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