Unencrypted iCloud Photo Stream to Amazon AWS?

Apple documentation says that all Photo Stream content is encrypted. Yet while using wireshark to fix my privatizing web proxy's Photo Stream connection, I observed that iPhoto's connection to Photo Stream via Amazon AWS is unencrypted over port 80. Here's the packet capture that shows the unencrypted header, request ID, access key, signature, and so forth:

GET /XXX?x-client-request-id=YYY&Expires=ZZZ&byte-range=54-1229619&AWSAccessKeyId=W WW&Signature=UUU HTTP/1.1

Host: us-nca-00001.s3-external-1.amazonaws.com:80

User-Agent: PhotoStreamAgent/40.34 CFNetwork/596.2.3 Darwin/12.2.0 (x86_64) (Macmini4%2C1)

Accept: */*

x-amz-date: Wed, 06 Feb 2013 22:37:58 GMT

Range: bytes=54-1229619

x-apple-request-uuid: 9F8EFA00-71F8-4799-9241-A8A15CF75079

Connection: close

HTTP/1.1 206 Partial Content

x-amz-id-2: XXX

x-amz-request-id: YYY

Date: Mon, 11 Feb 2013 23:09:17 GMT

Last-Modified: Mon, 11 Feb 2013 23:09:11 GMT

ETag: "ZZZ"

Accept-Ranges: bytes

Content-Range: bytes 54-1229619/1798693

Content-Type: application/octet-stream

Content-Length: 1229566

Connection: close

Server: AmazonS3

The content is "application/octet-stream" and I was not able to identify as gzipped or any other content -- I presume that its encrypted, but I am unable to determine this. Does anyone know what this is? Anyone know which encryption protocol Apple uses for Photo Stream? Or why Photo Stream is communicating with Amazon AWS over port 80?