How to reduce payload size/take advantage of data structure?

A frequently-asked question is how to reduce the amount of metadata the ESDK message format adds to the encrypted payload (e.g. https://github.com/aws/aws-encryption-sdk-python/issues/309).

This usually comes up in the context of data with more structure, such as database records, where you'd like to be able to share this metadata across multiple encrypted values somehow. Just removing elements of the message format can easily degrade safety, but relocating them or sharing them somehow could be valid and beneficial.

The ESDK is designed to provide easy-to-use, hard-to-misuse encryption of unstructured blobs, and trying to take advantage of structure might be breaking too many fundamental assumptions to be a good idea. This issue is intended to at least collect feature requests in this space, though, and to think about how we can meet this common need.

Start by reading the issue text and the linked aws-encryption-sdk-python issue #309 to understand the recurring payload-size request. Review the ESDK message-format assumptions described here and collect concrete use cases or feature requests. Done means a sufficiently scoped, safety-preserving proposal exists; this issue does not name files or tests.

Written by the indexing model from the issue text.