diff --git a/lib/rng.dart b/lib/rng.dart
index 260bf57..f9c0ec6 100644
--- a/lib/rng.dart
+++ b/lib/rng.dart
@@ -27,7 +27,20 @@ abstract class RNG {
 class MathRNG extends RNG {
   final Random _rnd;
 
-  MathRNG({int? seed}) : _rnd = Random(seed);
+  factory MathRNG.fromSeed({int? seed}) {
+    Random rnd = seed == null ? Random() : Random(seed);
+    return MathRNG._internal(rnd);
+  }
+
+  factory MathRNG.fromRandom({Random? rnd}) {
+    return MathRNG._internal(rnd ?? Random());
+  }
+
+  factory MathRNG.noSeed() {
+    return MathRNG._internal(Random());
+  }
+
+  const MathRNG._internal(this._rnd);
 
   @override
   Uint8List generateInternal() {
diff --git a/lib/uuid.dart b/lib/uuid.dart
index e65f7be..0e531eb 100644
--- a/lib/uuid.dart
+++ b/lib/uuid.dart
@@ -200,7 +200,7 @@ class Uuid {
     V1Options? config,
     int offset = 0,
   }) {
-    var result = config != null ? v1(config: config) : v1(options: options);
+    var result = options != null ? v1(options: options) : v1(config: config);
     return UuidParsing.parse(result, buffer: buffer, offset: offset);
   }
 
@@ -233,9 +233,9 @@ class Uuid {
       {@Deprecated('use config instead. Removal in 5.0.0')
       Map<String, dynamic>? options,
       V1Options? config}) {
-    return config != null
-        ? UuidValue.fromString(v1(config: config))
-        : UuidValue.fromString(v1(options: options));
+    return options != null
+        ? UuidValue.fromString(v1(options: options))
+        : UuidValue.fromString(v1(config: config));
   }
 
   /// Generates a RNG version 4 UUID
@@ -339,7 +339,7 @@ class Uuid {
     V4Options? config,
     int offset = 0,
   }) {
-    var result = config != null ? v4(config: config) : v4(options: options);
+    var result = options != null ? v4(options: options) : v4(config: config);
     return UuidParsing.parse(result, buffer: buffer, offset: offset);
   }
 
@@ -373,9 +373,9 @@ class Uuid {
       {@Deprecated('use config instead. Removal in 5.0.0')
       Map<String, dynamic>? options,
       V4Options? config}) {
-    return config != null
-        ? UuidValue.fromString(v4(config: config))
-        : UuidValue.fromString(v4(options: options));
+    return options != null
+        ? UuidValue.fromString(v4(options: options))
+        : UuidValue.fromString(v4(config: config));
   }
 
   /// Generates a namespace & name-based version 5 UUID
@@ -440,9 +440,9 @@ class Uuid {
     V5Options? config,
     int offset = 0,
   }) {
-    var result = config != null
-        ? v5(namespace, name, config: config)
-        : v5(namespace, name, options: options);
+    var result = options != null
+        ? v5(namespace, name, options: options)
+        : v5(namespace, name, config: config);
     return UuidParsing.parse(result, buffer: buffer, offset: offset);
   }
 
@@ -471,9 +471,9 @@ class Uuid {
       {@Deprecated('use config instead. Removal in 5.0.0')
       Map<String, dynamic>? options,
       V5Options? config}) {
-    return config != null
-        ? UuidValue.fromString(v5(namespace, name, config: config))
-        : UuidValue.fromString(v5(namespace, name, options: options));
+    return options != null
+        ? UuidValue.fromString(v5(namespace, name, options: options))
+        : UuidValue.fromString(v5(namespace, name, config: config));
   }
 
   /// Generates a draft time-based version 6 UUID
diff --git a/lib/v1.dart b/lib/v1.dart
index 1cdf0a0..7e2331d 100644
--- a/lib/v1.dart
+++ b/lib/v1.dart
@@ -12,7 +12,8 @@ class UuidV1 {
   /// Primarily sets up the seedBytes then generates the node id and clockseq
   void _init() {
     if (V1State.initialized) return;
-    Uint8List seedBytes = goptions?.rng?.generate() ?? MathRNG().generate();
+    Uint8List seedBytes =
+        goptions?.rng?.generate() ?? MathRNG.noSeed().generate();
 
     // Per 4.5, create a 48-bit node id (47 random bits + multicast bit = 1)
     List<int> nodeId = [
diff --git a/lib/v4.dart b/lib/v4.dart
index 522b755..dec3821 100644
--- a/lib/v4.dart
+++ b/lib/v4.dart
@@ -18,9 +18,11 @@ class UuidV4 {
   /// http://tools.ietf.org/html/rfc4122.html#section-4.4
   String generate({V4Options? options}) {
     // Use the built-in RNG or a custom provided RNG
+
     List<int> rng = options?.rng?.generate() ??
         goptions?.rng?.generate() ??
-        MathRNG().generate();
+        options?.rng?.generate() ??
+        MathRNG.noSeed().generate();
 
     // Use provided values over RNG
     List<int> rnds = options?.random ?? rng;
diff --git a/lib/v6.dart b/lib/v6.dart
index 5d83aab..c075744 100644
--- a/lib/v6.dart
+++ b/lib/v6.dart
@@ -16,7 +16,8 @@ class UuidV6 {
   /// Primarily sets up the seedBytes then generates the node id and clockseq
   void _init() {
     if (V6State.initialized) return;
-    Uint8List seedBytes = goptions?.rng?.generate() ?? MathRNG().generate();
+    Uint8List seedBytes =
+        goptions?.rng?.generate() ?? MathRNG.noSeed().generate();
 
