Yea, something must be wrong with the service. Cant install either right now, even with right credentials!
I am experiencing the exact same problem. Two days ago it worked for me. Now there is no way to make it work. As far as I remember http://repo.magento.com/ looked different a few days ago. Did any changes happen there while part of the Magento Website was offline yesterday ?
I also encountered similar problems, but it looks like I can not find the desired information at this link
Authentification seems to be working again.
(In case it is still not working for you I recommend generating a new pair of secure keys. That just worked for me.)
Can confirm that it's now working for us!
Is there a sollution now ? I still can not use connect manager
Use your public key as username and private key as password from your Magento connect account
https://www.magentocommerce.com/magento-connect/customer/account/
Connect -> Developers -> Secure Keys -> Create A New Access Key(Or using exsting key)
Also, you can find the public and private key at:
https://developer.magento.com/customer/account/
Developer Portal -> My Access Keys -> Create A New Access Key(Or using exsting key)
The error is caused by an incorrectly entered key.
Username: -> Public Key:
Password: -> Private Key: