diff --git a/.solhint.json b/.solhint.json
index 1968b23..5800f0b 100644
--- a/.solhint.json
+++ b/.solhint.json
@@ -1,7 +1,7 @@
 {
   "extends": "solhint:default",
   "rules": {
-    "func-order": false,
-    "not-rely-on-time": false
+    "func-order": "off",
+    "not-rely-on-time": "off"
   }
 }
diff --git a/dist/es/cipher.js b/dist/es/cipher.js
index ea1ae50..f2cc5a3 100644
--- a/dist/es/cipher.js
+++ b/dist/es/cipher.js
@@ -6,10 +6,10 @@ export function stringify(cipher) {
     // use compressed key because it's smaller
     var compressedKey = compress(cipher.ephemPublicKey);
 
-    var ret = Buffer.concat([new Buffer(cipher.iv, 'hex'), // 16bit
-    new Buffer(compressedKey, 'hex'), // 33bit
-    new Buffer(cipher.mac, 'hex'), // 32bit
-    new Buffer(cipher.ciphertext, 'hex') // var bit
+    var ret = Buffer.concat([Buffer.from(cipher.iv, 'hex'), // 16bit
+    Buffer.from(compressedKey, 'hex'), // 33bit
+    Buffer.from(cipher.mac, 'hex'), // 32bit
+    Buffer.from(cipher.ciphertext, 'hex') // var bit
     ]);
 
     return ret.toString('hex');
@@ -18,7 +18,7 @@ export function stringify(cipher) {
 export function parse(str) {
     if (typeof str !== 'string') return str;
 
-    var buf = new Buffer(str, 'hex');
+    var buf = Buffer.from(str, 'hex');
 
     var ret = {
         iv: buf.toString('hex', 0, 16),
diff --git a/dist/es/decrypt-with-private-key.js b/dist/es/decrypt-with-private-key.js
index 6b0802d..a17a93a 100644
--- a/dist/es/decrypt-with-private-key.js
+++ b/dist/es/decrypt-with-private-key.js
@@ -10,13 +10,13 @@ export default function decryptWithPrivateKey(privateKey, encrypted) {
     var twoStripped = removeTrailing0x(privateKey);
 
     var encryptedBuffer = {
-        iv: new Buffer(encrypted.iv, 'hex'),
-        ephemPublicKey: new Buffer(encrypted.ephemPublicKey, 'hex'),
-        ciphertext: new Buffer(encrypted.ciphertext, 'hex'),
-        mac: new Buffer(encrypted.mac, 'hex')
+        iv: Buffer.from(encrypted.iv, 'hex'),
+        ephemPublicKey: Buffer.from(encrypted.ephemPublicKey, 'hex'),
+        ciphertext: Buffer.from(encrypted.ciphertext, 'hex'),
+        mac: Buffer.from(encrypted.mac, 'hex')
     };
 
-    return decrypt(new Buffer(twoStripped, 'hex'), encryptedBuffer).then(function (decryptedBuffer) {
+    return decrypt(Buffer.from(twoStripped, 'hex'), encryptedBuffer).then(function (decryptedBuffer) {
         return decryptedBuffer.toString();
     });
 }
\ No newline at end of file
diff --git a/dist/es/encrypt-with-public-key.js b/dist/es/encrypt-with-public-key.js
index 40d82b0..9247618 100644
--- a/dist/es/encrypt-with-public-key.js
+++ b/dist/es/encrypt-with-public-key.js
@@ -9,7 +9,7 @@ export default function encryptWithPublicKey(publicKey, message) {
     // re-add the compression-flag
     var pubString = '04' + publicKey;
 
-    return encrypt(new Buffer(pubString, 'hex'), Buffer(message)).then(function (encryptedBuffers) {
+    return encrypt(Buffer.from(pubString, 'hex'), Buffer.from(message)).then(function (encryptedBuffers) {
         var encrypted = {
             iv: encryptedBuffers.iv.toString('hex'),
             ephemPublicKey: encryptedBuffers.ephemPublicKey.toString('hex'),
diff --git a/dist/es/hex.js b/dist/es/hex.js
index 2c20357..e715f2b 100644
--- a/dist/es/hex.js
+++ b/dist/es/hex.js
@@ -12,7 +12,7 @@ export function compress(hex) {
     hex = removeTrailing0x(hex);
 
