To get the actual public and secret keys, use `sodium_crypto_box_publickey()` and `sodium_crypto_box_secretkey()`.
(PHP 7 >= 7.2.0, PHP 8)
sodium_crypto_box_keypair — Randomly generate a secret key and a corresponding public key
Generates a secret key and a public key as one string.
To get the secret key out of this unified keypair string, see sodium_crypto_box_secretkey(). To get the public key out of this unified keypair string, see sodium_crypto_box_publickey().
This function has no parameters.
One string containing both the X25519 secret key and corresponding X25519 public key.
To get the actual public and secret keys, use `sodium_crypto_box_publickey()` and `sodium_crypto_box_secretkey()`.