover testnet/regtest too. (The old check
+    // looked for Zcash's "zxview" extended-FVK HRP, which DragonX never emits, so every real viewing
+    // key was rejected client-side.) Watch-only: reveals the address's funds but cannot spend them.
+    const std::string hrp = util::bech32Hrp(key);
+    return hrp == "zivks"                 // mainnet
+        || hrp == "zivktestsapling"       // testnet
+        || hrp == "zivkregtestsapling";   // regtest
 }
 
 bool WalletSecurityController::isRecognizedPrivateKey(const std::string& key)
 {
+    // Sapling z spending key (HRP "secret-extended-key-{main,test,regtest}"). These run ~300 chars,
+    // past the Bech32 length cap, so match by HRP prefix and let the daemon vet the payload.
     if (key.rfind("secret-extended-key-", 0) == 0) return true;               // Sapling z spending key
     if (key.size() >= 2 && key[0] == 'S' && key[1] == 'K') return true;       // Sprout z spending key
-    // Transparent WIF: base58, ~51-52 chars, common version prefixes.
-    if (key.size() >= 51 && key.size() <= 52 &&
-        (key[0] == '5' || key[0] == 'K' || key[0] == 'L' || key[0] == 'U')) return true;
+    // Transparent WIF: decode Base58Check and confirm it is actually a secret key — version byte plus
+    // a 32-byte key, optionally a compression flag (payload 33 or 34 bytes). This accepts BOTH the
+    // compressed ("U…") and uncompressed ("7…") mainnet forms and the testnet form, and rejects
+    // addresses / typos via the real checksum — the old length+first-char heuristic dropped the
+    // uncompressed mainnet key (which starts with '7', not one of 5/K/L/U).
+    std::vector<std::uint8_t> payload;
+    if (util::decodeBase58Check(key, payload) &&
+        (payload.size() == 33 || payload.size() == 34) &&
+        (payload[0] == 188 /* DragonX main/regtest SECRET_KEY */ ||
+         payload[0] == 128 /* DragonX testnet SECRET_KEY */)) {
+        return true;
+    }
     return false;
 }
 

src/services/wallet_security_controller.h

@@ -74,7 +74,7 @@ public:
                                                 std::size_t minLength = 4);
     static KeyKind classifyAddress(const std::string& address);
     static KeyKind classifyPrivateKey(const std::string& key);
-    // True if `key` is a shielded viewing key (extended full viewing key, "zxview…" — watch-only).
+    // True if `key` is a shielded viewing key (Sapling incoming viewing key, "zivks…" — watch-only).
     static bool isViewingKey(const std::string& key);
     // True if `key` looks like a recognized Z (Sapling/Sprout spending) or T (WIF) private key.
     static bool isRecognizedPrivateKey(const std::string& key);

src/util/address_validation.cpp

@@ -76,7 +76,7 @@ std::vector<int> bech32HrpExpand(const std::string& hrp)
 
 }  // namespace
 
-bool isValidBase58Check(const std::string& s)
+bool decodeBase58Check(const std::string& s, std::vector<std::uint8_t>& payloadOut)
 {
     if (s.size() < 5 || s.size() > 256) return false;
     std::vector<std::uint8_t> data;
@@ -88,7 +88,15 @@ bool isValidBase58Check(const std::string& s)
     unsigned char h2[crypto_hash_sha256_BYTES];
     crypto_hash_sha256(h1, data.data(), payloadLen);
     crypto_hash_sha256(h2, h1, sizeof(h1));
-    return std::memcmp(h2, data.data() + payloadLen, 4) == 0;
+    if (std::memcmp(h2, data.data() + payloadLen, 4) != 0) return false;
+    payloadOut.assign(data.begin(), data.begin() + payloadLen);
+    return true;
+}
+
+bool isValidBase58Check(const std::string& s)
+{
+    std::vector<std::uint8_t> payload;
+    return decodeBase58Check(s, payload);
 }
 
 bool isValidBech32(const std::string& s)
@@ -127,5 +135,18 @@ bool isValidBech32(const std::string& s)
     return bech32Polymod(combined) == 1;  // original Bech32 constant (Sapling, not Bech32m)
 }
 
+std::string bech32Hrp(const std::string& s)
+{
+    if (!isValidBech32(s)) return {};
+    // isValidBech32 already rejected mixed case and guaranteed a non-empty HRP before the
+    // final '1' separator, so lower-casing and splitting there recovers the HRP verbatim.
+    std::string lower(s);
+    std::transform(lower.begin(), lower.end(), lower.begin(),
+                   [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
+    const std::size_t sep = lower.rfind('1');
+    if (sep == std::string::npos) return {};
+    return lower.substr(0, sep);
+}
+
 }  // namespace util
 }  // namespace dragonx

src/util/address_validation.h

@@ -11,7 +11,9 @@
 
 #pragma once
 
+#include <cstdint>
 #include <string>
+#include <vector>
 
 namespace dragonx {
 namespace util {
@@ -20,9 +22,18 @@ namespace util {
 // (transparent R-addresses). Version-byte agnostic by design.
 bool isValidBase58Check(const std::string& s);
 
+// Decodes `s` as Base58Check; on success returns true and fills `payloadOut` with the
+// decoded bytes EXCLUDING the trailing 4-byte checksum (i.e. version byte + data). Lets
+// callers inspect the version byte / payload length (e.g. to tell a WIF from an address).
+bool decodeBase58Check(const std::string& s, std::vector<std::uint8_t>& payloadOut);
+
 // True if `s` is a valid Bech32 string (Sapling zs-addresses). The HRP is taken
 // from the string itself and folded into the checksum, so no HRP is hardcoded.
 bool isValidBech32(const std::string& s);
 
+// Returns the (lower-cased) human-readable prefix of a valid Bech32 string, or "" if
+// `s` is not valid Bech32. The HRP identifies the key/address type (e.g. "zivks").
+std::string bech32Hrp(const std::string& s);
+
 }  // namespace util
 }  // namespace dragonx