fix crypto.go for 2 issues:

[pckwan]

1. add a SHA3-256 hash of the message before passing it to be signed for
   the input fulfillment
2. use base64url encode, instead of base58 encode, to the resulting
   fulfillment string after it is signed

[jellevdp]

Great @pckwan - I ran the test and indeed its fixed.

[pckwan]

Thanks @jellevdp for the testing and review.
Please let me know if I need to do anything else in order for you to merge my pull request?
I don't think I have the permission to merge the fix from my fork repo to your main repo.

[bspark8]

@pckwan Thank you for making this patch! However, in my environment, "400 Bad Request response" occurs even after applying this patch.
It would be very grateful if you could see the current status!

(Example)
*** SIGNED TXN:
{"asset":{"data":{"assetID":"testID1"}},"id":"42389ed7907a53a8084704776fca6fa0c4e6b7693e681dd2b79f2a6d1ae9369f","inputs":[{"fulfillment":"pGSAIAYp4Z-T5qixw8ncCSaUYP8W1KdKrF5c8uLzB2Lp-D-3g
UB8-naUpGiielp5ZLK77oswo5DPZ5CqOAakI70DLKvqFssKEWTmZq0PdDC_p8F20brOLK0HEKSDXWr3eCjhv_IM","fulfills":null,"owners_before":["R4VCmawvk4ekcMvuUWZrmBaGmDSkfnntQb4UgVDtyQi"]}],"metadata":{"p
net":"earth"},"operation":"CREATE","outputs":[{"amount":"1","condition":{"details":{"public_key":"R4VCmawvk4ekcMvuUWZrmBaGmDSkfnntQb4UgVDtyQi","type":"ed25519-sha-256"},"uri":"ni:///sha-2
56;Binhn5PmqLHDydwJJpRg_xbUp0qsXlzy4vMHYun4P7c?cost=131072&fpt=ed25519-sha-256"},"public_keys":["R4VCmawvk4ekcMvuUWZrmBaGmDSkfnntQb4UgVDtyQi"]}],"version":"2.0"}

[dogusural]

It is probably related to the IPDB endpoint, try https://test.ipdb.io//api/v1/transactions?mode=sync

[bspark8]

Awesome! It works!

Currently, I quickly configured Bigchain DB in the local environment based on Docker by referring to the URL below.
(https://docs.bigchaindb.com/projects/server/en/latest/appendices/all-in-one-bigchaindb.html)

I first used js-bigchaindb-driver to see if "bigchaindb/bigchaindb:all-in-one" is the problem, and that js driver worked fine.

So I knew if there were still less resolved issues in go-bigchaindb-driver.
However, as you said, I sent a transaction to this place "https://test.ipdb.io//api/v1/transactions?mode=sync", and received "202 ACCEPTED".

If so, is "bigchaindb/bigchaindb:all-in-one" a problem? I would be very grateful if you could tell me more about the IPDB endpoint.