openssl_cms_read extracts certificate material from an encoded CMS/S/MIME input file into an array.
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: openssl_cms_read extracts certificate material from an encoded CMS/S/MIME input file into an array.
The OpenSSL extension must be enabled.
Syntax and Return Value
openssl_cms_read(string $input_filename, $certificates): bool| Parameter | Purpose |
|---|---|
| $input_filename (string) | Path to the file read by the CMS or PKCS#7 operation. |
| $certificates (mixed) | 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: Encrypted CMS data requires matching recipient certificate and private key; signing and verification additionally require certificate trust validation.
Example 1: Basic Operation
Read an existing CMS certificate-bearing file. A valid compatible PEM CMS sample must be supplied; handle false results explicitly.
<?php
$file = __DIR__ . '/signed-message.cms';
$certificates = [];
if (!is_file($file)) {
echo 'Provide a real cert-bearing CMS file for this demo';
} elseif (!openssl_cms_read($file, $certificates)) {
throw new RuntimeException('CMS certificate extraction failed');
} else {
echo count($certificates) . ' certificates extracted';
}Example 2: A Different Use Case
Read an existing CMS certificate-bearing file. A valid compatible PEM CMS sample must be supplied; handle false results explicitly.
<?php
// Check the alternative case.
$file = __DIR__ . '/signed-invoice.cms';
$certificates = [];
if (!is_file($file)) {
echo 'Provide a real cert-bearing CMS file for this demo';
} elseif (!openssl_cms_read($file, $certificates)) {
throw new RuntimeException('CMS certificate extraction failed');
} else {
echo count($certificates) . ' certificates extracted';
}Practical Example: Checking the Result
Read an existing CMS certificate-bearing file. A valid compatible PEM CMS sample must be supplied; handle false results explicitly.
<?php
// Verify the expected behavior before using results.
$file = __DIR__ . '/signed-contract.cms';
$certificates = [];
if (!is_file($file)) {
echo 'Provide a real cert-bearing CMS file for this demo';
} elseif (!openssl_cms_read($file, $certificates)) {
throw new RuntimeException('CMS certificate extraction failed');
} else {
echo count($certificates) . ' certificates extracted';
}Important Behavior and Edge Cases
Encrypted CMS data requires matching recipient certificate and private key; signing and verification additionally require certificate trust validation.
These file-based APIs write encoded containers. The self-signed test certificate used in examples is not production trust material.
Comparison with Related Functions
| Approach | Key distinction |
|---|---|
| openssl_cms_read | openssl_cms_read extracts certificate material from an encoded CMS/S/MIME input file into an array. |
| Related technique | CMS operations use files and encoding flags; raw openssl_encrypt handles byte strings instead. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Confusing this operation with a neighboring cryptographic or security mechanism | CMS operations use files and encoding flags; raw openssl_encrypt handles byte strings instead. |
| Ignoring a security prerequisite or failure case | Encrypted CMS data requires matching recipient certificate and private key; signing and verification additionally require certificate trust validation. |
Key Takeaways
- openssl_cms_read extracts certificate material from an encoded CMS/S/MIME input file into an array.
- Encrypted CMS data requires matching recipient certificate and private key; signing and verification additionally require certificate trust validation.
- CMS operations use files and encoding flags; raw openssl_encrypt handles byte strings instead.
Apply this behavior to a real application only after confirming the required extension, configuration and failure handling on the deployment runtime.