Use your public key as username and private key as password from your magento connect account
You can find public and private key at:
https://www.magentocommerce.com/magento-connect/customer/account/
developer tab -> Secure Keys -> Generate new or use existing key
Invalid credentials for 'https://repo.magento.com/packages.json'
原文：http://www.cnblogs.com/fengliang/p/6902327.html