<?php

if (class_exists('ParagonIE_Sodium_Core_Ed25519', false)) {

    return;

}

/**

 * Class ParagonIE_Sodium_Core_Ed25519

 */

abstract class ParagonIE_Sodium_Core_Ed25519 extends ParagonIE_Sodium_Core_Curve25519

{

    const KEYPAIR_BYTES = 96;

    const SEED_BYTES = 32;

    /**

     * @internal You should not use this directly from another application

     *

     * @return string (96 bytes)

     * @throws Exception

     * @throws SodiumException

     * @throws TypeError

     */

    public static function keypair()

    {

        $seed = random_bytes(self::SEED_BYTES);

        $pk = '';

        $sk = '';

        self::seed_keypair($pk, $sk, $seed);

        return $sk . $pk;

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $pk

     * @param string $sk

     * @param string $seed

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function seed_keypair(&$pk, &$sk, $seed)

    {

        if (self::strlen($seed) !== self::SEED_BYTES) {

            throw new RangeException('crypto_sign keypair seed must be 32 bytes long');

        }

        /** @var string $pk */

        $pk = self::publickey_from_secretkey($seed);

        $sk = $seed . $pk;

        return $sk;

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $keypair

     * @return string

     * @throws TypeError

     */

    public static function secretkey($keypair)

    {

        if (self::strlen($keypair) !== self::KEYPAIR_BYTES) {

            throw new RangeException('crypto_sign keypair must be 96 bytes long');

        }

        return self::substr($keypair, 0, 64);

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $keypair

     * @return string

     * @throws TypeError

     */

    public static function publickey($keypair)

    {

        if (self::strlen($keypair) !== self::KEYPAIR_BYTES) {

            throw new RangeException('crypto_sign keypair must be 96 bytes long');

        }

        return self::substr($keypair, 64, 32);

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $sk

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function publickey_from_secretkey($sk)

    {

        /** @var string $sk */

        $sk = hash('sha512', self::substr($sk, 0, 32), true);

        $sk[0] = self::intToChr(

            self::chrToInt($sk[0]) & 248

        );

        $sk[31] = self::intToChr(

            (self::chrToInt($sk[31]) & 63) | 64

        );

        return self::sk_to_pk($sk);

    }

    /**

     * @param string $pk

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function pk_to_curve25519($pk)

    {

        if (self::small_order($pk)) {

            throw new SodiumException('Public key is on a small order');

        }

        $A = self::ge_frombytes_negate_vartime(self::substr($pk, 0, 32));

        $p1 = self::ge_mul_l($A);

        if (!self::fe_isnonzero($p1->X)) {

            throw new SodiumException('Unexpected zero result');

        }

        # fe_1(one_minus_y);

        # fe_sub(one_minus_y, one_minus_y, A.Y);

        # fe_invert(one_minus_y, one_minus_y);

        $one_minux_y = self::fe_invert(

            self::fe_sub(

                self::fe_1(),

                $A->Y

            )

        );

        # fe_1(x);

        # fe_add(x, x, A.Y);

        # fe_mul(x, x, one_minus_y);

        $x = self::fe_mul(

            self::fe_add(self::fe_1(), $A->Y),

            $one_minux_y

        );

        # fe_tobytes(curve25519_pk, x);

        return self::fe_tobytes($x);

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $sk

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function sk_to_pk($sk)

    {

        return self::ge_p3_tobytes(

            self::ge_scalarmult_base(

                self::substr($sk, 0, 32)

            )

        );

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $message

     * @param string $sk

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function sign($message, $sk)

    {

        /** @var string $signature */

        $signature = self::sign_detached($message, $sk);

        return $signature . $message;

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $message A signed message

     * @param string $pk      Public key

     * @return string         Message (without signature)

     * @throws SodiumException

     * @throws TypeError

     */

    public static function sign_open($message, $pk)

    {

        /** @var string $signature */

        $signature = self::substr($message, 0, 64);

        /** @var string $message */

        $message = self::substr($message, 64);

        if (self::verify_detached($signature, $message, $pk)) {

            return $message;

        }

        throw new SodiumException('Invalid signature');

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $message

     * @param string $sk

     * @return string

     * @throws SodiumException

     * @throws TypeError

     */

    public static function sign_detached($message, $sk)

    {

        # crypto_hash_sha512(az, sk, 32);

        $az =  hash('sha512', self::substr($sk, 0, 32), true);

        # az[0] &= 248;

        # az[31] &= 63;

        # az[31] |= 64;

        $az[0] = self::intToChr(self::chrToInt($az[0]) & 248);

        $az[31] = self::intToChr((self::chrToInt($az[31]) & 63) | 64);

        # crypto_hash_sha512_init(&hs);

        # crypto_hash_sha512_update(&hs, az + 32, 32);

        # crypto_hash_sha512_update(&hs, m, mlen);

        # crypto_hash_sha512_final(&hs, nonce);

        $hs = hash_init('sha512');

        hash_update($hs, self::substr($az, 32, 32));

        hash_update($hs, $message);

        $nonceHash = hash_final($hs, true);

        # memmove(sig + 32, sk + 32, 32);

        $pk = self::substr($sk, 32, 32);

        # sc_reduce(nonce);

        # ge_scalarmult_base(&R, nonce);

        # ge_p3_tobytes(sig, &R);

        $nonce = self::sc_reduce($nonceHash) . self::substr($nonceHash, 32);

        $sig = self::ge_p3_tobytes(

            self::ge_scalarmult_base($nonce)

        );

