> Not for cli but the absolute basics are pretty easy to calculate yourself. E.g. calculating a discrete log. Or the Rivest-Shamir-Wagner Time Lock Puzzles. Or proof-of-posession with hash functions or merkle trees. Takes 20 lines of python code tops. 

Thanks. ChatGPT recommended [this library][1] and am going to code proof-of-possesion of a private key with it. 

[1]: https://pypi.org/project/pycryptodome/

denationalized

crypto

Are there any tools that apply zero knowledge proofs, much like GPG for ZK?

Not for cli but the absolute basics are pretty easy to calculate yourself. E.g. calculating a discrete log. Or the Rivest-Shamir-Wagner Time Lock Puzzles. Or proof-of-posession with hash functions or merkle trees. Takes 20 lines of python code tops. 

However, not advisable for real life opsec. More for learning and out of interest.

You mentioned symmetric and asymmetric encryption. Have you considered signature schemes as well? Very rarely usecases for zk-proofs actually need more than asymmetric signatures. 