diff --git a/composer.json b/composer.json
index f95de58..b28110e 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
     },
     "require": {
         "web3p/rlp": "~0.2",
-        "web3p/secp256k1": "~0.2",
-        "kornrunner/keccak": "~1"
+        "kornrunner/keccak": "~1",
+        "simplito/elliptic-php": "1.0.3"
     }
 }
diff --git a/composer.lock b/composer.lock
index b51bca3..658fa03 100644
--- a/composer.lock
+++ b/composer.lock
@@ -1,45 +1,73 @@
 {
     "_readme": [
         "This file locks the dependencies of your project to a known state",
-        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "d49eae17ce62b9584285247e680e8e4a",
+    "content-hash": "4a0c191d5a2902125fc452718993b5ce",
     "packages": [
         {
-            "name": "fgrosse/phpasn1",
-            "version": "dev-master",
+            "name": "kornrunner/keccak",
+            "version": "1.0.2",
             "source": {
                 "type": "git",
-                "url": "https://github.com/fgrosse/PHPASN1.git",
-                "reference": "0e27e71e3d0a8d5c3f1471d727fd9574d920f33c"
+                "url": "https://github.com/kornrunner/php-keccak.git",
+                "reference": "b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/fgrosse/PHPASN1/zipball/0e27e71e3d0a8d5c3f1471d727fd9574d920f33c",
-                "reference": "0e27e71e3d0a8d5c3f1471d727fd9574d920f33c",
+                "url": "https://api.github.com/repos/kornrunner/php-keccak/zipball/b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34",
+                "reference": "b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34",
                 "shasum": ""
             },
             "require": {
-                "ext-gmp": "*",
-                "php": ">=7.0.0"
+                "php": ">=7.1.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "~6.3",
-                "satooshi/php-coveralls": "dev-master"
-            },
-            "suggest": {
-                "php-curl": "For loading OID information from the web if they have not bee defined statically"
+                "phpunit/phpunit": "~7",
+                "satooshi/php-coveralls": "~2"
             },
             "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "2.0.x-dev"
+            "autoload": {
+                "psr-4": {
+                    "kornrunner\\": "src"
                 }
             },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Boris Momcilovic",
+                    "homepage": "https://github.com/kornrunner/php-keccak"
+                }
+            ],
+            "description": "Pure PHP implementation of Keccak",
+            "keywords": [
+                "keccak",
+                "sha-3"
+            ],
+            "time": "2018-03-05T10:32:01+00:00"
+        },
+        {
+            "name": "simplito/bigint-wrapper-php",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/simplito/bigint-wrapper-php.git",
+                "reference": "cf21ec76d33f103add487b3eadbd9f5033a25930"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/simplito/bigint-wrapper-php/zipball/cf21ec76d33f103add487b3eadbd9f5033a25930",
+                "reference": "cf21ec76d33f103add487b3eadbd9f5033a25930",
+                "shasum": ""
+            },
+            "type": "library",
             "autoload": {
                 "psr-4": {
-                    "FG\\": "lib/"
+                    "BI\\": "lib/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -48,58 +76,38 @@
             ],
             "authors": [
                 {
-                    "name": "Friedrich Große",
-                    "email": "friedrich.grosse@gmail.com",
-                    "homepage": "https://github.com/FGrosse",
-                    "role": "Author"
-                },
-                {
-                    "name": "All contributors",
-                    "homepage": "https://github.com/FGrosse/PHPASN1/contributors"
+                    "name": "Simplito Team",
+                    "email": "s.smyczynski@simplito.com",
+                    "homepage": "https://simplito.com"
                 }
             ],
-            "description": "A PHP Framework that allows you to encode and decode arbitrary ASN.1 structures using the ITU-T X.690 Encoding Rules.",
-            "homepage": "https://github.com/FGrosse/PHPASN1",
-            "keywords": [
-                "DER",
-                "asn.1",
-                "asn1",
-                "ber",
-                "binary",
-                "decoding",
-                "encoding",
-                "x.509",
-                "x.690",
-                "x509",
-                "x690"
-            ],
-            "time": "2017-12-17 10:21:51"
+            "description": "Common interface for php_gmp and php_bcmath modules",
+            "time": "2018-02-27T12:38:08+00:00"
         },
         {
-            "name": "kornrunner/keccak",
-            "version": "1.0.2",
+            "name": "simplito/bn-php",
+            "version": "1.1.2",
             "source": {
                 "type": "git",
-                "url": "https://github.com/kornrunner/php-keccak.git",
-                "reference": "b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34"
+                "url": "https://github.com/simplito/bn-php.git",
+                "reference": "e852fcd27e4acbc32459606d7606e45a85e42465"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/kornrunner/php-keccak/zipball/b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34",
-                "reference": "b3cd83ded1acff7af40b4ca5b8ea76b164ed0c34",
+                "url": "https://api.github.com/repos/simplito/bn-php/zipball/e852fcd27e4acbc32459606d7606e45a85e42465",
+                "reference": "e852fcd27e4acbc32459606d7606e45a85e42465",
                 "shasum": ""
             },
             "require": {
-                "php": ">=7.1.0"
+                "simplito/bigint-wrapper-php": "~1.0.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "~7",
-                "satooshi/php-coveralls": "~2"
+                "phpunit/phpunit": "*"
             },
             "type": "library",
             "autoload": {
                 "psr-4": {
-                    "kornrunner\\": "src"
+                    "BN\\": "lib/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -108,45 +116,40 @@
             ],
             "authors": [
                 {
-                    "name": "Boris Momcilovic",
-                    "homepage": "https://github.com/kornrunner/php-keccak"
+                    "name": "Simplito Team",
+                    "email": "s.smyczynski@simplito.com",
+                    "homepage": "https://simplito.com"
                 }
             ],
-            "description": "Pure PHP implementation of Keccak",
-            "keywords": [
-                "keccak",
-                "sha-3"
-            ],
-            "time": "2018-03-05T10:32:01+00:00"
+            "description": "Big number implementation compatible with bn.js",
+            "time": "2018-04-12T11:07:43+00:00"
         },
         {
-            "name": "mdanter/ecc",
-            "version": "dev-master",
+            "name": "simplito/elliptic-php",
+            "version": "1.0.3",
             "source": {
                 "type": "git",
-                "url": "https://github.com/phpecc/phpecc.git",
-                "reference": "7c77251d3a7f52ef4ebc1c023452aad96ab13c83"
+                "url": "https://github.com/simplito/elliptic-php.git",
+                "reference": "cab829d270dfd6acdff8383d862ed02a12d1f9dd"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpecc/phpecc/zipball/7c77251d3a7f52ef4ebc1c023452aad96ab13c83",
-                "reference": "7c77251d3a7f52ef4ebc1c023452aad96ab13c83",
+                "url": "https://api.github.com/repos/simplito/elliptic-php/zipball/cab829d270dfd6acdff8383d862ed02a12d1f9dd",
+                "reference": "cab829d270dfd6acdff8383d862ed02a12d1f9dd",
                 "shasum": ""
             },
             "require": {
                 "ext-gmp": "*",
-                "fgrosse/phpasn1": "v2.0.x",
-                "php": ">=7.0"
+                "simplito/bn-php": "~1.1.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.0",
-                "squizlabs/php_codesniffer": "~2",
-                "symfony/yaml": "~2.6|~3.0"
+                "phpbench/phpbench": "@dev",
+                "phpunit/phpunit": "*"
             },
             "type": "library",
             "autoload": {
                 "psr-4": {
-                    "Mdanter\\Ecc\\": "src/"
+                    "Elliptic\\": "lib/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -155,29 +158,21 @@
             ],
             "authors": [
                 {
-                    "name": "Matyas Danter",
-                    "homepage": "http://matejdanter.com/",
-                    "role": "Author"
-                },
-                {
-                    "name": "Thibaud Fabre",
-                    "email": "thibaud@aztech.io",
-                    "homepage": "http://aztech.io",
-                    "role": "Maintainer"
-                },
-                {
-                    "name": "Thomas Kerin",
-                    "email": "afk11@users.noreply.github.com",
-                    "role": "Maintainer"
+                    "name": "Simplito Team",
+                    "email": "s.smyczynski@simplito.com",
+                    "homepage": "https://simplito.com"
                 }
             ],
-            "description": "PHP Elliptic Curve Cryptography library",
-            "homepage": "https://github.com/phpecc/phpecc",
+            "description": "Fast elliptic curve cryptography",
+            "homepage": "https://github.com/simplito/elliptic-php",
             "keywords": [
-                "Diffie",
+                "Curve25519",
                 "ECDSA",
-                "Hellman",
+                "Ed25519",
+                "EdDSA",
+                "cryptography",
                 "curve",
+                "ecc",
                 "ecdh",
                 "elliptic",
                 "nistp192",
@@ -185,11 +180,9 @@
                 "nistp256",
                 "nistp384",
                 "nistp521",
-                "phpecc",
-                "secp256k1",
-                "secp256r1"
+                "secp256k1"
             ],
-            "time": "2018-02-12 08:51:13"
+            "time": "2018-04-12T11:17:52+00:00"
         },
         {
             "name": "web3p/rlp",
@@ -226,45 +219,6 @@
             ],
             "description": "Recursive Length Prefix Encoding in PHP.",
             "time": "2018-03-19T15:21:29+00:00"
-        },
-        {
-            "name": "web3p/secp256k1",
-            "version": "v0.2",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/web3p/secp256k1.git",
-                "reference": "f63f4e88de662311f114b510a1c17a460e20dbf2"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/web3p/secp256k1/zipball/f63f4e88de662311f114b510a1c17a460e20dbf2",
-                "reference": "f63f4e88de662311f114b510a1c17a460e20dbf2",
-                "shasum": ""
-            },
-            "require": {
-                "mdanter/ecc": "dev-master"
-            },
-            "require-dev": {
-                "phpunit/phpunit": "~6.0"
-            },
-            "type": "library",
-            "autoload": {
-                "psr-4": {
-                    "Web3p\\Secp256k1\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "sc0Vu",
-                    "email": "alk03073135@gmail.com"
-                }
-            ],
-            "description": "Ethereum secp256k1 library in PHP.",
-            "time": "2018-03-20T02:37:13+00:00"
         }
     ],
     "packages-dev": [
@@ -321,7 +275,7 @@
                 "constructor",
                 "instantiate"
             ],
-            "time": "2018-03-05 09:41:42"
+            "time": "2018-03-05T09:41:42+00:00"
         },
         {
             "name": "myclabs/deep-copy",
@@ -371,7 +325,7 @@
                 "object",
                 "object graph"
             ],
-            "time": "2017-12-18 00:20:24"
+            "time": "2017-12-18T00:20:24+00:00"
         },
         {
             "name": "phar-io/manifest",
@@ -426,7 +380,7 @@
                 }
             ],
             "description": "Component for reading phar.io manifest information from a PHP Archive (PHAR)",
-            "time": "2017-04-07 07:07:10"
+            "time": "2017-04-07T07:07:10+00:00"
         },
         {
             "name": "phar-io/version",
@@ -477,28 +431,28 @@
         },
         {
             "name": "phpdocumentor/reflection-common",
-            "version": "dev-master",
+            "version": "1.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionCommon.git",
-                "reference": "81339187a96c6fdb70cd876b129891f8ca501508"
+                "reference": "21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/81339187a96c6fdb70cd876b129891f8ca501508",
-                "reference": "81339187a96c6fdb70cd876b129891f8ca501508",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6",
+                "reference": "21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6",
                 "shasum": ""
             },
             "require": {
-                "php": ">=7.1"
+                "php": ">=5.5"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6"
+                "phpunit/phpunit": "^4.6"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.x-dev"
+                    "dev-master": "1.0.x-dev"
                 }
             },
             "autoload": {
@@ -527,30 +481,32 @@
                 "reflection",
                 "static analysis"
             ],
-            "time": "2018-02-14 18:58:54"
+            "time": "2017-09-11T18:02:19+00:00"
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "dev-master",
+            "version": "4.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "182609736818dc750d42470c0be2a5ed74bad3bd"
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/182609736818dc750d42470c0be2a5ed74bad3bd",
-                "reference": "182609736818dc750d42470c0be2a5ed74bad3bd",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/94fd0001232e47129dd3504189fa1c7225010d08",
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08",
                 "shasum": ""
             },
             "require": {
-                "php": ">=7.1",
-                "phpdocumentor/type-resolver": "^0",
-                "webmozart/assert": "^1"
+                "php": "^7.0",
+                "phpdocumentor/reflection-common": "^1.0.0",
+                "phpdocumentor/type-resolver": "^0.4.0",
+                "webmozart/assert": "^1.0"
             },
             "require-dev": {
-                "doctrine/instantiator": "^1",
-                "mockery/mockery": "^1"
+                "doctrine/instantiator": "~1.0.5",
+                "mockery/mockery": "^1.0",
+                "phpunit/phpunit": "^6.4"
             },
             "type": "library",
             "extra": {
@@ -560,7 +516,9 @@
             },
             "autoload": {
                 "psr-4": {
-                    "phpDocumentor\\Reflection\\": "src"
+                    "phpDocumentor\\Reflection\\": [
+                        "src/"
+                    ]
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -574,39 +532,41 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2018-02-14 19:00:58"
+            "time": "2017-11-30T07:14:17+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
-            "version": "dev-master",
+            "version": "0.4.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/TypeResolver.git",
-                "reference": "69bf1b199584f2004365a150c2e6cfbe852b6d66"
+                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/69bf1b199584f2004365a150c2e6cfbe852b6d66",
-                "reference": "69bf1b199584f2004365a150c2e6cfbe852b6d66",
+                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/9c977708995954784726e25d0cd1dddf4e65b0f7",
+                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7",
                 "shasum": ""
             },
             "require": {
-                "php": ">=7.1",
-                "phpdocumentor/reflection-common": "^2"
+                "php": "^5.5 || ^7.0",
+                "phpdocumentor/reflection-common": "^1.0"
             },
             "require-dev": {
-                "mockery/mockery": "^1.0",
-                "phpunit/phpunit": "^6.5"
+                "mockery/mockery": "^0.9.4",
+                "phpunit/phpunit": "^5.2||^4.8.24"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "0.x-dev"
+                    "dev-master": "1.0.x-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
-                    "phpDocumentor\\Reflection\\": "src"
+                    "phpDocumentor\\Reflection\\": [
+                        "src/"
+                    ]
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -619,7 +579,7 @@
                     "email": "me@mikevanriel.com"
                 }
             ],
-            "time": "2018-02-14 18:59:20"
+            "time": "2017-07-14T14:27:02+00:00"
         },
         {
             "name": "phpspec/prophecy",
@@ -627,19 +587,19 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "dfd6be44111a7c41c2e884a336cc4f461b3b2401"
+                "reference": "5d4764d0b9beb04d5b36801c868cfc79a12c70a3"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/dfd6be44111a7c41c2e884a336cc4f461b3b2401",
-                "reference": "dfd6be44111a7c41c2e884a336cc4f461b3b2401",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/5d4764d0b9beb04d5b36801c868cfc79a12c70a3",
+                "reference": "5d4764d0b9beb04d5b36801c868cfc79a12c70a3",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.2",
                 "php": "^5.3|^7.0",
                 "phpdocumentor/reflection-docblock": "^2.0|^3.0.2|^4.0",
-                "sebastian/comparator": "^1.1|^2.0",
+                "sebastian/comparator": "^1.1|^2.0|^3.0",
                 "sebastian/recursion-context": "^1.0|^2.0|^3.0"
             },
             "require-dev": {
@@ -682,7 +642,7 @@
                 "spy",
                 "stub"
             ],
-            "time": "2018-02-19 10:16:54"
+            "time": "2018-04-19T14:17:18+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
@@ -690,12 +650,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "982ce790a6f31b8f1319a15d86e4614b109af25e"
+                "reference": "83f09c29758c52e71bdb81ad2cc9124b85b5a4ef"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/982ce790a6f31b8f1319a15d86e4614b109af25e",
-                "reference": "982ce790a6f31b8f1319a15d86e4614b109af25e",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/83f09c29758c52e71bdb81ad2cc9124b85b5a4ef",
+                "reference": "83f09c29758c52e71bdb81ad2cc9124b85b5a4ef",
                 "shasum": ""
             },
             "require": {
@@ -745,7 +705,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-12-07 10:13:30"
+            "time": "2018-04-07T12:06:18+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",
@@ -792,7 +752,7 @@
                 "filesystem",
                 "iterator"
             ],
-            "time": "2017-11-27 13:52:08"
+            "time": "2017-11-27T13:52:08+00:00"
         },
         {
             "name": "phpunit/php-text-template",
@@ -882,7 +842,7 @@
             "keywords": [
                 "timer"
             ],
-            "time": "2018-01-06 05:27:16"
+            "time": "2018-01-06T05:27:16+00:00"
         },
         {
             "name": "phpunit/php-token-stream",
@@ -931,7 +891,7 @@
             "keywords": [
                 "tokenizer"
             ],
-            "time": "2017-11-27 08:47:38"
+            "time": "2017-11-27T08:47:38+00:00"
         },
         {
             "name": "phpunit/phpunit",
@@ -939,12 +899,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "ea739aae4742aa4eae1e98d4d06acdbf01692415"
+                "reference": "1617f456e1522f9b32723549ddc5a370f8322e91"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/ea739aae4742aa4eae1e98d4d06acdbf01692415",
-                "reference": "ea739aae4742aa4eae1e98d4d06acdbf01692415",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/1617f456e1522f9b32723549ddc5a370f8322e91",
+                "reference": "1617f456e1522f9b32723549ddc5a370f8322e91",
                 "shasum": ""
             },
             "require": {
@@ -1015,7 +975,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2018-03-15T16:51:04+00:00"
+            "time": "2018-04-16T03:59:19+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
@@ -1074,7 +1034,7 @@
                 "mock",
                 "xunit"
             ],
-            "time": "2018-01-07 17:10:51"
+            "time": "2018-01-07T17:10:51+00:00"
         },
         {
             "name": "sebastian/code-unit-reverse-lookup",
@@ -1119,11 +1079,11 @@
             ],
             "description": "Looks up which function or method a line of code belongs to",
             "homepage": "https://github.com/sebastianbergmann/code-unit-reverse-lookup/",
-            "time": "2017-03-04 10:23:55"
+            "time": "2017-03-04T10:23:55+00:00"
         },
         {
             "name": "sebastian/comparator",
-            "version": "dev-master",
+            "version": "2.1.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/comparator.git",
@@ -1183,7 +1143,7 @@
                 "compare",
                 "equality"
             ],
-            "time": "2018-02-01 13:46:46"
+            "time": "2018-02-01T13:46:46+00:00"
         },
         {
             "name": "sebastian/diff",
@@ -1235,20 +1195,20 @@
             "keywords": [
                 "diff"
             ],
-            "time": "2017-12-14 11:32:19"
+            "time": "2017-12-14T11:32:19+00:00"
         },
         {
             "name": "sebastian/environment",
-            "version": "3.1.0",
+            "version": "dev-master",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/environment.git",
-                "reference": "cd0871b3975fb7fc44d11314fd1ee20925fce4f5"
+                "reference": "cd35e43a53ec1c10424a5dec250c30e952e09ced"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/cd0871b3975fb7fc44d11314fd1ee20925fce4f5",
-                "reference": "cd0871b3975fb7fc44d11314fd1ee20925fce4f5",
+                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/cd35e43a53ec1c10424a5dec250c30e952e09ced",
+                "reference": "cd35e43a53ec1c10424a5dec250c30e952e09ced",
                 "shasum": ""
             },
             "require": {
@@ -1285,7 +1245,7 @@
                 "environment",
                 "hhvm"
             ],
-            "time": "2017-07-01T08:51:00+00:00"
+            "time": "2018-03-21T07:21:42+00:00"
         },
         {
             "name": "sebastian/exporter",
@@ -1352,7 +1312,7 @@
                 "export",
                 "exporter"
             ],
-            "time": "2017-11-16 09:48:09"
+            "time": "2017-11-16T09:48:09+00:00"
         },
         {
             "name": "sebastian/global-state",
@@ -1403,7 +1363,7 @@
             "keywords": [
                 "global state"
             ],
-            "time": "2017-11-16 09:49:42"
+            "time": "2017-11-16T09:49:42+00:00"
         },
         {
             "name": "sebastian/object-enumerator",
@@ -1450,7 +1410,7 @@
             ],
             "description": "Traverses array structures and object graphs to enumerate all referenced objects",
             "homepage": "https://github.com/sebastianbergmann/object-enumerator/",
-            "time": "2017-11-16 09:50:04"
+            "time": "2017-11-16T09:50:04+00:00"
         },
         {
             "name": "sebastian/object-reflector",
@@ -1495,7 +1455,7 @@
             ],
             "description": "Allows reflection of object attributes, including inherited and non-public ones",
             "homepage": "https://github.com/sebastianbergmann/object-reflector/",
-            "time": "2018-01-07 16:00:13"
+            "time": "2018-01-07T16:00:13+00:00"
         },
         {
             "name": "sebastian/recursion-context",
@@ -1548,7 +1508,7 @@
             ],
             "description": "Provides functionality to recursively process PHP variables",
             "homepage": "http://www.github.com/sebastianbergmann/recursion-context",
-            "time": "2017-11-16 10:04:08"
+            "time": "2017-11-16T10:04:08+00:00"
         },
         {
             "name": "sebastian/resource-operations",
@@ -1590,7 +1550,7 @@
             ],
             "description": "Provides a list of PHP built-in functions that operate on resources",
             "homepage": "https://www.github.com/sebastianbergmann/resource-operations",
-            "time": "2016-10-03 07:43:09"
+            "time": "2016-10-03T07:43:09+00:00"
         },
         {
             "name": "sebastian/version",
@@ -1681,12 +1641,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/webmozart/assert.git",
-                "reference": "0df1908962e7a3071564e857d86874dad1ef204a"
+                "reference": "23bf61bc8a7cc229d7ce8689b1bf818a9e192cac"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/assert/zipball/0df1908962e7a3071564e857d86874dad1ef204a",
-                "reference": "0df1908962e7a3071564e857d86874dad1ef204a",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/23bf61bc8a7cc229d7ce8689b1bf818a9e192cac",
+                "reference": "23bf61bc8a7cc229d7ce8689b1bf818a9e192cac",
                 "shasum": ""
             },
             "require": {
@@ -1723,7 +1683,7 @@
                 "check",
                 "validate"
             ],
-            "time": "2018-01-29 19:49:41"
+            "time": "2018-04-19T15:46:26+00:00"
         }
     ],
     "aliases": [],
diff --git a/src/Transaction.php b/src/Transaction.php
index bd1f613..cb94056 100644
--- a/src/Transaction.php
+++ b/src/Transaction.php
@@ -15,7 +15,8 @@
 use RuntimeException;
 use kornrunner\Keccak;
 use Web3p\RLP\RLP;
-use Web3p\Secp256k1\Secp256k1;
+use Elliptic\EC;
+use Elliptic\EC\KeyPair;
 use ArrayAccess;
 