     // if base64:true, we use our own function because it results in a smaller output
-    if (base64 === true) return new Buffer(hex, 'hex').toString('base64');
+    if (base64 === true) return Buffer.from(hex, 'hex').toString('base64');
 
     var string = '';
     while (hex.length % 4 != 0) {
@@ -32,7 +32,7 @@ export function decompress(compressedString) {
 
     // if base64:true, we use our own function because it results in a smaller output
     if (base64 === true) {
-        var ret = new Buffer(compressedString, 'base64').toString('hex');
+        var ret = Buffer.from(compressedString, 'base64').toString('hex');
         return addTrailing0x(ret);
     }
 
diff --git a/dist/es/public-key.js b/dist/es/public-key.js
index 28c6a0d..aa1377a 100644
--- a/dist/es/public-key.js
+++ b/dist/es/public-key.js
@@ -1,22 +1,23 @@
 import { publicKeyConvert } from 'secp256k1';
 import { pubToAddress, toChecksumAddress } from 'ethereumjs-util';
+import { hexToUnit8Array, uint8ArrayToHex } from './util';
 
 export function compress(startsWith04) {
 
     // add trailing 04 if not done before
-    var testBuffer = new Buffer(startsWith04, 'hex');
+    var testBuffer = Buffer.from(startsWith04, 'hex');
     if (testBuffer.length === 64) startsWith04 = '04' + startsWith04;
 
-    return publicKeyConvert(new Buffer(startsWith04, 'hex'), true).toString('hex');
+    return uint8ArrayToHex(publicKeyConvert(hexToUnit8Array(startsWith04), true));
 }
 
 export function decompress(startsWith02Or03) {
 
     // if already decompressed an not has trailing 04
-    var testBuffer = new Buffer(startsWith02Or03, 'hex');
+    var testBuffer = Buffer.from(startsWith02Or03, 'hex');
     if (testBuffer.length === 64) startsWith02Or03 = '04' + startsWith02Or03;
 
-    var decompressed = publicKeyConvert(new Buffer(startsWith02Or03, 'hex'), false).toString('hex');
+    var decompressed = uint8ArrayToHex(publicKeyConvert(hexToUnit8Array(startsWith02Or03), false));
 
     // remove trailing 04
     decompressed = decompressed.substring(2);
@@ -33,7 +34,7 @@ export function toAddress(publicKey) {
     // normalize key
     publicKey = decompress(publicKey);
 
-    var addressBuffer = pubToAddress(new Buffer(publicKey, 'hex'));
+    var addressBuffer = pubToAddress(Buffer.from(publicKey, 'hex'));
     var checkSumAdress = toChecksumAddress(addressBuffer.toString('hex'));
     return checkSumAdress;
 }
\ No newline at end of file
diff --git a/dist/es/recover-public-key.js b/dist/es/recover-public-key.js
index 14d4a6f..4f7e43e 100644
--- a/dist/es/recover-public-key.js
+++ b/dist/es/recover-public-key.js
@@ -1,5 +1,5 @@
-import { recover } from 'secp256k1';
-import { removeTrailing0x } from './util';
+import { ecdsaRecover } from 'secp256k1';
+import { removeTrailing0x, hexToUnit8Array, uint8ArrayToHex } from './util';
 
 /**
  * returns the publicKey for the privateKey with which the messageHash was signed
@@ -16,7 +16,7 @@ export default function recoverPublicKey(signature, hash) {
 
     var recoveryNumber = vValue === '1c' ? 1 : 0;
 
-    var pubKey = recover(new Buffer(removeTrailing0x(hash), 'hex'), new Buffer(sigOnly, 'hex'), recoveryNumber, false).toString('hex');
+    var pubKey = uint8ArrayToHex(ecdsaRecover(hexToUnit8Array(sigOnly), recoveryNumber, hexToUnit8Array(removeTrailing0x(hash)), false));
 
     // remove trailing '04'
     pubKey = pubKey.slice(2);
diff --git a/dist/es/sign-transaction.js b/dist/es/sign-transaction.js
index 34c8083..728e245 100644
--- a/dist/es/sign-transaction.js
+++ b/dist/es/sign-transaction.js
@@ -9,7 +9,7 @@ export default function signTransaction(rawTx, privateKey) {
     var address = addressByPublicKey(publicKey);
     if (address != rawTx.from) throw new Error('EthCrypto.signTransaction(): rawTx.from does not match the address of the privateKey');
 
-    var privateKeyBuffer = new Buffer(privateKey.replace(/^.{2}/g, ''), 'hex');
+    var privateKeyBuffer = Buffer.from(privateKey.replace(/^.{2}/g, ''), 'hex');
 
     var tx = new Transaction(rawTx);
     tx.sign(privateKeyBuffer);
diff --git a/dist/es/sign.js b/dist/es/sign.js
index 7073218..607f2fa 100644
--- a/dist/es/sign.js
+++ b/dist/es/sign.js
@@ -1,4 +1,4 @@
-import { sign as secp256k1_sign } from 'secp256k1';
+import { ecdsaSign as secp256k1_sign } from 'secp256k1';
 import { addTrailing0x, removeTrailing0x } from './util';
 
 /**
@@ -12,10 +12,10 @@ export default function sign(privateKey, hash) {
     hash = addTrailing0x(hash);
     if (hash.length !== 66) throw new Error('EthCrypto.sign(): Can only sign hashes, given: ' + hash);
 
-    var sigObj = secp256k1_sign(new Buffer(removeTrailing0x(hash), 'hex'), new Buffer(removeTrailing0x(privateKey), 'hex'));
+    var sigObj = secp256k1_sign(new Uint8Array(Buffer.from(removeTrailing0x(hash), 'hex')), new Uint8Array(Buffer.from(removeTrailing0x(privateKey), 'hex')));
 
-    var recoveryId = sigObj.recovery === 1 ? '1c' : '1b';
+    var recoveryId = sigObj.recid === 1 ? '1c' : '1b';
 
-    var newSignature = '0x' + sigObj.signature.toString('hex') + recoveryId;
+    var newSignature = '0x' + Buffer.from(sigObj.signature).toString('hex') + recoveryId;
     return newSignature;
 }
\ No newline at end of file
diff --git a/dist/es/util.js b/dist/es/util.js
index e31363c..876035f 100644
--- a/dist/es/util.js
+++ b/dist/es/util.js
@@ -4,4 +4,12 @@ export function removeTrailing0x(str) {
 
 export function addTrailing0x(str) {
     if (!str.startsWith('0x')) return '0x' + str;else return str;
+}
+
+export function uint8ArrayToHex(arr) {
+    return Buffer.from(arr).toString('hex');
+}
+
+export function hexToUnit8Array(str) {
+    return new Uint8Array(Buffer.from(str, 'hex'));
 }
\ No newline at end of file
diff --git a/dist/lib/cipher.js b/dist/lib/cipher.js
index 126c5bc..3bd24ef 100644
--- a/dist/lib/cipher.js
+++ b/dist/lib/cipher.js
@@ -14,10 +14,10 @@ function stringify(cipher) {
     // use compressed key because it's smaller
     var compressedKey = (0, _publicKey.compress)(cipher.ephemPublicKey);
 
-    var ret = Buffer.concat([new Buffer(cipher.iv, 'hex'), // 16bit
-    new Buffer(compressedKey, 'hex'), // 33bit
-    new Buffer(cipher.mac, 'hex'), // 32bit
-    new Buffer(cipher.ciphertext, 'hex') // var bit
+    var ret = Buffer.concat([Buffer.from(cipher.iv, 'hex'), // 16bit
+    Buffer.from(compressedKey, 'hex'), // 33bit
+    Buffer.from(cipher.mac, 'hex'), // 32bit
+    Buffer.from(cipher.ciphertext, 'hex') // var bit
     ]);
 
     return ret.toString('hex');
@@ -26,7 +26,7 @@ function stringify(cipher) {
 function parse(str) {
     if (typeof str !== 'string') return str;
 
-    var buf = new Buffer(str, 'hex');
+    var buf = Buffer.from(str, 'hex');
 
     var ret = {
         iv: buf.toString('hex', 0, 16),
diff --git a/dist/lib/decrypt-with-private-key.js b/dist/lib/decrypt-with-private-key.js
index 95dc83b..0219385 100644
--- a/dist/lib/decrypt-with-private-key.js
+++ b/dist/lib/decrypt-with-private-key.js
@@ -19,13 +19,13 @@ function decryptWithPrivateKey(privateKey, encrypted) {
     var twoStripped = (0, _util.removeTrailing0x)(privateKey);
 
     var encryptedBuffer = {
-        iv: new Buffer(encrypted.iv, 'hex'),
-        ephemPublicKey: new Buffer(encrypted.ephemPublicKey, 'hex'),
-        ciphertext: new Buffer(encrypted.ciphertext, 'hex'),
-        mac: new Buffer(encrypted.mac, 'hex')
+        iv: Buffer.from(encrypted.iv, 'hex'),
+        ephemPublicKey: Buffer.from(encrypted.ephemPublicKey, 'hex'),
+        ciphertext: Buffer.from(encrypted.ciphertext, 'hex'),
+        mac: Buffer.from(encrypted.mac, 'hex')
     };
 
-    return (0, _eccrypto.decrypt)(new Buffer(twoStripped, 'hex'), encryptedBuffer).then(function (decryptedBuffer) {
+    return (0, _eccrypto.decrypt)(Buffer.from(twoStripped, 'hex'), encryptedBuffer).then(function (decryptedBuffer) {
         return decryptedBuffer.toString();
     });
 }
\ No newline at end of file
diff --git a/dist/lib/encrypt-with-public-key.js b/dist/lib/encrypt-with-public-key.js
index 91b9180..c158e50 100644
--- a/dist/lib/encrypt-with-public-key.js
+++ b/dist/lib/encrypt-with-public-key.js
@@ -17,7 +17,7 @@ function encryptWithPublicKey(publicKey, message) {
     // re-add the compression-flag
     var pubString = '04' + publicKey;
 
-    return (0, _eccrypto.encrypt)(new Buffer(pubString, 'hex'), Buffer(message)).then(function (encryptedBuffers) {
+    return (0, _eccrypto.encrypt)(Buffer.from(pubString, 'hex'), Buffer.from(message)).then(function (encryptedBuffers) {
         var encrypted = {
             iv: encryptedBuffers.iv.toString('hex'),
             ephemPublicKey: encryptedBuffers.ephemPublicKey.toString('hex'),
diff --git a/dist/lib/hex.js b/dist/lib/hex.js
index 909a3bb..a10e3cb 100644
--- a/dist/lib/hex.js
+++ b/dist/lib/hex.js
@@ -14,7 +14,7 @@ function compress(hex) {
     hex = (0, _util.removeTrailing0x)(hex);
 
     // if base64:true, we use our own function because it results in a smaller output
-    if (base64 === true) return new Buffer(hex, 'hex').toString('base64');
+    if (base64 === true) return Buffer.from(hex, 'hex').toString('base64');
 
     var string = '';
     while (hex.length % 4 != 0) {
@@ -38,7 +38,7 @@ function decompress(compressedString) {
 
     // if base64:true, we use our own function because it results in a smaller output
     if (base64 === true) {
-        var ret = new Buffer(compressedString, 'base64').toString('hex');
+        var ret = Buffer.from(compressedString, 'base64').toString('hex');
         return (0, _util.addTrailing0x)(ret);
     }
 
diff --git a/dist/lib/public-key.js b/dist/lib/public-key.js
index c55904b..6a42363 100644
--- a/dist/lib/public-key.js
+++ b/dist/lib/public-key.js
@@ -11,22 +11,24 @@ var _secp256k = require('secp256k1');
 
 var _ethereumjsUtil = require('ethereumjs-util');
 
+var _util = require('./util');
+
 function compress(startsWith04) {
 
     // add trailing 04 if not done before
-    var testBuffer = new Buffer(startsWith04, 'hex');
+    var testBuffer = Buffer.from(startsWith04, 'hex');
     if (testBuffer.length === 64) startsWith04 = '04' + startsWith04;
 
