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erlang / otp

Erlang/OTP
http://erlang.org
Apache License 2.0
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add support for truncated SHA-512/t: SHA-512/256 and SHA-512/224 #5087

Open faried opened 3 years ago

faried commented 3 years ago

Is your feature request related to a problem? Please describe.

I was trying to port some code over from Javascript when I found out that crypto did not implement SHA-512. Truncated SHA-512 is SHA-512 with a different initial value, and with the output truncated at the right place (32 bytes for SHA-512/256, for example). The crypto module does not appear to export anything that will let me fiddle with this initial value.

OpenSSL has supported these functions 1.1.1, released almost three years ago.

Describe the solution you'd like

Add support for SHA512/256 to crypto.

Describe alternatives you've considered

I forked a pure Erlang implementation of SHA2 from 2015, disabled the code that loaded the NIF, and added my functions. It's not ideal, but it'll work for my current project.

HansN commented 3 years ago

This is currently not prioritized by Erlang/OTP, but Pull Requests are welcome.

KayEss commented 1 year ago

I'm wondering about taking a stab at adding the two truncated hash functions to the crypto module. I guess my strategy will be to go through occurrences of sha512 in the crypto module and add sha512_224 and sha512_256 where appropriate.

The open_ssl documentation https://www.openssl.org/docs/manmaster/man3/EVP_sha512_224.html lumps the truncated functions in with the ones that are already being used, so it should be a very simple change (I hope).

Is there anything I should keep in mind? So far I've cloned and built this project and I can run the tests using make ARGS="-suite crypto_SUITE" and I've read the contributing guide.

sverker commented 1 year ago

@KayEss If this is just about adding a new digest version then it should be quite straight forward. You will end up down in lib/crypto/c_src/digest.c and the array digest_types containing all the different supported digest types. Note that OpenSSL >= 3.0 uses a slightly different initialization with EVP_MD_fetch. Then also add tests and documentation.

KayEss commented 1 year ago

@sverker I have a commit that does the hash part of this: https://github.com/BiggestLab/otp/commit/d595652a47c763b0b491550ee94d77083e2a6ad7

Should I do a PR with this, or is there something obvious I ought to fix first?

sverker commented 1 year ago

@KayEss Looks good. Make it a PR.