git ssb

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var fs       = require('fs')
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var crypto   = require('crypto')
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var ecc      = require('eccjs')
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var k256     = ecc.curves.k256
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var Blake2s  = require('blake2s')
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var mkdirp   = require('mkdirp')
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var path     = require('path')
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var curve    = ecc.curves.k256
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var createHmac = require('hmac')
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function hash (data, enc) {
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  return new Blake2s().update(data, enc).digest('base64') + '.blake2s'
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}
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function isHash (data) {
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  return isString(data) && /^[A-Za-z0-9\/+]{43}=\.blake2s$/.test(data)
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}
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exports.isHash = isHash
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exports.hash = hash
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function isString(s) {
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  return 'string' === typeof s
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}
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function empty(v) { return !!v }
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function constructKeys() {
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  var privateKey = crypto.randomBytes(32)
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  var k          = keysToBase64(ecc.restore(k256, privateKey))
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  k.keyfile      = [
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  '# this is your SECRET name.',
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  '# this name gives you magical powers.',
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  '# with it you can mark your messages so that your friends can verify',
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  '# that they really did come from you.',
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  '#',
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  '# if any one learns this name, they can use it to destroy your identity',
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  '# NEVER show this to anyone!!!',
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  '',
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  k.private.toString('hex'),
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  '',
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  '# WARNING! It\'s vital that you DO NOT edit OR share your secret name',
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  '# instead, share your public name',
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  '# your public name: ' + k.id.toString('hex')
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  ].join('\n')
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  return k
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}
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function toBuffer(buf) {
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  if(buf == null) return buf
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  return new Buffer(buf.substring(0, buf.indexOf('.')), 'base64')
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}
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function keysToBase64 (keys) {
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  var pub = tag(keys.public, 'k256')
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  return {
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    public: pub,
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    private: tag(keys.private, 'k256'),
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    id: hash(pub)
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  }
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}
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function hashToBuffer(hash) {
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  if(!isHash(hash)) throw new Error('sign expects a hash')
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  return toBuffer(hash)
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}
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function keysToBuffer(key) {
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  return isString(key) ? toBuffer(key) : {
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    public: toBuffer(key.public),
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    private: toBuffer(key.private)
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  }
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}
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function reconstructKeys(privateKeyStr) {
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  privateKeyStr = privateKeyStr
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    .replace(/\s*\#[^\n]*/g, '')
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    .split('\n').filter(empty).join('')
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  var privateKey = (
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      !/\./.test(privateKeyStr)
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    ? new Buffer(privateKeyStr, 'hex')
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    : toBuffer(privateKeyStr)
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  )
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  return keysToBase64(ecc.restore(k256, privateKey))
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}
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function tag (key, tag) {
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  return key.toString('base64')+'.' + tag.replace(/^\./, '')
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}
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exports.load = function(namefile, cb) {
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  fs.readFile(namefile, 'ascii', function(err, privateKeyStr) {
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    if (err) return cb(err)
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    try { cb(null, reconstructKeys(privateKeyStr)) }
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    catch (e) { cb(err) }
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  })
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}
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exports.loadSync = function(namefile) {
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  return reconstructKeys(fs.readFileSync(namefile, 'ascii'))
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}
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exports.create = function(namefile, cb) {
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  var k = constructKeys()
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  mkdirp(path.dirname(namefile), function (err) {
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    if(err) return cb(err)
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    fs.writeFile(namefile, k.keyfile, function(err) {
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      if (err) return cb(err)
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      delete k.keyfile
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      cb(null, k)
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    })
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  })
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}
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exports.createSync = function(namefile) {
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  var k = constructKeys()
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  mkdirp.sync(path.dirname(namefile))
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  fs.writeFileSync(namefile, k.keyfile)
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  delete k.keyfile
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  return k
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}
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exports.loadOrCreate = function (namefile, cb) {
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  exports.load(namefile, function (err, keys) {
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    if(!err) return cb(null, keys)
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    exports.create(namefile, cb)
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  })
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}
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exports.loadOrCreateSync = function (namefile) {
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  try {
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    return exports.loadSync(namefile)
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  } catch (err) {
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    return exports.createSync(namefile)
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  }
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}
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//this should return a key pair:
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// {public: Buffer, private: Buffer}
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exports.generate = function () {
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  return keysToBase64(ecc.restore(curve, crypto.randomBytes(32)))
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}
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//takes a public key and a hash and returns a signature.
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//(a signature must be a node buffer)
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exports.sign = function (keys, hash) {
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  var hashTag = hash.substring(hash.indexOf('.'))
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  return tag(
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    ecc.sign(curve, keysToBuffer(keys), hashToBuffer(hash)),
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    hashTag + '.k256'
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  )
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}
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//takes a public key, signature, and a hash
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//and returns true if the signature was valid.
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exports.verify = function (pub, sig, hash) {
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  return ecc.verify(curve, keysToBuffer(pub), toBuffer(sig), hashToBuffer(hash))
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}
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function createHash() {
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  return new Blake2s()
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}
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exports.hmac = function (data, key) {
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  return createHmac(createHash, 64, key)
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    .update(data).digest('base64')+'.blake2s.hmac'
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}
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