sodium_crypto_auth_verify checks whether a supplied authenticator or signature matches the message and key.
The examples explain the data format, expected results and the difference between this API and nearby cryptographic operations.
What It Does
The operation is intended for: sodium_crypto_auth_verify checks whether a supplied authenticator or signature matches the message and key.
The sodium extension must be enabled.
Syntax and Return Value
sodium_crypto_auth_verify(string $mac, string $message, string $key): bool| Parameter | Purpose |
|---|---|
| $mac (string) | Use the PHP signature above to determine the exact expected input type; validate untrusted inputs before calling. |
| $message (string) | The plaintext or input message bytes; content is not automatically character-normalized. |
| $key (string) | Raw key bytes in the required algorithm-specific length; protect them from disclosure. |
The declared return type is shown above. Errors can include false results or exceptions depending on this API: Both parties must share the same secret. A MAC is not a public-key digital signature.
Example 1: Basic Operation
A keyed MAC authenticates a message; the tag is not encrypted data.
<?php
$message = "Account update";
$key = sodium_crypto_auth_keygen();
$tag = sodium_crypto_auth($message, $key);
var_dump(sodium_crypto_auth_verify($tag, $message, $key));Example 2: A Different Use Case
Check the MAC using the same message and secret key.
<?php
// Check the alternative case.
$message = "New order: 42";
$key = sodium_crypto_auth_keygen();
$tag = sodium_crypto_auth($message, $key);
var_dump(sodium_crypto_auth_verify($tag, $message, $key));Practical Example: Checking the Result
Show that modifying a message invalidates the authentication tag.
<?php
// Verify the expected behavior before using results.
$message = "Export completed";
$key = sodium_crypto_auth_keygen();
$tag = sodium_crypto_auth($message, $key);
var_dump(sodium_crypto_auth_verify($tag, $message . "!", $key) === false);Important Behavior and Edge Cases
Both parties must share the same secret. A MAC is not a public-key digital signature.
Both parties must share the same secret. A MAC is not a public-key digital signature.
Comparison with Related Functions
| Approach | Key distinction |
|---|---|
| sodium_crypto_auth_verify | sodium_crypto_auth_verify checks whether a supplied authenticator or signature matches the message and key. |
| Related technique | sodium_crypto_sign_detached instead uses public-key signatures. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Confusing this operation with a neighboring cryptographic or security mechanism | sodium_crypto_sign_detached instead uses public-key signatures. |
| Ignoring a security prerequisite or failure case | Both parties must share the same secret. A MAC is not a public-key digital signature. |
Key Takeaways
- sodium_crypto_auth_verify checks whether a supplied authenticator or signature matches the message and key.
- Both parties must share the same secret. A MAC is not a public-key digital signature.
- sodium_crypto_sign_detached instead uses public-key signatures.
Apply this behavior to a real application only after confirming the required extension, configuration and failure handling on the deployment runtime.