Error installing laravel 5 by composer

I'm using windows 7 and trying to install laravel by composer.I've installed composer in my system and added git to my path earlier.I also downloaded a fresh copy of laravel and paste it into my server.Now,when i run this comment to install laravel ,i get this error.

C:\xampp\htdocs\laravel-master>composer install

Loading composer repositories with package information

Installing dependencies (including require-dev)

• Installing symfony/var-dumper (v2.7.5)

  Downloading: 100%

  Downloading: 100%

  Downloading: 100%

  Failed to download symfony/var-dumper from dist: The http//http://ift.tt/1ZTkr0t fony/var-dumper/zipball/ba8c9a0edf18f70a7efcb8d3eb35323a10263338 file could not be downlo aded: failed to open stream: A connection attempt failed because the connected party did n ot properly respond after a period of time, or established connection failed because conne cted host has failed to respond.

  Now trying to download from source

  • Installing symfony/var-dumper (v2.7.5) Cloning ba8c9a0edf18f70a7efcb8d3eb35323a10263338

[RuntimeException] Failed to clone git@github.com:symfony/var-dumper.git via git, https, ssh protocols, aborting.

• git://github.com/symfony/var-dumper.git Cloning into 'C:\xampp\htdocs\laravel-master\vendor\symfony\var-dumper'... fatal: unable to connect to github.com: github.com[0: 192.30.252.128]: errno=No error

• http://ift.tt/1ZTkt8F Cloning into 'C:\xampp\htdocs\laravel-master\vendor\symfony\var-dumper'... fatal: unable to access 'http://ift.tt/1RlFXVE': Failed connec t to github.com:443; No error

  • git@github.com:symfony/var-dumper.git Cloning into 'C:\xampp\htdocs\laravel-master\vendor\symfony\var-dumper'... Warning: Permanently added 'github.com,192.30.252.131' (RSA) to the list of known h osts. Permission denied (publickey). fatal: Could not read from remote repository.

  Please make sure you have the correct access rights

  and the repository exists.

Any kind of help would be appreciated. Thanks in advance!

via Chebli Mohamed