Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange.
Before using it, identify which data, connection or runtime state the operation reads or changes. This avoids examples that appear to work but apply to a different context.
What Is sodium_crypto_kx_server_session_keys() in PHP?
Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange.
Syntax:
<?php
// Signature for reference only
sodium_crypto_kx_server_session_keys(string $server_key_pair, string $client_key) : array
Parameters and Return Value
$server_key_pair— Required string argument supplied to this operation.$client_key— Required string argument supplied to this operation.
The declared return type is array.
Example 1: Basic Usage
<?php
$clientKeyPair = sodium_crypto_kx_keypair();
$serverKeyPair = sodium_crypto_kx_keypair();
$sessionKeys = sodium_crypto_kx_server_session_keys($serverKeyPair, sodium_crypto_kx_publickey($clientKeyPair));
echo count($sessionKeys);Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange.
Example 2: Another Case
<?php
$clientKeyPair = sodium_crypto_kx_keypair();
$serverKeyPair = sodium_crypto_kx_keypair();
$sessionKeys = sodium_crypto_kx_server_session_keys($serverKeyPair, sodium_crypto_kx_publickey($clientKeyPair));
echo strlen($sessionKeys[0]);The second example changes the input or surrounding conditions, which matters when choosing this API for real application code.
Practical Example
<?php
$clientKeyPair = sodium_crypto_kx_keypair();
$serverKeyPair = sodium_crypto_kx_keypair();
$sessionKeys = sodium_crypto_kx_server_session_keys($serverKeyPair, sodium_crypto_kx_publickey($clientKeyPair));
// The pair contains receive and transmit keys in documented order.
var_dump(count($sessionKeys) === 2);The practical example is a teaching scenario. Change sample configuration and credentials before using a similar design in an application.
Important Behavior and Edge Cases
- Each party must use its own secret key and the other party’s authenticated public key; never log derived keys.
- Relevant PHP environment: sodium. Ensure the required extension and operating-system capabilities are present.
- Check results and release resources where necessary; successful syntax alone does not guarantee a successful operation.
Comparison With Related Functions
| Option | When to Use It |
|---|---|
sodium_crypto_kx_server_session_keys | Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange. |
sodium_crypto_kx_keypair | Use this related operation for its different responsibilities; do not assume identical inputs or return values. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using one directional key for both traffic directions | Use the receiving and transmitting keys for the correct communication direction. |
| Treating raw public keys as trusted identities | Authenticate peer public keys through a separate trust mechanism. |
| Logging session keys for debugging | Never record derived secret keys or the private keypair. |
Key Takeaways
- Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange.
- Each party must use its own secret key and the other party’s authenticated public key; never log derived keys.
- Validate inputs and handle failure conditions before integrating this operation into a production workflow.
Derives the matching receiving and sending keys on the server side of a libsodium public-key exchange. Use the appropriate runtime and treat any environment-dependent output as an example, not a guaranteed result.