ParagonIE_Sodium_Crypto32::secretstream_xchacha20poly1305_init_push

    public static function secretstream_xchacha20poly1305_init_push($key)
    {
        # randombytes_buf(out, crypto_secretstream_xchacha20poly1305_HEADERBYTES);
        $out = random_bytes(24);

        # crypto_core_hchacha20(state->k, out, k, NULL);
        $subkey = ParagonIE_Sodium_Core32_HChaCha20::hChaCha20($out, $key);
        $state = new ParagonIE_Sodium_Core32_SecretStream_State(
            $subkey,
            ParagonIE_Sodium_Core32_Util::substr($out, 16, 8) . str_repeat("\0", 4)
        );

        # _crypto_secretstream_xchacha20poly1305_counter_reset(state);
        $state->counterReset();

        # memcpy(STATE_INONCE(state), out + crypto_core_hchacha20_INPUTBYTES,
        #        crypto_secretstream_xchacha20poly1305_INONCEBYTES);
        # memset(state->_pad, 0, sizeof state->_pad);
        return array(
            $state->toString(),
            $out
        );
    }