     // Per 4.5, create a 48-bit node id (47 random bits + multicast bit = 1)
     List<int> nodeId = [
diff --git a/lib/v7.dart b/lib/v7.dart
index a3fe126..d7ee034 100644
--- a/lib/v7.dart
+++ b/lib/v7.dart
@@ -34,7 +34,7 @@ class UuidV7 {
 
     buf.setAll(0, timeList48);
     List<int> randomBytes = options?.randomBytes ??
-        (goptions?.rng?.generate() ?? MathRNG().generate());
+        (goptions?.rng?.generate() ?? MathRNG.noSeed().generate());
 
     buf.setRange(6, 16, randomBytes);
     buf.setRange(6, 7, [buf.getRange(6, 7).last & 0x0f | 0x70]);
diff --git a/lib/v8.dart b/lib/v8.dart
index fe986e9..048548c 100644
--- a/lib/v8.dart
+++ b/lib/v8.dart
@@ -56,7 +56,7 @@ class UuidV8 {
         5, 6, UuidParsing.parseHexToBytes(sprintf('0x%02i', [time.minute])));
 
     var randomBytes = options?.randomBytes ??
-        (goptions?.rng?.generate() ?? MathRNG().generate());
+        (goptions?.rng?.generate() ?? MathRNG.noSeed().generate());
 
     buf.setRange(6, 16, randomBytes);
     buf.setRange(6, 7, [buf.getRange(6, 7).last & 0x0f | 0x80]);
diff --git a/pubspec.yaml b/pubspec.yaml
index 20f6502..afac1a0 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@ repository: https://github.com/Daegalus/dart-uuid
 environment:
   sdk: ">=3.0.0 <4.0.0"
 dependencies:
-  crypto: ^3.0.0
+  cryptography: ^2.7.0
   sprintf: ^7.0.0
   meta: ^1.10.0
   fixnum: ^1.1.0
diff --git a/test/uuid_test.dart b/test/uuid_test.dart
index fecdfe5..935a4ef 100644
--- a/test/uuid_test.dart
+++ b/test/uuid_test.dart
@@ -8,7 +8,7 @@ import 'package:uuid/uuid.dart';
 import 'package:uuid/rng.dart';
 
 void main() {
-  var uuid = const Uuid();
+  var uuid = Uuid();
   const testTime = 1321644961388;
 
   group('[Version 1 Tests]', () {
@@ -118,7 +118,7 @@ void main() {
   group('[Version 4 Tests]', () {
     test('Check if V4 is consistent using a static seed', () {
       var u0 = uuid.v4(options: {
-        'rng': MathRNG(seed: 1),
+        'rng': MathRNG.fromSeed(seed: 1),
       });
       var u1 = 'a462502a-73af-4e41-bfc4-05957b7030dd';
       expect(u0, equals(u1));
@@ -127,7 +127,7 @@ void main() {
     test('Consistency check with buffer', () {
       var buffer = Uint8List(16);
       uuid.v4buffer(buffer, options: {
-        'rng': MathRNG(seed: 1),
+        'rng': MathRNG.fromSeed(seed: 1),
       });
 
       var u1 = 'a462502a-73af-4e41-bfc4-05957b7030dd';
@@ -136,10 +136,10 @@ void main() {
 
     test('Using Objects', () {
       var regular = uuid.v4(options: {
-        'rng': MathRNG(seed: 1),
+        'rng': MathRNG.fromSeed(seed: 1),
       });
       var obj = uuid.v4obj(options: {
-        'rng': MathRNG(seed: 1),
+        'rng': MathRNG.fromSeed(seed: 1),
       });
 
       expect(obj.uuid, equals(regular));
@@ -185,7 +185,7 @@ void main() {
 
       var numDuplicates = 0;
       for (var i = 0; i < numToGenerate; i++) {
-        final uuid = generator.v4();
+        final uuid = generator.v4(config: V4Options(null, MathRNG.noSeed()));
 
         if (!values.contains(uuid)) {
           values.add(uuid);
@@ -359,7 +359,7 @@ void main() {
     });
 
     test('Explicit options produce expected id', () {
-      final rand = MathRNG(seed: 1).generate();
+      final rand = MathRNG.fromSeed(seed: 1).generate();
       var options = V7Options(1321651533573, rand);
       var id = uuid.v7(config: options);
 
@@ -395,7 +395,7 @@ void main() {
 
     test('Using buffers', () {
       var buffer = Uint8List(16);
-      final rand = MathRNG(seed: 1).generate();
+      final rand = MathRNG.fromSeed(seed: 1).generate();
       var options = V7Options(testTime, rand);
 
       var wihoutBuffer = uuid.v7(config: options);
@@ -405,7 +405,7 @@ void main() {
     });
 
     test('Using Objects', () {
-      final rand = MathRNG(seed: 1).generate();
+      final rand = MathRNG.fromSeed(seed: 1).generate();
       var options = V7Options(testTime, rand);
 
       var regular = uuid.v7(config: options);
@@ -601,7 +601,7 @@ void main() {
         ],
       }.entries) {
         test(testCase.key, () {
-          final rand = MathRNG(seed: 1).generate();
+          final rand = MathRNG.fromSeed(seed: 1).generate();
           final uuid =
               Uuid().v8(config: V8Options(testCase.value[0] as DateTime, rand));
           expect(uuid.toUpperCase(), equals(testCase.value[1]));