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/*
* Datona Crypto Library
*
* datona-lib cryptographic features
*
* Copyright (C) 2020 Datona Labs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
const errors = require('./errors');
const assert = require('./assertions');
const ecdsa = require('secp256k1');
const CryptoJS = require('crypto-js');
const FS = (typeof window === 'undefined') ? require('fs') : window.FS;
const keccak256 = require('js-sha3').keccak256;
const rlp = require('rlp');
const randomBytes = require('crypto').randomBytes;
/*
* Classes
*/
/*
* Encapsulates a private key and provides cryptographic functions that use it
*/
class Key {
/*
* Constructs the instance with the given private key
*/
constructor(privateKey) {
assert.isPrivateKey(privateKey, "privateKey");
this.privateKey = Buffer.from(privateKey, 'hex');
this.publicKey = ecdsa.publicKeyCreate(this.privateKey, false);
this.address = publicKeyToAddress(this.publicKey);
}
/*
* Signs the given hash with this key
*/
sign(hash) {
assert.isHash(hash, "hash");
const signature = ecdsa.sign(Buffer.from(hash, 'hex'), this.privateKey);
return toDatonaSignature(signature);
}
/*
* Encrypts the given data for the given key using the Elliptic Curve Integrated Encryption Scheme
* - The key derivation function used is the standard datona crypto hash function.
* - The encryption scheme used is AES-GCM.
* ECIES has been selected instead of an asymmetric scheme like RSA for performance reasons.
*/
encrypt(publicKeyTo, data) {
assert.isInstanceOf(publicKeyTo, "public key", Buffer);
assert.isPresent(data, "data");
const sharedSecret = ecdsa.ecdh(publicKeyTo, this.privateKey).toString('hex');
return CryptoJS.AES.encrypt(data,hash(sharedSecret)).toString();
}
decrypt(publicKeyFrom, data) {
assert.isInstanceOf(publicKeyFrom, "public key", Buffer);
assert.isPresent(data, "data");
const sharedSecret = ecdsa.ecdh(publicKeyFrom, this.privateKey).toString('hex');
return CryptoJS.AES.decrypt(data,hash(sharedSecret)).toString(CryptoJS.enc.Utf8);
}
}
/*
* Exports
*/
module.exports = {
generateKey: generateKey,
sign: sign,
verify: verify,
recover: recover,
getSignatory: recover,
calculateContractAddress: calculateContractAddress,
publicKeyToAddress: publicKeyToAddress,
hexToUint8Array: hexToUint8Array,
uint8ArrayToHex: uint8ArrayToHex,
hash: hash,
fileToHash: fileToHash,
Key: Key,
Buffer: Buffer // export to give javascript visibility in browser
};
/*
* External Functions
*/
/*
* Generates a new Key object with a random private key. NB: This function does
* not use a true random source. Use only for experimental and test purposes.
*/
function generateKey() {
var privateKey;
do {
privateKey = randomBytes(32);
} while (!ecdsa.privateKeyVerify(privateKey));
return new Key(privateKey.toString('hex'));
}
/*
* Signs the given hash using the given private key
*/
function sign(hash, privateKey) {
assert.isHash(hash, "hash");
assert.isPrivateKey(privateKey, "privateKey");
const signature = ecdsa.sign(Buffer.from(hash, 'hex'), Buffer.from(privateKey, 'hex'));
return toDatonaSignature(signature);
}
/*
* Verifies that the signatory of the given hash and signature matches the given address
*/
function verify(hash, signature, address) {
assert.isAddress(address, "address");
return recover(hash, signature) === address;
}
/*
* Recovers the address of the signatory of the given hash and signature
*/
function recover(hash, signature) {
if (!assert.isHash(hash)) throw new errors.InvalidHashError("hash is missing or invalid");
try {
assert.isHexString(signature, "signature");
const sig = fromDatonaSignature(signature);
const publicKey = ecdsa.recover(Buffer.from(hash, 'hex'), sig.signature, sig.recovery, false);
const publicKeyBuf = Buffer.from(publicKey, 'hex').slice(1); // Remove leading 0x04
const hashOfPublicKey = keccak256(publicKeyBuf);
return "0x" + Buffer.from(hashOfPublicKey, 'hex').slice(-20).toString('hex');
} catch (error) {
throw new errors.InvalidSignatureError(error.message, error.details);
}
}
/*
* Generates a keccak256 hash of the given data string
*/
function hash(data) {
try {
return keccak256(data);
} catch (error) {
throw new errors.HashingError("failed to hash data: " + error.message, data);
}
}
/*
* Returns a promise to generate a keccak256 hash of the given file.
* If the nonce string is given, it is appended to the file.
*/
function fileToHash( file, nonce ){
return new Promise(
function( resolve, reject ){
try {
const hash = new keccak256.create();
const fd = FS.createReadStream(file);
fd.on('data', function(data) { hash.update(data); });
fd.on('error', function(err){ reject( new errors.FileSystemError(err) ); });
fd.on('close', function() {
Iif (nonce) hash.update(nonce);
hash.digest();
resolve(hash.hex());
});
}
catch(err){
reject( new errors.FileSystemError(err) );
}
});
}
/*
* Generates a contract address
*/
function calculateContractAddress(ownerAddress, nonce) {
assert.isAddress(ownerAddress, "calculateContractAddress ownerAddress");
assert.isNumber(nonce, "calculateContractAddress nonce");
try {
return "0x"+keccak256(rlp.encode([ownerAddress, nonce])).substring(24);
}
catch (error) {
throw new errors.CryptographicError("Failed to calculate contract address: "+error.message);
}
}
/*
* Calculates the address associated with a public key
*/
function publicKeyToAddress(publicKey) {
assert.isInstanceOf(publicKey, "publicKey", Uint8Array);
const addressBuf = hash(publicKey.slice(1)).slice(-20 * 2);
return "0x" + addressBuf.toString('hex');
}
/*
* Hex conversion functions
*/
function hexToUint8Array(hexString) {
assert.isHexString(hexString, 'hexString');
return Buffer.from(hexString, 'hex');
}
function uint8ArrayToHex(buffer) {
assert.isInstanceOf(buffer, "buffer", Uint8Array);
return Buffer.from(buffer).toString('hex');
}
/*
* Internal Functions
*/
/*
* converts a signature produced by the secp256k1 library (with it's s and r values) to a
* Datona Signature string
*/
function toDatonaSignature(sig) {
var recovery = Buffer.alloc(1);
recovery[0] = sig.recovery;
return sig.signature.toString('hex') + recovery.toString('hex');
}
/*
* converts a Datona Signature string into a signature object compatible with the
* secp256k1 library
*/
function fromDatonaSignature(sigStr) {
const sigBuffer = Buffer.from(sigStr, 'hex');
return {
signature: sigBuffer.slice(0, -1),
recovery: sigBuffer[sigBuffer.length - 1]
};
}
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