Reproduce snet-cli wallet generation procedure

Author: vsbogd

src/main/java/io/singularitynet/sdk/client/ConfigurationDependencyFactory.java

@@ -40,7 +40,7 @@ public IPFS getIpfs() {
     public Signer getSigner() {
         switch (config.getSignerType()) {
             case MNEMONIC:
-                return new MnemonicIdentity(config.getSignerMnemonic());
+                return new MnemonicIdentity(config.getSignerMnemonic(), 0);
             case PRIVATE_KEY:
                 return new PrivateKeyIdentity(config.getSignerPrivateKey());
             default:

src/main/java/io/singularitynet/sdk/ethereum/MnemonicIdentity.java

@@ -1,12 +1,29 @@
 package io.singularitynet.sdk.ethereum;
 
-import org.web3j.crypto.WalletUtils;
+import java.util.Arrays;
+
+import org.web3j.crypto.MnemonicUtils;
+import org.web3j.crypto.Bip32ECKeyPair;
 
 public class MnemonicIdentity extends PrivateKeyIdentity {
 
-    public MnemonicIdentity(String mnemonic) {
-        // FIXME: test that private key generated is equal to snet cli one
-        super(WalletUtils.loadBip39Credentials("", mnemonic).getEcKeyPair());
+    private static final int[] PATH_PREFIX = new int[] {
+        44 | Bip32ECKeyPair.HARDENED_BIT,
+        60 | Bip32ECKeyPair.HARDENED_BIT,
+        0 | Bip32ECKeyPair.HARDENED_BIT,
+        0
+    };
+
+    public MnemonicIdentity(String mnemonic, int walletIndex) {
+        super(wallet(mnemonic, walletIndex));
+    }
+
+    private static Bip32ECKeyPair wallet(String mnemonic, int walletIndex) {
+        byte[] seed = MnemonicUtils.generateSeed(mnemonic, "");
+        Bip32ECKeyPair master = Bip32ECKeyPair.generateKeyPair(seed);
+        int[] path = Arrays.copyOf(PATH_PREFIX, PATH_PREFIX.length + 1);
+        path[path.length - 1] = walletIndex;
+        return Bip32ECKeyPair.deriveKeyPair(master, path);
     }
 
 }

src/test/java/io/singularitynet/sdk/ethereum/MnemonicIndentityTest.java

@@ -0,0 +1,36 @@
+package io.singularitynet.sdk.ethereum;
+
+import static org.junit.Assert.*;
+import org.junit.*;
+
+import io.singularitynet.sdk.common.Utils;
+
+public class MnemonicIndentityTest {
+
+    private static String mnemonic = "insect lottery stable theme shrimp expose match frog entry always viable cabbage mechanic cinnamon spread";
+    private static byte[] message = Utils.strToBytes32("Some message");
+
+    @Test
+    public void generateMnemonicIdentityWallet0() {
+        PrivateKeyIdentity expected = fromBase64Key("pAIRj43MIe6/Yj6AigjI0X8jYzDSk929nUSkRBRJcVA=");
+
+        MnemonicIdentity actual = new MnemonicIdentity(mnemonic, 0);
+
+        assertArrayEquals("Signature", expected.sign(message), actual.sign(message));
+    }
+
+    @Test
+    public void generateMnemonicIdentityWallet42() {
+        PrivateKeyIdentity expected = fromBase64Key("gczjSyFyWK024XVHDipAsFr3EP3v3NtDanNsrO4O1D8=");
+
+        MnemonicIdentity actual = new MnemonicIdentity(mnemonic, 42);
+
+        assertArrayEquals("Signature", expected.sign(message), actual.sign(message));
+    }
+
+    private static PrivateKeyIdentity fromBase64Key(String key) {
+        byte[] privateKey = Utils.base64ToBytes(key);
+        return new PrivateKeyIdentity(privateKey);
+    }
+
+}