Function decrypt

pub fn decrypt(
    key: &Key,
    ctxt_msg: &mut [u8],
    iv: Iv,
    aad: &[u8],
    tag: &Tag,
) -> Result<(), Error>

AEAD decrypt the ciphertext in ctxt_msg with the key, iv, aad, and tag.

Returns the plaintext in ctxt_msg or an error if the decryption fails.