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Showing posts from October, 2020

I turned Amazon Prime Photos into an "unlimited" off-site data backup service via JPEG APP markers

It has been several years since the Amazon Cloud Drive service API went from "okay" to "completely non-functional." Since I haven't used the service for quite a while, I figured it would be an okay time to reveal how I used to use Amazon Prime Photos as an unlimited storage backup service. It all starts with modifying the JPEG file format in ways not really conceived of before. The JPEG file format is a chunked, structured binary file format. What this means is that JPEG format reserves the 0xFF byte for "markers" for the start of each "chunk" and each chunk has a specific structure. For example, a JPEG image starts with the Start of Image (SOI) marker, which is 0xFF 0xD8, so we know that if we see that sequence, we have found the start of a JPEG image. Similarly, the End of Image (EOI) marker is 0xFF 0xD9, which means we have found the end of a JPEG image. There are many other markers for specific purposes that have been reserved f