im trying to follow this tutorial - https://zokrates.github.io/sha256example.html

I built zokrates docker provided and copied the source code to the docker, and then tried to compile the code.

here is the code:

import "LIBSNARK/sha256packed"
def main(private field a, private field b, private field c, private field d) -> (field[2]):
h = sha256packed([a,b,c,d])
    return h

However, i faced following error messages:

Compilation failed: Semantic error: Function definition for function sha256packed with signature (field[4]) -> (_) not found.

what is wrong with this work?

1 Answer 1


This is probably an old answer by now, but I believe you were looking at an outdated version of the blog. ZoKrates have modified the SHA256 gadget, and the import now looks liek this:

import "hashes/sha256/512bitPacked.code" as sha256packed

The function signature also is a bit different now that what it was, but your code already seems to conform to the current version.

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