        # crypto_hash_sha512_init(&hs);

        # crypto_hash_sha512_update(&hs, sig, 64);

        # crypto_hash_sha512_update(&hs, m, mlen);

        # crypto_hash_sha512_final(&hs, hram);

        $hs = hash_init('sha512');

        hash_update($hs, self::substr($sig, 0, 32));

        hash_update($hs, self::substr($pk, 0, 32));

        hash_update($hs, $message);

        $hramHash = hash_final($hs, true);

        # sc_reduce(hram);

        # sc_muladd(sig + 32, hram, az, nonce);

        $hram = self::sc_reduce($hramHash);

        $sigAfter = self::sc_muladd($hram, $az, $nonce);

        $sig = self::substr($sig, 0, 32) . self::substr($sigAfter, 0, 32);

        try {

            ParagonIE_Sodium_Compat::memzero($az);

        } catch (SodiumException $ex) {

            $az = null;

        }

        return $sig;

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $sig

     * @param string $message

     * @param string $pk

     * @return bool

     * @throws SodiumException

     * @throws TypeError

     */

    public static function verify_detached($sig, $message, $pk)

    {

        if (self::strlen($sig) < 64) {

            throw new SodiumException('Signature is too short');

        }

            throw new SodiumException('S < L - Invalid signature');

        }

        if (self::small_order($sig)) {

            throw new SodiumException('Signature is on too small of an order');

        }

        if ((self::chrToInt($sig[63]) & 224) !== 0) {

            throw new SodiumException('Invalid signature');

        }

        $d = 0;

        for ($i = 0; $i < 32; ++$i) {

            $d |= self::chrToInt($pk[$i]);

        }

        if ($d === 0) {

            throw new SodiumException('All zero public key');

        }

        /** @var bool The original value of ParagonIE_Sodium_Compat::$fastMult */

        $orig = ParagonIE_Sodium_Compat::$fastMult;

        // Set ParagonIE_Sodium_Compat::$fastMult to true to speed up verification.

        ParagonIE_Sodium_Compat::$fastMult = true;

        /** @var ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A */

        $A = self::ge_frombytes_negate_vartime($pk);

        /** @var string $hDigest */

        $hDigest = hash(

            'sha512',

            self::substr($sig, 0, 32) .

                self::substr($pk, 0, 32) .

                $message,

            true

        );

        /** @var string $h */

        $h = self::sc_reduce($hDigest) . self::substr($hDigest, 32);

        /** @var ParagonIE_Sodium_Core_Curve25519_Ge_P2 $R */

        $R = self::ge_double_scalarmult_vartime(

            $h,

            $A,

            self::substr($sig, 32)

        );

        /** @var string $rcheck */

        $rcheck = self::ge_tobytes($R);

        // Reset ParagonIE_Sodium_Compat::$fastMult to what it was before.

        ParagonIE_Sodium_Compat::$fastMult = $orig;

        return self::verify_32($rcheck, self::substr($sig, 0, 32));

    }

    /**

     * @internal You should not use this directly from another application

     *

     * @param string $S

     * @return bool

     * @throws SodiumException

     * @throws TypeError

     */

    public static function check_S_lt_L($S)

    {

        if (self::strlen($S) < 32) {

            throw new SodiumException('Signature must be 32 bytes');

        }

        $L = array(

            0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,

            0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,

            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10

        );

        $c = 0;

        $n = 1;

        $i = 32;

        /** @var array<int, int> $L */

        do {

            --$i;

            $x = self::chrToInt($S[$i]);

            $c |= (

                (($x - $L[$i]) >> 8) & $n

            );

            $n &= (

                (($x ^ $L[$i]) - 1) >> 8

            );

        } while ($i !== 0);

        return $c === 0;

    }

    /**

     * @param string $R

     * @return bool

     * @throws SodiumException

     * @throws TypeError

     */

    public static function small_order($R)

    {

            /* 0 (order 4) */

            array(

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

            ),

            /* 1 (order 1) */

            array(

                0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

            ),

            /* 2707385501144840649318225287225658788936804267575313519463743609750303402022 (order 8) */

            array(

                0x26, 0xe8, 0x95, 0x8f, 0xc2, 0xb2, 0x27, 0xb0,

                0x45, 0xc3, 0xf4, 0x89, 0xf2, 0xef, 0x98, 0xf0,

                0xd5, 0xdf, 0xac, 0x05, 0xd3, 0xc6, 0x33, 0x39,

                0xb1, 0x38, 0x02, 0x88, 0x6d, 0x53, 0xfc, 0x05

            ),

            /* 55188659117513257062467267217118295137698188065244968500265048394206261417927 (order 8) */

            array(

                0xc7, 0x17, 0x6a, 0x70, 0x3d, 0x4d, 0xd8, 0x4f,

                0xba, 0x3c, 0x0b, 0x76, 0x0d, 0x10, 0x67, 0x0f,

                0x2a, 0x20, 0x53, 0xfa, 0x2c, 0x39, 0xcc, 0xc6,

                0x4e, 0xc7, 0xfd, 0x77, 0x92, 0xac, 0x03, 0x7a

            ),

            /* p-1 (order 2) */

            array(

                0x13, 0xe8, 0x95, 0x8f, 0xc2, 0xb2, 0x27, 0xb0,

                0x45, 0xc3, 0xf4, 0x89, 0xf2, 0xef, 0x98, 0xf0,

                0xd5, 0xdf, 0xac, 0x05, 0xd3, 0xc6, 0x33, 0x39,

                0xb1, 0x38, 0x02, 0x88, 0x6d, 0x53, 0xfc, 0x85

            ),