sodium_crypto_sign_ed25519_sk_to_curve25519

php Function Sodium Crypto Sign ED25519 Sk To Curve25519

Article About php function sodium_crypto_sign_ed25519_sk_to_curve25519

A function is a piece of code that does one specific task. There are many built-in functions in PHP that you can use to perform common programming tasks without writing a new custom function yourself. These functions are called standard functions because they are provided by the PHP core and come with every installation of PHP. There are also PECL functions and constants that you can add to your installation to extend the standard set of functions available in PHP.

Functions are passed information through arguments, which are specified after the function name in the parentheses. The information in an argument can be anything: an integer, a string, a map, a list, or a variable. If you do not specify the type of the information in an argument, PHP will try to guess what kind of data it is and may throw a Fatal Error if the function cannot convert the data into the correct type. To prevent PHP from doing this type juggling, you can declare the type of the return value of a function by adding a type declaration before the function's opening curly bracket.

sodium_crypto_sign_ed25519_sk_to_curve25519 example

public static function crypto_sign_ed25519_sk_to_curve25519($sk)
    {
        /* Type checks: */
        ParagonIE_Sodium_Core_Util::declareScalarType($sk, 'string', 1);

        /* Input validation: */
        if (ParagonIE_Sodium_Core_Util::strlen($sk) < self::CRYPTO_SIGN_SEEDBYTES) {
            throw new SodiumException('Argument 1 must be at least CRYPTO_SIGN_SEEDBYTES long.');
        }
        if (self::useNewSodiumAPI()) {
            if (is_callable('crypto_sign_ed25519_sk_to_curve25519')) {
                return sodium_crypto_sign_ed25519_sk_to_curve25519($sk);
            }
        }
        if (self::use_fallback('crypto_sign_ed25519_sk_to_curve25519')) {
            return (string) call_user_func('\\Sodium\\crypto_sign_ed25519_sk_to_curve25519', $sk);
        }

        $h = hash('sha512', ParagonIE_Sodium_Core_Util::substr($sk, 0, 32), true);
        $h[0] = ParagonIE_Sodium_Core_Util::intToChr(
            ParagonIE_Sodium_Core_Util::chrToInt($h[0]) & 248
        );
        $h[31] = ParagonIE_Sodium_Core_Util::intToChr(
            (