sodium_crypto_box_keypair_from_secretkey_and_publickey

php Function sodium_crypto_Box_From_SecretKeyAndPublicKey

php function sodium_crypto_box_keypair_from_secretkey_and_publickey is used to generate an encryption key pair for two parties to communicate. This key pair is then used to encrypt and decrypt messages between these two parties. This type of asymmetric encryption ensures that only the intended recipient can read a message. A signature tag is also included in the encrypted message which can be used to authenticate a message against tampering.

Using this technique, it is possible to encrypt data such as passwords in a manner that only the intended recipient can read them. In addition, the original data cannot be reverse-engineered from a hash, making the hash useless to attackers. This is a good method to protect sensitive information from malicious attackers that might intercept or steal your data.

Another useful feature of the libsodium library is that all of its algorithms are authenticated, meaning that an authentication tag is added to each encrypted message that can be verified against tampering. This prevents Chosen-ciphertext attacks that can occur with other methods, such as mcrypt or most ciphers from OpenSSL.

PHP has long supported the Libsodium library as a PECL extension, but as of PHP 7.2, it is integrated into the core, so it's likely that you already have this library installed and enabled (you can check using phpinfo()). To compile PHP with Libsodium support, you need to use the --with-sodium flag or install the libsodium library, which can be found in repositories such as libsodium-dev on Ubuntu/Debian or libsodium-devel on Fedora/RHEL.

sodium_crypto_box_keypair_from_secretkey_and_publickey example

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 (string) sodium_crypto_box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
        }
        if (self::use_fallback('crypto_box_keypair_from_secretkey_and_publickey')) {
            return (string) call_user_func('\\Sodium\\crypto_box_keypair_from_secretkey_and_publickey', $secretKey, $publicKey);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Crypto32::box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
        }
        return ParagonIE_Sodium_Crypto::box_keypair_from_secretkey_and_publickey($secretKey, $publicKey);
    }

    /** * Decrypt a message previously encrypted with crypto_box(). * * @param string $ciphertext Encrypted message * @param string $nonce Number to only be used Once; must be 24 bytes * @param string $keypair Your secret key and the sender's public key * @return string The original plaintext message * @throws SodiumException * @throws TypeError * @psalm-suppress MixedArgument * @psalm-suppress MixedInferredReturnType * @psalm-suppress MixedReturnStatement */