Encrypt blobs in private messages

4 files changed, 105 insertions, 34 deletions

diff --git a/lib/app.js b/lib/app.js
index 4219151..3a41086 100644
--- a/lib/app.js
+++ b/lib/app.js
@@ -11,6 +11,10 @@ var Contacts = require('ssb-contact')
 var About = require('./about')
 var Serve = require('./serve')
 var Render = require('./render')
+var BoxStream = require('pull-box-stream')
+var crypto = require('crypto')
+
+var zeros = new Buffer(24); zeros.fill(0)
 
 module.exports = App
 
@@ -168,16 +172,54 @@ App.prototype.publish = function (content, cb) {
   tryPublish(2)
 }
 
-App.prototype.addBlob = function (cb) {
+App.prototype.addBlobRaw = function (cb) {
   var done = multicb({pluck: 1, spread: true})
-  var hashCb = done()
-  var addCb = done()
-  done(function (err, hash, add) {
-    cb(err, hash)
+  var sink = pull(
+    hasher(done()),
+    u.pullLength(done()),
+    this.sbot.blobs.add(done())
+  )
+  done(function (err, hash, size, _) {
+    if (err) return cb(err)
+    cb(null, {link: hash, size: size})
   })
+  return sink
+}
+
+App.prototype.addBlob = function (isPrivate, cb) {
+  if (!isPrivate) return this.addBlobRaw(cb)
+  else return this.addBlobPrivate(cb)
+}
+
+App.prototype.addBlobPrivate = function (cb) {
+  var bufs = []
+  var self = this
+  // use the hash of the cleartext as the key to encrypt the blob
+  var hash = crypto.createHash('sha256')
+  return pull.drain(function (buf) {
+    bufs.push(buf)
+    hash.update(buf)
+  }, function (err) {
+    if (err) return cb(err)
+    var secret = hash.digest()
+    pull(
+      pull.values(bufs),
+      BoxStream.createBoxStream(secret, zeros),
+      self.addBlobRaw(function (err, link) {
+        if (err) return cb(err)
+        link.key = secret.toString('base64')
+        cb(null, link)
+      })
+    )
+  })
+}
+
+App.prototype.getBlob = function (id, key) {
+  if (!key) return this.sbot.blobs.get(id)
+  if (typeof key === 'string') key = new Buffer(key, 'base64')
   return pull(
-    hasher(hashCb),
-    this.sbot.blobs.add(addCb)
+    this.sbot.blobs.get(id),
+    BoxStream.createUnboxStream(key, zeros)
   )
 }
 
diff --git a/lib/render.js b/lib/render.js
index dd6d55e..3b4a142 100644
--- a/lib/render.js
+++ b/lib/render.js
@@ -129,6 +129,7 @@ Render.prototype.markdown = function (text, mentions) {
 Render.prototype.imageUrl = function (ref) {
   var m = /^blobstore:(.*)/.exec(ref)
   if (m) ref = m[1]
+  ref = ref.replace(/#/, '%23')
   return this.opts.img_base + ref
 }
 
@@ -161,8 +162,14 @@ Render.prototype.toUrl = function (href) {
       if (!u.isRef(href)) return false
       return this.opts.base + href
     case '&':
-      if (!u.isRef(href)) return false
-      return this.opts.blob_base + href
+      var parts = href.split('#')
+      var hash = parts.shift()
+      var key = parts.shift()
+      var fragment = parts.join('#')
+      if (!u.isRef(hash)) return false
+      return this.opts.blob_base + hash
+        + (key ? encodeURIComponent('#' + key) : '')
+        + (fragment ? '#' + fragment : '')
     case '#': return this.opts.base + 'channel/' +
       encodeURIComponent(href.substr(1))
     case '/': return this.opts.base + href.substr(1)
diff --git a/lib/serve.js b/lib/serve.js
index 8d3eeba..1ce18c6 100644
--- a/lib/serve.js
+++ b/lib/serve.js
@@ -24,7 +24,7 @@ module.exports = Serve
 
 var emojiDir = path.join(require.resolve('emoji-named-characters'), '../pngs')
 
-var urlIdRegex = /^(?:\/+(([%&@]|%25)(?:[A-Za-z0-9\/+]|%2[Ff]|%2[Bb]){43}(?:=|%3D)\.(?:sha256|ed25519))(?:\.([^?]*))?|(\/.*?))(?:\?(.*))?$/
+var urlIdRegex = /^(?:\/+(([%&@]|%25)(?:[A-Za-z0-9\/+]|%2[Ff]|%2[Bb]){43}(?:=|%3D)\.(?:sha256|ed25519))([^?]*)?|(\/.*?))(?:\?(.*))?$/
 
 function ctype(name) {
   switch (name && /[^.\/]*$/.exec(name)[0] || 'html') {
@@ -75,19 +75,18 @@ Serve.prototype.go = function () {
         gotData(err, data)
       })
       busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
-        var done = multicb({pluck: 1, spread: true})
         var cb = filesCb()
         pull(
           toPull(file),
-          u.pullLength(done()),
-          self.app.addBlob(done())
+          self.app.addBlob(!!data.private, function (err, link) {
+            if (err) return cb(err)
+            if (link.size === 0 && !filename) return cb()
+            link.name = filename
+            link.type = mimetype
+            data[fieldname] = link
+            cb()
+          })
         )
-        done(function (err, size, id) {
-          if (err) return cb(err)
-          if (size === 0 && !filename) return cb()
-          data[fieldname] = {link: id, name: filename, type: mimetype, size: size}
-          cb()
-        })
       })
       busboy.on('field', function (fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) {
         if (!(fieldname in data)) data[fieldname] = val
@@ -197,7 +196,7 @@ Serve.prototype.handle = function () {
     case '%25': m[2] = '%'; m[1] = decodeURIComponent(m[1])
     case '%': return this.id(m[1], m[3])
     case '@': return this.userFeed(m[1], m[3])
-    case '&': return this.blob(m[1])
+    case '&': return this.blob(m[1], m[3])
     default: return this.path(m[4])
   }
 }
@@ -809,7 +808,7 @@ function threadHeads(msgs, rootId) {
 }
 