-    return (0, _secp256k.publicKeyConvert)(new Buffer(startsWith04, 'hex'), true).toString('hex');
+    return (0, _util.uint8ArrayToHex)((0, _secp256k.publicKeyConvert)((0, _util.hexToUnit8Array)(startsWith04), true));
 }
 
 function decompress(startsWith02Or03) {
 
     // if already decompressed an not has trailing 04
-    var testBuffer = new Buffer(startsWith02Or03, 'hex');
+    var testBuffer = Buffer.from(startsWith02Or03, 'hex');
     if (testBuffer.length === 64) startsWith02Or03 = '04' + startsWith02Or03;
 
-    var decompressed = (0, _secp256k.publicKeyConvert)(new Buffer(startsWith02Or03, 'hex'), false).toString('hex');
+    var decompressed = (0, _util.uint8ArrayToHex)((0, _secp256k.publicKeyConvert)((0, _util.hexToUnit8Array)(startsWith02Or03), false));
 
     // remove trailing 04
     decompressed = decompressed.substring(2);
@@ -43,7 +45,7 @@ function toAddress(publicKey) {
     // normalize key
     publicKey = decompress(publicKey);
 
-    var addressBuffer = (0, _ethereumjsUtil.pubToAddress)(new Buffer(publicKey, 'hex'));
+    var addressBuffer = (0, _ethereumjsUtil.pubToAddress)(Buffer.from(publicKey, 'hex'));
     var checkSumAdress = (0, _ethereumjsUtil.toChecksumAddress)(addressBuffer.toString('hex'));
     return checkSumAdress;
 }
\ No newline at end of file
diff --git a/dist/lib/recover-public-key.js b/dist/lib/recover-public-key.js
index e972395..446f98e 100644
--- a/dist/lib/recover-public-key.js
+++ b/dist/lib/recover-public-key.js
@@ -24,7 +24,7 @@ function recoverPublicKey(signature, hash) {
 
     var recoveryNumber = vValue === '1c' ? 1 : 0;
 
-    var pubKey = (0, _secp256k.recover)(new Buffer((0, _util.removeTrailing0x)(hash), 'hex'), new Buffer(sigOnly, 'hex'), recoveryNumber, false).toString('hex');
+    var pubKey = (0, _util.uint8ArrayToHex)((0, _secp256k.ecdsaRecover)((0, _util.hexToUnit8Array)(sigOnly), recoveryNumber, (0, _util.hexToUnit8Array)((0, _util.removeTrailing0x)(hash)), false));
 
     // remove trailing '04'
     pubKey = pubKey.slice(2);
diff --git a/dist/lib/sign-transaction.js b/dist/lib/sign-transaction.js
index 4121fc3..f6c4a84 100644
--- a/dist/lib/sign-transaction.js
+++ b/dist/lib/sign-transaction.js
@@ -22,7 +22,7 @@ function signTransaction(rawTx, privateKey) {
     var address = (0, _publicKey.toAddress)(publicKey);
     if (address != rawTx.from) throw new Error('EthCrypto.signTransaction(): rawTx.from does not match the address of the privateKey');
 
-    var privateKeyBuffer = new Buffer(privateKey.replace(/^.{2}/g, ''), 'hex');
+    var privateKeyBuffer = Buffer.from(privateKey.replace(/^.{2}/g, ''), 'hex');
 
     var tx = new _ethereumjsTx.Transaction(rawTx);
     tx.sign(privateKeyBuffer);
diff --git a/dist/lib/sign.js b/dist/lib/sign.js
index 987487b..5dc58ec 100644
--- a/dist/lib/sign.js
+++ b/dist/lib/sign.js
@@ -20,10 +20,10 @@ function sign(privateKey, hash) {
     hash = (0, _util.addTrailing0x)(hash);
     if (hash.length !== 66) throw new Error('EthCrypto.sign(): Can only sign hashes, given: ' + hash);
 
