added some utility extensions

lib/utilities/extensions/extensions.dart

@@ -0,0 +1,3 @@
+export 'impl/big_int.dart';
+export 'impl/string.dart';
+export 'impl/uint8_list.dart';

lib/utilities/extensions/impl/big_int.dart

@@ -0,0 +1,33 @@
+import 'dart:typed_data';
+
+extension BigIntExtensions on BigInt {
+  String get toHex {
+    if (this < BigInt.zero) {
+      throw Exception("BigInt value is negative");
+    }
+
+    final String hex = toRadixString(16);
+    if (hex.length % 2 == 0) {
+      return hex;
+    } else {
+      return "0$hex";
+    }
+  }
+
+  String get toHexUppercase => toHex.toUpperCase();
+
+  Uint8List get toBytes {
+    if (this < BigInt.zero) {
+      throw Exception("BigInt value is negative");
+    }
+    BigInt number = this;
+    int bytes = (number.bitLength + 7) >> 3;
+    final b256 = BigInt.from(256);
+    final result = Uint8List(bytes);
+    for (int i = 0; i < bytes; i++) {
+      result[bytes - 1 - i] = number.remainder(b256).toInt();
+      number = number >> 8;
+    }
+    return result;
+  }
+}

lib/utilities/extensions/impl/string.dart

@@ -0,0 +1,17 @@
+import 'dart:typed_data';
+
+import 'package:dart_bs58/dart_bs58.dart';
+import 'package:dart_bs58check/dart_bs58check.dart';
+import 'package:hex/hex.dart';
+import 'package:stackwallet/utilities/extensions/extensions.dart';
+
+extension StringExtensions on String {
+  Uint8List get toUint8ListFromHex =>
+      Uint8List.fromList(HEX.decode(startsWith("0x") ? substring(2) : this));
+
+  Uint8List get toUint8ListFromBase58Encoded => bs58.decode(this);
+
+  Uint8List get toUint8ListFromBase58CheckEncoded => bs58check.decode(this);
+
+  BigInt get toBigIntFromHex => toUint8ListFromHex.toBigInt;
+}

lib/utilities/extensions/impl/uint8_list.dart

@@ -0,0 +1,36 @@
+import 'dart:typed_data';
+
+import 'package:dart_bs58/dart_bs58.dart';
+import 'package:dart_bs58check/dart_bs58check.dart';
+import 'package:hex/hex.dart';
+
+extension Uint8ListExtensions on Uint8List {
+  String get toHex {
+    return HEX.encode(this);
+  }
+
+  String get toBase58Encoded {
+    return bs58.encode(this);
+  }
+
+  String get toBase58CheckEncoded {
+    return bs58check.encode(this);
+  }
+
+  /// returns copy of byte list in reverse order
+  Uint8List get reversed {
+    final reversed = Uint8List(length);
+    for (final byte in this) {
+      reversed.insert(0, byte);
+    }
+    return reversed;
+  }
+
+  BigInt get toBigInt {
+    BigInt number = BigInt.zero;
+    for (final byte in this) {
+      number = (number << 8) | BigInt.from(byte & 0xff);
+    }
+    return number;
+  }
+}

pubspec.lock

@@ -355,14 +355,14 @@ packages:
     source: hosted
     version: "1.0.0"
   dart_bs58:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: dart_bs58
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.1"
   dart_bs58check:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: dart_bs58check
       url: "https://pub.dartlang.org"
@@ -716,7 +716,7 @@ packages:
     source: hosted
     version: "2.2.0"
   hex:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: hex
       url: "https://pub.dartlang.org"

pubspec.yaml

@@ -146,6 +146,9 @@ dependencies:
   dropdown_button2: 1.7.2
   string_validator: ^0.3.0
   equatable: ^2.0.5
+  dart_bs58: ^1.0.1
+  dart_bs58check: ^3.0.2
+  hex: ^0.2.0
 
 dev_dependencies:
   flutter_test: