PHP sodium_crypto_aead_aes256gcm_is_available() Function: Usage and Examples

sodium_crypto_aead_aes256gcm_is_available checks whether this CPU and library support hardware-accelerated AES-256-GCM.

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_aead_aes256gcm_is_available checks whether this CPU and library support hardware-accelerated AES-256-GCM.

The sodium extension must be enabled.

Syntax and Return Value

sodium_crypto_aead_aes256gcm_is_available(): bool

This API accepts no required parameters, or its signature must be checked on the target runtime.

The declared return type is shown above. Errors can include false results or exceptions depending on this API: Never reuse a nonce with the same key; additional authenticated data is checked but not encrypted. Modified ciphertext fails authentication.

Example 1: Basic Operation

Check the required key length or CPU support without exposing generated key bytes.

<?php
var_dump(sodium_crypto_aead_aes256gcm_is_available());

Example 2: A Different Use Case

Branch on the runtime hardware capability before choosing AES-GCM.

<?php
if (sodium_crypto_aead_aes256gcm_is_available()) {
    echo 'Use hardware-accelerated AEAD when supported';
} else { echo 'Select XChaCha20-Poly1305 instead'; }

Practical Example: Checking the Result

Branch on the runtime hardware capability before choosing AES-GCM.

<?php
$available = sodium_crypto_aead_aes256gcm_is_available();
var_dump(is_bool($available));

Important Behavior and Edge Cases

Never reuse a nonce with the same key; additional authenticated data is checked but not encrypted. Modified ciphertext fails authentication.

Changing even one ciphertext, nonce or associated-data byte should cause authentication to fail. Store or transmit the nonce alongside ciphertext without reusing it for this key.

Comparison with Related Functions

Approach	Key distinction
sodium_crypto_aead_aes256gcm_is_available	sodium_crypto_aead_aes256gcm_is_available checks whether this CPU and library support hardware-accelerated AES-256-GCM.
Related technique	secretbox authenticates ciphertext but does not accept additional authenticated data.

Common Beginner Mistakes

Mistake	Correct approach
Confusing this operation with a neighboring cryptographic or security mechanism	secretbox authenticates ciphertext but does not accept additional authenticated data.
Ignoring a security prerequisite or failure case	Never reuse a nonce with the same key; additional authenticated data is checked but not encrypted. Modified ciphertext fails authentication.

Key Takeaways

sodium_crypto_aead_aes256gcm_is_available checks whether this CPU and library support hardware-accelerated AES-256-GCM.
Never reuse a nonce with the same key; additional authenticated data is checked but not encrypted. Modified ciphertext fails authentication.
secretbox authenticates ciphertext but does not accept additional authenticated data.

Apply this behavior to a real application only after confirming the required extension, configuration and failure handling on the deployment runtime.