-    var sigObj = (0, _secp256k.sign)(new Buffer((0, _util.removeTrailing0x)(hash), 'hex'), new Buffer((0, _util.removeTrailing0x)(privateKey), 'hex'));
+    var sigObj = (0, _secp256k.ecdsaSign)(new Uint8Array(Buffer.from((0, _util.removeTrailing0x)(hash), 'hex')), new Uint8Array(Buffer.from((0, _util.removeTrailing0x)(privateKey), 'hex')));
 
-    var recoveryId = sigObj.recovery === 1 ? '1c' : '1b';
+    var recoveryId = sigObj.recid === 1 ? '1c' : '1b';
 
-    var newSignature = '0x' + sigObj.signature.toString('hex') + recoveryId;
+    var newSignature = '0x' + Buffer.from(sigObj.signature).toString('hex') + recoveryId;
     return newSignature;
 }
\ No newline at end of file
diff --git a/dist/lib/util.js b/dist/lib/util.js
index 1f83c67..df7f5b2 100644
--- a/dist/lib/util.js
+++ b/dist/lib/util.js
@@ -5,10 +5,20 @@ Object.defineProperty(exports, "__esModule", {
 });
 exports.removeTrailing0x = removeTrailing0x;
 exports.addTrailing0x = addTrailing0x;
+exports.uint8ArrayToHex = uint8ArrayToHex;
+exports.hexToUnit8Array = hexToUnit8Array;
 function removeTrailing0x(str) {
     if (str.startsWith('0x')) return str.substring(2);else return str;
 }
 
 function addTrailing0x(str) {
     if (!str.startsWith('0x')) return '0x' + str;else return str;
+}
+
+function uint8ArrayToHex(arr) {
+    return Buffer.from(arr).toString('hex');
+}
+
+function hexToUnit8Array(str) {
+    return new Uint8Array(Buffer.from(str, 'hex'));
 }
\ No newline at end of file
diff --git a/package.json b/package.json
index 84542bc..5e71e15 100644
--- a/package.json
+++ b/package.json
@@ -115,6 +115,6 @@
     "ethereumjs-tx": "2.1.2",
     "ethereumjs-util": "6.2.0",
     "ethers": "4.0.47",
-    "secp256k1": "3.8.0"
+    "secp256k1": "4.0.1"
   }
 }
diff --git a/src/cipher.js b/src/cipher.js
index 34bb7b5..53f46ac 100644
--- a/src/cipher.js
+++ b/src/cipher.js
@@ -10,10 +10,10 @@ export function stringify(cipher) {
     const compressedKey = compress(cipher.ephemPublicKey);
 
     const ret = Buffer.concat([
-        new Buffer(cipher.iv, 'hex'), // 16bit
-        new Buffer(compressedKey, 'hex'), // 33bit
-        new Buffer(cipher.mac, 'hex'), // 32bit
-        new Buffer(cipher.ciphertext, 'hex') // var bit
+        Buffer.from(cipher.iv, 'hex'), // 16bit
+        Buffer.from(compressedKey, 'hex'), // 33bit
+        Buffer.from(cipher.mac, 'hex'), // 32bit
+        Buffer.from(cipher.ciphertext, 'hex') // var bit
     ]);
 
     return ret.toString('hex');
@@ -25,7 +25,7 @@ export function parse(str) {
     if (typeof str !== 'string')
         return str;
 
-    const buf = new Buffer(str, 'hex');
+    const buf = Buffer.from(str, 'hex');
 
     const ret = {
         iv: buf.toString('hex', 0, 16),
diff --git a/src/decrypt-with-private-key.js b/src/decrypt-with-private-key.js
index ee2552e..62e576a 100644
--- a/src/decrypt-with-private-key.js
+++ b/src/decrypt-with-private-key.js
@@ -16,15 +16,15 @@ export default function decryptWithPrivateKey(privateKey, encrypted) {
     const twoStripped = removeTrailing0x(privateKey);
 
