Where to set aws access/secret key for kube-up.sh to work correctly in Kubernetes (aws)

I am trying to setup a Kubernetes cluster on my AWS account using the kube-up.sh setup script that is bundled with kubernetes source at kubernetes/cluster/kube-up.sh

But when I ran kube-up.sh I am getting the following error:

pranjal:~/go/src/http://ift.tt/1Qogb1r ./kube-up.sh
Starting cluster using os distro: ubuntu
Starting cluster using provider: aws
... calling verify-prereqs
... calling kube-up
Uploading to Amazon S3
Creating kubernetes-staging-6b790c161af2b2c39939b542c73b775a
make_bucket failed: s3://kubernetes-staging-6b790c161af2b2c39939b542c73b775

I am sure that my the tool is not able to read my AWS Access Key and Secret. I stored it in .aws/config. I am not sure where I should set it for it to be able to read it correctly and work.