56 lines
1.7 KiB
JavaScript
56 lines
1.7 KiB
JavaScript
var AESCBC = require('./aescbc');
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var Keypair = require('../keypair');
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var Point = require('../point');
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var Hash = require('../hash');
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var Pubkey = require('../pubkey');
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var Privkey = require('../privkey');
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// http://en.wikipedia.org/wiki/Integrated_Encryption_Scheme
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var ECIES = function ECIES() {
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if (!(this instanceof ECIES))
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return new ECIES();
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};
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ECIES.encrypt = function(messagebuf, topubkey, fromkeypair, ivbuf) {
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if (!fromkeypair)
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fromkeypair = Keypair().fromRandom();
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var r = fromkeypair.privkey.bn;
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var R = fromkeypair.pubkey.point;
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var Rpubkey = fromkeypair.pubkey;
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var Rbuf = Rpubkey.toDER(true);
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var KB = topubkey.point;
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var P = KB.mul(r);
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var S = P.getX();
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var Sbuf = S.toBuffer({size: 32});
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var kEkM = Hash.sha512(Sbuf);
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var kE = kEkM.slice(0, 32);
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var kM = kEkM.slice(32, 64);
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var c = AESCBC.encryptCipherkey(messagebuf, kE, ivbuf);
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var d = Hash.sha256hmac(c, kM);
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var encbuf = Buffer.concat([Rbuf, c, d]);
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return encbuf;
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};
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ECIES.decrypt = function(encbuf, toprivkey) {
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var kB = toprivkey.bn;
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var frompubkey = Pubkey().fromDER(encbuf.slice(0, 33));
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var R = frompubkey.point;
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var P = R.mul(kB);
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if (P.eq(new Point()))
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throw new Error('P equals 0');
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var S = P.getX();
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var Sbuf = S.toBuffer({size: 32});
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var kEkM = Hash.sha512(Sbuf);
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var kE = kEkM.slice(0, 32);
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var kM = kEkM.slice(32, 64);
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var c = encbuf.slice(33, encbuf.length - 32);
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var d = encbuf.slice(encbuf.length - 32, encbuf.length);
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var d2 = Hash.sha256hmac(c, kM);
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if (d.toString('hex') !== d2.toString('hex'))
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throw new Error('Invalid checksum');
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var messagebuf = AESCBC.decryptCipherkey(c, kE);
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return messagebuf;
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};
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module.exports = ECIES;
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