diff --git a/composer.json b/composer.json
index e03dcef..673a69e 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
         "guzzlehttp/guzzle": "^6.3|^7.0",
         "PHP": "^7.2|^8.0",
         "kornrunner/keccak": "~1.0",
-        "phpseclib/phpseclib": "~2.0.30",
+        "phpseclib/phpseclib": "~3.0",
         "ext-mbstring": "*"
     },
     "require-dev": {
diff --git a/src/Utils.php b/src/Utils.php
index 8883c2b..d016007 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -11,11 +11,12 @@
 
 namespace Web3;
 
+use phpseclib3\Math\BigInteger;
 use RuntimeException;
 use InvalidArgumentException;
 use stdClass;
 use kornrunner\Keccak;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class Utils
 {
@@ -293,7 +294,7 @@ class Utils
      * 
      * @param BigNumber|string $number
      * @param string $unit
-     * @return \phpseclib\Math\BigInteger
+     * @return \phpseclib3\Math\BigInteger
      */
     public static function toWei($number, $unit)
     {
@@ -319,26 +320,7 @@ class Utils
             }
             $whole = $whole->multiply($bnt);
 
-            // There is no pow function in phpseclib 2.0, only can see in dev-master
-            // Maybe implement own biginteger in the future
-            // See 2.0 BigInteger: https://github.com/phpseclib/phpseclib/blob/2.0/phpseclib/Math/BigInteger.php
-            // See dev-master BigInteger: https://github.com/phpseclib/phpseclib/blob/master/phpseclib/Math/BigInteger.php#L700
-            // $base = (new BigNumber(10))->pow(new BigNumber($fractionLength));
-
-            // So we switch phpseclib special global param, change in the future
-            switch (MATH_BIGINTEGER_MODE) {
-                case $whole::MODE_GMP:
-                    static $two;
-                    $powerBase = gmp_pow(gmp_init(10), (int) $fractionLength);
-                    break;
-                case $whole::MODE_BCMATH:
-                    $powerBase = bcpow('10', (string) $fractionLength, 0);
-                    break;
-                default:
-                    $powerBase = pow(10, (int) $fractionLength);
-                    break;
-            }
-            $base = new BigNumber($powerBase);
+            $base = (new BigNumber(10))->pow(new BigNumber($fractionLength));
             $fraction = $fraction->multiply($bnt)->divide($base)[0];
 
             if ($negative1 !== false) {
@@ -381,7 +363,7 @@ class Utils
      * 
      * @param BigNumber|string|int $number
      * @param string $unit
-     * @return \phpseclib\Math\BigInteger
+     * @return \phpseclib3\Math\BigInteger
      */
     public static function fromWei($number, $unit)
     {
@@ -484,7 +466,7 @@ class Utils
      * Change number or number string to bignumber.
      * 
      * @param BigNumber|string|int $number
-     * @return array|\phpseclib\Math\BigInteger
+     * @return array|\phpseclib3\Math\BigInteger
      */
     public static function toBn($number)
     {
@@ -545,4 +527,4 @@ class Utils
         }
         return $bn;
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/BigNumberFormatterTest.php b/test/unit/BigNumberFormatterTest.php
index 87dc621..43ac8ba 100644
--- a/test/unit/BigNumberFormatterTest.php
+++ b/test/unit/BigNumberFormatterTest.php
@@ -3,7 +3,7 @@
 namespace Test\Unit;
 
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 use Web3\Formatters\BigNumberFormatter;
 
 class BigNumberFormatterTest extends TestCase
@@ -39,4 +39,4 @@ class BigNumberFormatterTest extends TestCase
         $this->assertEquals($bigNumber->toString(), '1');
         $this->assertTrue($bigNumber instanceof BigNumber);
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/ContractTest.php b/test/unit/ContractTest.php
index 5061abc..06bd0c1 100644
--- a/test/unit/ContractTest.php
+++ b/test/unit/ContractTest.php
@@ -10,7 +10,7 @@ use Web3\Contract;
 use Web3\Utils;
 use Web3\Contracts\Ethabi;
 use Web3\Formatters\IntegerFormatter;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class ContractTest extends TestCase
 {
@@ -1514,4 +1514,4 @@ class ContractTest extends TestCase
             }
         });
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/EthApiTest.php b/test/unit/EthApiTest.php
index 2f58bc4..b138839 100644
--- a/test/unit/EthApiTest.php
+++ b/test/unit/EthApiTest.php
@@ -5,7 +5,7 @@ namespace Test\Unit;
 use RuntimeException;
 use InvalidArgumentException;
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class EthApiTest extends TestCase
 {
@@ -822,4 +822,4 @@ class EthApiTest extends TestCase
 
         $eth->protocolVersion();
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/EthBatchTest.php b/test/unit/EthBatchTest.php
index 976fe20..42394b8 100644
--- a/test/unit/EthBatchTest.php
+++ b/test/unit/EthBatchTest.php
@@ -4,7 +4,7 @@ namespace Test\Unit;
 
 use RuntimeException;
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class EthBatchTest extends TestCase
 {
@@ -48,4 +48,4 @@ class EthBatchTest extends TestCase
             $this->assertTrue($data[1] !== null);
         });
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/NetApiTest.php b/test/unit/NetApiTest.php
index 4914235..6ad02b0 100644
--- a/test/unit/NetApiTest.php
+++ b/test/unit/NetApiTest.php
@@ -5,7 +5,7 @@ namespace Test\Unit;
 use RuntimeException;
 use InvalidArgumentException;
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class NetApiTest extends TestCase
 {
@@ -111,4 +111,4 @@ class NetApiTest extends TestCase
 
         $net->version();
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/NetBatchTest.php b/test/unit/NetBatchTest.php
index 8d6d5e3..cee8bf0 100644
--- a/test/unit/NetBatchTest.php
+++ b/test/unit/NetBatchTest.php
@@ -4,7 +4,7 @@ namespace Test\Unit;
 
 use RuntimeException;
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 
 class NetBatchTest extends TestCase
 {
@@ -50,4 +50,4 @@ class NetBatchTest extends TestCase
             $this->assertTrue($data[2] instanceof BigNumber);
         });
     }
-}
\ No newline at end of file
+}
diff --git a/test/unit/UtilsTest.php b/test/unit/UtilsTest.php
index 566c699..117a96a 100644
--- a/test/unit/UtilsTest.php
+++ b/test/unit/UtilsTest.php
@@ -5,7 +5,7 @@ namespace Test\Unit;
 use InvalidArgumentException;
 use stdClass;
 use Test\TestCase;
-use phpseclib\Math\BigInteger as BigNumber;
+use phpseclib3\Math\BigInteger as BigNumber;
 use Web3\Utils;
 use Web3\Contract;
 
@@ -649,4 +649,4 @@ class UtilsTest extends TestCase
         $this->expectException(InvalidArgumentException::class);
         $bn = Utils::toBn(new stdClass);
     }
-}
\ No newline at end of file
+}