I'm trying to reverse engineer a REST API and there is an endpoint that delivers images. Some of them are jpegs but other ones look like they're base64 encoded, except they don't appear to be, as they contain invalid chars such as & and -. If I "repair" the invalid chars I can base64 decode it, but it's just random binary data I can't discern anything from (does base64 have a checksum built in or can I base64-decode any string that has valid base64 characters?).
The data is around ~74 KB for an image I'm requesting in 500px width. Here is a bit of the content:
The API is sending a
Content-Transfer-Encoding: binary header with the response.
Are there other common formats to encode binary data that I may not be aware of or does anyone have an idea what kind of data this could be?