diff --git a/lib/conf/package.js b/lib/conf/package.js
index 403fc2b30..6e3856315 100644
--- a/lib/conf/package.js
+++ b/lib/conf/package.js
@@ -1,18 +1,17 @@
-var fs     = require('fs'),
-    path   = require('path'),
-    needle = require('needle'),
-    system = require('./../system'),
-    rmdir  = require('./../utils/rmdir'),
-    os_name = system.os_name;
-
-var releases_host    = 'http://s3.amazonaws.com',
+var fs         = require('fs'),
+    path       = require('path'),
+    needle     = require('needle'),
+    createHash = require('crypto').createHash,
+    system     = require('./../system'),
+    rmdir      = require('./../utils/rmdir'),
+    os_name    = system.os_name;
+
+var releases_host    = 'https://s3.amazonaws.com',
     releases_url     = releases_host + '/prey-releases/node-client/',
     latest_text      = 'latest.txt',
-    latest_checksums = 'latest/shasums.txt',
+    checksums        = 'shasums.json',
     package_format   = '.zip';
 
-// TODO: validate checksums
-
 var log = function(str) {
   if (process.stdout.writable)
     process.stdout.write(str + '\n');
@@ -25,6 +24,43 @@ var is_greater_than = function(first, second){
   return a > b ? true : false;
 };
 
+// returns sha1 checksum for file
+var checksum_for = function(file, cb) {
+  var error,
+      hash   = createHash('sha1'),
+      stream = fs.ReadStream(file);
+
+  stream.on('error', function(e) {
+    if (!error) cb(e);
+    error = e;
+  })
+
+  stream.on('data', function(d) {
+    hash.update(d);
+  });
+
+  stream.on('end', function() {
+    if (!error) cb(null, hash.digest('hex'));
+  });
+}
+
+var verify_checksum = function(url, filename, file, cb) {
+  log('Fetching checksum: ' + url);
+  needle.get(url, { parse: true }, function(err, resp) {
+    if (err) return cb(err);
+
+    var checksum = resp.body[filename];
+    if (!checksum)
+      return cb(new Error('Unable to retrieve checksum for ' + filename));
+
+    log('Got checksum from remote: ' + checksum + '. Calculating file hash...');
+    checksum_for(file, function(err, res) {
+      var valid = (res && res.trim() == checksum.trim());
+      cb(err, valid);
+    })
+  })
+}
+
 var package = module.exports;
 
 package.new_version_available = function(current, cb) {
@@ -39,46 +75,33 @@ package.new_version_available = function(current, cb) {
 package.get_upstream_version = function(cb){
   // log('Checking latest version...');
 
-  var done = function(ver) {
-    // log('Latest upstream version: ' + ver);
-    cb(null, ver);
-  }
-
-  needle.get(releases_url + latest_text, function(err, resp, body){
-    if (!err && body != '')
-      return done(body.toString().trim());
-
-    needle.get(releases_url + latest_checksums, function(err, resp, body){
-      if (err) return cb(err);
-
-      var match = body.toString().match(/prey-([\d\.]+)\.zip/);
-      if (!match)
-        return cb(new Error('Unable to determine latest version from ' + latest_checksums))
+  needle.get(releases_url + latest_text, function(err, resp, body) {
+    var ver = body && body.toString().trim();
+    log('Latest upstream version: ' + ver);
 
-      done(match[1]);
-    });
+    cb(err, ver);
   });
-
 }
 
 package.get_latest = function(current_version, dest, cb){
-  package.new_version_available(current_version, function(err, version){
+  package.new_version_available(current_version, function(err, version) {
     if (err || !version)
       return cb(err || new Error('Already running latest version.'));
 
     if (fs.existsSync(path.join(dest, version)))
       return cb(new Error('Version ' + version + ' already installed.'));
 
-    package.get_version(version, dest, function(err){
+    package.get_version(version, dest, function(err) {
       cb(err, version);
     });
   });
 };
 
-package.get_version = function(version, dest, cb){
+package.get_version = function(version, dest, cb) {
   log('Fetching version ' + version);
-  package.download_release(version, function(err, file){
+  package.download_release(version, function(err, file) {
     if (err) return cb(err);
+
     package.install(file, dest, function(err, installed_version) {
       fs.unlink(file, function() {
         cb(err, installed_version);
@@ -87,23 +110,37 @@ package.get_version = function(version, dest, cb){
   });
 }
 
-package.download_release = function(version, cb){
-  var arch = process.arch == 'x64' ? 'x64' : 'x86';
-  var release = ['prey', os_name, version, arch].join('-') + package_format;
-  var host_path = releases_url + version + '/';
-  package.download(host_path + release, cb);
+package.download_release = function(version, cb) {
+
+  var arch      = process.arch == 'x64' ? 'x64' : 'x86',
+      release   = ['prey', os_name, version, arch].join('-') + package_format,
+      host_path = releases_url + version + '/';
+
+  package.download(host_path + release, function(err, file) {
+
+    verify_checksum(host_path + checksums, release, file, function(err, valid) {
+      if (err || !valid)
+        return cb && cb(err || new Error('Invalid checksum for file: ' + release));
+
+      log('File checksum is valid! ' + file)
+      return cb && cb(null, file);
+    })
+  });
 }
 
-package.download = function(url, cb){
+package.download = function(url, cb) {
   log('Downloading package: ' + url);
   var file = system.tempfile_path(path.basename(url));
 
-  needle.get(url, { output: file }, function(err, resp, data){
+  return cb(null, file);
+
+  needle.get(url, { output: file }, function(err, resp, data) {
+
     if (err || resp.statusCode != 200)
       return cb && cb(err || new Error('Unexpected response: \n\n' + data.toString()));
 
     fs.exists(file, function(exists) {
-      if (!exists) return cb(new Error('File not found!'));
+      if (!exists) return cb && cb(new Error('File not found!'));
 
       log('Got file: ' + file)
       return cb && cb(null, file);