 class Transaction implements ArrayAccess
@@ -64,10 +65,17 @@ class Transaction implements ArrayAccess
     /**
      * secp256k1
      * 
-     * @var \Web3p\Secp256k1\Secp256k1
+     * @var \Elliptic\EC
      */
     protected $secp256k1;
 
+    /**
+     * privateKey
+     * 
+     * @var \Elliptic\EC\KeyPair
+     */
+    protected $privateKey;
+
     /**
      * construct
      * 
@@ -84,7 +92,7 @@ public function __construct(array $txData=[])
             }
         }
         $this->rlp = new RLP;
-        $this->secp256k1 = new Secp256k1;
+        $this->secp256k1 = new EC('secp256k1');
     }
 
     /**
@@ -210,11 +218,8 @@ public function getTxData()
      * @param string $value
      * @return string
      */
-    public function sha3($value)
+    public function sha3(string $value)
     {
-        if (!is_string($value)) {
-            throw new InvalidArgumentException('The value to sha3 function must be string.');
-        }
         $hash = Keccak::hash($value, 256);
 
         if ($hash === $this::SHA3_NULL_HASH) {
@@ -226,19 +231,21 @@ public function sha3($value)
     /**
      * serialize
      * 
-     * @return string
+     * @return \Web3p\RLP\RLP\Buffer
      */
     public function serialize()
     {
-        $v = 37;
         $chainId = $this->offsetGet('chainId');
 
