I'm not sure how to write this block header digest/hash generation in another language then C(++). Is this even possible without a lot of hacking?

If so: Could a language-neutral format for the digest message be documented?

If not: This would be a very undesireable lock-in: EOS blocks will not be able to be validated on other blockchains like ethereum. Perhaps this hash function should be refined in a more language-neutral way.

Edit 1 (May 10) I found this serialiser that was written for steem data types, but obviously there's a lot of interoperability!

  • A better question might be: "How can I calculate the block digest?" May 8, 2018 at 23:12
  • ^ Exactly, clear documentation on this would be extremely useful.
    – wanheda
    May 8, 2018 at 23:21

1 Answer 1


Here's how the C++ code calculates the block digest:

  • digest_type::hash(*this) serializes the block into a binary form, then runs the binary through sha-256.
  • block.hpp#L125 identifies the order that the fields are serialized in.
  • The types of these fields is at block.hpp#L18
  • Each type has its own serialization procedure. Most of them live in libraries/fc.
  • Here's an example of how it serializes an unsigned_int. This is a 32-bit type which serializes to 1-5 bytes depending on value: raw.hpp#L210

Note: many users of the JSON RPC API have to serialize objects to binary form, so I suspect someone will create documentation of this process.

Note: the block fields may still change. I pointed to the master branch as of 2018-05-08.

  • Awesome, could you link to such a type serialisation procedure in libraries/fc?
    – wanheda
    May 8, 2018 at 23:19
  • @toonsevrin added May 8, 2018 at 23:28
  • Take a look at my post edit, quite a nice resource!
    – wanheda
    May 10, 2018 at 14:40

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