diff --git a/examples/testNode.js b/examples/testNode.js
index 7e9c666..470630b 100644
--- a/examples/testNode.js
+++ b/examples/testNode.js
@@ -2,9 +2,9 @@ const { Account, Wallet } = require('@harmony/account');
 const { isAddress, isPrivateKey, numberToHex } = require('@harmony/utils');
 const { HttpProvider, Messenger } = require('@harmony/network');
 
-async function testEncrypt() {
-  const wallet = new Wallet();
+const wallet = new Wallet();
 
+async function testEncrypt() {
   const mne = wallet.generateMnemonic();
 
   console.log('---hint: please write these down');
@@ -28,3 +28,15 @@ async function testEncrypt() {
 }
 
 testEncrypt();
+
+async function testSign(prvKey, data) {
+  const newAcc = wallet.addByPrivateKey(prvKey);
+
+  const result = await newAcc.sign(data);
+  console.log(result);
+}
+
+testSign(
+  '0x0123456789012345678901234567890123456789012345678901234567890123',
+  '0x06',
+);
diff --git a/gulpfile.js b/gulpfile.js
index efc86f9..b6d74c6 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -6,6 +6,7 @@ const packages = [
   'harmony-account',
   'harmony-network',
   'harmony-utils',
+  'harmony-transaction',
 ];
 
 task('cleanBrowser', async () => {
diff --git a/packages/harmony-account/src/account.ts b/packages/harmony-account/src/account.ts
index 4c73c89..04fd018 100644
--- a/packages/harmony-account/src/account.ts
+++ b/packages/harmony-account/src/account.ts
@@ -7,6 +7,9 @@ import {
   decrypt,
   EncryptOptions,
   Keystore,
+  sign,
+  isSignature,
+  Signature,
 } from '@harmony/crypto';
 
 import { isPrivateKey, add0xToString } from '@harmony/utils';
@@ -118,11 +121,20 @@ class Account {
     return '';
   }
   /**
-   * @function signTransaction
+   * @function sign
    * @return {Promise<void>} sign transaction
    */
-  async signTransaction(): Promise<void> {
-    console.log('sign transaction');
+  async sign(message: string): Promise<Signature> {
+    if (this.privateKey && isPrivateKey(this.privateKey)) {
+      const signature: Signature = await sign(message, this.privateKey);
+      if (isSignature(signature)) {
+        return signature;
+      } else {
+        throw new Error('Cannot sign');
+      }
+    } else {
+      throw new Error('Privatekey not found or not correct');
+    }
   }
   /**
    * @function _new private method create Account
diff --git a/packages/harmony-account/tsconfig.json b/packages/harmony-account/tsconfig.json
index 53ddc87..f517c81 100644
--- a/packages/harmony-account/tsconfig.json
+++ b/packages/harmony-account/tsconfig.json
@@ -1,8 +1,6 @@
 {
   "extends": "../../tsconfig.base.json",
   "compilerOptions": {
-    "baseUrl": ".",
-    "paths": { "*": ["types/*"] },
     "outDir": "dist",
     "rootDir": "src"
   },
diff --git a/packages/harmony-crypto/src/bytes.ts b/packages/harmony-crypto/src/bytes.ts
index df13895..5dec6e5 100644
--- a/packages/harmony-crypto/src/bytes.ts
+++ b/packages/harmony-crypto/src/bytes.ts
@@ -336,7 +336,7 @@ export function hexZeroPad(value: string, length: number): string {
   return value;
 }
 
-function isSignature(value: any): value is Signature {
+export function isSignature(value: any): value is Signature {
   return value && value.r != null && value.s != null;
 }
 
diff --git a/packages/harmony-crypto/src/index.ts b/packages/harmony-crypto/src/index.ts
index 0eb5021..04a5ef9 100644
--- a/packages/harmony-crypto/src/index.ts
+++ b/packages/harmony-crypto/src/index.ts
@@ -4,6 +4,7 @@ import bip39 from 'bip39';
 export * from './random';
 export * from './keyTool';
 export * from './keystore';
+export * from './bytes';
 
 // export types
 export * from './types';
diff --git a/packages/harmony-crypto/src/keyTool.ts b/packages/harmony-crypto/src/keyTool.ts
index c091e20..45749fb 100644
--- a/packages/harmony-crypto/src/keyTool.ts
+++ b/packages/harmony-crypto/src/keyTool.ts
@@ -4,6 +4,7 @@ import * as errors from './errors';
 
 import { keccak256 } from './keccak256';
 import { randomBytes } from './random';
+import { isPrivateKey, strip0x } from '@harmony/utils';
 
 const secp256k1 = elliptic.ec('secp256k1');
 
@@ -48,7 +49,10 @@ export const getAddressFromPrivateKey = (privateKey: string): string => {
 };
 
 export const getPublic = (privateKey: string, compress?: boolean): string => {
-  const ecKey = secp256k1.keyFromPrivate(privateKey.slice(2), 'hex');
+  if (!isPrivateKey(privateKey)) {
+    throw new Error(`${privateKey} is not PrivateKey`);
+  }
+  const ecKey = secp256k1.keyFromPrivate(strip0x(privateKey), 'hex');
   return ecKey.getPublic(compress || false, 'hex');
 };
 
