ParagonIE_Sodium_Core_AEGIS128L::encrypt( string $msg, string $ad, string $key, string $nonce ): array

68    public static function encrypt($msg, $ad, $key, $nonce)69    {70        $state = self::init($key, $nonce);71        // ad_blocks = Split(ZeroPad(ad, 256), 256)72        // for ai in ad_blocks:73        //     Absorb(ai)74        $ad_len = self::strlen($ad);75        $msg_len = self::strlen($msg);76        $ad_blocks = ($ad_len + 31) >> 5;77        for ($i = 0; $i < $ad_blocks; ++$i) {78            $ai = self::substr($ad, $i << 5, 32);79            if (self::strlen($ai) < 32) {80                $ai = str_pad($ai, 32, "\0", STR_PAD_RIGHT);81            }82            $state->absorb($ai);83        }84 85        // msg_blocks = Split(ZeroPad(msg, 256), 256)86        // for xi in msg_blocks:87        //     ct = ct || Enc(xi)88        $ct = '';89        $msg_blocks = ($msg_len + 31) >> 5;90        for ($i = 0; $i < $msg_blocks; ++$i) {91            $xi = self::substr($msg, $i << 5, 32);92            if (self::strlen($xi) < 32) {93                $xi = str_pad($xi, 32, "\0", STR_PAD_RIGHT);94            }95            $ct .= $state->enc($xi);96        }97        // tag = Finalize(|ad|, |msg|)98        // ct = Truncate(ct, |msg|)99        $tag = $state->finalize(100            $ad_len << 3,101            $msg_len << 3102        );103        // return ct and tag104        return array(105            self::substr($ct, 0, $msg_len),106            $tag107        );108    }