     const encryptedBuffer = {
-        iv: new Buffer(encrypted.iv, 'hex'),
-        ephemPublicKey: new Buffer(encrypted.ephemPublicKey, 'hex'),
-        ciphertext: new Buffer(encrypted.ciphertext, 'hex'),
-        mac: new Buffer(encrypted.mac, 'hex')
+        iv: Buffer.from(encrypted.iv, 'hex'),
+        ephemPublicKey: Buffer.from(encrypted.ephemPublicKey, 'hex'),
+        ciphertext: Buffer.from(encrypted.ciphertext, 'hex'),
+        mac: Buffer.from(encrypted.mac, 'hex')
     };
 
 
     return decrypt(
-        new Buffer(twoStripped, 'hex'),
+        Buffer.from(twoStripped, 'hex'),
         encryptedBuffer
     ).then(decryptedBuffer => decryptedBuffer.toString());
 }
diff --git a/src/encrypt-with-public-key.js b/src/encrypt-with-public-key.js
index ee4a904..fb007b4 100644
--- a/src/encrypt-with-public-key.js
+++ b/src/encrypt-with-public-key.js
@@ -15,8 +15,8 @@ export default function encryptWithPublicKey(publicKey, message) {
 
 
     return encrypt(
-        new Buffer(pubString, 'hex'),
-        Buffer(message)
+        Buffer.from(pubString, 'hex'),
+        Buffer.from(message)
     ).then(encryptedBuffers => {
         const encrypted = {
             iv: encryptedBuffers.iv.toString('hex'),
diff --git a/src/hex.js b/src/hex.js
index a9e7e7f..430a5e7 100644
--- a/src/hex.js
+++ b/src/hex.js
@@ -14,7 +14,7 @@ export function compress(hex, base64 = false) {
 
     // if base64:true, we use our own function because it results in a smaller output
     if (base64 === true)
-        return new Buffer(hex, 'hex').toString('base64');
+        return Buffer.from(hex, 'hex').toString('base64');
 
     let string = '';
     while (hex.length % 4 != 0) { // we need it to be multiple of 4
@@ -31,7 +31,7 @@ export function decompress(compressedString, base64 = false) {
 
     // if base64:true, we use our own function because it results in a smaller output
     if (base64 === true) {
-        const ret = new Buffer(compressedString, 'base64').toString('hex');
+        const ret = Buffer.from(compressedString, 'base64').toString('hex');
         return addTrailing0x(ret);
     }
 
diff --git a/src/public-key.js b/src/public-key.js
index 22d709d..7442cd3 100644
--- a/src/public-key.js
+++ b/src/public-key.js
@@ -5,30 +5,34 @@ import {
     pubToAddress,
     toChecksumAddress
 } from 'ethereumjs-util';
+import {
+    hexToUnit8Array,
+    uint8ArrayToHex
+} from './util';
 
 export function compress(startsWith04) {
 
     // add trailing 04 if not done before
-    const testBuffer = new Buffer(startsWith04, 'hex');
+    const testBuffer = Buffer.from(startsWith04, 'hex');
     if (testBuffer.length === 64) startsWith04 = '04' + startsWith04;
 
 
-    return publicKeyConvert(
-        new Buffer(startsWith04, 'hex'),
+    return uint8ArrayToHex(publicKeyConvert(
+        hexToUnit8Array(startsWith04),
         true
-    ).toString('hex');
+    ));
 }
 
 export function decompress(startsWith02Or03) {
 
     // if already decompressed an not has trailing 04
-    const testBuffer = new Buffer(startsWith02Or03, 'hex');
+    const testBuffer = Buffer.from(startsWith02Or03, 'hex');
     if (testBuffer.length === 64) startsWith02Or03 = '04' + startsWith02Or03;
 
-    let decompressed = publicKeyConvert(
-        new Buffer(startsWith02Or03, 'hex'),
+    let decompressed = uint8ArrayToHex(publicKeyConvert(
+        hexToUnit8Array(startsWith02Or03),
         false
-    ).toString('hex');
+    ));
 
     // remove trailing 04
     decompressed = decompressed.substring(2);
@@ -45,7 +49,7 @@ export function toAddress(publicKey) {
     // normalize key
     publicKey = decompress(publicKey);
 
