eth-crypto

eth-crypto

Cryptographic javascript-functions for ethereum and how to use them together with web3 and solidity.

Tutorials

Creating Keys and use them for ethereum-transactions

In this tutorial we will create an ethereum-identity and use it so send transactions to the blockchain. Creating transactions.

Sign and validate data with solidity

Sending encrypted and signed data to other identites

Functions

Install

  npm install eth-crypto --save

// es6
import EthCrypto from 'eth-crypto';

// node
const EthCrypto = require('eth-crypto');

API

createIdentity()

Creates a new ethereum-identity with privateKey, publicKey and address as hex-string.

  const identity = EthCrypto.createIdentity();
  /* > {
      address: '0x3f243FdacE01Cfd9719f7359c94BA11361f32471',
      privateKey: '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07',
      publicKey: 'bf1cc3154424dc22191941d9f4f50b063a2b663a2337e5548abea633c1d06ece...'
  } */

publicKeyByPrivateKey()

Derives the publicKey from a privateKey and returns it as hex-string.

  const publicKey = EthCrypto.publicKeyByPrivateKey(
      '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07'
  );
  // > 'bf1cc3154424dc22191941d9f4f50b063a2b663a2337e5548abea633c1d06ece...'

addressByPublicKey()

Derives the ethereum-address from the publicKey.

  const address = EthCrypto.publicKeyToAddress(
      'bf1cc3154424dc22191941d9f4f50b063a2b663a2337e5548abea633c1d06ece...'
  );
  // > '0x3f243FdacE01Cfd9719f7359c94BA11361f32471'

sign()

Signs the message with the privateKey. Returns the signature as object with hex-strings.

  const signature = EthCrypto.sign(
      '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07', // privateKey
      'foobar' // message
  );
  /* > {
        v: '0x1b',
        r: '0xc04b809d8f33c46ff80c44ba58e866ff0d5126d9943b58bee03cc5279450cacc',
        s: '0x757a3393b695ba83b2aba0c35c150399bf7959493aad80d51d917435b1a7ebda'
    } */

recover()

Recovers the signers address from the signature.

    const signer = EthCrypto.recover(
      {
          v: '0x1b',
          r: '0xc04b809d8f33c46ff80c44ba58e866ff0d5126d9943b58bee03cc5279450cacc',
          s: '0x757a3393b695ba83b2aba0c35c150399bf7959493aad80d51d917435b1a7ebda'
      }, // signature
      'foobar' // signed message
  );
  // > '0x3f243FdacE01Cfd9719f7359c94BA11361f32471'

encryptWithPublicKey()

Encrypts the message with the publicKey so that only the corresponding privateKey can decrypt it. Returns (async) the encrypted data as object with hex-strings.

    const encrypted = await EthCrypto.encryptWithPublicKey(
        'bf1cc3154424dc22191941d9f4f50b063a2b663a2337e5548abea633c1d06ece...', // publicKey
        'foobar' // message
    );
    /* >  {
            iv: '02aeac54cb45283b427bd1a5028552c1',
            ephemPublicKey: '044acf39ed83c304f19f41ea66615d7a6c0068d5fc48ee181f2fb1091...',
            ciphertext: '5fbbcc1a44ee19f7499dbc39cfc4ce96',
            mac: '96490b293763f49a371d3a2040a2d2cb57f246ee88958009fe3c7ef2a38264a1'
        } */

decryptWithPrivateKey()

Decrypts the encrypted data with the privateKey. Returns (async) the message as string.

    const message = await EthCrypto.decryptWithPrivateKey(
        '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07', // privateKey
        {
            iv: '02aeac54cb45283b427bd1a5028552c1',
            ephemPublicKey: '044acf39ed83c304f19f41ea66615d7a6c0068d5fc48ee181f2fb1091...',
            ciphertext: '5fbbcc1a44ee19f7499dbc39cfc4ce96',
            mac: '96490b293763f49a371d3a2040a2d2cb57f246ee88958009fe3c7ef2a38264a1'
        } // encrypted-data
    );
    // 'foobar'