git ssb

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var ssbKeys = require('ssb-keys')
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var isMsg = require('ssb-ref').isMsg
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var u = require('./util')
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var invite_key = require('./cap')
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function code(err, c) {
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  err.code = 'peer-invites:'+c
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  return err
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}
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function isObject (o) {
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  return o && 'object' === typeof o
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}
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function toBuffer(str) {
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  return Buffer.isBuffer(str) ? str : Buffer.from(str, 'base64')
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}
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//this should really be refactored out somewhere.
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function toMsgId(msg) {
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  return '%'+ssbKeys.hash(JSON.stringify(msg, null, 2))
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}
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//derive key for private field
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function hash (seed) {
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  if(!Buffer.isBuffer(seed)) throw new Error('expected seed as buffer')
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  return u.hash(seed)
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}
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//derive key for reveal field
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function hash2 (seed) {
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  if(!Buffer.isBuffer(seed)) throw new Error('expected seed as buffer')
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  return u.hash(u.hash(seed))
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}
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exports.createInvite = function (seed, host, reveal, private, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  seed = toBuffer(seed)
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  var keys = ssbKeys.generate(null, seed) //K
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  if(keys.id === host)
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    throw code(new Error('do not create invite with own public key'), 'peer-invites:no-own-goal')
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  return ssbKeys.signObj(keys, caps.peerInvite, {
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    type: 'peer-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: reveal ? u.box(reveal, hash2(seed)) : undefined,
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    private: private ? u.box(private, hash(seed)) : undefined
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  })
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}
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exports.verifyInvitePublic = function (msg, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  if(msg.content.host != msg.author)
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    throw code(new Error('host did not match author'), 'host-must-match-author')
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  if(!ssbKeys.verifyObj(msg.content.invite, caps.peerInvite, msg.content))
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    throw code(new Error('invalid invite signature'), 'invite-signature-failed')
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  //an ordinary message so doesn't use special hmac_key, unless configed to.
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  if(!ssbKeys.verifyObj(msg.author, caps.sign, msg))
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    throw code(new Error('invalid host signature'), 'host-signature-failed')
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  return true
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}
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exports.verifyInvitePrivate = function (msg, seed, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  seed = toBuffer(seed)
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  exports.verifyInvitePublic(msg, caps)
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  if(msg.content.reveal) {
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    var reveal = u.unbox(msg.content.reveal, hash2(seed))
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    if(!reveal) throw code(new Error('could not decrypt reveal field'), 'decrypt-reveal-failed')
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  }
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  if(msg.content.private) {
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    var private = u.unbox(msg.content.private, hash(seed))
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    if(!private) throw code(new Error('could not decrypt private field'), 'decrypt-private-failed')
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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, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  seed = toBuffer(seed)
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  exports.verifyInvitePrivate(msg, seed, caps)
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  var keys = ssbKeys.generate(null, seed) //K
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  if(keys.id != msg.content.invite)
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    throw code(new Error('seed does not match invite'), 'seed-must-match-invite')
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  var inviteId = toMsgId(msg)
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  var content = {
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    type: 'peer-invite/accept',
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    receipt: inviteId,
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    id: id
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  }
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  if(msg.content.reveal)
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    content.key = hash2(seed).toString('base64')
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  return ssbKeys.signObj(keys, caps.peerInvite, content)
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}
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exports.verifyAcceptOnly = function (accept, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  if(accept.content.type !== 'peer-invite/accept')
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    throw code(new Error('accept must be type: "peer-invite/accept", was:'+JSON.stringify(accept.content.type)), 'accept-message-type')
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  if(!isMsg(accept.content.receipt))
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    throw code(new Error('accept must reference invite message id'), 'accept-reference-invite')
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  //verify signed as ordinary message.
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  if(!ssbKeys.verifyObj(accept.content.id, caps.sign, accept))
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    throw code(new Error('acceptance must be signed by claimed key'), 'accept-signature-failed')
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}
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exports.verifyAccept = function (accept, invite_msg, caps) {
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  if(!isObject(caps)) throw new Error('caps *must* be provided')
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  if(!invite_msg) throw new Error('invite must be provided')
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  exports.verifyAcceptOnly(accept, caps)
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  if(invite_msg.content.type !== 'peer-invite')
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    throw code(new Error('accept must be type: invite, was:'+accept.content.type), 'peer-invites:invite-message-type')
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  var invite_id = toMsgId(invite_msg)
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  var reveal
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  if(invite_id !== accept.content.receipt)
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    throw code(new Error('acceptance not matched to given invite, got:'+invite_id+' expected:'+accept.content.receipt), 'accept-wrong-invite')
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  if(accept.author === invite_msg.content.id)
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    throw code(new Error('guest must use a new key, not the same seed'), 'guest-key-reuse')
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  if(invite_msg.content.reveal) {
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    if(!accept.content.key)
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      throw code(new Error('accept missing reveal key, when invite has it'), 'accept-must-reveal-key')
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    reveal = u.unbox(invite_msg.content.reveal, toBuffer(accept.content.key))
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    if(!reveal) throw code(new Error('accept did not correctly reveal invite'), 'decrypt-accept-reveal-failed')
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  }
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  if(!ssbKeys.verifyObj(invite_msg.content.invite, caps.peerInvite, accept.content))
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    throw code(new Error('did not verify invite-acceptance contents'), 'accept-invite-signature-failed')
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  //an ordinary message, so does not use hmac_key
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  return reveal || true
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}
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exports.createConfirm =  function (accept) {
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  return {
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    type: 'peer-invite/confirm',
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    embed: accept,
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    //second pointer back to receipt, so that links can find it
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    //(since it unfortunately does not handle links nested deeper
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    //inside objects. when we look up the message,
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    //confirm that content.embed.content.receipt is the same)
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    receipt: accept.content.receipt
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  }
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}
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