sodium_crypto_auth

    (PHP 7 >= 7.2.0, PHP 8)

    sodium_crypto_auth — Compute a tag for the message

    Description

    sodium_crypto_auth(string $message, #[\SensitiveParameter] string $key): string

    Symmetric message authentication via sodium_crypto_auth() provides integrity, but not confidentiality.

    Unlike with digital signatures (e.g. sodium_crypto_sign_detached()), any party capable of verifying a message is also capable of authenticating their own messages. (Hence, symmetric authentication.)

    Parameters

    message

    The message you intend to authenticate

    key

    Authentication key

    Return Values

    Authentication tag

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    User Contributed Notes 1 note

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    craig at craigfrancis dot co dot uk
    6 years ago
    Here's a quick example on how to use sodium_crypto_auth(); where you have a message that you want to sign, so anyone who can access the *shared* key can confirm that the message hasn't been tampered with.This is similar to sodium_crypto_sign_detached(), but both signer and verifier have access to the same key.<?php$key = sodium_crypto_auth_keygen();//--------------------------------------------------// Person 1, signing$message = 'Hello';$signature = sodium_crypto_auth($message, $key);//--------------------------------------------------// Person 2, verifying$message_valid = sodium_crypto_auth_verify($signature, $message, $key);if (!$message_valid) {    exit('Message has been changed.');}?>
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