-        if ($chainId) {
-            $v = (int) $chainId * 2 + 35;
+        // sort tx data
+        if (ksort($this->txData) !== true) {
+            throw new RuntimeException('Cannot sort tx data by keys.');
+        }
+        if ($chainId && $chainId > 0) {
+            $txData = array_fill(0, 9, '');
+        } else {
+            $txData = array_fill(0, 6, '');
         }
-        $this->offsetSet('v', $v);
-        $txData = array_fill(0, 9, '');
-
         foreach ($this->txData as $key => $data) {
             if ($key >= 0) {
                 $txData[$key] = $data;
@@ -255,15 +262,23 @@ public function serialize()
      */
     public function sign(string $privateKey)
     {
-        $txHash = $this->hash();
-        $rlp = new RLP;
-        $secp256k1 = new Secp256k1;
-        $signature = $secp256k1->sign($txHash, $privateKey);
-        $r = $signature->getR();
-        $s = $signature->getS();
+        $txHash = $this->hash(false);
+        $privateKey = $this->secp256k1->keyFromPrivate($privateKey, 'hex');
+        $signature = $privateKey->sign($txHash);
+        $r = $signature->r;
+        $s = $signature->s;
+        $v = $signature->recoveryParam + 35;
 
-        $this->offsetSet('r', '0x' . gmp_strval($r, 16));
-        $this->offsetSet('s', '0x' . gmp_strval($s, 16));
+        $chainId = $this->offsetGet('chainId');
+
+        if ($chainId && $chainId > 0) {
+            $v += (int) $chainId * 2;
+        }
+
+        $this->offsetSet('r', '0x' . $r->toString(16));
+        $this->offsetSet('s', '0x' . $s->toString(16));
+        $this->offsetSet('v', $v);
+        $this->privateKey = $privateKey;
 
