// 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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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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} else {
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if (signType !== 'rsa' && signType !== 'ecdsa/rsa') throw new Error('wrong private key type')
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}
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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 = [0x30, total, 0x02, r.length]
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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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