Amazon S3 Announces Support for Bucket Policies
aws.amazon.com
aws.amazon.com
aws:CurrentTime — For date/time conditions (see Date Conditions)
aws:SecureTransport — Boolean representing whether the request was sent using SSL (see Boolean Conditions)
aws:SourceIp — The requester's IP address, for use with IP address conditions (see IP Address)
aws:UserAgent — Information about the requester's client application, for use with string conditions (see String Conditions)
aws:EpochTime — Number of seconds since epoch.
aws:Referer — Same the the HTTP referer field.
(from http://docs.amazonwebservices.com/AmazonS3/latest/dev/Access...)