sodium_pad pads binary data to a multiple of a block size.
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_pad pads binary data to a multiple of a block size.
The sodium extension must be enabled.
Syntax and Return Value
sodium_pad(string $string, int $block_size): string| Parameter | Purpose |
|---|---|
| $string (string) | Use the PHP signature above to determine the exact expected input type; validate untrusted inputs before calling. |
| $block_size (int) | Use the PHP signature above to determine the exact expected input type; validate untrusted inputs before calling. |
The declared return type is shown above. Errors can include false results or exceptions depending on this API: Encoding does not encrypt or authenticate data; exact byte lengths and formats still matter.
Example 1: Basic Operation
Inspect the output: this operation works on raw byte strings and does not by itself provide encryption.
<?php
$message = "Account update";
$padded = sodium_pad($message, 16);
echo strlen($padded) . ' bytes';Example 2: A Different Use Case
Inspect the output: this operation works on raw byte strings and does not by itself provide encryption.
<?php
// Check the alternative case.
$message = "New order: 42";
$padded = sodium_pad($message, 16);
echo strlen($padded) . ' bytes';Practical Example: Checking the Result
Inspect the output: this operation works on raw byte strings and does not by itself provide encryption.
<?php
// Verify the expected behavior before using results.
$message = "Export completed";
$padded = sodium_pad($message, 16);
echo strlen($padded) . ' bytes';Important Behavior and Edge Cases
Encoding does not encrypt or authenticate data; exact byte lengths and formats still matter.
Encoding does not encrypt or authenticate data; exact byte lengths and formats still matter.
Comparison with Related Functions
| Approach | Key distinction |
|---|---|
| sodium_pad | sodium_pad pads binary data to a multiple of a block size. |
| Related technique | Cryptographic primitives such as secretbox and auth provide actual security properties. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Confusing this operation with a neighboring cryptographic or security mechanism | Cryptographic primitives such as secretbox and auth provide actual security properties. |
| Ignoring a security prerequisite or failure case | Encoding does not encrypt or authenticate data; exact byte lengths and formats still matter. |
Key Takeaways
- sodium_pad pads binary data to a multiple of a block size.
- Encoding does not encrypt or authenticate data; exact byte lengths and formats still matter.
- Cryptographic primitives such as secretbox and auth provide actual security properties.
Apply this behavior to a real application only after confirming the required extension, configuration and failure handling on the deployment runtime.