add some cryptography stuff

np.md

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+# NP
+
+- class of languages whose membership proofs can be verified in polynomial time
+- the [[discrete-log|Discrete Log]] problem is an example of an NP problem
+  - from $`g^x`$ in a finite field it is hard to compute $`\log_g\left(g^x\right)`$, but easy to check $`g^x = g^y`$ to validate a knowledge proof of $`x`$