Openssl removed ripemd160 support. Code using hashlib's 'ripemd160' algorithm may fail.

[cmdruid]

I'm posting this issue in order to help anyone who comes across this problem.

If you try to use the code:
hashlib.new('ripemd160', thingtobehashed).digest()

and you receive this error:
ValueError: unsupported hash type ripemd160

It is because Hashlib uses openssl under the hood, and openssl has recently decided to depreciate support for the ripemd160 algorithm. See the relevant issues below:

openssl/openssl#16994
bitcoin/bitcoin#23710

There may be some way to re-enable support for ripemd160 under the hood, but I think an easier solution is to just copy/paste the pure python implementation of ripemd160 and use that instead. See the link below (code courtesy of the legend Pieter Wuille):

https://github.com/bitcoin/bitcoin/blob/master/test/functional/test_framework/ripemd160.py

If you would like, I can submit a PR that adds this file to the chapters and updates the existing hash160 function (with notes explaining the issue). But maybe there's a cleaner way to fix this, I don't know.

[vvronskyFX]

Nice catch @cmdruid can you specify which chapter we will encounter this on?

Also, should we create a separate file that includes the entire "ripemd160.py" and import that file into our scripts?

[cmdruid]

Nice catch @cmdruid can you specify which chapter we will encounter this on?

Starting from chapter 4, it is used in the helper.py file. So the issue would be addressing chapters 4-13.

Also, should we create a separate file that includes the entire "ripemd160.py" and import that file into our scripts?

Yes that is correct. The ripemd160.py seems to work just fine as a replacement.

[vvronskyFX]

Thanks @cmdruid - so far I haven't ran into any issues using "hash160".

So far the only big issue I had was on this problem: #254

Thank you for sharing this information!

[gudnuf]

You can change your openssl config to enable ripemd160.

https://stackoverflow.com/questions/72409563/unsupported-hash-type-ripemd160-with-hashlib-in-python