Awesome Open Source
Awesome Open Source

follow on Twitter

eth-crypto

Cryptographic javascript-functions for ethereum and tutorials on how to use them together with web3js and solidity.

Tutorials

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...'
  } */

You can also create an identity by providing your own entropy-buffer. Use this with caution, a bad entropy can result in an unsecure private key.

  const entropy = Buffer.from('f2dacf...', 'utf-8'); // must contain at least 128 chars
  const identity = EthCrypto.createIdentity(entropy);
  /* > {
      address: '0x59c8d4d645B0a3b230DE368d815ebDE372d37Ea8',
      privateKey: '0x18cea40e44624867ddfd775b2898cdb2da29b4be92ee072b9eb02d43b6f2473a',
      publicKey: '991ce4643653ef452327ee3d1a56af19c84599d340ffd427e784...'
  } */

publicKeyByPrivateKey()

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

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

publicKey.toAddress()

Derives the ethereum-address from the publicKey.

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

publicKey.compress()

Compresses an uncompressed publicKey.

  const address = EthCrypto.publicKey.compress(
      '04a34d6aef3eb42335fb3cacb59...'
  );
  // > '03a34d6aef3eb42335fb3cacb59478c0b44c0bbeb8bb4ca427dbc7044157a5d24b' // compressed keys start with '02' or '03'

publicKey.decompress()

Decompresses a compressed publicKey.

  const address = EthCrypto.publicKey.decompress(
      '03a34d6aef3eb42335fb3c...'
  );
  // > 'a34d6aef3eb42335fb3cacb5947' // non-compressed keys start with '04' or no prefix

sign()

Signs the hash with the privateKey. Returns the signature as hex-string.

  const message = 'foobar';
  const messageHash = EthCrypto.hash.keccak256(message);
  const signature = EthCrypto.sign(
      '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07', // privateKey
      messageHash // hash of message
  );
  // > '0xc04b809d8f33c46ff80c44ba58e866ff0d5..'

recover()

Recovers the signers address from the signature.

    const signer = EthCrypto.recover(
      '0xc04b809d8f33c46ff80c44ba58e866ff0d5..',
      EthCrypto.hash.keccak256('foobar') // signed message hash
  );
  // > '0x3f243FdacE01Cfd9719f7359c94BA11361f32471'

recoverPublicKey()

Recovers the signers publicKey from the signature.

    const signer = EthCrypto.recoverPublicKey(
      '0xc04b809d8f33c46ff80c44ba58e866ff0d5..', // signature
      EthCrypto.hash.keccak256('foobar') // message hash
  );
  // > 'bf1cc3154424dc22191941d9f4f50b063a2b663a2337e5548abea633c1d06ece..'

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'

cipher.stringify()

Transforms the object with the encrypted data into a smaller string-representation.

const str = EthCrypto.cipher.stringify({
    iv: '02aeac54cb45283b427bd1a5028552c1',
    ephemPublicKey: '044acf39ed83c304f19f41ea66615d7a6c0068d5fc48ee181f2fb1091...',
    ciphertext: '5fbbcc1a44ee19f7499dbc39cfc4ce96',
    mac: '96490b293763f49a371d3a2040a2d2cb57f246ee88958009fe3c7ef2a38264a1'
});
// > '59ab06532fc965b0107977f43e69e5a4038db32099dab281c8f5aece2852...'

cipher.parse()

Parses the string-representation back into the encrypted object.

const str = EthCrypto.cipher.parse('59ab06532fc965b0107977f43e69e5a4038db32099dab281c8f5aece2852...');
/* >  {
        iv: '02aeac54cb45283b427bd1a5028552c1',
        ephemPublicKey: '044acf39ed83c304f19f41ea66615d7a6c0068d5fc48ee181f2fb1091...',
        ciphertext: '5fbbcc1a44ee19f7499dbc39cfc4ce96',
        mac: '96490b293763f49a371d3a2040a2d2cb57f246ee88958009fe3c7ef2a38264a1'
    } */

signTransaction()

Signs a raw transaction with the privateKey. Returns a serialized tx which can be submitted to the node.

const identity = EthCrypto.createIdentity();
const rawTx = {
    from: identity.address,
    to: '0x86Fa049857E0209aa7D9e616F7eb3b3B78ECfdb0',
    value: 1000000000000000000,
    gasPrice: 5000000000,
    nonce: 0,
    gasLimit: 21000
};
const signedTx = EthCrypto.signTransaction(
    rawTx,
    identity.privateKey
);
console.log(signedTx);
// > '071d3a2040a2d2cb...'

// you can now send the tx to the node
const receipt = await web3.eth.sendSignedTransaction(signedTx);

txDataByCompiled()

Creates the data-string which must be submitted with an transaction to create a contract-instance.

const SolidityCli = require('solidity-cli');

// create compiled solidity-code
const compiled = await SolidityCli.compileCode(
    'contract ExampleContract {...'
)[':ExampleContract'];

const createCode = EthCrypto.txDataByCompiled(
    compiled.interface, // abi
    compiled.bytecode, // bytecode
    [identity.address] // constructor-arguments
);

// now you can submit this to the blockchain
const serializedTx = EthCrypto.signTransaction(
    {
        from: identity.address,
        nonce: 0,
        gasLimit: 5000000,
        gasPrice: 5000000000,
        data: createCode
    },
    identity.privateKey
);
const receipt = await web3.eth.sendSignedTransaction(serializedTx);

calculateContractAddress()

Calculates the address for the contract from the senders address and the nonce, without deploying it to the blockchain.

// pre-calculate address
const calculatedAddress = EthCrypto.calculateContractAddress(
    account.address, // address of the sender
    3 // nonce with which the contract will be deployed
);

const rawTx = {
    from: account.address,
    gasPrice: parseInt(gasPrice),
    nonce: 3,
    data: compiled.code
};
const receipt = await state.web3.eth.sendTransaction(rawTx);

console.log(receipt.contractAddress === calculatedAddress);
// > true

hex compress/decompress

"Compress" or "decompress" a hex-string to make it smaller. You can either compress to utf16 which reduces the size to about 1/4, or to base64 which reduces the size to about 4/5. This is not a real compression, it just make your string smaller when you have to store it in utf-16 anyways.

const hexString = '0x107be946709e41b7895eea9f2dacf998a0a9124acbb786f0fd1a826101581a07'; // 66 chars

const utf16 = EthCrypto.hex.compress(hexString); // compress to utf16
// > 'ၻ炞䆷襞ⶬ輦ꂩቊ쮷蛰ﴚ艡Řᨇ' // 16 chars

const base64 = EthCrypto.hex.compress(hexString, true); // compress to base64
// > 'EHvpRnCeQbeJXuqfLaz5mKCpEkrLt4bw/RqCYQFYGgc=' // 44 chars

EthCrypto.hex.decompress(utf16); // decompress from utf16
// > '0x107be946709e41b7895eea9f2d...'

EthCrypto.hex.decompress(base64, true); // decompress from base64
// > '0x107be946709e41b7895eea9f2d...'


Get A Weekly Email With Trending Projects For These Topics
No Spam. Unsubscribe easily at any time.
Javascript (1,512,666
Blockchain (8,549
Tutorial (7,087
Ethereum (6,975
Solidity (6,365
Encryption (2,683
Smart Contracts (2,246
Dapp (1,424
Web3 (1,052
Truffle (707
Transaction (691
Signature (518
Cipher (370
Web3js (343
Eth (324
Sign (196
Related Projects