ParagonIE_Sodium_Compat::crypto_scalarmult

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Summery Summery

Calculate the shared secret between your secret key and your recipient’s public key.

Syntax Syntax

ParagonIE_Sodium_Compat::crypto_scalarmult( string $secretKey, string $publicKey )

Description Description

Algorithm: X25519 (ECDH over Curve25519)

Parameters Parameters

$secretKey

(string) (Required)

$publicKey

(string) (Required)

Return Return

(string)

Source Source

File: wp-includes/sodium_compat/src/Compat.php

    public static function crypto_scalarmult($secretKey, $publicKey)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($secretKey, 'string', 1);
        ParagonIE_Sodium_Core_Util::declareScalarType($publicKey, 'string', 2);

        /* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($secretKey) !== self::CRYPTO_BOX_SECRETKEYBYTES) {
            throw new SodiumException('Argument 1 must be CRYPTO_BOX_SECRETKEYBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($publicKey) !== self::CRYPTO_BOX_PUBLICKEYBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_BOX_PUBLICKEYBYTES long.');
        }

        if (self::useNewSodiumAPI()) {
            return sodium_crypto_scalarmult($secretKey, $publicKey);
        }
        if (self::use_fallback('crypto_scalarmult')) {
            return (string) call_user_func('\\Sodium\\crypto_scalarmult', $secretKey, $publicKey);
        }

        /* Output validation: Forbid all-zero keys */
        if (ParagonIE_Sodium_Core_Util::hashEquals($secretKey, str_repeat("\0", self::CRYPTO_BOX_SECRETKEYBYTES))) {
            throw new SodiumException('Zero secret key is not allowed');
        }
        if (ParagonIE_Sodium_Core_Util::hashEquals($publicKey, str_repeat("\0", self::CRYPTO_BOX_PUBLICKEYBYTES))) {
            throw new SodiumException('Zero public key is not allowed');
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::scalarmult($secretKey, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::scalarmult($secretKey, $publicKey);
    }

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