openssl_digest calculates a message digest with an algorithm supported by OpenSSL.
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_digest calculates a message digest with an algorithm supported by OpenSSL.
The OpenSSL extension must be enabled.
Syntax and Return Value
openssl_digest(string $data, string $digest_algo, bool $binary = ...): string|false| Parameter | Purpose |
|---|---|
| $data (string) | The input data bytes. Use the exact original bytes when verifying. |
| $digest_algo (string) | Use the PHP signature above to determine the exact expected input type; validate untrusted inputs before calling. |
| $binary (bool) | 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: A digest does not authenticate a message without a key; use hash_hmac or a signature for authenticity.
Example 1: Basic Operation
This digest does not provide authentication on its own.
<?php
echo bin2hex(openssl_digest("annual report", "sha256", true));Example 2: A Different Use Case
This digest does not provide authentication on its own.
<?php
// Check the alternative case.
echo bin2hex(openssl_digest("invoice 42", "sha256", true));Practical Example: Checking the Result
This digest does not provide authentication on its own.
<?php
// Verify the expected behavior before using results.
echo bin2hex(openssl_digest("signed event", "sha256", true));Important Behavior and Edge Cases
A digest does not authenticate a message without a key; use hash_hmac or a signature for authenticity.
A digest does not authenticate a message without a key; use hash_hmac or a signature for authenticity.
Comparison with Related Functions
| Approach | Key distinction |
|---|---|
| openssl_digest | openssl_digest calculates a message digest with an algorithm supported by OpenSSL. |
| Related technique | hash() provides hashing through PHP’s hash extension rather than OpenSSL. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Confusing this operation with a neighboring cryptographic or security mechanism | hash() provides hashing through PHP’s hash extension rather than OpenSSL. |
| Ignoring a security prerequisite or failure case | A digest does not authenticate a message without a key; use hash_hmac or a signature for authenticity. |
Key Takeaways
- openssl_digest calculates a message digest with an algorithm supported by OpenSSL.
- A digest does not authenticate a message without a key; use hash_hmac or a signature for authenticity.
- hash() provides hashing through PHP’s hash extension rather than OpenSSL.
Apply this behavior to a real application only after confirming the required extension, configuration and failure handling on the deployment runtime.