         return $this->serialize()->toString('hex');
     }
@@ -271,11 +286,80 @@ public function sign(string $privateKey)
     /**
      * hash
      *
+     * @param bool $includeSignature
      * @return string
      */
-    public function hash()
+    public function hash($includeSignature=false)
     {
-        $serializedTx = $this->serialize()->toString('utf8');
+        $chainId = $this->offsetGet('chainId');
+
+        // sort tx data
+        if (ksort($this->txData) !== true) {
+            throw new RuntimeException('Cannot sort tx data by keys.');
+        }
+        if ($includeSignature) {
+            $txData = $this->txData;
+        } else {
+            if ($chainId && $chainId > 0) {
+                $v = (int) $chainId;
+                $this->offsetSet('r', '');
+                $this->offsetSet('s', '');
+                $this->offsetSet('v', $v);
+                $txData = array_fill(0, 9, '');
+            } else {
+                $txData = array_fill(0, 6, '');
+            }
+
+            foreach ($this->txData as $key => $data) {
+                if ($key >= 0) {
+                    $txData[$key] = $data;
+                }
+            }
+        }
+        $serializedTx = $this->rlp->encode($txData)->toString('utf8');
+
         return $this->sha3($serializedTx);
     }
+
+    /**
+     * getFromAddress
+     * 
+     * @return string
+     */
+    public function getFromAddress()
+    {
+        $from = $this->offsetGet('from');
+
+        if ($from) {
+            return $from;
+        }
+        if (!isset($this->privateKey) || !($this->privateKey instanceof KeyPair)) {
+            // recover from hash
+            $r = $this->offsetGet('r');
+            $s = $this->offsetGet('s');
+            $v = $this->offsetGet('v');
+            $chainId = $this->offsetGet('chainId');
+
+            if (!$r || !$s) {
+                throw new RuntimeException('Invalid signature r and s.');
+            }
+            $txHash = $this->hash(false);
+
+            if ($chainId && $chainId > 0) {
+                $v -= ($chainId * 2);
+            }
+            $v -= 35;
+            $publicKey = $this->secp256k1->recoverPubKey($txHash, [
+                'r' => $r,
+                's' => $s
+            ], $v);
+            $publicKey = $publicKey->encode('hex');
+        } else {
+            $publicKey = $this->privateKey->getPublic(false, 'hex');
+        }
+        $from = '0x' . substr($this->sha3(substr(hex2bin($publicKey), 1)), 24);
+
+        $this->offsetSet('from', $from);
+        return $from;
+    }
 }
\ No newline at end of file
diff --git a/test/unit/TransactionTest.php b/test/unit/TransactionTest.php
index 72eee74..9ad21f6 100644
--- a/test/unit/TransactionTest.php
+++ b/test/unit/TransactionTest.php
@@ -100,11 +100,11 @@ public function testSet()
     }
 
     /**
-     * testSerialize
+     * testSha3
      * 
      * @return void
      */
-    public function testSerialize()
+    public function testSha3()
     {
         $transaction = new Transaction([
             'nonce' => '0x01',
@@ -113,11 +113,21 @@ public function testSerialize()
             'gas' => '0x76c0',
             'gasPrice' => '0x9184e72a000',
             'value' => '0x9184e72a',
+            'chainId' => 4,
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
 
-        $this->assertEquals('f852018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675258080', $transaction->serialize()->toString('hex'));
+        $this->assertNull($transaction->sha3(''));
+        $this->assertEquals('47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad', $transaction->sha3('hello world'));
+    }
 
+    /**
+     * testHash
+     * 
+     * @return void
+     */
+    public function testHash()
+    {
         $transaction = new Transaction([
             'nonce' => '0x01',
             'from' => '0xb60e8dd61c5d32be8058bb8eb970870f07233155',
@@ -125,20 +135,11 @@ public function testSerialize()
             'gas' => '0x76c0',
             'gasPrice' => '0x9184e72a000',
             'value' => '0x9184e72a',
-            'chainId' => 4,
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
 
-        $this->assertEquals('f852018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f0724456752b8080', $transaction->serialize()->toString('hex'));
-    }
+        $this->assertEquals('79617051b33e38636c12fb761abf62c20a9dd5a743ca5f338f04f2cf5f2ec6bd', $transaction->hash());
 
-    /**
-     * testSha3
-     * 
-     * @return void
-     */
-    public function testSha3()
-    {
         $transaction = new Transaction([
             'nonce' => '0x01',
             'from' => '0xb60e8dd61c5d32be8058bb8eb970870f07233155',
@@ -150,16 +151,15 @@ public function testSha3()
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
 
-        $this->assertNull($transaction->sha3(''));
-        $this->assertEquals('47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad', $transaction->sha3('hello world'));
+        $this->assertEquals('8aace0c8df439c9cc9f313b116f1db03e0811ca07e582d351aad1c9d6542c23d', (string) $transaction);
     }
 
     /**
-     * testHash
+     * testSign
      * 
      * @return void
      */
-    public function testHash()
+    public function testSign()
     {
         $transaction = new Transaction([
             'nonce' => '0x01',
@@ -170,9 +170,16 @@ public function testHash()
             'value' => '0x9184e72a',
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
+        $this->assertEquals('f892018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f07244567523a0a48d3ce9c68bb49825aea5335bd07432823e858e8a504767d08290c28aafddf8a0416c7abc3a67080db0ad07c42de82db4e05518f99595119677398c68d431ab37', $transaction->sign($this->testPrivateKey));
+    }
 
-        $this->assertEquals('710aee292b0f1749aaa0cfef67111e2f716afbdb475e7f250bdb80c6655b0a66', $transaction->hash());
-
+    /**
+     * testSerialize
+     * 
+     * @return void
+     */
+    public function testSerialize()
+    {
         $transaction = new Transaction([
             'nonce' => '0x01',
             'from' => '0xb60e8dd61c5d32be8058bb8eb970870f07233155',
@@ -180,29 +187,96 @@ public function testHash()
             'gas' => '0x76c0',
             'gasPrice' => '0x9184e72a000',
             'value' => '0x9184e72a',
-            'chainId' => 4,
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
 
