Feature: add conversion functions between 0x and bech32 address

lib/bip/address/eth_addr.dart

@@ -1,3 +1,5 @@
+import 'package:blockchain_utils/bech32/bech32.dart';
+import 'package:blockchain_utils/hex/hex.dart';
 import 'package:blockchain_utils/bip/address/addr_dec_utils.dart';
 import 'package:blockchain_utils/bip/address/decoder.dart';
 import 'package:blockchain_utils/bip/coin_conf/constant/coins_conf.dart';
@@ -126,3 +128,54 @@ class EthAddrEncoder implements BlockchainAddressEncoder {
         EthAddrUtils._checksumEncode(addr);
   }
 }
+
+/// Some cosmos-sdk chains integrate EVM modules, which means in the same chain,
+/// both bech32 and 0x addresses are supported.
+/// Here provides a utility methods to convert between each other.
+/// Note: Addresses are convertible if and only if both addresses are derived using the same coin type.
+class EthBech32Converter {
+  /// Encodes an Ethereum address in Bech32 format.
+  /// This method takes a hexadecimal Ethereum address and a prefix,
+  /// converts the address to bytes, and then encodes to Bech32-format address.
+  ///
+  /// Parameters:
+  ///   - hexAddress: The hexadecimal representation of the Ethereum address.
+  ///   - prefix: The Bech32 prefix to be used for encoding.
+  ///
+  /// Returns:
+  ///   A Bech32-encoded address.
+  ///
+  /// Throws:
+  ///  - AssertionError: If the length of the cleaned hexadecimal address is not equal to the expected Ethereum address length.
+  static String ethAddressToBech32(String ethAddress, prefix) {
+
+    final cleanHex = AddrDecUtils.validateAndRemovePrefix(
+      ethAddress, CoinsConf.ethereum.params.addrPrefix!
+    );
+    assert(
+      cleanHex.length == EthAddrConst.addrLen,
+      "Invalid Ethereum address length: ${cleanHex.length}, expected: ${EthAddrConst.addrLen}"
+    );
+    final hexAddressBytes = hex.decode(cleanHex);
+    return Bech32Encoder.encode(prefix, hexAddressBytes);
+  }
+
+  /// Decodes a Bech32-encoded address.
+  /// This method takes a Bech32-encoded address
+  /// and decodes it to its hexadecimal representation.
+  ///
+  /// Parameters:
+  ///   - bech32Address: The Bech32-encoded Ethereum address.
+  ///
+  /// Returns:
+  ///   A string representing the Ethereum address.
+  static String bech32ToEthAddress(String bech32Address, prefix) {
+    final decoded = Bech32Decoder.decode(prefix, bech32Address);
+    final hexEncoded = hex.encode(decoded);
+    assert(
+      hexEncoded.length == EthAddrConst.addrLen,
+      "Invalid Ethereum address length: ${hexEncoded.length}, expected: ${EthAddrConst.addrLen}"
+    );
+    return '${CoinsConf.ethereum.params.addrPrefix!}$hexEncoded';
+  }
+}

test/address/eth/eth_test.dart

@@ -1,9 +1,12 @@
+import 'package:blockchain_utils/bech32/bech32.dart';
+import 'package:blockchain_utils/bip/address/addr_dec_utils.dart';
 import 'package:blockchain_utils/bip/address/eth_addr.dart';
+import 'package:blockchain_utils/bip/coin_conf/constant/coins_conf.dart';
 import '../../quick_hex.dart';
 import 'package:blockchain_utils/utils/utils.dart';
 import 'package:test/test.dart';
 
-import 'test_vector.dart' show testVector;
+import 'test_vector.dart' show testVector, convertorTestVector;
 
 void main() {
   test("eth address test", () {
@@ -16,4 +19,49 @@ void main() {
       expect(decode.toHex(), i["decode"]);
     }
   });
+
+  test("eth address convertor test", () {
+    for (final i in convertorTestVector) {
+      final bech32Address = i["bech32"]!;
+      final ethAddress = i["hex"]!;
+      expect(
+          AddrDecUtils.validateAndRemovePrefix(
+                  ethAddress, CoinsConf.ethereum.params.addrPrefix!
+          ).length,
+          EthAddrConst.addrLen
+      );
+
+      final prefix = bech32Address.split(Bech32Const.separator)[0];
+
+      // Convert Bech32 to Hex
+      final convertedHex =
+          EthBech32Converter.bech32ToEthAddress(bech32Address, prefix);
+      expect(convertedHex, ethAddress.toLowerCase(),
+          reason:
+              "Converting $bech32Address, Expected: $ethAddress, but got: $convertedHex");
+
+      // Convert Hex to Bech32
+      final convertedBech32 =
+          EthBech32Converter.ethAddressToBech32(ethAddress, prefix);
+      expect(convertedBech32, bech32Address,
+          reason:
+              "Converting $ethAddress, Expected: $bech32Address, but got: $convertedBech32");
+    }
+
+    final invalidAddressWithWrongLength =
+        "0x1448b2449076672aCD167b91406c09552101C5";
+    expect(
+        AddrDecUtils.validateAndRemovePrefix(
+            invalidAddressWithWrongLength,
+            CoinsConf.ethereum.params.addrPrefix!
+        ).length,
+        isNot(EthAddrConst.addrLen)
+    );
+
+    (
+      () => EthBech32Converter.ethAddressToBech32(
+          invalidAddressWithWrongLength, "eth"),
+      throwsA(isA<AssertionError>())
+    );
+  });
 }

test/address/eth/test_vector.dart

@@ -350,3 +350,19 @@ final List<Map<String, dynamic>> testVector = [
     "params": {}
   }
 ];
+
+final List<Map<String, String>> convertorTestVector = [
+  {
+    "bech32": "mantra1z3yty3yswenj4ngk0wg5qmqf25ssr3wfqayuhv",
+    "hex": "0x1448b2449076672aCD167b91406c09552101C5C9"
+  },
+  {
+    "bech32": "crc1gwqac243g2z3vryqsev6acq965f9ttwhw9r7vk",
+    "hex": "0x4381dc2ab14285160c808659aee005d51255add7"
+  },
+  {
+    "bech32": "plq1l2hvlkqw3jzh9w5kv47gfmxfqqldrvnm50fv6p",
+    "hex": "0xFaAEcfd80e8c8572bA96657c84eCc9003Ed1b27B"
+  }
+];
+