-    const addressBuffer = pubToAddress(new Buffer(publicKey, 'hex'));
+    const addressBuffer = pubToAddress(Buffer.from(publicKey, 'hex'));
     const checkSumAdress = toChecksumAddress(addressBuffer.toString('hex'));
     return checkSumAdress;
 }
diff --git a/src/recover-public-key.js b/src/recover-public-key.js
index 4db0261..2074a43 100644
--- a/src/recover-public-key.js
+++ b/src/recover-public-key.js
@@ -1,8 +1,10 @@
 import {
-    recover
+    ecdsaRecover
 } from 'secp256k1';
 import {
-    removeTrailing0x
+    removeTrailing0x,
+    hexToUnit8Array,
+    uint8ArrayToHex
 } from './util';
 
 
@@ -21,12 +23,12 @@ export default function recoverPublicKey(signature, hash) {
 
     const recoveryNumber = vValue === '1c' ? 1 : 0;
 
-    let pubKey = recover(
-        new Buffer(removeTrailing0x(hash), 'hex'),
-        new Buffer(sigOnly, 'hex'),
+    let pubKey = uint8ArrayToHex(ecdsaRecover(
+        hexToUnit8Array(sigOnly),
         recoveryNumber,
+        hexToUnit8Array(removeTrailing0x(hash)),
         false
-    ).toString('hex');
+    ));
 
     // remove trailing '04'
     pubKey = pubKey.slice(2);
diff --git a/src/sign-transaction.js b/src/sign-transaction.js
index ed75812..7ecba20 100644
--- a/src/sign-transaction.js
+++ b/src/sign-transaction.js
@@ -15,7 +15,7 @@ export default function signTransaction(
     if (address != rawTx.from)
         throw new Error('EthCrypto.signTransaction(): rawTx.from does not match the address of the privateKey');
 
-    const privateKeyBuffer = new Buffer(privateKey.replace(/^.{2}/g, ''), 'hex');
+    const privateKeyBuffer = Buffer.from(privateKey.replace(/^.{2}/g, ''), 'hex');
 
     const tx = new Transaction(rawTx);
     tx.sign(privateKeyBuffer);
diff --git a/src/sign.js b/src/sign.js
index 98d2fb7..afa2bbe 100644
--- a/src/sign.js
+++ b/src/sign.js
@@ -1,5 +1,5 @@
 import {
-    sign as secp256k1_sign
+    ecdsaSign as secp256k1_sign
 } from 'secp256k1';
 import {
     addTrailing0x,
@@ -19,12 +19,12 @@ export default function sign(privateKey, hash) {
         throw new Error('EthCrypto.sign(): Can only sign hashes, given: ' + hash);
 
     const sigObj = secp256k1_sign(
-        new Buffer(removeTrailing0x(hash), 'hex'),
-        new Buffer(removeTrailing0x(privateKey), 'hex')
+        new Uint8Array(Buffer.from(removeTrailing0x(hash), 'hex')),
+        new Uint8Array(Buffer.from(removeTrailing0x(privateKey), 'hex'))
     );
 
-    const recoveryId = sigObj.recovery === 1 ? '1c' : '1b';
+    const recoveryId = sigObj.recid === 1 ? '1c' : '1b';
 
-    const newSignature = '0x' + sigObj.signature.toString('hex') + recoveryId;
+    const newSignature = '0x' + Buffer.from(sigObj.signature).toString('hex') + recoveryId;
     return newSignature;
 }
diff --git a/src/util.js b/src/util.js
index 982f103..60620ab 100644
--- a/src/util.js
+++ b/src/util.js
@@ -9,3 +9,11 @@ export function addTrailing0x(str) {
         return '0x' + str;
     else return str;
 }
+
+export function uint8ArrayToHex(arr) {
+    return Buffer.from(arr).toString('hex');
+}
+
+export function hexToUnit8Array(str) {
+    return new Uint8Array(Buffer.from(str, 'hex'));
+}
diff --git a/test/unit.test.js b/test/unit.test.js
index 7ecd4f5..f701dfa 100644
--- a/test/unit.test.js
+++ b/test/unit.test.js
@@ -170,7 +170,7 @@ describe('unit.test.js', () => {
                         AsyncTestUtil.randomString(12),
                         message
                     ),
-                    'RangeError'
+                    'Error'
                 );
             });
         });