git ssb

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'use strict'
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var sodium     = require('chloride')
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var pb         = require('private-box')
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var u          = require('./util')
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var isBuffer = Buffer.isBuffer
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//UTILS
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function clone (obj) {
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  var _obj = {}
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  for(var k in obj) {
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    if(Object.hasOwnProperty.call(obj, k))
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      _obj[k] = obj[k]
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  }
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  return _obj
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}
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var hmac = sodium.crypto_auth
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exports.hash = u.hash
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exports.getTag = u.getTag
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function isObject (o) {
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  return 'object' === typeof o
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}
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function isFunction (f) {
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  return 'function' === typeof f
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}
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function isString(s) {
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  return 'string' === typeof s
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}
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var curves = {}
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curves.ed25519 = require('./sodium')
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function getCurve(keys) {
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  var curve = keys.curve
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  if(!keys.curve && isString(keys.public))
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    keys = keys.public
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  if(!curve && isString(keys))
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    curve = u.getTag(keys)
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  if(!curves[curve]) {
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    throw new Error(
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      'unkown curve:' + curve +
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      ' expected: '+Object.keys(curves)
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    )
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  }
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  return curve
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}
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//this should return a key pair:
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// {curve: curve, public: Buffer, private: Buffer}
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exports.generate = function (curve, seed) {
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  curve = curve || 'ed25519'
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  if(!curves[curve])
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    throw new Error('unknown curve:'+curve)
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  return u.keysToJSON(curves[curve].generate(seed), curve)
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}
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//import functions for loading/saving keys from storage
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var storage = require('./storage')(exports.generate)
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for(var key in storage) exports[key] = storage[key]
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exports.loadOrCreate = function (filename, cb) {
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  exports.load(filename, function (err, keys) {
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    if(!err) return cb(null, keys)
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    exports.create(filename, cb)
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  })
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}
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exports.loadOrCreateSync = function (filename) {
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  try {
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    return exports.loadSync(filename)
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  } catch (err) {
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    return exports.createSync(filename)
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  }
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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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function sign (keys, msg) {
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  if(isString(msg))
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    msg = new Buffer(msg)
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  if(!isBuffer(msg))
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    throw new Error('msg should be buffer')
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  var curve = getCurve(keys)
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  return curves[curve]
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    .sign(u.toBuffer(keys.private || keys), msg)
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    .toString('base64')+'.sig.'+curve
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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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function verify (keys, sig, msg) {
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  if(isObject(sig))
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    throw new Error('signature should be base64 string, did you mean verifyObj(public, signed_obj)')
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  return curves[getCurve(keys)].verify(
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    u.toBuffer(keys.public || keys),
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    u.toBuffer(sig),
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    isBuffer(msg) ? msg : new Buffer(msg)
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  )
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}
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// OTHER CRYPTO FUNCTIONS
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exports.signObj = function (keys, hmac_key, obj) {
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  if(!obj) obj = hmac_key, hmac_key = null
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  var _obj = clone(obj)
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  var b = new Buffer(JSON.stringify(_obj, null, 2))
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  if(hmac_key) b = hmac(b, hmac_key)
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  _obj.signature = sign(keys, b)
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  return _obj
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}
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exports.verifyObj = function (keys, hmac_key, obj) {
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  if(!obj) obj = hmac_key, hmac_key = null
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  obj = clone(obj)
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  var sig = obj.signature
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  delete obj.signature
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  var b = new Buffer(JSON.stringify(obj, null, 2))
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  if(hmac_key) b = hmac(b, hmac_key)
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  return verify(keys, sig, b)
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}
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exports.box = function (msg, recipients) {
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  msg = new Buffer(JSON.stringify(msg))
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  recipients = recipients.map(function (keys) {
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    return sodium.crypto_sign_ed25519_pk_to_curve25519(u.toBuffer(keys.public || keys))
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  })
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  return pb.multibox(msg, recipients).toString('base64')+'.box'
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}
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exports.unbox = function (boxed, keys) {
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  boxed = u.toBuffer(boxed)
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  var sk = sodium.crypto_sign_ed25519_sk_to_curve25519(u.toBuffer(keys.private || keys))
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  var msg = pb.multibox_open(boxed, sk)
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  if(msg) return JSON.parse(''+msg)
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}
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exports.randomKey = function () {
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  var b = new Buffer(32)
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  sodium.randombytes(b, 32)
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  return b.toString('base64')
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}
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