<?php 
declare(strict_types=1); 
 
if (class_exists('ParagonIE_Sodium_Core_AEGIS_State256', false)) { 
    return; 
} 
 
if (!defined('SODIUM_COMPAT_AEGIS_C0')) { 
    define('SODIUM_COMPAT_AEGIS_C0', "\x00\x01\x01\x02\x03\x05\x08\x0d\x15\x22\x37\x59\x90\xe9\x79\x62"); 
} 
if (!defined('SODIUM_COMPAT_AEGIS_C1')) { 
    define('SODIUM_COMPAT_AEGIS_C1', "\xdb\x3d\x18\x55\x6d\xc2\x2f\xf1\x20\x11\x31\x42\x73\xb5\x28\xdd"); 
} 
 
class ParagonIE_Sodium_Core_AEGIS_State256 
{ 
    /** @var array<int, string> $state */ 
    protected array $state; 
 
    public function __construct() 
    { 
        $this->state = array_fill(0, 6, ''); 
    } 
 
    /** 
     * @internal Only use this for unit tests! 
     * @return string[] 
     */ 
    public function getState(): array 
    { 
        return array_values($this->state); 
    } 
 
    /** 
     * @param array $input 
     * @return self 
     * @throws SodiumException 
     * 
     * @internal Only for unit tests 
     */ 
    public static function initForUnitTests(array $input): self 
    { 
        if (count($input) < 6) { 
            throw new SodiumException('invalid input'); 
        } 
        $state = new self(); 
        for ($i = 0; $i < 6; ++$i) { 
            $state->state[$i] = $input[$i]; 
        } 
        return $state; 
    } 
 
    /** 
     * @param string $key 
     * @param string $nonce 
     * @return self 
     */ 
    public static function init( 
        #[SensitiveParameter] 
        string $key, 
        string $nonce 
    ): self { 
        $state = new self(); 
        $k0 = ParagonIE_Sodium_Core_Util::substr($key, 0, 16); 
        $k1 = ParagonIE_Sodium_Core_Util::substr($key, 16, 16); 
        $n0 = ParagonIE_Sodium_Core_Util::substr($nonce, 0, 16); 
        $n1 = ParagonIE_Sodium_Core_Util::substr($nonce, 16, 16); 
 
        // S0 = k0 ^ n0 
        // S1 = k1 ^ n1 
        // S2 = C1 
        // S3 = C0 
        // S4 = k0 ^ C0 
        // S5 = k1 ^ C1 
        $k0_n0 = $k0 ^ $n0; 
        $k1_n1 = $k1 ^ $n1; 
        $state->state[0] = $k0_n0; 
        $state->state[1] = $k1_n1; 
        $state->state[2] = SODIUM_COMPAT_AEGIS_C1; 
        $state->state[3] = SODIUM_COMPAT_AEGIS_C0; 
        $state->state[4] = $k0 ^ SODIUM_COMPAT_AEGIS_C0; 
        $state->state[5] = $k1 ^ SODIUM_COMPAT_AEGIS_C1; 
 
        // Repeat(4, 
        //   Update(k0) 
        //   Update(k1) 
        //   Update(k0 ^ n0) 
        //   Update(k1 ^ n1) 
        // ) 
        for ($i = 0; $i < 4; ++$i) { 
            $state->update($k0); 
            $state->update($k1); 
            $state->update($k0 ^ $n0); 
            $state->update($k1 ^ $n1); 
        } 
        return $state; 
    } 
 
    /** 
     * @param string $ai 
     * @return static 
     * @throws SodiumException 
     */ 
    public function absorb(string $ai): static 
    { 
        if (ParagonIE_Sodium_Core_Util::strlen($ai) !== 16) { 
            throw new SodiumException('Input must be an AES block in size'); 
        } 
        return $this->update($ai); 
    } 
 
    /** 
     * @param string $ci 
     * @return string 
     * @throws SodiumException 
     */ 
    public function dec(string $ci): string 
    { 
        if (ParagonIE_Sodium_Core_Util::strlen($ci) !== 16) { 
            throw new SodiumException('Input must be an AES block in size'); 
        } 
        // z = S1 ^ S4 ^ S5 ^ (S2 & S3) 
        $z = $this->state[1] 
            ^ $this->state[4] 
            ^ $this->state[5] 
            ^ ParagonIE_Sodium_Core_Util::andStrings($this->state[2], $this->state[3]); 
        $xi = $ci ^ $z; 
        $this->update($xi); 
        return $xi; 
    } 
 
