ParagonIE_Sodium_Crypto::aead_chacha20poly1305_ietf_encrypt( string $message = '', string $ad = '', string $nonce = '', string $key = '' ): string

274    public static function aead_chacha20poly1305_ietf_encrypt(275        $message = '',276        $ad = '',277        $nonce = '',278        $key = ''279    ) {280        /** @var int $len - Length of the plaintext message */281        $len = ParagonIE_Sodium_Core_Util::strlen($message);282 283        /** @var int $adlen - Length of the associated data */284        $adlen = ParagonIE_Sodium_Core_Util::strlen($ad);285 286        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */287        $block0 = ParagonIE_Sodium_Core_ChaCha20::ietfStream(288            32,289            $nonce,290            $key291        );292        $state = new ParagonIE_Sodium_Core_Poly1305_State($block0);293        try {294            ParagonIE_Sodium_Compat::memzero($block0);295        } catch (SodiumException $ex) {296            $block0 = null;297        }298 299        /** @var string $ciphertext - Raw encrypted data */300        $ciphertext = ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(301            $message,302            $nonce,303            $key,304            ParagonIE_Sodium_Core_Util::store64_le(1)305        );306 307        $state->update($ad);308        $state->update(str_repeat("\x00", ((0x10 - $adlen) & 0xf)));309        $state->update($ciphertext);310        $state->update(str_repeat("\x00", ((0x10 - $len) & 0xf)));311        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));312        $state->update(ParagonIE_Sodium_Core_Util::store64_le($len));313        return $ciphertext . $state->finish();314    }