The tests are missing negative tests and test-vectors

[cgrigis]

Security Code Review observation:

For example, it seems the shuffle tests are not testing the verification of a wrong shuffle nor providing test-vectors.

[K1li4nL]

At least the following packages are missing negatives:

• shuffle
• proof/deniable
• proof/proof
• proof/dleq/dleq
• sign/anon (has no test)
• sign/bdn
• sign/cosi
• sign/schnorr
• sign/tbls

[pierluca]

@K1li4nL added you back to discuss (when you're back) what we can do here.