Two issues with posting a photo via the v2 API:
1. The API seems to expect a lot of character/byte conversions to use the Latin 1 character set, but in the OAuth 1.0a spec it says UTF-8 should be used. It would probably be good to standardize on UTF-8 for all character/byte conversions unless a spec explicitly says to do otherwise.
2. The "data[N]" parameter names used in the OAuth signature base string should be doubly OAuth percent encoded, but the API appears to expect them to only be singly encoded. Doubly-encoding them per the spec results in an error response to the post.
You can see my post to the Tumblr API Discussion Google Group here for more info:
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