git ssb

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var ssbKeys = require('ssb-keys')
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var chloride = require('chloride')
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function box (data, key) {
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  if(!data) return
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  var b = new Buffer(JSON.stringify(data))
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  return chloride.crypto_secretbox_easy(b, key.slice(0, 24), key).toString('base64')
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}
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function unbox (ctxt, key) {
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  //var b = new Buffer(JSON.stringify(data))
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  var b = new Buffer(ctxt, 'base64')
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  var ptxt = chloride.crypto_secretbox_open_easy(b, key.slice(0, 24), key)
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  if(!ptxt) return
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  try {
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    return JSON.parse(ptxt)
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  } catch(err) {
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    console.error(err)
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  }
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}
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function hash(s) {
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  return chloride.crypto_hash_sha256(
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    'string' == typeof s ? new Buffer(s, 'utf8') : s
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  )
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}
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var invite_key = hash("user-invites:development")
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exports.createInvite = function (seed, host, reveal, private) {
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  var keys = ssbKeys.generate(null, seed) //K
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  if(keys.id === host)
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    throw new Error('do not create invite with own public key')
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  return ssbKeys.signObj(keys, invite_key, {
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    type: 'invite',
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    invite: keys.id,
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    host: host, //sign our own key, to prove we created K
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    reveal: box(reveal, hash(hash(seed))),
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    private: box(private, hash(seed))
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  })
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}
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exports.verifyInvitePublic = function (msg) {
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  if(!ssbKeys.verifyObj(msg.content.invite, invite_key, msg.content))
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    throw new Error('invalid guest signature')
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  if(msg.content.host != msg.author)
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    throw new Error('host did not match author')
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  //an ordinary message so doesn't use special hmac_key
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  if(!ssbKeys.verifyObj(msg.author, msg))
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    throw new Error('invalid host signature')
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  return true
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}
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exports.verifyInvitePrivate = function (msg, seed) {
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  exports.verifyInvitePublic(msg)
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  if(msg.content.reveal) {
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    var reveal = unbox(msg.content.reveal, hash(hash(seed)))
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    if(!reveal) throw new Error('could not decrypt message to be revealed')
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  }
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  if(msg.content.private) {
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    var private = unbox(msg.content.private, hash(seed))
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    if(!reveal) throw new Error('could not decrypt private message')
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  }
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  return {reveal: reveal, private: private}
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}
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exports.createAccept = function (msg, seed, id) {
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  var keys = ssbKeys.generate(null, seed) //K
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  if(keys.id != msg.content.invite) throw new Error('seed does not match invite')
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  var inviteId = '%'+ssbKeys.hash(JSON.stringify(msg, null, 2))
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  return ssbKeys.signObj(keys, invite_key, {
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    type: 'invite/accept',
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    reciept: inviteId,
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    id: id,
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    key: msg.content.reveal ? hash(hash(seed)).toString('base64') : undefined
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  })
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}
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exports.verifyAccept = function (accept, invite) {
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  var reveal
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  if('%'+ssbKeys.hash(JSON.stringify(invite, null, 2)) !== accept.content.reciept)
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    throw new Error('acceptance not matched to given invite')
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  if(accept.author === invite.content.id)
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    throw new Error('invitee must use a new key, not the same seed')
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  if(invite.content.reveal) {
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    reveal = unbox(invite.content.reveal, new Buffer(accept.content.key, 'base64'))
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    if(!reveal) throw new Error('accept did not correctly reveal invite')
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  }
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  if(!ssbKeys.verifyObj(invite.content.invite, invite_key, accept.content))
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    throw new Error('did not verify invite-acceptance contents')
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  //an ordinary message, so does not use hmac_key
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  if(!ssbKeys.verifyObj(accept.content.id, accept))
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    throw new Error('acceptance must be signed by claimed key')
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  return reveal || true
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}
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