Poseidon V1 variable-length input collision via implicit zero-padding

Impact Poseidon V1 PoseidonSponge accepts variable-length inputs without injective padding. When a caller provides fewer inputs than the sponge rate inputs.len k, hashm1, ..., mk equals hashm1, ..., mk, 0 because both produce identical pre-permutation states. This affects any use of PoseidonSpong...