    /** 
     * @param string $cn 
     * @return string 
     * 
     * @throws SodiumException 
     */ 
    public function decPartial(string $cn): string 
    { 
        $len = ParagonIE_Sodium_Core_Util::strlen($cn); 
        // z = S1 ^ S4 ^ S5 ^ (S2 & S3) 
        $z = $this->state[1] 
            ^ $this->state[4] 
            ^ $this->state[5] 
            ^ ParagonIE_Sodium_Core_Util::andStrings($this->state[2], $this->state[3]); 
 
        // t = ZeroPad(cn, 128) 
        $t = str_pad($cn, 16, "\0"); 
 
        // out = t ^ z 
        $out = $t ^ $z; 
 
        // xn = Truncate(out, |cn|) 
        $xn = ParagonIE_Sodium_Core_Util::substr($out, 0, $len); 
 
        // v = ZeroPad(xn, 128) 
        $v = str_pad($xn, 16, "\0"); 
        // Update(v) 
        $this->update($v); 
 
        // return xn 
        return $xn; 
    } 
 
    /** 
     * @param string $xi 
     * @return string 
     * @throws SodiumException 
     */ 
    public function enc( 
        #[SensitiveParameter] 
        string $xi 
    ): string { 
        if (ParagonIE_Sodium_Core_Util::strlen($xi) !== 16) { 
            throw new SodiumException('Input must be an AES block in size'); 
        } 
        // z = S1 ^ S4 ^ S5 ^ (S2 & S3) 
        $z = $this->state[1] 
            ^ $this->state[4] 
            ^ $this->state[5] 
            ^ ParagonIE_Sodium_Core_Util::andStrings($this->state[2], $this->state[3]); 
        $this->update($xi); 
        return $xi ^ $z; 
    } 
 
    /** 
     * @param int $ad_len_bits 
     * @param int $msg_len_bits 
     * @return string 
     */ 
    public function finalize( 
        int $ad_len_bits, 
        int $msg_len_bits 
    ): string { 
        $encoded = ParagonIE_Sodium_Core_Util::store64_le($ad_len_bits) . 
            ParagonIE_Sodium_Core_Util::store64_le($msg_len_bits); 
        $t = $this->state[3] ^ $encoded; 
 
        for ($i = 0; $i < 7; ++$i) { 
            $this->update($t); 
        } 
 
        return ($this->state[0] ^ $this->state[1] ^ $this->state[2]) . 
            ($this->state[3] ^ $this->state[4] ^ $this->state[5]); 
    } 
 
    /** 
     * @param string $m 
     * @return static 
     */ 
    public function update(string $m): static 
    { 
        /* 
            S'0 = AESRound(S5, S0 ^ M) 
            S'1 = AESRound(S0, S1) 
            S'2 = AESRound(S1, S2) 
            S'3 = AESRound(S2, S3) 
            S'4 = AESRound(S3, S4) 
            S'5 = AESRound(S4, S5) 
         */ 
        list($s_0, $s_1) = ParagonIE_Sodium_Core_AES::doubleRound( 
            $this->state[5],$this->state[0] ^ $m, 
            $this->state[0], $this->state[1] 
        ); 
 
        list($s_2, $s_3) = ParagonIE_Sodium_Core_AES::doubleRound( 
            $this->state[1], $this->state[2], 
            $this->state[2], $this->state[3] 
        ); 
        list($s_4, $s_5) = ParagonIE_Sodium_Core_AES::doubleRound( 
            $this->state[3], $this->state[4], 
            $this->state[4], $this->state[5] 
        ); 
 
        /* 
            S0  = S'0 
            S1  = S'1 
            S2  = S'2 
            S3  = S'3 
            S4  = S'4 
            S5  = S'5 
         */ 
        $this->state[0] = $s_0; 
        $this->state[1] = $s_1; 
        $this->state[2] = $s_2; 
        $this->state[3] = $s_3; 
        $this->state[4] = $s_4; 
        $this->state[5] = $s_5; 
        return $this; 
    } 
} 
 
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