'use strict';
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// much of this based on https://github.com/indutny/self-signed/blob/gh-pages/lib/rsa.js
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var Buffer = require('safe-buffer').Buffer;
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var createHmac = require('create-hmac');
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var crt = require('browserify-rsa');
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var EC = require('elliptic').ec;
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var BN = require('bn.js');
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var parseKeys = require('parse-asn1');
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var curves = require('./curves.json');
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var RSA_PKCS1_PADDING = 1;
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function sign(hash, key, hashType, signType, tag) {
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var priv = parseKeys(key);
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if (priv.curve) {
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// rsa keys can be interpreted as ecdsa ones in openssl
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if (signType !== 'ecdsa' && signType !== 'ecdsa/rsa') { throw new Error('wrong private key type'); }
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return ecSign(hash, priv);
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} else if (priv.type === 'dsa') {
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if (signType !== 'dsa') { throw new Error('wrong private key type'); }
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return dsaSign(hash, priv, hashType);
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}
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if (signType !== 'rsa' && signType !== 'ecdsa/rsa') { throw new Error('wrong private key type'); }
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if (key.padding !== undefined && key.padding !== RSA_PKCS1_PADDING) { throw new Error('illegal or unsupported padding mode'); }
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hash = Buffer.concat([tag, hash]);
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var len = priv.modulus.byteLength();
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var pad = [0, 1];
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while (hash.length + pad.length + 1 < len) { pad.push(0xff); }
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pad.push(0x00);
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var i = -1;
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while (++i < hash.length) { pad.push(hash[i]); }
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var out = crt(pad, priv);
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return out;
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}
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function ecSign(hash, priv) {
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var curveId = curves[priv.curve.join('.')];
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if (!curveId) { throw new Error('unknown curve ' + priv.curve.join('.')); }
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var curve = new EC(curveId);
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var key = curve.keyFromPrivate(priv.privateKey);
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var out = key.sign(hash);
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return Buffer.from(out.toDER());
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}
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function dsaSign(hash, priv, algo) {
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var x = priv.params.priv_key;
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var p = priv.params.p;
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var q = priv.params.q;
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var g = priv.params.g;
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var r = new BN(0);
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var k;
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var H = bits2int(hash, q).mod(q);
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var s = false;
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var kv = getKey(x, q, hash, algo);
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while (s === false) {
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k = makeKey(q, kv, algo);
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r = makeR(g, k, p, q);
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s = k.invm(q).imul(H.add(x.mul(r))).mod(q);
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if (s.cmpn(0) === 0) {
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s = false;
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r = new BN(0);
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}
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}
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return toDER(r, s);
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}
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function toDER(r, s) {
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r = r.toArray();
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s = s.toArray();
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// Pad values
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if (r[0] & 0x80) { r = [0].concat(r); }
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if (s[0] & 0x80) { s = [0].concat(s); }
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var total = r.length + s.length + 4;
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var res = [
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0x30, total, 0x02, r.length
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];
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res = res.concat(r, [0x02, s.length], s);
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return Buffer.from(res);
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}
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function getKey(x, q, hash, algo) {
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x = Buffer.from(x.toArray());
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if (x.length < q.byteLength()) {
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var zeros = Buffer.alloc(q.byteLength() - x.length);
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x = Buffer.concat([zeros, x]);
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}
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var hlen = hash.length;
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var hbits = bits2octets(hash, q);
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var v = Buffer.alloc(hlen);
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v.fill(1);
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var k = Buffer.alloc(hlen);
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k = createHmac(algo, k).update(v).update(Buffer.from([0])).update(x).update(hbits).digest();
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v = createHmac(algo, k).update(v).digest();
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k = createHmac(algo, k).update(v).update(Buffer.from([1])).update(x).update(hbits).digest();
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v = createHmac(algo, k).update(v).digest();
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return { k: k, v: v };
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}
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function bits2int(obits, q) {
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var bits = new BN(obits);
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var shift = (obits.length << 3) - q.bitLength();
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if (shift > 0) { bits.ishrn(shift); }
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return bits;
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}
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function bits2octets(bits, q) {
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bits = bits2int(bits, q);
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bits = bits.mod(q);
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var out = Buffer.from(bits.toArray());
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if (out.length < q.byteLength()) {
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var zeros = Buffer.alloc(q.byteLength() - out.length);
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out = Buffer.concat([zeros, out]);
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}
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return out;
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}
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function makeKey(q, kv, algo) {
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var t;
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var k;
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do {
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t = Buffer.alloc(0);
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while (t.length * 8 < q.bitLength()) {
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kv.v = createHmac(algo, kv.k).update(kv.v).digest();
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t = Buffer.concat([t, kv.v]);
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}
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k = bits2int(t, q);
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kv.k = createHmac(algo, kv.k).update(kv.v).update(Buffer.from([0])).digest();
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kv.v = createHmac(algo, kv.k).update(kv.v).digest();
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} while (k.cmp(q) !== -1);
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return k;
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}
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function makeR(g, k, p, q) {
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return g.toRed(BN.mont(p)).redPow(k).fromRed().mod(q);
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}
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module.exports = sign;
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module.exports.getKey = getKey;
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module.exports.makeKey = makeKey;
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