 
-Serve.prototype.id = function (id, ext) {
+Serve.prototype.id = function (id, path) {
   var self = this
   if (self.query.raw != null) return self.rawId(id)
 
@@ -845,16 +844,14 @@ Serve.prototype.id = function (id, ext) {
             channel: channel,
           }),
           self.wrapPage(id),
-          self.respondSink(200, {
-            'Content-Type': ctype(ext),
-          })
+          self.respondSink(200)
         )
       })
     )
   })
 }
 
-Serve.prototype.userFeed = function (id, ext) {
+Serve.prototype.userFeed = function (id, path) {
   var self = this
   var q = self.query
   var opts = {
@@ -874,9 +871,7 @@ Serve.prototype.userFeed = function (id, ext) {
       self.wrapMessages(),
       self.wrapUserFeed(isScrolled, id),
       self.wrapPage(about.name || id),
-      self.respondSink(200, {
-        'Content-Type': ctype(ext)
-      })
+      self.respondSink(200)
     )
   })
 }
@@ -905,10 +900,27 @@ Serve.prototype.emoji = function (emoji) {
   serveEmoji(this.req, this.res, emoji)
 }
 
-Serve.prototype.blob = function (id) {
+Serve.prototype.blob = function (id, path) {
   var self = this
   var blobs = self.app.sbot.blobs
-  if (self.req.headers['if-none-match'] === id) return self.respond(304)
+  var etag = id + (path || '')
+  if (self.req.headers['if-none-match'] === etag) return self.respond(304)
+  var key
+  if (path) {
+    path = decodeURIComponent(path)
+    if (path[0] === '#') {
+      try {
+        key = new Buffer(path.substr(1), 'base64')
+      } catch(err) {
+        return self.respond(400, err.message)
+      }
+      if (key.length !== 32) {
+        return self.respond(400, 'Bad blob key')
+      }
+    } else {
+      return self.respond(400, 'Bad blob request')
+    }
+  }
   var done = multicb({pluck: 1, spread: true})
   blobs.want(id, function (err, has) {
     if (err) {
@@ -918,7 +930,7 @@ Serve.prototype.blob = function (id) {
     if (!has) return self.respond(404, 'Not found')
     blobs.size(id, done())
     pull(
-      blobs.get(id),
+      self.app.getBlob(id, key),
       pull.map(Buffer),
       ident(done().bind(self, null)),
       self.respondSink()
@@ -927,11 +939,14 @@ Serve.prototype.blob = function (id) {
       if (err) console.trace(err)
       type = type && mime.lookup(type)
       if (type) self.res.setHeader('Content-Type', type)
-      if (typeof size === 'number') self.res.setHeader('Content-Length', size)
+      // don't serve size for encrypted blob, because it refers to the size of
+      // the ciphertext
+      if (typeof size === 'number' && !key)
+        self.res.setHeader('Content-Length', size)
       if (self.query.name) self.res.setHeader('Content-Disposition',
         'inline; filename='+encodeDispositionFilename(self.query.name))
       self.res.setHeader('Cache-Control', 'public, max-age=315360000')
-      self.res.setHeader('etag', id)
+      self.res.setHeader('etag', etag)
       self.res.writeHead(200)
     })
   })
@@ -1290,6 +1305,7 @@ Serve.prototype.wrapThread = function (opts) {
         branches: opts.branches,
         postBranches: opts.postBranches,
         recps: recps,
+        private: opts.recps != null,
       }, function (err, composer) {
         if (err) return cb(err)
         cb(null, [
@@ -1428,6 +1444,7 @@ Serve.prototype.composer = function (opts, cb) {
     blobs[data.upload.link] = {
       type: data.upload.type,
       size: data.upload.size,
+      key: data.upload.key,
     }
   }
   if (data.blob_type && blobs[data.blob_link]) {
@@ -1443,11 +1460,13 @@ Serve.prototype.composer = function (opts, cb) {
   }
 
   if (data.upload) {
+    var href = data.upload.link
+      + (data.upload.key ? '#' + data.upload.key : '')
     // TODO: be able to change the content-type
     var isImage = /^image\//.test(data.upload.type)
     data.text = (data.text ? data.text + '\n' : '')
       + (isImage ? '!' : '')
-      + '[' + data.upload.name + '](' + data.upload.link + ')'
+      + '[' + data.upload.name + '](' + href + ')'
   }
 
   // get bare feed names
@@ -1509,6 +1528,8 @@ Serve.prototype.composer = function (opts, cb) {
       h('table.ssb-msgs',
         h('tr.msg-row',
           h('td.msg-left', {colspan: 2},
+            opts.private ?
+              h('input', {type: 'hidden', name: 'private', value: '1'}) : '',
             h('input', {type: 'file', name: 'upload'})
           ),
           h('td.msg-right',
diff --git a/package.json b/package.json
index 7b77ca5..c09174c 100644
--- a/package.json
+++ b/package.json
@@ -12,6 +12,7 @@
     "hashlru": "^2.1.0",
     "mime-types": "^2.1.12",
     "multicb": "^1.2.1",
+    "pull-box-stream": "^1.0.12",
     "pull-cat": "^1.1.11",
     "pull-hash": "^1.0.0",
     "pull-hyperscript": "^0.2.2",