-        $this->assertEquals('dd4238507087c6d354079ea5a4c8da7abde43252f0accf79601d0fa1a10300d8', (string) $transaction);
+        $this->assertEquals('f84f018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675', $transaction->serialize()->toString('hex'));
+
+        // sign tx
+        $transaction->sign($this->testPrivateKey);
+
+        $this->assertEquals('f892018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f07244567523a0a48d3ce9c68bb49825aea5335bd07432823e858e8a504767d08290c28aafddf8a0416c7abc3a67080db0ad07c42de82db4e05518f99595119677398c68d431ab37', $transaction->serialize()->toString('hex'));
     }
 
     /**
-     * testSign
+     * testEIP155
+     * you can find test case here: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
      * 
      * @return void
      */
-    public function testSign()
+    public function testEIP155()
     {
         $transaction = new Transaction([
-            'nonce' => '0x01',
-            'from' => '0xb60e8dd61c5d32be8058bb8eb970870f07233155',
-            'to' => '0xd46e8dd67c5d32be8058bb8eb970870f07244567',
-            'gas' => '0x76c0',
-            'gasPrice' => '0x9184e72a000',
-            'value' => '0x9184e72a',
-            'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
+            'nonce' => '0x09',
+            'to' => '0x3535353535353535353535353535353535353535',
+            'gas' => '0x5208',
+            'gasPrice' => '0x4a817c800',
+            'value' => '0xde0b6b3a7640000',
+            'chainId' => 1,
+            'data' => ''
         ]);
-        $this->assertEquals('f892018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f07244567525a08d8bfd01c48454b5b3fed2361cbd0e8c3282d5bd2e26762e4c9dfbe1ef35f325a06d6a5dc397934b5544835f34ff24263cbc00bdd516b6f0df3f29cdf6c779ccfb', $transaction->sign($this->testPrivateKey));
+        $this->assertEquals('daf5a779ae972f972197303d7b574746c7ef83eadac0f2791ad23db92e4c8e53', $transaction->hash(false));
+        $this->assertEquals('f86c098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a028ef61340bd939bc2195fe537567866003e1a15d3c71ff63e1590620aa636276a067cbe9d8997f761aecb703304b3800ccf555c9f3dc64214b297fb1966a3b6d83', $transaction->sign('0x4646464646464646464646464646464646464646464646464646464646464646'));
+    }
+
+    /**
+     * testGetFromAddress
+     * 0x9d8a62f656a8d1615c1294fd71e9cfb3e4855a4f
+     * 
+     * @return void
+     */
+    public function testGetFromAddress()
+    {
+        $transaction = new Transaction([
+            'nonce' => '0x09',
+            'to' => '0x3535353535353535353535353535353535353535',
+            'gas' => '0x5208',
+            'gasPrice' => '0x4a817c800',
+            'value' => '0xde0b6b3a7640000',
+            'chainId' => 1,
+            'data' => ''
+        ]);
+        // sign tx
+        $transaction->sign('0x4646464646464646464646464646464646464646464646464646464646464646');
+        $r = $transaction['r'];
+        $s = $transaction['s'];
+        $v = $transaction['v'];
+
+        // get from privatekey
+        $fromA = $transaction->getFromAddress();
+
+        $transaction = new Transaction([
+            'nonce' => '0x09',
+            'to' => '0x3535353535353535353535353535353535353535',
+            'gas' => '0x5208',
+            'gasPrice' => '0x4a817c800',
+            'value' => '0xde0b6b3a7640000',
+            'chainId' => 1,
+            'data' => ''
+        ]);
+        $transaction['r'] = $r;
+        $transaction['s'] = $s;
+        $transaction['v'] = $v;
+
+        // get from r, s, v
+        $fromB = $transaction->getFromAddress();
+
+        $transaction = new Transaction([
+            'from' => '0x9d8a62f656a8d1615c1294fd71e9cfb3e4855a4f',
+            'nonce' => '0x09',
+            'to' => '0x3535353535353535353535353535353535353535',
+            'gas' => '0x5208',
+            'gasPrice' => '0x4a817c800',
+            'value' => '0xde0b6b3a7640000',
+            'chainId' => 1,
+            'data' => ''
+        ]);
+
+        // get from transaction
+        $fromC = $transaction->getFromAddress();
+
+        $this->assertEquals('0x9d8a62f656a8d1615c1294fd71e9cfb3e4855a4f', $fromA);
+        $this->assertEquals($fromA, $fromB);
+        $this->assertEquals($fromB, $fromC);
     }
 }
\ No newline at end of file