Expose StoredKey encryption parameters

include/TrustWalletCore/TWStoredKey.h

@@ -105,4 +105,8 @@ TWData* _Nullable TWStoredKeyExportJSON(struct TWStoredKey* _Nonnull key);
 TW_EXPORT_METHOD
 bool TWStoredKeyFixAddresses(struct TWStoredKey* _Nonnull key, TWData* _Nonnull password);
 
+/// Retrieve stored key encoding parameters, as JSON string.
+TW_EXPORT_PROPERTY
+TWString* _Nullable TWStoredKeyEncryptionParameters(struct TWStoredKey* _Nonnull key);
+
 TW_EXTERN_C_END

src/interface/TWStoredKey.cpp

@@ -178,3 +178,11 @@ bool TWStoredKeyFixAddresses(struct TWStoredKey* _Nonnull key, TWData* _Nonnull
         return false;
     }
 }
+
+TWString* _Nullable TWStoredKeyEncryptionParameters(struct TWStoredKey* _Nonnull key) {
+    if (!key->impl.id) {
+        return nullptr;
+    }
+    const std::string params = key->impl.payload.json().dump();
+    return TWStringCreateWithUTF8Bytes(params.c_str());
+}

swift/Tests/Keystore/KeystoreKeyTests.swift

@@ -119,4 +119,25 @@ class KeystoreKeyTests: XCTestCase {
         let data = keystore.decryptPrivateKey(password: password)
         XCTAssertEqual(data?.hexString, "4357b2f9a6150ba969bc52f01c98cce5313595fe49f2d08303759c73e5c7a46c")
     }
+
+    struct KdfParams: Decodable {
+        let dklen: Int
+        let n: Int
+    }
+
+    struct EncryptionParameters: Decodable {
+        let kdf: String
+        let kdfparams: KdfParams
+    }
+
+    func testEncryptionParameters() {
+        let url = Bundle(for: type(of: self)).url(forResource: "key", withExtension: "json")!
+        let key = StoredKey.load(path: url.path)!
+
+        let paramsData = key.encryptionParameters!.data(using: .utf8)!
+        let params = try! JSONDecoder().decode(EncryptionParameters.self, from: paramsData)
+
+        XCTAssertEqual(params.kdf, "scrypt");
+        XCTAssertEqual(params.kdfparams.n, 262144);
+    }
 }

tests/interface/TWStoredKeyTests.cpp

@@ -14,6 +14,7 @@
 #include "../src/HexCoding.h"
 
 #include <gtest/gtest.h>
+#include <nlohmann/json.hpp>
 
 #include <fstream>
 
@@ -225,3 +226,37 @@ TEST(TWStoredKey, getWalletPasswordInvalid) {
     ASSERT_NE(WRAP(TWHDWallet, TWStoredKeyWallet(key.get(), password.get())).get(), nullptr);
     ASSERT_EQ(WRAP(TWHDWallet, TWStoredKeyWallet(key.get(), passwordInvalid.get())).get(), nullptr);
 }
+
+TEST(TWStoredKey, encryptionParameters) {
+    const auto key = createDefaultStoredKey();
+    const auto params = WRAPS(TWStoredKeyEncryptionParameters(key.get()));
+
+    nlohmann::json jsonParams = nlohmann::json::parse(string(TWStringUTF8Bytes(params.get())));
+
+    // compare some specific parameters
+    EXPECT_EQ(jsonParams["kdfparams"]["n"], 4096);
+    EXPECT_EQ(std::string(jsonParams["cipherparams"]["iv"]).length(), 32);
+
+    // compare all keys, except dynamic ones (like cipherparams/iv)
+    jsonParams["cipherparams"] = {};
+    jsonParams["ciphertext"] = "<ciphertext>";
+    jsonParams["kdfparams"]["salt"] = "<salt>";
+    jsonParams["mac"] = "<mac>";
+    const auto params2 = jsonParams.dump();
+    assertJSONEqual(params2, R"(
+        {
+            "cipher": "aes-128-ctr",
+            "cipherparams": null,
+            "ciphertext": "<ciphertext>",
+            "kdf": "scrypt",
+            "kdfparams": {
+                "dklen": 32,
+                "n": 4096,
+                "p": 6,
+                "r": 8,
+                "salt": "<salt>"
+            },
+            "mac": "<mac>"
+        }        
+    )");
+}