# Functions
DeriveSecret computes a cSIDH shared secret.
Validate returns true if 'pub' is a valid cSIDH public key, otherwise false.
# Constants
PrivateKeySize is a size of cSIDH/512 private key in bytes.
PublicKeySize is a size of cSIDH/512 public key in bytes.
SharedSecretSize is a size of cSIDH/512 shared secret in bytes.