@@ -98,3 +102,20 @@ export const toChecksumAddress = (address: string): string => {
 
   return '0x' + chars.join('');
 };
+
+export const sign = (
+  digest: bytes.Arrayish | string,
+  privateKey: string,
+): bytes.Signature => {
+  if (!isPrivateKey(privateKey)) {
+    throw new Error(`${privateKey} is not PrivateKey`);
+  }
+  const keyPair = secp256k1.keyFromPrivate(strip0x(privateKey), 'hex');
+  const signature = keyPair.sign(bytes.arrayify(digest), { canonical: true });
+  return {
+    recoveryParam: signature.recoveryParam,
+    r: bytes.hexZeroPad('0x' + signature.r.toString(16), 32),
+    s: bytes.hexZeroPad('0x' + signature.s.toString(16), 32),
+    v: 27 + signature.recoveryParam,
+  };
+};
diff --git a/packages/harmony-crypto/src/rlp.ts b/packages/harmony-crypto/src/rlp.ts
new file mode 100644
index 0000000..9f9fbd9
--- /dev/null
+++ b/packages/harmony-crypto/src/rlp.ts
@@ -0,0 +1,159 @@
+// this file is ported from https://github.com/ethers-io/ethers.js/blob/master/src.ts/utils/rlp.ts
+// and done some fixes
+import { arrayify, hexlify, Arrayish } from './bytes';
+
+function arrayifyInteger(value: number): number[] {
+  const result = [];
+  while (value) {
+    result.unshift(value & 0xff);
+    value >>= 8;
+  }
+  return result;
+}
+
+function unarrayifyInteger(
+  data: Uint8Array,
+  offset: number,
+  length: number,
+): number {
+  let result = 0;
+  for (let i = 0; i < length; i++) {
+    result = result * 256 + data[offset + i];
+  }
+  return result;
+}
+
+function _encode(object: any[] | string): number[] {
+  if (Array.isArray(object)) {
+    let payload: number[] = [];
+    object.forEach((child) => {
+      payload = payload.concat(_encode(child));
+    });
+
+    if (payload.length <= 55) {
+      payload.unshift(0xc0 + payload.length);
+      return payload;
+    }
+
+    // tslint:disable-next-line: no-shadowed-variable
+    const length = arrayifyInteger(payload.length);
+    length.unshift(0xf7 + length.length);
+
+    return length.concat(payload);
+  }
+
+  const data: number[] = Array.prototype.slice.call(arrayify(object));
+
+  if (data.length === 1 && data[0] <= 0x7f) {
+    return data;
+  } else if (data.length <= 55) {
+    data.unshift(0x80 + data.length);
+    return data;
+  }
+
+  const length = arrayifyInteger(data.length);
+  length.unshift(0xb7 + length.length);
+
+  return length.concat(data);
+}
+
+export function encode(object: any): string {
+  return hexlify(_encode(object));
+}
+
+interface Decoded {
+  result: any;
+  consumed: number;
+}
+
+function _decodeChildren(
+  data: Uint8Array,
+  offset: number,
+  childOffset: number,
+  length: number,
+): Decoded {
+  const result = [];
+
+  while (childOffset < offset + 1 + length) {
+    const decoded = _decode(data, childOffset);
+
+    result.push(decoded.result);
+
+    childOffset += decoded.consumed;
+    if (childOffset > offset + 1 + length) {
+      throw new Error('invalid rlp');
+    }
+  }
+
+  return { consumed: 1 + length, result };
+}
+
+// returns { consumed: number, result: Object }
+function _decode(
+  data: Uint8Array,
+  offset: number,
+): { consumed: number; result: any } {
+  if (data.length === 0) {
+    throw new Error('invalid rlp data');
+  }
+
+  // Array with extra length prefix
+  if (data[offset] >= 0xf8) {
+    const lengthLength = data[offset] - 0xf7;
+    if (offset + 1 + lengthLength > data.length) {
+      throw new Error('too short');
+    }
+
+    const length = unarrayifyInteger(data, offset + 1, lengthLength);
+    if (offset + 1 + lengthLength + length > data.length) {
+      throw new Error('to short');
+    }
+
+    return _decodeChildren(
+      data,
+      offset,
+      offset + 1 + lengthLength,
+      lengthLength + length,
+    );
+  } else if (data[offset] >= 0xc0) {
+    const length = data[offset] - 0xc0;
+    if (offset + 1 + length > data.length) {
+      throw new Error('invalid rlp data');
+    }
+
+    return _decodeChildren(data, offset, offset + 1, length);
+  } else if (data[offset] >= 0xb8) {
+    const lengthLength = data[offset] - 0xb7;
+    if (offset + 1 + lengthLength > data.length) {
+      throw new Error('invalid rlp data');
+    }
+
+    const length = unarrayifyInteger(data, offset + 1, lengthLength);
+    if (offset + 1 + lengthLength + length > data.length) {
+      throw new Error('invalid rlp data');
+    }
+
+    const result = hexlify(
+      data.slice(offset + 1 + lengthLength, offset + 1 + lengthLength + length),
+    );
+    return { consumed: 1 + lengthLength + length, result };
+  } else if (data[offset] >= 0x80) {
+    const length = data[offset] - 0x80;
+    if (offset + 1 + length > data.length) {
+      throw new Error('invlaid rlp data');
+    }
+
+    const result = hexlify(data.slice(offset + 1, offset + 1 + length));
+    return { consumed: 1 + length, result };
+  }
+  return { consumed: 1, result: hexlify(data[offset]) };
+}
+
+export function decode(data: Arrayish): any {
+  const bytes = arrayify(data) || new Uint8Array();
+  const decoded = _decode(bytes, 0);
+  if (decoded.consumed !== bytes.length) {
+    throw new Error('invalid rlp data');
+  }
+  return decoded.result;
+}
diff --git a/packages/harmony-transaction/package.json b/packages/harmony-transaction/package.json
new file mode 100644
index 0000000..5a7f9f7
--- /dev/null
+++ b/packages/harmony-transaction/package.json
@@ -0,0 +1,20 @@
+{
+  "name": "@harmony/transaction",
+  "version": "0.0.1",
+  "description": "transaction package for harmony",
+  "main": "dist/index.js",
+  "node": "dist/index.js",
+  "browser": "dist/index.js",
+  "module": "dist/index.esm.js",
+  "jsnext:main": "dist/index.esm.js",
+  "typings": "dist/index.d.ts",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "neeboo@firestack.one",
+  "license": "ISC",
+  "dependencies": {
+    "@harmony/crypto": "^0.0.1",
+    "@harmony/utils": "^0.0.1"
+  }
+}
diff --git a/packages/harmony-transaction/src/factory.ts b/packages/harmony-transaction/src/factory.ts
new file mode 100644
index 0000000..4c1044a
--- /dev/null
+++ b/packages/harmony-transaction/src/factory.ts
@@ -0,0 +1,3 @@
+class TransactionFactory {}
+
+export { TransactionFactory };
diff --git a/packages/harmony-transaction/src/index.ts b/packages/harmony-transaction/src/index.ts
new file mode 100644
index 0000000..7cd1838
--- /dev/null
+++ b/packages/harmony-transaction/src/index.ts
@@ -0,0 +1,2 @@
+export * from './factory';
+export * from './transaction';
diff --git a/packages/harmony-transaction/src/transaction.ts b/packages/harmony-transaction/src/transaction.ts
new file mode 100644
index 0000000..6c0e61c
--- /dev/null
+++ b/packages/harmony-transaction/src/transaction.ts
@@ -0,0 +1,2 @@
+class Transaction {}
+export { Transaction };
diff --git a/packages/harmony-transaction/tsconfig.json b/packages/harmony-transaction/tsconfig.json
new file mode 100644
index 0000000..34bb5ff
--- /dev/null
+++ b/packages/harmony-transaction/tsconfig.json
@@ -0,0 +1,12 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src"
+  },
+  "include": ["src", "../../typings/**/*.d.ts"],
+  "references": [
+    { "path": "../harmony-utils" },
+    { "path": "../harmony-crypto" }
+  ]
+}
diff --git a/scripts/packages.js b/scripts/packages.js
index 4e13a93..962b474 100644
--- a/scripts/packages.js
+++ b/scripts/packages.js
@@ -3,4 +3,5 @@ export default [
   'harmony-crypto',
   'harmony-account',
   'harmony-network',
+  'harmony-transaction',
 ];
diff --git a/scripts/packagesList.js b/scripts/packagesList.js
index c4f995b..ab32034 100644
--- a/scripts/packagesList.js
+++ b/scripts/packagesList.js
@@ -3,4 +3,5 @@ module.exports = [
   { name: 'HarmonyUtils', dest: 'harmony-utils' },
   { name: 'HarmonyCrypto', dest: 'harmony-crypto' },
   { name: 'HarmonyAccount', dest: 'harmony-account' },
+  { name: 'HarmonyTransaction', dest: 'harmony-transaction' },
 ];
diff --git a/scripts/packagesTs.ts b/scripts/packagesTs.ts
index 2c8b042..88e4f86 100644
--- a/scripts/packagesTs.ts
+++ b/scripts/packagesTs.ts
@@ -3,6 +3,7 @@ const packages = [
   'harmony-crypto',
   'harmony-account',
   'harmony-network',
+  'harmony-transaction',
 ];
 
 export { packages };
diff --git a/typings/elliptic.d.ts b/typings/elliptic.d.ts
index e85b22f..ad5e127 100644
--- a/typings/elliptic.d.ts
+++ b/typings/elliptic.d.ts
@@ -45,6 +45,7 @@ declare namespace Elliptic {
   }
 
   interface KeyPair {
+    sign(arg0: Uint8Array | null, arg1: { canonical: boolean }): any;
     fromPublic(ec: Curve, pub: BN, enc: string): KeyPair;
     fromPrivate(ec: Curve, priv: BN, enc: string): KeyPair;
     // this is broken, but we can't fix it without changing the upstream